ALTERNATOR
This unit converts the 12-volt DC (Direct Current) from the battery into AC (Alternating Current) at the rate of 13.8 to 14.2 volts, which is necessary to operate your car's performance and electrical systems.

ANTIFREEZE
A chemical solution (Ethyline glycol) that lowers the freezing point and raises the boiling point of the engine coolant.

ANTILOCK BRAKING SYSTEM (ABS)
When ABS-equipped brakes are pressed hard (for instance in the case of a panic stop) the ABS system pumps the brakes up to 30 times per second to prevent them from locking up. ABS helps the driver maintain control and stop the car in a straight line, rather than spinning out of control.

ANTI-ROLL BAR
A suspension component that reduces body roll.

AUTOMATIC TRANSMISSION
A transmission where the gears are shifted automatically by a computer though the use of hydraulics and electricity.

AXLE
A steel shaft that connects the differential to the drive wheels.

AXLE WRAP
Oscillatory rotation of a solid axle about its axis due to driving or braking torque, usually when located by a leaf spring.

AUTOMATIC HUBS
Some drive systems require manual "locking in" of the front wheels in order to drive in 4 wheel drive, because they freewheel when the 4 WD is not engaged. On vehicles equipped with automatic hubs, "locking in" the front wheels requires only the flip of a switch.


B

BALL JOINT
A flexible ball and socket joint used primarily in front suspensions.

BEAM AXLE
A rigid axle supporting the non-driven wheels.

BELTLINE
The line that separates a car's greenhouse from its lower body.

BRAKE FADE
The vehicle takes longer to stop the second or third time brakes are applied due to a buildup of heat in friction surfaces.

BRAKE FLUID
A hydroscopic fluid (absorbs water) with a high boiling point, used in hydraulic brake systems.


C

CALIPER
A device consisting of two plates lined with brake pads that press against the sides the disc rotor to slow it's rotation.

CAMBER
Inclination of a wheel outward with respect to the body.

CASTER
Inclination of the steering axis in the longitudinal plane.

CATALYTIC CONVERTOR
An emissions control device that is part of the exhaust system. Its purpose is to reduce harmful tailpipe emissions caused by the engine. The catalytic converter lowers exhaust emissions by creating a catalysis (chemical reaction) within itself. Here is how it works: Hot exhaust gas flows through the converter, which is filled with sulfur or platinum balls. The sulfur or platinum heats up to combustion temperatures, thus burning any unburned gases that might be in the exhaust flow, reducing tailpipe emissions.

CHASSIS
The frame of the car which provides the strength and serves as the foundation of the vehicle. The body, engine, drivetrain components, and suspension are attached to the chassis.

CLADDING
Protective and decorative panels along the lower body.

CLUTCH
A coupling device used to engage or disengage the flow of power from the engine to the transmission.

CLUTCH-STARTER INTERLOCK
A safety device that prevents a car from being started while it's in gear. The clutch must be depressed for the engine to start.

CONTINUOUSLY VARIABLE TRANSMISSION (CVT)
An automatic transmission that uses belts and pulleys instead of gears wheels to allow an infinite number of gears.

CRUMPLE ZONE
Front and rear portions of a vehicle's body that are designed to crush progressively to better absorb the energy of a crash.


D

DAYTIME RUNNING LIGHTS (DRLs)
Lights that automatically turn on when the vehicle is started.

DETONATION
Rapid, uncontrolled fuel combustion in the combustion chamber, which can cause severe engine damage.

DRIVETRAIN
The components that are responsible for transferring power to the drive wheels of your vehicle. Some of the major components in the drive train include: transmission, differentials, transfer case, drive shafts and half shafts wheel bearings, and universal joints.


E

EXPANSION VALVE
A valve designed to meter the flow of refrigerant in the vehicle's air conditioner, based on the heat load it senses coming from the evaporator core.

EVAPORATOR CORE
The cold air that comes from your car's air conditioner comes from this core. A chemical is pumped through the evaporator core (which is much like a small radiator or heater core). The evaporator carries the cold chemical into the car where an interesting exchange takes place ... the chemical exchanges cold air for hot air! It literally saps the hot air out of the car by absorption. The cold air that is radiated from the evaporator is then blown into the car's ventilation system, cooling you down. Dehumidification also takes place during air conditioning. Ever wonder where all that water comes from that drips under your car? Now you know!


F

FASCIA
The front of a vehicle - grille, headlights, bumper and valance.

FLAT RATE
A method of payment for the work of automotive technicians. If an operation calls for a time frame of two hours (called the "flat rate" for that job), than the labor charge will be 2X the shop's hourly rate. If the technician is proficient at this particular operation and is able to do it in half the time, the customer still pays for two hours of labor, and the tech earns two hours of pay for one hour of work. Conversely, if the tech does the job in more than the allowed time, the customer still pays for two hours. This method of payment holds a standard hourly rate for the customer, and yet rewards high skilled technicians.

FLOORPAN
The largest stamped metal part in a car's body, it forms the floor and also provides the attachment points for many of the car's mechanical parts.

FLYWHEEL
A metal disc bolted to the end of the crankshaft. The inertia of the spinning flywheel while the engine is running smooths the engine's operation.

FOUR-WHEEL DRIVE
Three sub-terms are defined under this heading: Full time 4WD, Part Time 4WD, and Permanent 4WD. FULL TIME 4WD: The most commonly used 4 WD system on the market. Full time 4WD offers both a two-wheel drive mode for summertime driving or dry-road conditions, and an automatic 4WD mode for changing road conditions. There is also 4WD high and 4WD low modes for when the going really gets tough. The automatic 4WD mode makes this system convenient for many drivers. In addition to the transmission and transfer gearbox, a center differential is used to couple the front and rear wheels. The differential allows the front and rear wheels to turn at different speeds as needed, letting the full time 4WD work automatically. Very simply, when engaged in automatic 4WD on a dry straight road, the system operates in two-wheel drive. When the wheels start to spin due to slippery road conditions, the system reacts by progressively locking the front and rear wheels together to optimize traction. This system is limited in that it requires the driver to determine when to engage it. PART TIME 4WD: This is the most basic of all 4WD systems. It gives the driver the ability to choose when to drive in two-wheel drive or 4WD. This is all good and well, until you realize that you really can't engage the 4 WD on pavement unless it is very, very slippery. That is because, when you engage 4WD with this system, you lock the front and rear wheels together through the transmission and transfer gearbox. This is great for straight-ahead traction on very slippery surfaces. However, on dry pavement it makes for odd driving, cornering, and handling characteristics. Also, you can harm the drive train components by driving in 4WD for extended periods while on dry pavement. So why choose this type of system? Three reasons: 1. It is less costly to build and therefore to purchase 2. It is often very durable under heavy stress 3. When you don't need 4WD, you can disengage it. PERMANENT 4WD: This system is similar to full-time 4WD, but it has no two-wheel drive mode. The vehicle is always in 4WD, so you don't have to determine whether conditions are right to engage it. It still has transmission, transfer gearbox, and center differential coupling the front and rear wheels. The only difference is that torque (power) is constantly being applied to all the wheels, giving maximum traction in all weather and road conditions. Current systems have high and low modes for when the going gets tough. However (and most importantly), the system does the thinking for you. It automatically applies as much lock up (to all the wheels) as necessary for maximum traction.

FUEL INJECTION
Fuel injection is an electronic fuel delivery system that increases performance and fuel economy. It achieves this by monitoring engine conditions and providing the correct air/fuel mixture based on the engine's demand. Unlike a carburetor, which mixes fuel and air together before loading it into the intake manifold (and ultimately, the cylinder intake port), fuel injection injects the fuel directly into the combustion chamber through the cylinder head. This enables more precise control over the quantity and air/fuel mix, thus delivering optimum performance and economy. The need for a carburetor is eliminated, as well as the need for complex and imprecise tuning.


G


H

HORSEPOWER (HP)
The standard unit of measurement of an engine's power. One horsepower is the amount of energy needed to lift 550 pounds one foot in one second.


I


J


K

KNOCK SENSOR
A sensor that detects the point of detonation in the engine's cylinders. The knock sensor sends this information to the car's computerized engine-control system, which makes adjustments to keep the engine operating near its detonation limit and running more efficiently.


L

LIMITED-SLIP DIFFERENTIAL
A differential that detects slippage in one wheel and sends torque to the other wheel which is not spinning. It operates automatically.

LOCKING DIFFERENTIAL
Locks both wheels on the axle, forcing them to turn together and allowing for maximum traction.


M

MASTER CYLINDER
The hydraulic pump that pushes the brake fluid through the brake lines, ultimately applying the brakes.

MCPHERSON STRUT
A component that combines a coil spring and a shock absorber.


N


O

OCTANE
The measure of the anti-knock properties of gasoline. The higher the octane number, the less likelihood of knocking.

OVERDRIVE
A gear ratio that reduces engines RPMs at highway speeds, thus improving fuel economy.


P

PILLAR
The roof supports on either sides of a car's windshield.

POWER STEERING
A system that uses a hydraulic pressure booster to reduce steering effort.


Q


R

RACK AND PINION STEERING
This steering system allows for more responsive handling and is found mostly in newer cars. It consists of a steering shaft that is controlled (or turned) by the steering wheel. At the end of the shaft there is a small gear called the pinion gear. The pinion gear meshes with a toothed bar called the rack. This bar is connected to the steering linkage (tie rods) that control the two front wheels. When the steering wheel is turned right or left, the rack is moved right or left, resulting in the steering of the vehicle.

RADIAL TIRE
A type of tire in which the cords of the body plies run at right angles (radially) to the tire's centre line.

RECIRCULATING-BALL STEERING
A steering mechanism which uses a worm gear that meshes another gear that actuates the steering arm. Ball bearings in a recirculating track reduce friction between the two components.

ROCKER PANEL
The lower portion of a car's body between the front and rear wheel openings.

ROTARY (WANKEL) ENGINE
A variation of the internal combustion engine perfected by Felix Wankel during the 1950s and 60s which uses a triangle-shaped rotor instead of conventional cylinders and pistons.


S

SHOCK ABSORBERS
Shock absorbers cushion road vibration and bumps. They are connected to the wheel and the car frame and are filled with oil, and sometimes air or nitrogen, to soften the shock of rough roads.

STEERING GEOMETRY
Angles at which the steering's components and related suspension parts are set. These affect handling and include camber, caster, toe-in, and trail.

SUPERCHARGER
A mechanically driven air compressor that increases the amount of air-fuel mixture supplied to the engine to increase power output.

SUSPENSION
A vehicle's suspension system is made up of the components on which the vehicle rides. These include shock absorbers, struts, springs (coil or leaf), sway bars, ball joints, control arms, or torsion bars. These parts work together to provide a smooth comfortable ride, as well as good control and handling of the vehicle. They take a beating on a daily basis and therefore wear out. This wear causes the alignment angles to go out of adjustment, which results in tire wear and poor handling. That is why it's a good practice to have alignment checks every 12,000 miles or 12 months, whichever comes first.


T

TACHOMETER
An instrument used to used to measure engine speed in revolutions per minute (RPM).

TIMING BELT
Many of today's cars are equipped with a timing belt in place of the old timing chain. The function of this small yet critical member is to keep your engine mechanically "in time." How they work: In a four-stroke internal combustion engine (intake, compression, power, exhaust) the top half of the engine must be synchronized (or in time) with the bottom half to complete the four stroke cycle. The timing belt achieves this by meshing with cogs connected to the crankshaft and camshaft. The driving of these components in perfect time achieves the four stroke cycle, producing power in the engine. The timing belt is made out of rubber and is subject to wear and tear due to mechanical and environmental conditions. The bottom line with timing belts is to have them checked every 25,000 miles and replaced every 50,000 miles. Telltale signs of a failing belt are cracks, cuts, worn or broken teeth, and deterioration from wear and exposure to harmful fluids and/or high temperatures. If the belt's teeth are gone, the valve timing can be affected by either excessive advancement or retardation, resulting in poor engine performance. If the belt breaks, major engine damage can occur on some engines.

TRACTION CONTROL
Traction control is an option on many cars today. When engaged, it "senses" when a driving tire has no traction. The system will then conpensate for this by slowing the spinning wheel through partial application of the brake. The system uses wheel speed sensors to monitor the wheel speed. When traction is lost, the sensor prompts the brake computer to partially apply the brake to the wheel that is spinning, allowing it to gain traction. I call it "Antilock brakes in reverse." This system improves traction in areas where it may normally be hard to do so (snow, gravel, and rain). Traction Control has its origins in Formula 1 Racing where optimum traction is a must for safety and maximum performance.

TRANSAXLE
A combination of transmission and differential found in front-wheel-drive vehicles. The differential is inside the transaxle, and the drive axles are connected through constant velocity joints (CV joints) to the wheels.

TRANSFER CASE
An auxiliary gearbox attached to the transmission, which allows you to shift into a high and low range for serious pulling.

TURBOCHARGER
Similar to a supercharger but powered by exhaust gases.


U

UNIVERSAL JOINT
A joint that transmits rotary motion between two shafts that are not in a straight line.


V

VALVE
A valve is a device that is controlled mechanically or electrically to meter or prevent the flow of a liquid or gas. Most internal combustion engines use intake and exhaust valves to control the flow of the air/fuel mixture into the combustion chamber and to exhaust burned gases. Some engines have up to four valves per cylinder to increase efficiency and performance. Valves are used in other automotive applications as well. Cooling systems, transmissions, and air conditioning systems use valves where metering of a liquid or gas is necessary.

VALVE BODY
The valve body is the brain of the transmission. Up and down shifting is controlled by the valve body through hydraulic pressure and electronic commands from the vehicle's performance system. The valve body directs the flow of transmission oil to where it is needed in order for the transmission to perform a function (for example, the application of "passing gear"). The environment within which the valve body operates must be sterile. Varnish buildup and wear material can clog the valve body, causing erratic shift patterns of the transmission. This is why the transmission fluid and filter should be changed every 30,000 miles.

VALVETRAIN
The components which cause the valves to open and close, including the camshaft, tappets (or, cam followers), pushrods, rocker arms, valve springs and valves.

VEHICLE IDENTIFICATION NUMBER (VIN)
A 17-digit combination of letters and numbers unique to each vehicle. It is located on the driver's side of the dashboard at the base where the windshield glass and dashboard meet.

VISCOSITY
The resistance to flow of a liquid, such as motor oil.


W


X


Y


Z