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Adjustable Shock Absorbers

  • Rear shock absorbers that provide load leveling without a host of moving parts or an on board air compressor
  • Internal shock valving senses ride height and uses energy from the vehicle’s motion to increase hydraulic pressure and raise the shock to the desired ride level
  • As the vehicle is driven, the shocks quickly “pump up” to the necessary pressure, and the vehicle’s original ride level is restored

Aerodynamic Drag

  • Drag or resistance produced by a moving object, such as a motor vehicle, as it displaces the air in its path
  • Usually measured in pounds, aerodynamic drag increases in proportion to an object’s frontal area, drag coefficient and the square of its speed

Air Dam

  • Soft, lower body extension attached below the front bumper improving vehicle performance by limiting the amount of airflow directed under the vehicle
  • Improves aerodynamics and redirects the airflow to the engine compartment for improved engine cooling or air conditioning performance
  • Assists in reducing aerodynamic lift, turbulence and drag

Air Dryer

  • A component of the air conditioning system
  • Condenses and filters moisture and contaminants from pressurized air from the air compressor
  • Most air dryers use a drying agent known as a desiccant to remove moisture from the air
  • Moisture is automatically expelled when the compressor unloads

Air Suspension Seat

  • Single seat, either driver or passenger, which incorporates an air-activated suspension system to help eliminate the jolts and bounces of the truck cab
  • Note: Normally air suspension seats require that the truck be equipped with air brakes to supply air to the seat
  • Some seats feature an integral air compressor so the occupant can energize the seat on vehicles that are not equipped with air brakes

Air/Fuel Mixture

  • The measure or ratio of the amounts of air and fuel being fed to the engine’s cylinders. The power train control module (PCM) computer adjusts the air/fuel mixture to provide the best combination of performance and fuel efficiency
  • A higher percentage of fuel to air is described as a rich mixture, while a lower percentage of fuel to air is termed a lean mixture
  • On Ford vehicles, the air/fuel mixture is measured by an electronic sensor that provides input to the power train control module systems


  • During a moderate-to-severe frontal impact, the airbag is designed to inflate in approximately 1/20th of a second (less time than it takes to blink an eye) and begins to deflate immediately thereafter. In that brief period, the airbag can help reduce the risk of injury to the head and chest of the driver and/or the right front seat passenger
  • Electronic diagnostic module continuously monitors the airbag for proper operation
  • When the ignition switch is turned to the ON position, the airbag indicator light on the instrument cluster illuminates for approximately six seconds to signal that the system is functioning properly. Should a fault occur in the system, the airbag indicator light flashes, stays on or fails to illuminate when the ignition switch is turned to the Start position. This signifies immediate service is required
  • Always put small children and child seats in the rear seating positions (except jump seats). Deactivate the passenger airbag with the airbag shutoff switch (if equipped) when using a rear-facing child safety seat in the front passenger seat
  • Dual-stage Airbags
  • Can deploy at two different levels, or nor at all, depending on the information sent to the Restraint Control Module from various sensors located within the vehicle
  • In less severe collision events, the airbags will deploy in the lower or first stage of deployment force
  • In more severe collision events, airbags will deploy at both stages or at full force
  • Seat sensors, in some front passenger seats, can detect the weight of passengers and deploy only if the occupant is above a certain weightSecond Generation Airbags
  • Designed to inflate with less force than that employed in earlier or first generation designs
  • The airbags reduce the peak inflation pressure and/or rise rate
  • Rise rate is the force and speed with which an airbag inflates and is controlled by factors such as the type and amount of inflator gas, the actual airbag size and the design of the vent used to release the pressure from the airbag once deployed
  • Note: The airbag is not a substitute for safety belts. Safety belts must be properly worn at all times to maximize the effectiveness of the system. Always secure children in the back seat (except jump seats).

All-Wheel Drive (AWD)

  • Continuously monitors wheel speed, throttle position and steering-wheel angle sensors to determine the vehicle’s conditions and driver’s intent. The system then determines the optimal amount of front and rear torque for the given conditions to not only reduce wheel slip but to prevent the slip from occurring in the first place
  • Helps ensure the vehicle will be sure-footed on the road in a variety of conditions, such as fast cornering, uneven pavement, potholes, slippery surfaces and anything that compromises traction
  • Vehicle normally functions in front-wheel-drive mode
  • When sensors detect that wheel slip is occurring or even just likely to occur, the All-Wheel-Drive (AWD) system can react within as little as 50 milliseconds to distribute up to 100 percent of the available torque to the rear wheels
  • Controller may detect a difference in wheel speed front-to-rear even in good weather, such as when driving through sand, mud or wet leaves
  • How the System Works
  • All-Wheel Drive uses electromagnetic activation of an internal clutch pack
  • Engages when sensors detect wheel slip in the front wheels, and often acts preemptively to prevent slip from happening in the first place
  • When activated, the system uses force from an electromagnet to push clutch plates together
  • Drive shaft torque is transmitted through the unit to the rear wheels, taking power from the front wheel sand sending it to the rear
  • Benefits of the System
  • No driver interaction is required to activate AWD. It’s there when your customers need it
  • The system can send up to 100 percent of the engine’s torque to front or rear as needed to avoid wheel slip
  • Operates with speed and sophistication to help provide peace of mind and driving confidence
  • Releases just as quickly, avoiding binding or wheel skid once traction improves
  • Benefits on either wet or dry pavement. Because the system can transfer torque quickly away from the front wheels, it helps reduce the type of understeer often associated with front-wheel-drive vehicles to provide improved vehicle control
  • Lightweight with few moving parts, for little impact on fuel economy
  • When AWD is combined with All-Speed Traction Control or the AdvanceTrac® system, a high degree of torque can be sent to the wheel with the best traction, even if the other three wheels have no traction at all

Alternative Fuel Vehicle (also see E85 Vehicles and Flexible Fuel Vehicle {FFV})

  • Refers to any type of vehicle that uses nontraditional fuel or power sources:
  • Methanol/Ethanol
  • Compressed Natural Gas (CNG)
  • Propane
  • Electricity (as in Escape Hybrid)


  • Engine-driven device that converts mechanical energy into alternating electrical current
  • Provides power to run all of the vehicle’s electrical components when the engine is running
  • Single or dual heavy-duty alternators that provide additional charging capacity are also available for applications such as cold-climate operation (temperatures below -20°F) where battery drain and accessory use are typically very high, and vehicles are equipped for towing purposes

Alternator Capacity

  • To determine minimum capacity for an alternator:
  • Minimum alternator output = Total load x 1.20, where total load comprises continuous night-winter load
  • Add 20 percent (.20) to accommodate anticipated intermittent load
  • In most cases, a 2.51:1 or better alternator drive ratio will provide a reasonably adequate system output

Ambient Interior Lighting

  • Utilizes Light-Emitting Diode (LED) lights to illuminate the vehicle interior: foot wells, cup holders, and controls, depending upon the vehicle
  • Offers the ability to change color to suit your mood. Color selections include aqua, blue, green, purple, red, yellow or white lighting

Anti-theft Systems

  • Perimeter anti-theft alarm system
  • Guards the vehicle's doors, hood and trunk/lift gate. When an unauthorized entry occurs, the system trigger sand will:– Flash the head lamps, parking lamps and theft-indicator lamp on the instrument panel
  • Sound the horn. Note: It will not be triggered by breaking glass or entry into the vehicle through a window. The perimeter anti-theft alarm system is designed to work with the factory-installed Remote Keyless Entry System. SecuriLock® passive anti-theft ignition system
  • Uses a sophisticated electronically coded ignition key to start the vehicle. The system is designed to help prevent the engine from being started unless a coded key programmed to the vehicle is used. There is no battery on the key itself; the small amount of energy required to identify the key is supplied by the vehicle
  • SecuriLock is designed so that it is not necessary for the driver to follow any procedure to arm the system. It is automatically armed when the key is removed from the ignition and is disarmed when the key is reinserted into the ignition
  • Spare keys will be available from dealerships. Customers can program their keys by using each original (2) key in the proper sequence and finally inserting a new key for programming (see Owner's Guide for more details)
  • There are billions of possible codes

Auto lamp System

  • Provides ambient-light-sensitive automatic on-off control of the exterior lights normally controlled by the head lamp control switch
  • Comes preprogrammed to keep the lights on for approximately 20 seconds after the ignition switch is turned off
  • If desired, the time delay can be reprogrammed on some vehicles to keep the lights on for up to 3 minutes after the ignition is turned off. See the vehicle Owner’s Guide for more details

Auto lock

  • Auto lock feature will lock all the doors, lift gate and lift gate window when all doors are closed, the ignition is in the ON position, the vehicle is shifted into any drive gear putting the vehicle in motion
  • See the vehicle Owner’s Guide for vehicle-specific information on the range of functions

Auxiliary Springs

  • Used on many light trucks for load stability or to support heavy loads with minimal effect on ride characteristics
  • Help control roll and sway of trucks with high bodies that carry loads that might shift when cornering or operating on high-crowned roads
  • Usually used on rear leaf springs, and are mounted to act only after the regular springs are partially deflected under heavy loads

Axle Ratio

  • The number of output shaft (on front-wheel-drive vehicles) or drive shaft (on rear-wheel-drive vehicles) revolutions required to rotate the axle one full turn
  • For a rear-wheel-drive vehicle with an axle ratio of 3.55:1, the drive shaft would have to rotate 3.55 times to rotate the rear axle once. This is also known as the Final Drive Ratio
  • Lower numeric axle ratios tend to be more fuel-efficient. Higher axle ratios deliver added torque for increased power for acceleration and trailer towing
  • Front-wheel-drive vehicles employ an Axle Transfer Ratio, essentially a Final Drive Ratio

Axle, 2-speed

  • Type of rear drive axle offering two reduction ratios and a control mechanism for selecting either ratio at the driver’s discretion
  • "Lo" axle range (the higher numerical ratio) provides maximum pulling power
  • "Hi" range (the lower numerical ratio) provides maximum road speed
  • 2-speed rear axle permits split-shifting in the lower transmission gears to obtain evenly spaced gear steps that optimize available engine power
  • 2-speed axle can be used in Lo range for crisp performance at slower speeds or in Hi range for maximum economy on the highway

Axles, Rear Drive

  • Full-floating Rear Axle — Generally used in heavier-duty applications. The full-floating axle shafts “float” within the outer axle housing where they drive the wheels. The outer housing supports the entire rear weight through double-opposed wheel bearings, which absorb all load and wheel stress
  • Semi-floating Rear Axle — The axle shafts and wheel bearings not only support the total weight, but also transmit driving torque to the wheels. This axle system also resists stress due to skidding, turning corners and other traction forces
  • See Live Axle for more information

Balance Shaft

  • Engine shaft designed so it rotates in a way that reduces or cancels out vibrations produced by the engine, resulting in reduced noise, vibration and harshness (NVH) in the passenger compartment
  • In 4-cylinder engines, two shafts turning in opposite directions on either side of the engine’s crankshaft are generally used, while in V-type engines, a single balance shaft is used

Battery Saver

Feature on some vehicles that automatically turns off interior or under hood lights after a set period of time (e.g., 30–45 minutes), to help prevent battery power drainage and save enough power to restart the vehicle.

Bio-foam Seat Materials

  • Type of foam used in Mustang and Escape/Escape Hybrid seat production
  • Production of bio-foam is designed to emit less carbon dioxide into the atmosphere
  • Material is designed to require less energy to produce than the petroleum-based foam
  • Emphasizes Ford’s commitment to its environmental responsibility

Body-on-frame Construction

  • Type of vehicle construction with the body attached to a separate frame, often with rubber mounts to reduce squeaks and rattles, helping to isolate road noise and vibration
  • Typically more sturdy and robust when compared to vehicles with unibody construction
  • Provides a solid foundation that contributes to payload and towing capability

Bore and Stroke

  • While these two terms are frequently used together, they are two totally different measurements
  • Bore is the measurement of the inside diameter of a cylinder
  • Stroke is the distance the piston travels from top-dead-center (TDC) to bottom-dead-center (BDC) of the cylinder

Box Side Steps

  • Frame-mounted steps located on each side of the truck cargo box and in front of the rear wheel well used to make it easy to access the cargo box. Able to support up to 500 lbs.
  • Allow convenient side access to the cargo box using a release lever located on the step
  • Return to stowage position by pushing the steps back into/under the cargo box

Boxed Frame

As the name implies, a "boxed" frame has four sides, which provides additional strength. It is a closed structural section that has greater resistance to twisting and torsion forces than comparably sized "open" frame designs.

Brake Bias

Front/rear distribution of a vehicle’s braking power. Generally the front of a vehicle where the engine and majority of weight and steering functions are located supplies the greater amount of braking power.

Brake Modulation

The process of varying pedal pressure to hold a vehicle on the verge of lockup to supply maximum braking efficiency. Anti-lock Braking Systems (ABS) employ computer-controlled modulators to maximize braking efficiency.

Brake/Shift Interlock (Automatic Transmissions)

  • Requires driver to depress the brake pedal in order to shift out of Park and into any gear
  • Prevents accidental engagement of drive gears
  • Vehicles with a floor-mounted gearshift lever include a manual override in the console; vehicles with a column-mounted gearshift include a manual override under the steering column

Braking Systems

  • Ford Motor Company uses a number of different braking systems on its passenger cars, crossovers, SUVs and light trucks, including the following: Four-wheel Anti-lock Braking System (ABS)
  • Helps provide straight, more controlled stops, while helping the driver maintain steering control undermost road conditions, including slippery road surfaces
  • ABS computer-controlled sensors prevent wheels from locking up, even when the driver presses hard on the brake pedal
  • Sensors continuously monitor the speed of each wheel. When impending wheel lockup is detected, the computer signals the hydraulic control unit to apply and release (automatically “pumping”) the brakes several times per second with split-second timing, providing a level of braking efficiency that even professional race car drivers cannot duplicate and resulting in shorter stopping distances and greater braking and steering control
  • Three-channel ABS
  • Uses three individual channels to monitor and control brake pressure to the front wheels individually and to both rear wheels together
  • Four-channel ABS
  • Operates similarly to the three-channel system, except that both rear wheels are monitored and operated separately
  • ABS Functionality
  • Computer continuously monitors the ABS for malfunctions. Should a problem develop, an instrument panel light alerts the driver that the ABS computer has shut down and the brakes have been returned to normal, non-ABS operation
  • Driver should never pump the brakes in a vehicle equipped with ABS. This defeats the system and increases stopping distances. For best performance, the driver should apply maximum pedal pressure
  • When using ABS, the driver may feel a slight pulsing sensation; this is completely normal
  • Dual Diagonal Braking System
  • All Ford vehicles feature either a diagonal or front-rear split hydraulic brake system with warning lamp (excluding F-650/F-750 with air brakes)
  • With this system, diagonal circuits link front and rear wheels at opposite corners, so braking capacity is retained even if one of the two circuits malfunctions
  • Power-assisted Four-wheel Disc Brakes
  • Four-wheel disc brakes consist of a disc at each wheel that rotates at wheel speed and is straddled by a caliper that squeezes the inner and outer faces of the disc to provide stopping or braking power
  • Disc brakes provide a more linear response, and therefore operate more efficiently at high temperatures than drum brakes
  • Power-assisted disc brakes use a vacuum-assist to provide power to the master cylinder, thereby greatly reducing pedal effort
  • Ford power-assisted disc brakes are self-adjusting with pad clearance automatically maintained by the limited retracting action of the piston in the caliper Power-assisted Front Disc/Rear Drum Brakes Combination of the front disc and rear drum brake system. Drum brakes are a type of brake that has an iron casting shaped like a shallow drum that rotates with the wheel. Curved brake shoes are forced into contact with the inner face of the drum to provide stopping or braking power. Power-assisted drum brakes use a vacuum-assist to provide power to the master cylinder, thereby greatly reducing pedal effort. Features of this system include:
  • Front disc brake pad clearance automatically maintained by the limited retracting action of the piston in the caliper
  • Adjustment of the rear drum brakes is accomplished when the brake pedal is applied while the vehicle is moving in Reverse
  • Both front and rear brakes are self-adjusting
  • Note: Availability of braking systems varies according to model. Refer to the individual vehicle sections of the 2009Source Books or to the Ordering Guide for specific availability.

Breakaway Valve

Safety valve designed to protect the air supply of a tractor or leading trailer and automatically apply the brakes of a trailing unit in the event of accidental separation.

Cam Profile

Shape of each lobe on a camshaft that determines the amount or duration of time an intake or exhaust valve is open and the valve’s maximum opening, or "lift."


Inclination of the plane of a wheel to the vertical plane of symmetry of a vehicle.


Shaft in an engine block or cylinder head that includes a series of lobes which regulates opening and closing the intake and exhaust valves, allowing the engine to "breathe."

Cargo Management Rails

  • Two aluminum rails attached to the upper rail of a cargo box
  • Include four adjustable tie-down cleats that can be positioned along the cargo box rails, providing secure attachment points to keep cargo in place

Cargo Tie-down Net

  • Usually made of nylon mesh
  • Secures cargo and packages in a vehicle's luggage compartment or rear cargo area


The angle between the steering axis and the true vertical axis when viewed from the side. Caster is considered "positive" when the steering axis is inclined upward and toward the rear.

Catalytic Converter

  • Muffler-shaped device in the exhaust system
  • Usually contains platinum, palladium and/or rhodium, which acts as a catalyst in a chemical reaction that converts unburned hydrocarbons, carbon monoxide and oxides of nitrogen into water vapor, carbon dioxide and other gases that are less toxic than untreated exhaust fumes

Center Differential

Used in some four-wheel-drive vehicles to distribute power to the front and rear differentials.

Center of Gravity (Center of Mass)

Point at which the entire weight of a body is considered to be concentrated so that, if supported at this point, the body would remain in equilibrium in any position.

Charge Motion Control Valves

  • Electronically controlled metal flap located at the end of each intake runner
  • These flaps are specially shaped to speed up the intake charge at low engine speed and induce a tumble effecting the combustion chamber that results in a more thorough fuel/air mixture and quicker, more efficient burn
  • At higher engine speed the flaps are completely open and do not affect the intake charge


  • Portion of the vehicle that includes:
  • Suspension
  • Steering components
  • Power train
  • Brakes
  • Fuel system Refer to the Power trains section of this book for details concerning Ford power train systems.

Chassis Cab

  • Unfinished truck featuring an occupant compartment, or cab, without a cargo bed
  • A chassis cab requires the addition of cargo-carrying (cargo box, flatbed), work-performing (tow lift) or load-bearing (dump assembly) components to perform its intended functions

Climate-controlled Seats

  • Feature a tiny thermoelectric device that allows the occupant to cool or warm the seat and backrest depending on outdoor temperature and personal preference
  • The thermoelectric modules are solid-state devices with surfaces that turn hot or cold depending on the polarity of the applied direct current electricity
  • Heat-transfer components attached to the modules cool or heat the air that is blown past them and then is circulated through ducts and pads in the seats and onto the occupants
  • Each seat has individual electronic controls to adjust the level of cooling or heating desired


  • Mechanical device that engages and disengages the engine from the transmission/Trans axle during shifting, operated by a pedal to the left of the brake pedal
  • Depressing the clutch pedal interrupts power flow to the transmission/Trans axle. Releasing the clutch pedal with the gearshift in place will reengage the transmission/trans axle
  • Clutch must be fully depressed to start a vehicle with a manual transmission/transaxle

Coil Spring

Spiral-shaped spring that can be compressed or extended without permanent deformation and that is widely used in front and rear suspension systems, including the Macpherson strut front suspension used on many Ford vehicles

Combustion Chamber

Portion of the engine where the air/fuel mixture is ignited and converted to mechanical energy; includes all the space above the piston at top-dead-center (TDC), including the cylinder head, which forms the top of the combustion chamber.

Command Seating TM

  • Front-seat design that is raised higher when compared to a typical seat design
  • Gives the driver and front passenger a "commanding" seating position for comfort and excellent visibility and helps provide drivers a better view of the road due to the raised seat design
  • This is achieved partly by raising the seat's hip pivot point
  • Makes getting into and out of the seats easier

Compression Ratio

Ratio between the engine cylinder volume (including the cylinder head volume) when the piston is at the bottom of its stroke and the engine cylinder volume when the piston is at the top of its stroke.

Connecting Rod

  • Mechanical link between the piston and the crankshaft that enables the piston’s up-and-down travel to be converted into the crankshaft's rotational motion
  • Some Ford engines use forged, powdered-metal, cracked connecting rods. These connecting rods are manufactured using a process pioneered by Ford
  • Connecting rods are typically forged from a flat or round metal billet. Powdered-metal rods, however, begin as loose metal powder blended to the required composition and forged in a form that is nearly at the final "net shape"

Constant Velocity (CV) Joint (Front-wheel-drive Vehicles)

  • Refined version of a universal joint, typically used on front-wheel-drive vehicles or rear independent suspensions of rear-wheel-drive vehicles to help reduce vibrations inherent in normal universal joints
  • The CV joint — or double universal joint — cancels out vibrations caused by the transfer of driving power to the wheels

Control Arm

Suspension element that typically connects a spindle or hub to the frame or body with the use of bushings and/or ball joints.

Control Trac®

Refer to the 4WD/AWD Operations section of this book for details concerning 4x4 operations.


Horizontal portion of the vehicle body behind the engine and immediately to the rear of the hood and under the windshield.


  • Primary shaft in the engine that converts the up-and-down motion of the pistons into rotary motion
  • Crankshaft forces the pistons, via the connecting rods, upward to compress the air/fuel mixture prior to combustion. The combustion of the fuel then forces the piston downward, causing the crankshaft to rotate
  • Crankshaft is connected to the flywheel and clutch or torque converter flex plate, which transmits power to the transmission

Cross member

Any one of the several horizontal supporting members in a vehicle structure positioned laterally between the side members.

Cross-Car Beam or Cross cowl Beam

Located behind the vehicle dashboard, this feature helps reduce steering wheel movement in the event of a frontal collision and enhances structural rigidity

Crumple Zones

Sections of a vehicle body and/or frame engineered to progressively deform in a collision, thereby absorbing impact forces instead of transferring them to the passenger compartment. Also known as crush zones.

Curb Weight

Weight of a vehicle with standard equipment, oil, lubricants, coolant and a full tank of fuel. Note: This definition may differ from definitions used by governmental regulatory agencies.


Incomplete vehicle (based on the Ford E-Series Van) that includes a driver/passenger compartment without a rear wall and is intended for use with specialized conversion bodies.

Cylinder Head

Aluminum or iron casting that houses the top of the intake and exhaust ports and most or all of the valvetrain. It is located directly above the cylinders.


  • Tubes in an engine block where the pistons move up and down. The number of cylinders and their configurations determine the engine type ("in-line," "V type," etc.)
  • Cylinders are cast into an engine block formed of cast iron or aluminum and then bored and drilled to the final bore diameter

Deflection Rate, Spring

Load in pounds required to deflect or compress a spring one inch.

Defroster, Rear-window

  • Feature designed to defog the rear glass quickly and assist in melting snow and ice. Required in some states.
  • Electric rear-window defroster features a silver-filled ceramic heating grid silk-screened on the inside of the glass and includes an instrument panel indicator light and a timer for automatic shutoff
  • Lines in the heating grid are widely spaced so they do not interfere with rear vision


  • Also known as engine knocking or pre-ignition
  • Detonation is caused by ignition of the air/fuel mixture in the combustion chamber independent of the spark plug firing
  • This condition is an engine malfunction and can often be eliminated by a regular tune-up or use of proper grade fuel
  • See Knock Sensor for more information

Diesel Particulate Filter (DPF)

  • Located in the exhaust system after the diesel oxidation catalyst
  • "Scrubs" the particulates in the exhaust gases by trapping them after they have left the combustion chamber
  • Periodically cleans itself through a process known as "regeneration" which is a process similar to a small incinerator that burns off the trapped particles
  • Passive generation burns off soot naturally when exhaust temperatures are high enough
  • Active regeneration (forced burn-off) occurs as needed depending on operational use


  • System of gears in the final drive assembly of a vehicle to transmit torque to the driving wheels regardless of whether the vehicle is moving straight ahead or turning a corner
  • Differential allows the wheels to turn at different speeds while delivering equal torque
  • When cornering, the driving wheel on the inside of the turn travels in a smaller radius than the outside wheel to prevent the outside wheel from dragging in the turn

Displacement, Engine

Engine displacement is the measure of the total cylindrical volume through which the pistons of an engine move from one end of the stroke to the other. The formula to determine the displacement of an engine is: Displacement = .7854 x Bore x Bore x Stroke x Number of Cylinders. For example: The displacement of the 4.6L V8 engine is: 280.3 (0.7854 x 3.55 x 3.55 x 3.54 x 8).


Dipping of a vehicle's nose that occurs when the brakes are applied and the load is transferred from the rear to the front suspension.

Domestic Content

Percentage of a given vehicle's parts that are manufactured (versus assembled) in the United States as determined by the manufacturer and shown in the Domestic Content Label on a new vehicle.

Domestic Content Label

  • All Ford vehicles produced on or after October 1, 1995,bear a Domestic Content Label affixed to the fuel economy label, price sticker or other readily visible label
  • This label communicates:
  • Vehicle line average percentage (value-based) of domestic content (U.S. and Canadian)
  • Names of at least two of the countries (if any) providing15 percent or more (by value) of all components
  • City and country of final assembly
  • The country of origin of the engine and transmission/transaxle

Drag Coefficient (Cd)

  • Measure of a vehicle's efficiency as an aerodynamic shape, useful for comparison with other vehicle designs
  • A mathematical factor that, when multiplied by the projected square footage area of the vehicle, gives its drag force in pounds
  • Cd is derived by measuring the drag force and dividing it by the product of dynamic pressure and vehicle frontal area
  • Drag coefficient (Cd) = force/dynamic pressure x frontal area; the lower the Cd number, the better the aerodynamic efficiency

Drive line

Components that connect the transmission/transaxle to the driving axle, including the universal/constant velocity joints and drive shaft/half shafts.

Drive shaft

Shaft that transmits power from the transmission to the axle differential assembly on rear-wheel-drive vehicles.


Drive train

Also called the drive line, it includes all power-transmitting components such as the clutch, transaxle/transmission and drive axle.

Dual Overhead Camshaft (DOHC) Design

  • Engine design with two camshafts fitted atop the cylinder head, one to operate the intake valves and the other to operate the exhaust valves, resulting in improved performance and fuel efficiency
  • A DOHC design has multiple intake and exhaust valves per cylinder, providing more flow into and out of each cylinder for greater performance

Dual-zone Electronic Automatic Temperature Control

  • Climate control system that maintains a specified cabin temperature setting using either air conditioning or heat
  • Controls are arranged to enable the driver and the front-seat passenger to set the same or different temperature levels within 20 degrees of each other to suit their individual comfort

E85 Vehicles

  • E85 vehicles are also called Flexible Fuel Vehicles (FFV) due to their ability to operate on a blend of85 percent ethanol fuel and 15 percent unleaded gasoline
  • Ethanol is derived primarily from corn but can be made from virtually any starch feed stock such as sugarcane, wheat or barley. Because it is produced from crops, it is a renewable fuel and reduces dependence on imported oil
  • Current Ford vehicles with FFV capability are: Focus – 2.0L I4, Explorer – 3.5L V6, Taurus – 3.5L V6, F-150 – 3.7L V6, 5.0L V8, Expedition - 5.4L V8, Navigator - 5.4L V8, E-Series – 4.6L V8, 5.4L V8, Super Duty Pickup and Chassis Cab – 6.2L V8
  • See Flexible Fuel Vehicle (FFV)

Easy Fuel TM Cap less Fuel Filler System

  • A standard-size unleaded fuel nozzle can be inserted directly into the fuel filler neck, opening a spring-loaded door to the tank
  • A rubber seal on the fuel filler door helps keep dirt from entering the Easy Fuel system
  • Helps reduce fuel tank evaporative emissions by eliminating a missing or improperly installed gas cap
  • Includes an emergency funnel (stored near spare tire jack) that must be used with the Easy Fuel system to accept fuel from a gas can or other secondary refueling device

Eco-friendly Seating Fabric

  • Seat fabric manufactured from 100 percent postindustrial polyester fabric that would have been previously disposed of as scrap
  • Emphasizes Ford’s commitment to its environmental responsibility

Electronic Automatic Temperature Control (EATC)

A climate control system that automatically maintains a specified cabin temperature using either air conditioning or heat. The system automatically sets the blower speed and displays desired temperature set points. It offers manual controls to override automatic settings when necessary.

Electronic Brake Force Distribution (EBD)

Automatically optimizes the front-to-rear brake force distribution to reduce the tendency of rear wheel lockup, especially when the vehicle is unloaded. Effective in braking conditions before ABS operates, EBD also eliminates the need for a hydraulic brake-proportioning valve.

Electronic Fuel Injection (EFI)

  • A modern, efficient method of fuel delivery that replaced carburetors in all Ford passenger cars and light trucks with gasoline engines
  • EFI precisely controls the amount of fuel used and improves the dispersion of fuel in the air charge, improving drive ability, fuel economy and performance of the engine
  • Variations of EFI used in Ford vehicles include: Multi-port Electronic Fuel Injection (MEFI)Also known as “direct port” injection, MEFI uses individual port-mounted injectors to deliver fuel directly to the intake inlet for each cylinder. This more even distribution of fuel improves power balance between the cylinders, maximizes combustion efficiency and improves drive ability and performance. The system “squirts” fuel into each cylinder with every revolution of the crankshaft. Sequential Multi-port Electronic Fuel Injection (SEFI)Specific type of multi-port injection that delivers fuel in more precisely timed pulses corresponding to the opening of each intake valve, SEFI takes advantage of the atomized fuel spray from the injectors to achieve a more precise combustion for better performance, often with improved fuel economy.

Electronic Ignition

  • Ford Motor Company designed-and-built electronic ignition is standard on all domestic gasoline engines. The system is either an:
  • Electronic Ignition (EI) System, or
  • Integrated Electronic Ignition (EI) System — coil-on-plug (COP)

Electronic Throttle Control (ETC)

  • Also known as "Drive-by-Wire."
  • ETC translates accelerator motions and other inputs into control of engine power
  • The accelerator pedal controls the throttle by means of a computer-controlled stepping motor in lieu of a conventional linkage from pedal to throttle
  • It works by integrating throttle movements with the vehicle’s electronically controlled functions such as cruise control or idle speed
  • Enhances control, drive ability and performance

Emissions Standards

  • All vehicles sold by an auto maker must meet a U.S. EPA Federal fleet average of Tier 2 Bin 5. Each California Emissions State must meet a different fleet average
  • California uses the Low Emissions Vehicle grading system while EPA has chosen to categorize emissions standards into a "Tier and Bin" system

Energy-absorbing Steering Column

In all passenger cars and light trucks sold in the U.S., energy-absorbing steering columns are designed to collapse in the event of occupant contact in a frontal collision, reducing the potential head and chest injuries to the driver.

Engine Exhaust Brake

System added to a diesel engine that allows the driver to energize an engine-derived vehicle retardation system. Some engine brakes use compression pressures while the most common are those that employ engine exhaust. In either case, the principle is to let the engine help retard the vehicle speed, thus saving on wheel brake wear.

Engines — Diesel

  • Ford diesel engines provide certain advantages for some applications, including many truck applications. Diesel engines use no spark plugs, require a lower rpm range to produce peak power (especially torque) output and produce higher torque than horsepower for optimized towing performance. Additionally, diesel engines deliver more efficient fuel economy than gasoline engines and maximize fuel efficiency at idle, making them ideal for tasks requiring prolonged idle time. In a diesel engine:
  • Diesel fuel is compressed until it reaches a temperature hot enough for combustion
  • Glow plugs are used to preheat the air in the cylinders and to ensure easy starting on cold days
  • Heavier-weight components are used in some areas to handle the higher compression ratio — generally more than twice that of gasoline engines

Engines — Gasoline

  • There are two types of piston configurations available on Ford passenger cars and light trucks: In-line (I-4) and V-type (V6, V8 or V10).In-line engine — has all of the cylinders in a single line with the pistons moving vertically in the cylinders.
  • Pairs of pistons are located 180 degrees of crankshaft revolution from one another in an in-line 4-cylinder engine
  • V-angle engine — has cylinder banks formed in a V-type engine design, measured in degrees.
  • A 60-degree V6 is narrow by design and has excellent natural balance characteristics
  • Engine vibration is reduced as the number of cylinders is increased, whatever the V-angle, because the impulse of each cylinder firing occurs more frequently

EPA Fuel Economy Ratings

  • Fuel economy is measured under controlled conditions in a laboratory using a standardized test procedure specified by federal law and implemented by the Environmental Protection Agency (EPA). Manufacturers test their own vehicles— usually preproduction prototypes —and report the results to the EPA. The EPA reviews the results and confirms about 10–15 percent of them through their own tests at the National Vehicles and Fuel Emissions Laboratory. Vehicle is driven on a roller dynamometer (the vehicle remains stationary while the driven wheels are allowed to roll) and a hose is connected to the tailpipe to collect engine exhaust. The carbon in the exhaust is measured to calculate the amount of fuel burned during the test. This is more accurate than using calculations based on distance traveled and the amount of fuel consumed. Five separate test schedules are driven to simulate the driving conditions of city, highway, and hot weather with air conditioning on, high-speed driving and acceleration, and cold weather environments. The latter three tests are new for 2008 model year vehicles and will likely result in a decrease in mpg versus the same model tested under the pre-2008 test procedure. Driving cycles: City — 23 stops with accelerations to 20–60 mph. Highway — approximately 13 minutes of mixed rural and interstate driving with speeds ranging from30 to 60 mph. High Speed — aggressive accelerations to speeds of up to 80 mph with six minutes of driving 60–80 mph. Air Conditioning — 10 minutes of accelerations to varying speeds up to 60 mph with the air conditioning on while the vehicle is in an environment of 95 degrees and approximately 40 percent relative humidity. Cold — represents urban driving in 20-degree weather. The vehicle is started with the engine cold and driven in simulated stop-and-go rush hour traffic. For more information, visit


Science of the interface between human and machine. In automobiles, ergonomics pertains to the designing and arrangement of instrumentation, switches and controls, so they can be most effectively and safely operated by occupants.

Exhaust Gas Recirculation (EGR)

System in which a portion of the exhaust gases is recirculated into the combustion chamber for additional burning. Mixing exhaust gases with a new air/fuel mixture helps reduce harmful nitrogen oxide emissions.

Fifth Wheel

  • Device used to couple a trailer with a truck
  • In most F-Series pickup models, the fifth wheel is an upper mounting on the pickup box floor
  • The upper fifth wheel engages a trailer and consists of a plate and a rigidly mounted kingpin
  • A lower fifth wheel mounts on a tractor frame and consists of a base, rocking plate and locking mechanism that engages the kingpin on the trailer

Final Drive Ratio

See Axle Ratio.

Flexible Fuel Vehicle (FFV)

  • Vehicle that operates on any blend of fuel ethanol and unleaded gasoline, containing up to 85 percent ethanol fuel. Should ethanol (E85) not be immediately available, this vehicle can operate normally on unleaded gasoline
  • See Alternative Fuel Vehicle and E85 Vehicles


Heavy-duty metal disc attached to an engine’s crankshaft that transfers power to the transmission and helps reduce engine vibration. It features a toothed edge driven by the starter motor to start the engine

Fog Lamps

Auxiliary lamps that are generally integrated into the front fascia and designed to help illuminate the roadway in foggy or misty conditions.

Ford Work Solutions TM

  • Ford Work Solutions provide unprecedented levels of connectivity, flexibility and security to assist owners in the utilization of the vehicle for commercial purposes. In-dash Computer
  • Provides full high-speed Internet access using the Sprint® Mobile Broadband Network and a Gar min®
  • Navigation System
  • Utilizes Microsoft® Windows® for Automotive software that allows users to print invoices, check inventories and access documents stored on their home or office computer networks while on the road
  • Printing capability requires an optional onboard, Bluetooth® enabled ink jet printer
  • Crew Chief™
  • Networks a fleet of vehicles
  • Provides real-time vehicle location and maintenance checks on individual units such as tire pressure, fuel levels, or Diagnostic Trouble Codes (DTCs)
  • Calculates fuel usage and fuel tax reporting, helping to manage fleet costs more efficiently
  • Tool Link™
  • Utilizes Radio Frequency Identification (RFID) tags to mark/scan expensive tools, equipment or materials
  • Located inside the truck cargo box are two antennas that scan the toolbox for items listed on the preprogrammed inventory
  • Data is transmitted to a reader mounted inside the truck cab and displayed on the in-dash computer screen ,alerting the driver to any inventory discrepancies
  • Cable Lock
  • Convenient system providing simple and inexpensive means of securing tools and equipment to the cargo box
  • Steel-cable (10mm diameter) in a protective plastic sheathing that can easily be woven through tools/equipment and then locked to the cargo box utilizing a robust, cuff-style clasp
  • Stored in a spring-loaded corrosion and impact-resistant housing mounted to the rear of the cargo box wall
  • Provides an inexpensive and convenient means of securing tools/equipment stored in a truck cargo box

Four-valves-per-cylinder Engine Design

Power train design that uses two intake and two exhaust valves per cylinder. The improved flow of air/fuel mixture into the engine and exhaust gas out of the engine boosts power.

Four-wheel Drive

Refer to the 4WD/AWD Operations section of this book for detailed descriptions of each system.

Front-wheel Drive (FWD)

Drive configuration in which the engine power is supplied to the front wheels via half shafts.

Frontal Area

  • Frontal area of a vehicle can be a contributing factor when determining the size of trailer a vehicle can tow
  • Larger frontal area will add drag, thus reducing the vehicle’s ability to tow a trailer
  • For many vehicles, frontal area restrictions limit a trailer's size to a specific Gross Combined Weight Rating (GCWR)
  • The frontal area is also a determining factor in selecting an incomplete vehicle that complies with emissions requirements

Fuel Pump Inertia Shutoff Switch

Impact-activated switch, standard on all Ford cars and trucks, that automatically shuts off the fuel being pumped to the engine, for added safety in the event of a collision. Once the inertia-type switch is triggered, it must be reset manually. Refer to the specific vehicle’s Owner’s Guide for details on resetting the switch.


  • Also called g-force
  • Unit of measure for lateral acceleration or "road holding" ability
  • One g is equivalent to 32.2 feet/second2, the rate at which an object accelerates due to gravity


Coating of steel with zinc to help form a rust-preventive surface.

GAWR (Gross Axle Weight Rating)

Weight specified by the vehicle manufacturer as the load-carrying capacity of a single-axle system, front or rear. The GAWR is limited by the lowest individual rating of tires, wheels, springs or the axle itself.

GCWR (Gross Combination Weight Rating)

Weight specified by the manufacturer as the maximum loaded weight of a towing vehicle and its trailer. The sum of the loaded vehicle weight of the truck and trailer should not exceed the GCWR.GCWR = vehicle curb weight + payload + trailer weight + driver and passengers

Glad Hand

  • Quick-release couplings, attached to the tractor cab, that connect the tractor brake hoses to the trailer
  • These couplings open the supply line when twisted together and close the line when twisted apart to prevent the loss of air pressure

Glass, Solar-tinted

  • Automotive window glass with construction that helps prevent ultraviolet ray penetration of the passenger compartment
  • Solar-tinted glass helps reduce heat buildup in the interior of the vehicle by blocking out a significant portion of the solar energy. It accomplishes this not by reflecting the rays, but by absorbing the radiation and reradiating the majority of it to the exterior of the vehicle

Grade ability

  • Grade-climbing ability is the percent of grade a vehicle will climb with a given load
  • A 1 percent grade is equivalent to a rise of 1 foot in a horizontal distance of 100 feet; a 2 percent grade is a2-foot rise in a horizontal distance of 100 feet, etc.
  • Grade-climbing ability will affect a vehicle’s performance and should be considered when determining payload or trailer towing requirements
  • On steeper grades, a vehicle will be under more stress to handle these heavy requirements

GVVW (Gross Vehicle Weight)

  • Actual weight of a vehicle as determined by the total of the curb weight, payload, driver, passengers and optional equipment
  • Gross Vehicle Weight should not exceed the Gross Vehicle Weight Rating (GVWR) or the vehicle’s warranty could be voided
  • Refer to the specific vehicle’s Owner’s Guide for more information

GVWR (Gross Vehicle Weight Rating)

  • Maximum allowable weight of a fully loaded vehicle (includes curb weight, optional equipment, payload weight and weight of driver and all passengers)
  • GVWR for a particular vehicle is shown on the vehicle’s Safety Compliance Certification Label usually located on the left front door lock facing or on the door latch post pillar


Hip pivot point or H-point refers to where a vehicle occupant's hip, the pivot joint of the torso and thigh, would be located when in the seated position.

Half Shafts

Rotating shafts that transmit power from the transaxle to the front wheels in front-wheel-drive vehicles.

Heater, Engine Block Immersion

  • Feature that helps provide quick engine starting by keeping engine block coolant warm to build up heat for the heater system. The engine block immersion heater plugs into a conventional "AC" electrical outlet and is:
  • Suggested for use when temperatures are between 0°F and -10°F
  • Recommended between -10°F and -20°F
  • Strongly recommended below -20°F

Height-Adjustable Safety Belt

Multiple-position front-seat shoulder safety belt anchor that is height adjustable to allow a comfortable and proper fit of the outboard safety belts.

High-Intensity Discharge (HID) Head lamps

  • HID lighting systems use a special quartz bulb with no filament
  • Bulb is filled primarily with xenon gas along with a small amount of mercury and other metal salts
  • Bulb features two electrodes separated by a small gap (about 4mm or 3/16th inch). When high voltage current is applied to the electrodes, it excites the gases inside the bulb and forms an electrical arc between the electrodes
  • Hot ionized gas produces a "plasma discharge" which generates an intense, bluish-white light
  • Because there is no brittle filament inside a xenon HID bulb to break or burn out, the head lamps typically last up to three times longer than halogen head lamps (3000 hours versus 1000 hours of continuous operation, which is equivalent to 5 to 10 years of normal driving)


  • Amount of power needed to lift a 550-lb. object at a rate of one foot in one second
  • Horsepower is expressed as the torque in lb.-ft. times the number of revolutions per minute divided by the constant 5252:
  • Gross horsepower is obtained by a dynamometer test of an engine equipped only with the built-in accessories essential to its operation, such as fuel pump, oil pump, coolant pump and built-in emissions-control equipment
  • Net horsepower is obtained by a dynamometer test of a complete engine equipped with all the accessories necessary to perform its intended functions unaided, including the air-intake system, exhaust system, cooling system, generator, starter and emissions-control equipment
  • Torque is what gets a vehicle moving, and horsepower is the force required to keep a vehicle moving once torque has started the vehicle moving from a standstill

Hotchkiss-Design Rear Axle

  • Solid rear axle that uses leaf springs as the axle-locating mechanism as well as the primary suspension and load control
  • See Rigid Axle for more information


  • Manual-locking Hubs
  • Require the driver to get out of the vehicle and lock or unlock the hubs at the wheel
  • A shifter on the floor of the vehicle allows the driver to shift between two- and four-wheel drive
  • To disengage the hubs, stop the vehicle and rotate both hub lock selector knobs to the FREE position
  • Standard on F-Series Super Duty® 4x4 models
  • Automatic-locking Hubs
  • Front hubs lock without the driver having to exit the vehicle
  • All the driver needs to do is stop the vehicle and move the transfer case shift lever straight back to the 4H position
  • To revert back to two-wheel drive, move the shift lever straight forward to the 2H position
  • To immediately disengage the hubs, operate the vehicle in 2H in the opposite direction for approximately 10 feet

Hybrid Vehicle

Vehicle that combines a fuel-efficient internal combustion gas engine with one or more electric motors, plus an energy storage device such as a battery.

Hydraulic Lifter

Maintenance-free valve lifter that can adjust its length slightly using simple valving and the engine’s oil pressure to maintain zero clearance in the valve train to reduce valve train noise.

Hydro bushing

Large liquid-filled bushing that helps isolate the vehicle from road or engine vibrations due to the suspension traveling on uneven road surfaces. A hydro bushing is a bushing filled with fluid (glycol). This type of bushing can be made to react to different vibration frequencies compared to a conventional rubber or urethane bushing which is designed for one specific frequency. Hydro bushings are designed to provide a more comfortable ride in a vehicle.

Hydro forming

  • Manufacturing process that involves pumping fluid into a tubular blank within a die, so the pressure will expand and form a component, providing many structural advantages
  • Allows for major shape alteration, making it ideal for automotive structural parts such as engine cradles, radiator supports and body rails. Various shaped and sized holes can be punched in the tube almost anywhere during the process

Hydro mounts

  • An engine mount filled with fluid (glycol)
  • This type of engine mount can be made to react to different vibration frequencies compared to a conventional rubber mount that is designed for one specific frequency
  • Designed to provide a more comfortable ride in a vehicle, whether sitting still (idle) or traveling

Illuminated Entry

  • Provides convenience and security after dark
  • All interior courtesy lights illuminate and remain on for 20 seconds or until the ignition is turned on

Incomplete Vehicles

  • Light truck chassis and other light truck incomplete vehicles that are completed by subsequent manufacturers, such as motor homes, special delivery vans and other specialized vocational units
  • Safety, emissions and noise compliance representations are included with all light truck incomplete vehicle products (such as Chassis Cab models and Cutaways) manufactured by Ford Motor Company in the form of an Incomplete Vehicle Manual
  • Completed vehicles are required to be certified by the final manufacturer

Independent Suspension

Any suspension in which the movement, or angle, of a wheel is not directly affected by the vertical motion of the opposite wheel.

Intake Manifold

System of passages directing the intake air from the throttle body into the intake ports of the cylinder head.

Intake Port

Passageway in the cylinder head leading from the intake manifold to the intake valve(s).

Integrated Trailer Brake Controller

Electronic or electro hydraulic device installed in a tow vehicle used to activate the braking system of the trailer being towed. Controller uses actual braking pressure of the tow vehicle to calculate how much braking force to apply to the trailer. Most after market add-on controllers use a timer or proportional load basis to calculate the amount of brake force required. Since the Ford trailer brake controller is fully integrated into the truck’s onboard computer, this is the first and only controller able to adapt its output based on the status of the Anti-lock Braking System (ABS) to help provide more controlled, stable stops. Trailer brake controller is also fully integrated into the instrument panel design for the convenience of the driver during hookup and operation.

Integrated Wheel End (IWE) System

Provides Expedition with an outstanding four-wheel-drive system. The system is vacuum operated. In two-wheel-drive mode, a vacuum is applied to withdraw the clutch ring from the wheel hub coupler, completely separating the axle shaft from the wheel end. This avoids "back driving" the axle shafts, resulting in less wear and drag and slightly improved fuel economy. In four-wheel-drive mode the vacuum is shut off, the clutch ring engages the wheel hub coupler, and the axle shaft and hub are locked together to provide the necessary additional traction.

Inter cooler

Used on supercharged and turbo charged vehicles, the inter cooler is mounted at the front of the vehicle in the air stream and cools the compressed intake air as it flows over fins and plates inside the inter cooler. The inter cooler removes heat (produced by supercharging/turbo charging) from the compressed air before it enters the engine's intake system. This action generates a denser, cooler intake charge and increases the engine’s ability to produce horsepower and torque. Inter cooling also increases the detonation threshold of the engine because of the cooler air charge, meaning the engine can be run with more ignition advance for higher performance, or run lower octane fuel before experiencing detonation. The cooler intake air also allows the engine to run slightly cooler, reducing the chance of overheating.

Inter cooling

  • System for cooling pressurized intake air to obtain improved combustion efficiency and fuel economy
  • The cooling process increases the density of the intake charge, promoting more thorough combustion with reduced emissions


  • For a front axle assembly, the kingpin is a pin that connects the front axle and steering knuckles, about which the knuckles pivot
  • For semi-trailers, the kingpin is the pin that is locked into the fifth wheel on the pickup bed to couple the trailer with the towing vehicle

Knock Sensor

  • Sensor mounted to the engine and designed to detect the high-frequency vibrations caused by detonation
  • By using a knock sensor, a vehicle's engine controls can keep the engine operating near its detonation limit, thereby maintaining power and efficiency
  • See Detonation for more information

Ladder-type Frame

Chassis in which parallel side members are joined at intervals by transverse beams, or cross members, giving the appearance of a ladder.

LATCH (Lower Anchors and Tethers for Children) System

  • Child safety seat installation method consisting of a top tether anchor point and two rigid bars where the seat cushion meets the seat back, designed to make proper installation of a child safety seat easier
  • See page 5-13 of the Safety section of this book

Leaf Spring

Long, flat, thin, flexible section of spring steel or composite material used in suspensions (especially rear suspensions) to deflect force.

Leaf Spring, Parabolic Taper Leaf

Leaf springs that are thicker in the center section to carry the loads and provide suspension characteristics. Fewer leaves are required than with multi-leaf “piles”; therefore, weight may be reduced.

Limited-slip Differential

  • Designed to transmit driving force (power) to the wheel/tire with the most traction
  • As one tire begins to slip (lose grip), available torque is automatically transferred to the tire with better grip to provide improved traction
  • See Differential for more information
  • Refer to the charts in the individual vehicle sections of the Source Book for specific applications and axle ratios

Live Axle

  • Rigid axle incorporating a differential assembly, housing and axle shafts to power the two wheels it is supporting
  • See Axles, Rear Drive for more information

Load-equalizing Hitch

  • Used in conjunction with a hitch platform (receiver) to distribute tongue weight to all towing vehicle and trailer wheels. Required for certain Class III and all Class IV applications

Load-equalizing Trailer Hitch

See Trailer Hitch.

Load-leveling Rear Suspension

See Suspension Systems — Rear.

Lockup Torque Converter

Because the automatic transmission is linked to the engine by a fluid coupling, rather than by the mechanical clutch of a manual transmission, there is a potential loss of efficiency due to slippage. The lockup torque converter improves fuel economy by eliminating this slippage. An internal clutch system provides a positive, direct connection between the engine and transmission. It is usually controlled by the power train computer and will operate only after the vehicle has moved away from a stop or shifted out of low gear.

Longitudinally Mounted Engine Design

Engine compartment layout with the engine mounted front to rear, as opposed to side to side. This layout is most often found in rear-wheel-drive vehicles, where the power must run from the front of the vehicle to drive the rear wheels.

MacPherson Strut

See Suspension Systems — Front

Main Bearings

In an engine block that support the crankshaft.

Mass Airflow Sensor

  • Engine system monitoring feature that employs a hot-wire sensing device positioned between the air filter and the throttle body to measure the mass of airflow into the engine.
  • Information is fed into the Electronic Engine Control system, which then automatically adjusts the fuel flow to provide more efficient combustion
  • Mass airflow sensor provides precise air metering for better engine performance, greater fuel efficiency and reduced exhaust emissions

Mirror, Electro chromic Auto-dimming

Automatically adjusts to Night mode when illuminated from the rear at a predetermined level and returns to Day mode after illumination is reduced below threshold levels. Features Reverse-gear override when backing out of dark areas and replaces the conventional day/night inside rearview mirror.

Modular Engines

Family of engines that share engineering elements and manufacturing features, enabling the same basic design or components to be adapted for a variety of configurations (6-, 8- or 10-cylinder models) and applications.

Monobeam Suspension

See Suspension Systems — Front.


  • MP3 is a compression technology that allows for the shrinking of the size of an audio and/or video file while maintaining excellent sound quality. It is an open standard so no one group controls the technology and those who do have technology interests are compelled to license it. This means that music can be downloaded to a computer quickly and played back at CD quality sound reproduction
  • MP3 stands for MPEG-1 Layer 3. MPEG stands for Moving Pictures Experts Group

Multi-leaf Spring

Leaf spring with several leaves bundled together.

Multi-valve Engine Design

Engine design that uses more than one intake and/or exhaust valve per cylinder for increased engine breathing, resulting in increased horsepower and torque, especially at higher engine speeds. For example, a 16-valve, 4-cylinder engine provides two intake and two exhaust valves per cylinder.

Navigation System

  • Navigation Systems used in Ford vehicles can be operated via hand control buttons, touch-screen controls or voice commands (certain models). The system tracks vehicle location using a GPS device and compares that to maps stored on an internal hard drive (most 2009 models) or on a DVD.
  • Voice activation (if equipped) recognizes certain voice commands to operate the system hands-free
  • 6.5-inch or 8-inch LCF color touch screen operates navigation and audio functions
  • Destination selection search methods include:
  • Street address
  • Point of Interest (POI)
  • Freeway entrance/exit search
  • Previous destination
  • Turn-by-turn voice prompts include street name pronunciations
  • Supports North American English, Canadian French and North American Spanish
  • Help menu for basic operation, driving restrictions and navigation DVD
  • Automatic rerouting recalculates a new route if a turn is missed
  • Emergency button provides nearest emergency facility to choose as a destination (hospital or police)
  • Valet lockout mode disables operation of the Navigation System
  • Address book saves the most frequently used destinations for quick and easy routing

Noise, Vibration and Harshness (NVH)

Noise, vibration and harshness are sound and ride characteristics occupants may experience while in a moving vehicle.

Nominal Tonnage (Nominal Weight Rating)

Term used by Ford and other truck manufacturers to generally categorize the load capacity of a vehicle series and to describe the general, usable cargo capability the vehicle series can expect to handle. Additional information: Page 3-7 in the Payload Workbook section of this book.

Octane Rating

  • Octane is the measure of gasoline’s ability to resist auto-ignition, which can cause engine knock
  • Two laboratory test methods measure gasoline octane value
  • Research Octane Number (RON)
  • Motor Octane Number (MON)
  • RON correlated best with low-speed, mild engine knocking conditions
  • MON correlates with high-temperature engine knocking conditions with part-throttle operation
  • North America typically uses the Anti-Knock Index of (RON + MON)/2 to specify octane rating
  • Vehicles are designed and calibrated to a certain octane value
  • When a customer uses gasoline with an octane level lower than specified, engine knock may result and could lead to service engine damage


Device used to measure and register mileage throughout a vehicle's lifetime. Many vehicles also offer "trip odometers" that can be reset to measure distance traveled during any given trip or time period.

On-Board Diagnostics II System (OBD II)

  • Continuously monitors the power train
  • Pinpoints malfunctions and wear for virtually every component and system that can increase emissions
  • System allows Service Technicians to diagnose power train problems and helps reduce service time and cost

One-Touch-Down Driver’s Power Window

  • Feature provides the driver with a one-touch-down button that completely lowers the driver’s window for hands-free convenience. The window also can be lowered and stopped at any position
  • Refer to individual vehicle sections for availability

One-Touch-Up/Down Power Window

Completely lowers the window by pushing on the switch once and raises it by pulling on the switch once.


Transmission/transaxle gear ratio of less than 1:1 that is designed for economical highway driving. The overdrive gear allows the engine to operate at lower rpm while maintaining the given vehicle speed, thus requiring less fuel because the engine is doing less work.

Overhead Camshaft (OHC) Design

See Single Overhead Camshaft (SOHC) Design and Dual Overhead Camshaft (DOHC) Design.

Overhead Valve (OHV) Design

Engine design with the valves located in the cylinder head and the camshaft located within the engine block with push rods and rocker arms to actuate, or open, the valves.

Partial Zero Emissions Vehicle (PZEV)

  • 120,000 miles of driving. By comparison, a vehicle certified to the Federal Tier 2 Bin 5 California LEV II emissions standards currently in effect emits about 29 pounds over the same 120,000 miles. To achieve a PZEV rating, a vehicle must meet certain criteria, including:
  • Meet the Super Ultra Low Emissions Vehicle (SULEV II) standards for tailpipe pollution
  • Demonstrate zero fuel-based evaporative emissions
  • The manufacturer’s warranty must ensure that emissions-related components are covered for 15 years or 150,000 miles, whichever comes first(1)


  • Weight of the actual cargo and occupant(s) carried by a vehicle
  • Payload capacities are computed by subtracting the curb weight of the vehicle from its specified Gross Vehicle Weight Rating (GVWR)
  • Addition of any optional equipment or passengers adds to the vehicle weight and subtracts from the allowable payload
  • Trucks with a GVWR of Class 6 or higher calculate payload by simply subtracting the weight of the completed vehicle from the GVWR to determine payload


Pillars are the vertical beams that support the roof and separate passenger compartment windows. A-pillar — First, or most forward, roof support pillar located on either side of the windshield. Also known as "windshield pillar" or "A-post" B-pillar — Center roof support that divides the front and rear doors on 4-door and passenger wagon models. On2-door models, the B-pillar separates the door and rear quarter window/panel. On vans and passenger wagons, the B-pillar is behind the front doors C-pillar — Rear roof supporting member on most vehicles. On CUVs/SUVs, this pillar separates the rear doors and quarter panel glass D-pillar — Vertical, or sometimes diagonal, roof support member at the extreme rear of the roof or greenhouse structure on mini vans, CUVs/SUVs and some sedan body styles


  • Cylindrical component, closed at one end, and attached to the crankshaft by a connecting rod
  • The force of an explosion in the cylinder's combustion chamber forces the closed end of the piston down, causing the connecting rod to move the crankshaft


  • Rotation along an imaginary lateral or transverse axis situated between the front and rear wheels of a vehicle causing the vehicle to move up or down on the side-to-side axis.
  • Often, during hard braking, the vehicle's nose will pitch down — this is called "dive" or "diving"
  • During acceleration, the rear of the vehicle’s pitch is lower. This motion is called "squat" or "squatting"


Chamber between the throttle body and the passages of an intake manifold used to help promote the even distribution of the intake charge and to enhance airflow and engine performance.

Pogo Stick

  • Flexible, vertical spring-wound tube mounted behind the cab and used to support extra-long air hoses and electrical lines
  • See Glad Hand

Porthole-in-frame Design

Frame design that locates the rear axle shafts through the frame rails to allow for a lower step-in height and center of gravity. This design is exclusive to Explorer, Expedition and Sport Trac.


Unit of measure for engine torque commonly abbreviated as lb.-ft. The commonly used term of “foot-pounds” is more properly a measurement of work rather than torque.

Power Adjustable Brake and Accelerator Pedals

Power adjustable pedals allow for the forward or rearward adjustment (up to 3 inches) of the accelerator and brake pedals through the activation of an instrument-panel-mounted switch. This is an especially useful feature for drivers of smaller stature, allowing them to comfortably reach the pedals while being able to maintain the required distance from the steering-wheel-mounted airbag. This feature can be packaged together with an available seat position memory system on certain vehicles for the ultimate in comfort and convenience.

Power Band

Rpm range over which an engine delivers a substantial portion of its peak power. The power band generally extends from slightly below the engine’s torque peak to slightly above its power peak.

Power Takeoff (PTO)

Power takeoff refers to using the vehicle’s power train as a power source to perform some work other than moving the vehicle. Examples of this work include operating auxiliary equipment such as a wrecker and snowplow lifts, dump bodies, hydraulic/pneumatic tools and so on. The PTO unit is located between the power train and the device it powers. When a vehicle is doing this work while it is not moving, keep in mind that it is also deprived of the cooling benefits airflow provides. Because of this, it is important not to block the front grille or bumper openings. Specific precautions are listed in the Body Builders Layout Book. While Ford does not offer the actual PTO units, Ford F-Series Super Duty® engineers worked closely with two PTO after market suppliers (Parker Chelsea and Muncie) during development of the truck. This work helped create two different Ford-specific after market units that bolt directly onto the transmission’s power takeoff interface (the interface is standard on F-Series Super Duty models equipped with a manual transmission, optional with automatic transmission).

Power Takeoff (PTO) Provision

  • Power Takeoff (PTO) Provision is an added benefit for customers with specific auxiliary power needs. It enables up fitters to supply auxiliary power to hydraulically driven accessories such as dump bodies, sprayers, pumps, generators, etc. Front-mounted, front-powered equipment is often powered by a direct drive shaft from the front of the engine. The adaptation of the vehicle to allow this installation is called the Power Takeoff Provision. This includes an adapter plate on the engine, and in some instances clearance through the grille or front-end sheet metal. An optional front frame extension for mounting equipment is available on all models except the Pro Loader. The F-650 and F-750extensions are bolted on, while the F-750S extension has an integral extension of the frame rail.
  • Transmission Power Takeoff Provision– A specific option code must be ordered to get a PTO gear and port with the TorqShift® 5-speed automatic transmission
  • 85P for E-Series Van/Cutaway
  • 62R for F-Series Super Duty®
  • 44B for LCF– The 6-speed manual overdrive transmission has a PTO gear and a port standard (NA on E-Series and LCF)
  • Stationary Elevated Idle Control (SEIC)– This standard feature in all E-350/E-450, F-250/F-350/F-450/F-550 and Ford LCF models provides the "throttle-kicker," replacing the Auxiliary Idle Control Kit in prior model years. It consists of a strategy embedded in the power train control module (PCM), and a set of blunt-cut wires to command it– The selling dealer will need to obtain the customer interface (e.g., PTO controller or switch) from the aftermarket NOTE: "Up fitter Switches,"(Standard on F-350/F-450/F-550 Chassis Cabs, option code 66Son F-250/F-350 Pickups) may be used as a PTO switch. SEIC provides engine speeds of 910 to 2400 rpm for 5.4L and 6.8L gas engines, and 1200 to 2400 rpm for all (4.5L, 6.0L and 6.4L) diesel engines. It also automatically locks the torque converter providing power to the PTO gear for the TorqShift automatic transmission when the operator turns on the PTO switch. Instructions to up fitters for completing the SEIC/PTO circuitry are detailed in the 2008 Model Year Light Truck Body Builders Layout Book, found at Refer to the latest Dealer Ordering Guide for model and engine restrictions.

Power train

Name given to the combination of engine, transmission/transaxle and differential (rear-wheel drive only) for any particular model. See the Power trains section of this book for details concerning Ford power train systems.

Power train Control Module (PCM) with On-Board Diagnostics (OBD II)

  • PCM with OBD II was developed to accommodate the goals of achieving mandated emissions control and improving vehicle performance
  • The latest PCM incorporates more functions, more memory and more new integrated circuits than the former control system, helping it be more precise than its predecessors PCM features and benefits:
  • Potential improvements in:– Performance– Drive ability– Fuel economy– Emissions control
  • Through state-of-the-art technologies, Ford Service Technicians are able to fully reprogram the PCM memory by electronically “talking” to a single connector on the vehicle, allowing the module to receive upgrades rather than requiring replacement
  • PCM system enables Ford vehicles to comply with the latest California Air Resources Board (CARB) OBD II requirements designed to help maintain vehicle emissions control. As more stringent emissions regulations are adopted in the future, the PCM will be able to adapt to these as well PCM enables Ford to meet OBD II requirements by monitoring:
  • Catalyst efficiency
  • Fuel system
  • Evaporative emissions
  • Exhaust gas recirculation
  • Other emissions-related control systems as well as various sensors and actuators The PCM also helps improve accuracy during repair procedures. The PCM’s enhanced capability expands the ability of Ford Service Technicians to trace problems, even intermittent problems, quickly and easily.
  • Through the use of diagnostic scan tools, Technicians also are able to retrieve recorded vehicle performance history from PCM, leading to quicker and more accurate diagnoses

Power-to-weight Ratio

Although power-to-weight ratios may be configured in many ways, they are generally the proportion of the vehicle's curb weight divided by the vehicle’s horsepower measured at peak rpm. A vehicle that produces more horsepower or torque than another vehicle of equal weight will have a greater power-to-weight ratio.


  • Pounds per square inch — the measurement of pressure that results from a specified amount of gas in a limited volume. For example, the more air that is put into a tire, the greater the psi
  • Normal atmospheric pressure is 14.7 psi

Pulse Vacuum Hub lock (PVH) System

  • This high technology provides F-Series Super Duty® with an outstanding four-wheel-drive system
  • Allows synchronous hub lock engagement when the driver shifts on-the-fly, resulting in smooth, quiet functioning
  • 4x4 engagements and disengagements can be made while driving at virtually any speed
  • No shift delays, even in extremely cold temperatures
  • Allows total disengagement of front wheels when in the 4x2 mode, resulting in maximized performance and fuel economy
  • No regular service intervals required under normal driving conditions. This does not include severe off-road maintenance
  • F-Series Super Duty 4x4 models equipped with the PVH system feature a manual override

Push rod

Connecting link in an operating mechanism that opens the valve for the duration and lift of the cam, allowing the engine to intake and exhaust the air/fuel mixture. In a conventional layout, the force is transferred to the rocker arms.

Quiet Steel®(1)

Quiet Steel is constructed of steel laminates that absorb sounds and harmonics to help insulate engine noise from the cabin. The F-150 and Expedition dash panels are made of Quiet Steel.

Rack-and-pinion Steering

See Steering Systems.


  • Component of the engine cooling system that stores coolant and consists of a series of tubes that allow air to pass through, dissipating excess heat.
  • The coolant circulates through the engine to help reduce engine heat
  • Fresh air is drawn through the radiator to remove heat from the engine coolant

Rear View Camera

  • Camera located in the rear of the vehicle
  • Automatically engages when the vehicle is placed in Reverse
  • Displays within the electro chromic auto-dimming rearview mirror or on the Navigation Screen, depending upon the vehicle
  • Vehicle centerline, rear bumper orientation, and green/red/yellow trajectory lines are shown within the display, helping the driver to assess the vehicle’s proximity to surrounding objects in the rear

Rear-wheel Drive

Drive configuration where the engine power is supplied to the rear wheels via a drive shaft and rear differential assembly.


Maximum recommended engine revolutions per minute (rpm). A tachometer, standard or available on some models, displays a red area to alert the driver that the engine speed is beyond the recommended rate.

Resisting Bending Moment (RBM)

Result of multiplying yield strength and section modulus when comparing frames of the same material, the one with the largest section modulus will be the strongest. When comparing frames of different materials, the frame with the highest RBM has the greater strength.

Reverse Sensing System (Reverse Vehicle Aid Sensor)

  • Helps audibly alert drivers of certain objects close to the rear of the vehicle (within approximately 6 feet) as the driver backs the vehicle up slowly. As the vehicle approaches an object, a warning tone beeps. The beeps increase in frequency as the vehicle gets closer to the object, until it becomes a continuous tone at less than approximately 10 inches from the object
  • System activates automatically when the vehicle is shifted into Reverse. Pressing a switch on the instrument panel will turn the system off. An "Off" light on the switch illuminates to indicate the system is not active. The system reactivates when the vehicle is again placed in Reverse

Reverse Sensing System (Reverse Vehicle Aid Sensor) cont'd

  • Customer Benefits
  • Helps make getting in and out of tight parking spaces easier. The system:
  • Detects what the driver may not see, such as other vehicles, fences, walls, concrete posts, plant containers ,fire hydrants and the like
  • Enables drivers to use better judgment in tight parking situations
  • Provides information to drivers to help reduce damage from hitting objects at low speeds (90 percent of backup collisions are at speeds less than 5 mph)
  • How It Works
  • Four ultrasonic sensors in the vehicle’s rear bumper transmit signals
  • When the signals contact an object, they bounce back to the sensors on the vehicle
  • Within milliseconds, the system calculates the distance to the object, based on the time it took the signal to travel from the object back to the sensor
  • If the distance is within approximately 6 feet, the alert is sounded
  • System continues to send out and monitor signals, adjusting the warning beep according to the object’s distance from the vehicle

Ride Height

Distance between the ground and a specified point on the vehicle body with properly inflated tires. The lowest point of the bumper is generally used as the vehicle measuring point.

Rigid Axle

Simple non-independent suspension consisting of a rigid transverse member with wheel hubs that are solidly bolted to it. The axle can be attached to the vehicle body by leaf springs or by a combination of suspension arms and links. See Hotchkiss-Design Rear Axle.

Ring-and-pinion Gear

Set that uses a small gear (the pinion gear) to turn a larger diameter annular gear (the ring gear).

Road holding

Ability of the vehicle to maintain traction with, or grip, the pavement while cornering.



Rotation along an imaginary axis running the length of the vehicle between the driver's-side and passenger's-side wheels. Roll causes the vehicle to tilt or lean left or right. A stabilizer bar can often counteract the effects of roll.


Revolutions per minute, the number of engine crankshaft rotations completed in one minute. Configured in thousands, a tachometer will report the engine’s rpm to the driver and help alert the driver as to when proper shifting is required.

Safety Belt Energy Management Retractors

See page 5-10 in the Safety section of this book.

Safety Belts

System of belts or harnesses designed to restrain and help reduce the risk of injury to occupants in the event of side, rear, rollover or frontal collisions. Refer to the Safety section of this book for details concerning Ford safety belt systems.

Safety Cell Construction

  • Integrated body structure designed to work as a system to provide protection for occupants. Its major design features include:
  • Front-end structure with a reinforced sub frame to provide energy absorption
  • Cross cowl beam that helps provide an additional mounting point for the steering column and airbag mountings, reducing their movement in the event of a frontal impact
  • High-strength side door intrusion beams
  • Sheet metal at the front and rear corners that collapses progressively and predictably to dissipate some of the energy of an impact

Seats, Hi-back

Back of this individual seat is about as high as the top of the occupant’s head. It tapers in from shoulder height to form an integral head restraint.

Section Modulus

Measure of the strength of frame side rails determined by the cross-section area and shape of the side rails. When comparing frames of the same material, the one with the largest section modulus will be the strongest. When comparing frames of different materials, the frame with the highest Resisting Bending Moment (RBM) has the greater strength.

Self-adjusting Clutch

Optional self-adjusting clutch, once installed, does not have to be adjusted again. When the release bearing travel exceeds 1/2-inch, the self-adjusting mechanism returns the clutch and pedal free play to normal operating conditions as the clutch pedal is actuated. A self-adjusting clutch eliminates eight to ten clutch adjustments over the life of a clutch.

Sequential Multi-port Electronic Fuel Injection (SEFI)

Specific type of multi-port injection that delivers fuel in more precisely timed pulses corresponding to the opening of each intake valve. SEFI takes advantage of the atomized fuel spray from the injectors to achieve a more precise combustion for better performance, often with improved fuel economy.

Shock Absorber

  • Provides mechanical or hydraulic friction to control deflection of automobile springs
  • Oil in the shocks is forced through small passages to absorb the force of a road shock
  • Pressurized gas is used in many shock absorbers to prevent aeration of the oil. This reduces the tendency of the shock to overheat on rough road surfaces

Short- and Long-Arm (SLA) Suspension

  • Independent design that allows either wheel to react to road imperfections with minimal effect on the opposite wheel. Several distinct advantages over MacPherson struts include camber control, turning geometry and lower component package height. These advantages permit a lower hood line. Major design features include:
  • Gas-pressurized shock absorbers to maintain optimum ride control over a variety of road surfaces
  • Control arms to help absorb braking and acceleration forces
  • Coil springs or torsion bars (on select vehicles)

Single Overhead Camshaft (SOHC) Design

Engine design with the camshaft located atop the cylinder head, operating both the intake and exhaust valves. SOHC V6 and V8 engines, which are designed with cylinders in two banks, have a total of two cams, one for each cylinder head. The one cam in each head operates the intake and exhaust valves, resulting in improved performance and fuel efficiency. All engines using the overhead cam design offer the potential for greater power output and higher engine speeds (rpm) when compared with overhead valve designs.

SIRIUS® Travel Link™(1)

  • Real-time traffic information
  • Provides incident, speed and flow information for 80 major cities in the continental U.S.
  • Updates every 2.5 minutes
  • View graphical overlay of incidents
  • Route recalculation based on traffic data
  • Real-time weather information
  • Provides current weather and 5-day forecast reports that are updated every 5 minutes
  • Current conditions update every 30 minutes
  • Region of interest can be defined by customer
  • Fuel pricing
  • Search for pricing en route or based on current location for over 120,000 gas stations
  • Displays pricing for regular, mid-grade and premium when available
  • Diesel pricing displayed where available
  • Sports updates and movie listings
  • Score summaries and schedules for major sports
  • Updates every 5 minutes
  • User can personalize for favorite teams
  • Movie listings for over 4,500 theatres, including times, movie summary and directions to the theater

Skid pad

Large, flat expanse of smooth pavement used for various handling tests, e.g., road holding. Generally, road holding is measured as the highest speed a vehicle can maintain without losing adhesion while maintaining the given diameter of a large circle (e.g., 250 feet, 300 feet, etc.) or the g-force generated at that speed.

Skid plate

Deflector plate under a vehicle that helps provide protection from off-road debris. Transfer case and fuel tank skid plates are common on Ford 4x4 vehicles.

Slack Adjusters (automatic/manual)

  • All Ford air brake trucks come equipped with automatic slack adjusters
  • When properly maintained, slack adjusters retain accurate shoe-to-drum clearances (slack)
  • This promotes even brake wear, reducing brake downtime and expense
  • Properly adjusted brakes are a plus factor for vehicle safety

Society of Automotive Engineers (SAE)

The organization that sets American automotive standards for automotive measurements, including horsepower, torque and lubricants.

Split-port Induction (SPI)

  • Most split-port induction systems have a dual-runner engine intake design promoting high-volume/high-velocity airflow to increase engine performance.
  • Dual-runner design features long, small-diameter runners tuned for low engine rpm torque and short, large-diameter runners tuned for high rpm horsepower
  • Runner usage is controlled by the electronic engine controls and integral throttle-body valves
  • SPI engines use a cylinder head with two runners per cylinder. These runners carry the air charge to the intake side of the combustion chamber. At lower engine speeds, the air charge is directed through a narrow pathway that results in a higher air velocity, quickening engine response. As engine speed increases above 3000 rpm, the second path works to further enhance engine power and operating efficiency

Spring Rating

  • Any one of several methods of describing spring ratings currently used in the light truck industry, including:
  • Rating at Pad — The amount of weight above the pad that can actually be supported by the springs, including the chassis, body and payload weights
  • Rating at Ground — Includes the Rating at Pad plus the weight of components between the spring and ground (axle, brakes, tires and wheels)
  • Sprung Weight — The weight of those components supported by the spring, such as the frame, engine, body, payload, etc.
  • Unsprung Weight — The portion of the weight of the chassis (i.e., axle, wheels, tires, brakes, etc.) not supported by the springs, as well as one-half the weight of the springs and drive shaft

Stabilizer Bar

Bar or tube that provides added support for suspension members to minimize body lean or roll. The stabilizer is transversely mounted and used at the front and/or rear suspension to resist unequal vertical motion across the width of the vehicle.

Steering Systems

  • Rack-and-pinion
  • Essentially, a rack-and-pinion system as described previously with a power-assist feature reducing steering effort
  • Major design features include:– Rack-and-pinion gears that are engineered for low turning effort, good return ability and handling– Lightweight power steering pump– Power assist
  • Speed-sensitive, Variable-assist Steering
  • Major design features include:– A microprocessor-controlled system that electronically varies the assist based on signals received from vehicle speed sensors. This sophisticated system provides improved maneuverability with maximum assist at low speeds, such as when parking– Decreases assist at highway speeds to provide improved road feel
  • Manual Recirculating Ball-and-nut
  • Uses a worm gear surrounded by ball bearings that travel in a recirculating track
  • Performs well in isolating the driver from the feedback of uneven road surfaces
  • Power Recirculating Ball-and-nut
  • Major design features include:– Linkage steering gear forward of the front wheel axis that combines with a lightweight steering pump for maximum assist when turning the wheel– Power assist for low-speed turning and parking


Maximum distance traveled by a piston between bottom-dead-center (BDC) and top-dead-center (TDC). If the stroke is increased, the displacement increases and vice versa.


Suspension element that uses a reinforced shock absorber as one of the wheel’s locating members, typically by solidly connecting the wheel hub to the bottom of the strut.

Sub frame

Partial frame that connects the vehicle’s power train and front suspension or rear components to its underbody.

Sub frame, Isolated

  • Attaches to the front or rear structure of some Ford vehicles
  • Provides support for the engine, transmission and often the suspension
  • Provides added strength and rigidity to the vehicle’s construction
  • Uses rubber mounts to reduce levels of noise, vibration and harshness


  • Supercharger is a large air pump that is normally mounted on the engine intake manifold and belt-driven by the crankshaft
  • Most superchargers contain two impellers that compress the incoming air charge
  • Advantage of compressing the intake air is that you allow more air to enter each cylinder. The engine’s fuel control computer then adds more fuel to compensate for the added air, increasing the power and torque output of the engine
  • Typical boost provided by a supercharger is 6 to 8 pounds per square inch (psi)

Suspension Systems - Front

  • The springs, torsion bars, shock absorbers, linkages and locating members acting together to control motions caused by tires passing over uneven road surfaces to reduce the effect on the vehicle body.
  • MacPherson Strut
  • Focus, Edge, Taurus, Taurus X, Mustang, Escape and Escape Hybrid
  • Type of suspension layout in which a coil spring is positioned over a shock-absorbing strut with fewer parts and less weight than conventional suspension systems
  • Monobeam Twin-Coil
  • F-250/F-350 4x4 Pickups, F-450 Pickup, F-350 4x4 Chassis Cabs and F-450/F-550 Chassis Cabs
  • Solid non-independent suspension. The axle is located and attached to the frame by extremely robust radius arms. The use of coil springs allows for improved damping and ride comfort as well as improved steering geometry
  • Monobeam
  • F-650/F-750 Chassis Cabs, Ford LCF
  • Solid non-independent suspension usually used on medium-duty four-wheel-drive trucks attached to the frame by leaf springs and to the wheels by kingpins. Also serves as the front axle on these applications
  • Short- and Long-Arm (SLA)
  • Fusion, Ranger, F-150, Explorer, Sport Trac and Expedition
  • Independent design that allows either wheel to react to road imperfections with minimal effect on the opposite wheel. Design features include:– Shock absorbers to maintain ride control (gas pressurized on select vehicles)– Upper and lower control arms to absorb acceleration and braking forces– Coil springs or torsion bars
  • Twin I-Beam
  • E-Series, F-250/F-350 4x2 Pickups and F-350 4x2 Chassis Cab
  • Independent front suspension that uses two parallel I-Beams with one end connected to each wheel and the other fixed to the frame
  • Design combines the superior strength of a solid I-Beam suspension, with the flexibility and ride comfort of a fully independent suspension

Suspension Systems - Rear

  • Air Suspension
  • F-650/F-750 Chassis Cabs
  • Air suspension system replaces the leaf springs or coil springs with reinforced rubber airbags or bladders
  • Airbags are located between the frame and axle and provide the weight-carrying capacity of the rear axle
  • Air spring suspensions provide a smoother, more compliant ride than typical leaf spring suspensions
  • Multi-link
  • Taurus and Taurus X use an independent design that is mounted on U-shaped sub frame. Upper and lower control arms with gas-pressurized shock absorbers mounted in a coil-over-shock design. Stabilizer bar reduces body lean while cornering
  • Fusion and the Edge use an independent design that is mounted to a sub frame and works like a double-wishbone setup. Twist-blade control arms with gas-pressurized shock absorbers, coil springs and a stabilizer bar
  • Expedition uses a second-generation independent design with five-link design for better control of fore/aft and lateral load forces, monotube shocks which allow for more precise tuning and a better ride, and a stabilizer bar with high-precision bushings and low-friction ball joint links for improved on-center steering feel. Porthole in-frame design, with axle shafts passing through the frame rails, provides a lower step-in height and a lower center of gravity
  • Rigid Axle
  • Mustang, Ranger, all F-Series Pickups and Chassis Cabs, E-Series and Ford LCF
  • Also known as a solid or live axle
  • Non-independent suspension that uses an axle which runs nearly the width of the vehicle– On trucks, the axle is located by leaf springs. Gas-pressurized shock absorbers help provide a smooth ride– On Mustang, the axle is located with coil springs, one upper and two lower control arms. Gas-pressurized shock absorbers help provide a smooth ride
  • Short- and Long-Arm (SLA)
  • Focus
  • Independent design that allows either wheel to react to road imperfections with minimal effect on the opposite wheel. Design features include:– Shock absorbers to maintain ride control (gas pressurized on select vehicles)– Upper and lower control arms to absorb acceleration and braking force– Coil springs or torsion bars
  • Trailing Arm
  • Explorer and Sport Trac
  • Independent design uses trailing blade with coil-over-shocks to help provide precise handling and minimize ride harshness, porthole-in-frame design with axle shafts passing through the frame rails and a stabilizer bar for improved on-center feel
  • Double Lateral Link and Semi-trailing Arm
  • Escape and Escape Hybrid
  • Independent suspension that uses one trailing arm and two lateral links per side
  • Shock absorbers and coil springs provide a smooth ride Load-leveling
  • Expedition
  • Suspension that uses rear air springs, an air compressor and electronic components to help keep the vehicle level when towing a trailer or hauling heavy loads.
  • Multi-leaf Rear Spring
  • Ranger, all F-Series, E-Series and Ford LCF
  • Spring built from superimposed, narrow flat-sectioned plates or blades that resist load in bending
  • Spring operates in conjunction with a solid axle suspension as a system that includes the wheels being mounted to a rigid beam axle. Major design features include:– Parabolic tapered leaf springs that react to differing loads, providing a smooth ride regardless of load conditions– Leaves which are actually long flat bars that are bracket-mounted at each end and arc in the center to provide the necessary stiffness– Leaf number that will differ from truck to truck, depending on individual load ratings– Many trucks have two-stage, variable-rate leaf springs, with the first set of leaves handling most requirements. The shorter, second set reacts under heavy load or suspension demands as required


  • Ford and Microsoft have teamed up to develop Ford SYNC®. This exclusive technology will change the way customers use their digital media and Bluetooth®(1) wireless technology enabled mobile phones. SYNC allows drivers to stay connected to the information, entertainment and people they care about while on the road. (1) The Bluetooth word mark and logos are trademarks of the Bluetooth, SIG, Inc. SYNC features:
  • Voice-activated(2) hands-free calling with advanced calling features like caller ID, call waiting, conference calling (2) Driving while distracted can result in loss of vehicle control. Only use mobile phones and other devices, even with voice commands, when it is safe to do so.
  • Uninterrupted connections that allow going directly from cell phone to the vehicle’s hands-free phone during the call
  • Voice-controlled media player
  • Audible text messages
  • Instant voice recognition and ring tone support
  • Automatic phone book transfer for mobile phones with this feature
  • Multilingual intelligence (English, French, Spanish)Some 2009 Ford vehicles (mid-model introduction) equipped with SYNC will also include 911 Assist and Vehicle Health Report as new/additional features.911 Assist
  • If an airbag deploys in a 911 Assist-equipped vehicle, SYNC will place a call to the local 911 emergency operator
  • SYNC makes the call on a properly paired, turned on and Bluetooth-enabled mobile phone
  • There is a 10-second delay before the call is placed, allowing a vehicle occupant to cancel the call if 911 is not needed Vehicle Health Report (VHR)
  • On demand, or at set mileage intervals, SYNC will gather diagnostic information and send it to Ford via a Bluetooth-enabled and paired mobile phone
  • A text message regarding critical vehicle concerns can be immediately sent to the owner with properly set SYNC preferences
  • Owners can also view their complete VHR at, including diagnostics, maintenance, recalls and Multipoint Inspection items and make any repair or maintenance appointments as needed


  • Synchromesh clutch is typically a drum or sleeve that slides back and forth on a splined output shaft by means of a shifting fork
  • Generally, it has a bronze cone on each side that engages with a tapered mating cone. When this drum, or sleeve, is moved along the output shaft, the cone acts as a clutch
  • Upon contacting the gear that is to be engaged, the output shaft is sped up or slowed down as required until the speeds of the output shaft and the gear are synchronized, or are “in sync” with each other

Synchronized Gears

  • Synchronized gears are used in manual transmissions to facilitate the meshing of two gears by causing the speed of both gears to coincide
  • This helps move clutch assemblies to the specific chosen gear
  • A synchronizer will help prevent an improper shift that could damage the transmission, such as shifting into first gear at highway speeds


Gauge on the vehicle instrument cluster indicating engine speed measured in crankshaft revolutions per minute (rpm).

Tailgate Step

  • An integrated steel step and handle that folds down from the top of an open tailgate
  • Allows an easier step up into the cargo box and stores itself once the tailgate is closed

Tappets, Hydraulic Roller Valve

  • Also known as valve lifters
  • A device in the valve system that transmits the action of the cam to the valve or the push rod
  • Hydraulic lifters are designed to automatically take up the clearance that exists between the valve and the lifter
  • This is known as valve lash

Theater-style Seating

  • Also known as “stadium seating”
  • Second- and/or third-row seats are raised slightly higher than the preceding seats in front, similar to seats found in a movie theater or stadium
  • Allows rear-seat passengers to have a better view of the road through the windshield

Three-valves-per-cylinder Engine Design

Power train design that usually uses two intake valves and one exhaust valve per cylinder. The improved flow of air/ fuel into and out of the engine improves operation virtually to the level of a four-valve-per-cylinder design but with somewhat less complexity and cost.

Throttle Body

Housing containing a valve to regulate the airflow through the intake manifold and usually located between the air cleaner and the intake manifold.

Tire Information

  • Most Ford car and light truck tires carry a P-metric designation such as P185/70R14 or an LT-metric designation such as LT235/70R16. In the charts below, the alphabetical or metric and load range letters used are obtained from Tire and Rim Association Standard Tables. P-metric Steel-belted Radial-ply Tires All Ford cars and most light trucks have P-metric steel-belted radial-ply tires as standard equipment. They are designed in accordance with nationally accepted dimensional standards. Benefits include:
  • Improved fuel economy through increased inflation pressure (up to 35 psi; 44 psi for some light trucks)
  • Lighter weight
  • Tread compounds designed for reduced rolling resistance LT-metric Steel-belted Radial Tires
  • LT-metric designates a light truck radial tire with a metric tire designation
  • Available with both all-season and all-terrain tread patterns for greater versatility
  • Designed to support larger vehicles and heavier loads Medium-Duty Truck Tires used on Ford medium-duty trucks (F-650/F-750 and Ford LCF) are of a radial-ply design. They fall into several classes of service conditions:
  • Over-the-road (highway) tires are used on paved surfaces for local and/or long distance runs
  • Mixed service tires are for use on a variety of surfaces such as pavement, gravel, dirt or other unpaved surfaces
  • All-position tires have treads that are suitable for general over-the-road operation
  • Steering axle tires usually feature circumferential grooves that equalize pressure across the tread face
  • Drive axle tires have deep treads and block-type patterns for extra traction All-season Tires Most Ford vehicles use all-season tires with a wraparound block-type tread design that offers the following benefits:
  • Increased traction in mud and snow
  • May be used year-round as standard passenger car or light truck tires Tread compounds and tire construction used with the all-season tires are formulated to convert less energy to heat when flexing compared to previous compounds. This helps reduce rolling resistance compared to previously designed steel-belted radial-ply tires. All-terrain Tires
  • All-terrain tires are available on several light trucks, primarily on 4x4 models. As their name indicates, all-terrain tires are designed for both on- and off-road use over a variety of surfaces
  • Generally, they have a deeper, wider tread design than all-season tires for better gripping on a variety of surfaces Aspect Ratio
  • Measurement of a tire’s unloaded sidewall height divided by its width
  • As an example, a tire with an aspect ratio of 75 would have a section height that is 75 percent of the tire's width
  • Lower aspect ratio reflects a shorter, wider tire that offers greater contact with the road. Dual Spacing Distance between the center lines of both tires on a dual-rear setup. Flotation Tires
  • Tires with an extra-wide tread width are often referred to as flotation tires
  • Usual applications are for off-road operation where soft sand, mud, marshy or snowy conditions are typical Offset
  • On dual wheels, the distance from the center of the rim midway between the flanges to the outer mounting face of the wheel
  • On single wheels, this is the distance from the center of the rim to the wheel mounting surface Performance Tires, All-season
  • Performance tires generally have aggressive tread designs and are distinguished by large, solid tread blocks separated by open channels to promote water drainage and prevent hydroplaning
  • A key benefit of performance tires is optimized steering response and adhesion during acceleration, braking and cornering, usually with some small penalty in ride harshness and tread noise Ply Rating (PR), Load Range (B), Load Index/Speed Designation (97V) or Standard Load Rating (SL or XL)
  • Ply rating is a standard unit of tire casing strength, based on the strength of cord plies
  • The term is used to indicate the load-carrying ability of a given tire
  • It is an index of tire strength and does not necessarily represent the number of cord plies in the tire
  • Ply rating is indicated as 4PR, 6PR, 8PR, etc.
  • Load range (B, C, D, etc.) is gradually replacing the term "ply rating"
  • Load index/speed designation (92T, 97H, 97V, etc.)
  • P-metric passenger-type tires are offered with a standard load rating (SL — up to 35 psi) or extra load rating(XL — up to 41 psi)Radial-Ply Tires Type of tire that has one or more rubberized plies of cords running from bead to bead at right angles to the tread and parallel to each other, plus two or more plies of reinforced belts that encircle the tire under the tread. Rim Width Distance between the inside surfaces of the rim flanges. Speed Designations Tires are laboratory wheel-tested at specified load and inflation pressure for the speed designation. R-rated tires are specified for speeds up to and including 106 mph S-rated tires are specified for speeds up to and including 112 mph T-rated tires are specified for speeds up to and including 118 mph H-rated tires are specified for speeds up to and including 130 mph V-rated tires are specified for speeds up to and including 149 mph Z-rated tires are specified for speeds over 149 mph NOTE: Speed designations are for reference only. Actual speed capability of tires may change in vehicle applications. Tire Clearance to Vehicle Distance between the tire sidewall or tread and the nearest part of the vehicle's chassis, suspension or body. Tire Loaded Radius
  • Distance from the center of the wheel to the road with tire loaded to rated capacity
  • Static radius applied when vehicle is at rest Tire Revolutions per Mile Term used for the number of times the tire revolves when traveling one mile. Tire Section Width Maximum outer width of an inflated new tire from sidewall to sidewall, exclusive of ribs, bars, decorations, etc. Track Width Lateral distance between the centers of the front or rear tires. Unidirectional Tires Tread pattern designed for rotation in the direction indicated on the sidewall and used in some performance tire designs, e.g., Goodyear Eagle VR60 tires.

Tire Pressure Monitoring System (TPMS)

  • TPMS uses a tire pressure sensor mounted to a metal band in the wheel’s drop well
  • Sensors use radio frequency transmitters to send tire pressure information to the vehicle’s onboard computer
  • The computer illuminates a warning light and sounds an audible tone when tire pressure is significantly low
  • System is completely hidden from sight and uses a standard rubber valve stem
  • Can be used on steel or aluminum wheels
  • Replacing the tire can be easily done without removing the sensor
  • TPMS provides a more accurate tire pressure reading because it measures actual tire pressure as opposed to wheel speed like the Low Tire Warning System
  • Senses temperature-based pressure loss where all four wheels are affected
  • Resetting the system is easy. Once cold tire pressure has been restored to its recommended level, TPMS-equipped vehicles simply need to be driven over 20 mph for at least 2 minutes to be reset


  • Turning or twisting force that produces rotation, expressed in pound-feet (lb.-ft.)
  • Torque affects the vehicle’s performance when accelerating, when carrying heavy loads or when towing a trailer
  • See Torque Rating How torque is generated in one cylinder of a four-stroke engine
  • Combustion of gas in the cylinder creates pressure against the piston
  • That pressure creates a force on the piston that pushes it down
  • The force is transmitted from the piston to the connecting rod, and from the connecting rod to the crankshaft
  • The point where the connecting rod attaches to the crankshaft is some distance from the center of the shaft
  • The horizontal distance changes as the crankshaft spins, so the torque also changes since torque equals force multiplied by distance

Torque Converter

  • Device in an automatic transmission/transaxle that transforms mechanical power (torque) from the engine into hydro kinetic (fluid) power to the transmission.
  • Torque converter serves as a hydraulic clutch
  • Engine is mechanically linked to an impeller, which is made up of a series of blades within a housing filled with transmission fluid
  • Impeller responds directly to engine speed, which transfers energy to the fluid
  • Turbine, which consists of a separate series of blades, absorbs this fluidic energy and transmits power to the transmission
  • This mechanism allows for a smooth transfer of power from the engine to the transmission

Torque Rating

Measure of an engine's power capability whereby the amount of twisting or rotating effort being exerted on the crankshaft is expressed in pound-feet (lb.-ft.) of force. The unit "pound-foot" represents the force of one pound acting at a right angle to the rotating crankshaft at a distance of one foot in length. Torque is what gets the vehicle moving and horsepower is what keeps the vehicle moving.

Torque Steer

  • Unwanted imbalance of driving force between the front wheels of a front-wheel-drive vehicle that causes the car to pull to the left or right under heavy acceleration
  • Driver senses torque steer as a turning force at the steering wheel when the vehicle is accelerating from a start. Under normal driving conditions, torque steer is virtually eliminated in Ford vehicles

Torsion Bar

Spring consisting of a long solid or tubular rod with one end fixed to the chassis and the other twisted by a lever connected to the suspension.

Traction Control — All-Speed

All-Speed Traction Control uses a combination of brake and/or engine control to maximize available traction on slippery or loose driving surfaces.

Traction-Lock (Limited-slip)

Rear-wheel-drive mechanical system that operates within the differential. Traction-Lock provides added traction on slippery surfaces, particularly when one rear drive wheel has poor traction. Limited-slip is not offered on front-wheel-drive vehicles.

Tractor Brake Control Valve

Mechanism added to a tractor or trailer brake system that safeguards the air supply on the towing unit and automatically applies the brakes on the trailer if it accidentally becomes separated.

Trailer Hitch

There are two types of trailer hitches:

Trailer Sway Control

  • Works in conjunction with the AdvanceTrac® or AdvanceTrac® with RSC® (Roll Stability Control TM) system to help maintain vehicle/trailer stability while towing a trailer
  • Measures the yaw motion of a vehicle and applies brake force to individual wheels, and if necessary, reduces engine power to help the driver regain control of the vehicle/trailer
  • If equipped with the Integrated Trailer Brake Controller, the trailer brakes will also be activated to reduce the sway condition and help the driver regain control of the vehicle/trailer

Trailer Tongue Load

Weight in pounds that a trailer (loaded or unloaded) exerts directly on the hitch ball attached to the towing vehicle. This load is considered in maintaining the loading limits of the vehicle.

Trailing Arm

Suspension element that consists of a longitudinal member that pivots from the body at its forward end and has a wheel hub rigidly attached to its trailing end. Similar to a semi-trailing arm, except that its pivot axis is perpendicular to the car's longitudinal center.

Trailing Link

Suspension link mounted ahead of a wheel and aligned to resist longitudinal motions in the wheel.

Transfer Case

An auxiliary device on a four-wheel-drive vehicle that allows power to be delivered to front and rear differentials.


  • Transaxle
  • Power-transmission device, attached to one end of the engine, combining the functions of the transmission and the drive axle (final drive and differential) into a single assembly
  • Typically used on front-wheel-drive applications Transmission
  • Metal case containing an assembly of shafts, gears and related parts used to transmit power from the engine to the drive shaft or final drive of an automotive vehicle; provides different gear ratios as well as Neutral and Reverse. May be manual, automatic or continuously variable. Typically used on rear-wheel-drive applications Manual Transmission/Transaxle
  • System in which gears are selected by the driver by means of a hand-operated gearshift lever and afoot-operated clutch
  • Manual transmissions are typically 5-speed, but high-performance vehicles often use a 6-speed manual Automatic Transmission/Transaxle
  • Automatic transmissions have hydraulically operated gear sets that require no gear shifting or clutching by the driver
  • Gears are shifted automatically through the use of hydraulics and electric signals from an on-board computer
  • A series of gears are applied as the need arises. This need is determined by vehicle weight, load and demand placed upon the performance system
  • Automatic transmissions come in 4, 5 and 6 speeds. The highest gear is for overdrive Electronically Controlled Continuously Variable Transmission (eCVT)
  • Used exclusively in the Escape Hybrid
  • Uses an electronically controlled planetary gear set that includes the traction motor and power management electronics in one compact assembly
  • Planetary gear set can vary the distribution of power between the gasoline engine and the electric drive system or both, depending on driving conditions
  • There are no defined gear "steps" as in a conventional transmission
  • The planetary gear set allows the gasoline engine to operate at its most efficient or powerful engine speed relative to the vehicle's speed. This contributes to efficiency and performance

Transverse-mounted Engine

  • Power train layout design in which the engine crankshaft centerline is aligned parallel to the drive axle (s)
  • Engine is mounted sideways in the engine compartment, usually allowing additional interior room

Tuned Intake/Exhaust Systems

Intake and/or exhaust systems that harness the pressure pulses and resonances inside various passages and chambers in the intake and exhaust manifolds to increase the flow of the intake charge into and out of the combustion chambers.


A supercharger that is driven by a turbine turned by exhaust gases from the engine.

Turning Diameter

Combination of the proper front axle equipment results in an important performance specification. The turning diameter will be of significance to the individual owner as well as the fleet operator. The turning diameter is defined as the diameter of the outside track made by the outside front tire during the shortest turn. The diagram shows the diameter made by the outside edge of the bumper during the shortest turn. Note: When comparing competitive truck specifications, note whether they spec a diameter or radius dimension.

Twin I-Beam Suspension

See Suspension Systems — Front.

Ultra Low Sulfur Diesel (ULSD) Fuel

  • Diesel fuel with a maximum sulphur content of 15 parts per million (ppm).
  • The Environmental Protection Agency (EPA) has mandated this fuel must be used in new model year 2008diesel engines
  • This mandate does not apply to carryover engines like the 6.0L Power Stroke® V8 turbo diesel currently in use in many Ford E-Series trucks


  • Under steer is a condition that occurs when a vehicle turns at a smaller angle than the steering wheel input because of front tire slippage. When this occurs, the steering wheel must be turned at a greater angle to achieve the desired turn. Under steer will be affected by the amount of wheel turn lock-to-lock as well as the vehicle's weight and the speed of the vehicle when encountering turns
  • Over steer occurs when the vehicle turns more than steering wheel input and is indicated by rear tire slippage. It can make the vehicle hard to control. Because of this, engineers often design suspensions that tend toward under steer as a safety measure

Unitized Body Construction (Unibody)

  • With unitized body construction, the front, rear and side rails are welded together with the floor pan, cross members and torque boxes to form a single "unit," whereas body-on-frame construction has two pieces, the body and the frame
  • Commonly used for car and mini van construction in which a solid robust frame is not required
  • Provides an advantage of less vehicle weight that helps contribute to performance and fuel economy

Unsprung Weight

  • Components such as tires, wheels and brakes are not supported by the suspension and are considered unsprung weight
  • Reducing unsprung weight improves ride and handling by allowing the tires to respond more rapidly to road irregularities
  • Independent rear suspension reduces unsprung weight by attaching the differential to the chassis rather than solidly mounting it with the axle

Variable Cam Timing

  • Variable camshaft timing allows the valves to be operated at different points in the combustion cycle, to provide performance that is precisely tailored to the engine’s specific speed and load at that instant
  • The power train control module (PCM) directs solenoids to alter the oil flow in the hydraulic cam timing mechanism, which rotates the camshafts in relation to their drive sprockets
  • The unit can shift between fully advanced and fully retarded in milliseconds
  • The result is enhanced efficiency under low-load conditions, such as at idle or highway cruising, and increased power for brisk acceleration or times of high demand
  • Variable valve timing reduces pumping losses, the work required to pull air in and push exhaust out of the cylinder

Variable-rate Coil Spring

  • A coil spring operating with a variable number of active coils
  • Under load, some of the coils will come in contact with one another, thereby becoming inactive– Process is controlled by the wire diameter of each coil, which is continuously variable for approximately one-third the total number of coils– Increases the stiffness of the spring in proportion to the load


  • Abbreviation for Vehicle Identification Number
  • Refer to for specific information

Viscous Coupling

  • Fluid coupling in which the input and output shafts mate with thin, alternately spaced discs in a cylindrical chamber filled with a viscous fluid that clings to the discs, thereby causing them to resist the speed differences between the two shafts
  • Used to limit the speed differences between two inputs on a differential or between two axles on a vehicle

Weight Definitions — Actual Weights

  • Curb Weight
  • Weight of the vehicle including standard equipment, oil, lubricants and a full tank of fuel. Does not include optional contents or other optional equipment, the weight of driver, passengers or cargo Option Weight
  • Weight of any added equipment not included in the base curb weight Passenger Weight
  • Defined as 150 lbs. multiplied by the number of seating positions, including the driver, that the vehicle can carry Payload
  • Gross payload is defined as the weight of all passengers, options and cargo
  • Net payload is defined as the weight that can be placed in the truck after subtracting for passenger and optional equipment Gross Vehicle Weight (GVW)
  • Weight of the vehicle including passengers, options and all cargo Trailer Weight
  • Weight of a trailer including all attachments, lights, etc. Gross Combination Weight (GCW)
  • Gross Vehicle Weight plus the trailer weight Gross Axle Weight
  • Weight loaded on the front or rear axle Tongue Weight
  • Amount of the trailer’s weight that presses down on the trailer hitch (usually 10–15 percent of the trailer’s weight ,approximately 25 percent for fifth-wheel applications)

Weight Distribution

Portion of a vehicle’s total weight that will be supported by each axle and each tire. Proper distribution of vehicle weight is critical to braking, handling and to the service life of components such as axles, springs, bearings and tires.

Weight Ratings

  • Weight ratings are not actual weights, they are ratings that must be adhered to when the vehicle is in use. Payload Rating
  • Advertised payload rating. It is the maximum allowable payload for the truck Allowable Weight
  • Maximum amount of weight that can be placed in the vehicle after subtracting allowances for passenger sand options Gross Vehicle Weight Rating (GVWR)
  • Maximum allowable weight of the loaded vehicle with payload Gross Axle Weight Rating (GAWR)
  • Maximum allowable weight to be placed on an individual axle. Gross Axle Weight Ratings are provided for both front and rear axles Gross Combination Weight Rating (GCWR)
  • Maximum allowable weight of the vehicle, its trailer and all associated passengers, cargo and equipment NOTE: Actual weights should never exceed the listed weight ratings. Remind customers that exceeding the recommended weight ratings could disqualify their warranty coverage.

Weight-carrying (Non-weight-distributing) Hitch

  • Commonly used to tow small- and medium-size trailers

Weight-distributing Receiver Hitch

  • Used in conjunction with a hitch platform (receiver), distributes tongue weight to all towing vehicle and trailer wheels
  • Required for certain Class III and all Class IV applications
  • Weight-distributing hitch platforms are welded or bolted to the vehicle frame. Bolt-on types are recommended because they can be removed
  • Properly installed bolt-on weight-distributing hitch platform will not weaken the vehicle or underbody as heat from welding might
  • Equalizing arms are connected from the hitch to the trailer’s A-frame and are adjusted for best towing performance. Lengths of chain are pulled up and tightened to bend spring bars upward, which lifts some of the weight from the rear wheels and transfers weight to the other wheels of the vehicle and trailer


Distance between the center points of the front and rear wheels.


Vehicle’s rotation about its vertical axis. Excessive yaw rate is often referred to as fishtailing.

Yield Strength

Maximum amount of stress in pounds per square inch to which a frame may be subjected through loading and return to its original shape upon removal of the stress with no deformation.