The Automotive Terms Glossary

Active noise control (ANC): A program used to control noise in the engine. To achieve this, a loudspeaker is installed in the intake system, and this generates a sound wave of the same amplitude, but it has an opposite phase. In essence, it cancels out the noise in the engine.

Adaptive cruise control (ACC): An adaptive cruise control system can actually scan the area for large objects in front of the car. The car brakes automatically if the object is close enough for a collision.

Antilock braking system (ABS): Antilock brakes keep the brakes from locking up when they are pressed on suddenly. The brakes actually “pump” themselves on icy or wet roads so that the driver doesn’t have to.

Aspirator Valve: The aspirator valve helps oxidize HC and CO and supplies additional air to the catalytic converter by use of a one-way valve. This valve is attached to the exhaust system of the engine. Sometimes an aspirator valve is used rather than a belt-driven air injection pump.

Automated clearance sensing: Allows high vehicles to clear low objects such as bridges or tunnels. It employs commercial vehicle operations (CVO) technology.

Automatic Transmission: A transmission that uses a torque converter instead of a manually-operated clutch to shift gears.

Axle, Front: The front axle supports the weight of a truck with a crossbeam. It is usually connected to the spindle with king pins.

Axle, Rear: The rear axles can connect both rear wheels to the center differential in the case of a real-wheel drive car. In the case of a front-wheel drive vehicle, it is a crossbeam that connects the rear wheels to support the back of the vehicle.

BabySmart: Technology that allows for detection of a child in a seat so that an airbag will not fire at full capacity. This was developed by Mercedes-Benz and is called child seat presence orientation detection (CPOD).

Backfire: A explosive sound caused by a combustion of gases in the exhaust system.

Ball Joint: A ball and socket that is contained in a vehicle’s suspension system. It connects the control arm to the steering knuckle, and the wheels can become misaligned if the joint becomes loose.

Battery: The battery is the storage cell for the electrical energy needed to start the engine of the vehicle. All cars, and most trucks, use a 12-volt battery, and most are maintenance-free. Sometimes, if a vehicle won’t start, a battery can be jump-started with the battery of another vehicle.

Bearing: A support between a stationary and moving part to reduce friction.

Bluetooth: A communications system that allows your mobile devices, headsets, radios, and digital assistants to connect wirelessly to that they can be used hands-free. This is especially relevant when driving a vehicle.

Bonded Lining: Friction material, or brake lining, and adhesive that is attached to the brake shoe.

Boots: The protective covers that surround CV joints. They are made of protective rubber or hard plastic called Hytrel.

Brake Drum: A circular metal component that rotates and is the basis of the drum brake system. It rotates with the road wheel, which is a set of fixed braked shoes that act on the drum by expanding.

Brake Fluid: The fluid that is used to moisturize brakes. Brake systems use a glycol-based hydraulic fluid and absorbs moisture over time. There are several different types of brake fluid: DOT 3 or DOT 4 is used in cars and light trucks; DOT 5 is silicone-based and cannot be used with anti-lock brakes.

Brake Hose: A rubber hose that is used to join brake components.

Brake Lines: The hoses and tubes through which brake fluid flows from the master cylinder to the brakes at each of the wheels. Leakage of brake fluid from cracks in brake lines can be one cause of loss of brakes.

Brake Pad: A pad used for lining with disc brakes consisting of a brake shoe and the lining.

Brakes: Brakes stop a vehicle using hydraulic pressure when the brake pedal is pushed. This action of pushing down the pedal pumps fluid from the master cylinder to the brakes, which are placed at each wheel. The brake linings squeeze against the rotors and drums; friction is created; and the vehicle is stopped.

Caliper: A device that holds a piston and two brake pads and is hydraulically activated to force the pads against a rotor to stop a vehicle.

Casing: The body of a tire, or carcass. It is made of plies that form the structure to give it shape.

Caster: This is considered the angle between the steering axis and a vertical line. It is measured in degrees and minutes and is viewed from the side.

Catalytic Converter: A device that converts harmful byproducts from an exhaust system into carbon dioxide and water vapor. This is done through a heat-producing chemical reaction.

Check Valve: A valve that is used to permit only one-directional flow of air or fuel.

Coolant: Made of ethylene glycol, coolant is used in vehicles to lower the freezing point of water in the cooling system. This prevents parts of the pipes from freezing and lubricates the water pump.

Diesel Fuel: Diesel fuel is a heavier fuel than gasoline, in fact, it is almost an oil. It is used in heavier trucks, jet planes, and even some automobiles. It has a slower evaporation rate and is cheaper than gasoline.

Direct Injection Engine: An engine that used Direct Injection allows the fuel to be injected directly into the combustion chamber, above the piston. Smaller diesel engines have just recently begun utilizing this technology, but large diesels have been using it for a long time. The process allows for cleaner emissions, less burn-off on operation, and increased full-throttle power.

Disc Brakes: This system uses a rotor that rotates at the same speed as the wheel, and a caliper lined with brake pads straddles it. Small pistons that squeeze against the disc to slow it down and stop it operate these. These are more efficient than drum brakes during high temperatures and in wet conditions.

Drive shaft: The drive shaft is responsible for getting the power from the transmission to the differential. Vehicles with four-wheel drive have two drive shafts at least, one to the front differential, and one to the rear differential.

Drive train: The drive train refers to all the vehicle parts that produce power and get the power to the wheels. This includes the transmission, engine, drive shafts, transfer case, differentials, axle shafts, and wheel hubs.

Drum Brakes: A drum brake uses cylindrical, cast iron housing that contains curved brake shoes that are forced into contact with an inner drum to provide braking to stop a vehicle. They are simple and effective, but less effective than disc brakes under harsher conditions. Many times drum brakes will be used on the rear brakes and disc brakes on the front.

Dual Exhaust System: With a dual exhaust system, there is “breathing” capacity in the engine, and there are less exhaust gases in the engine at the end of each exhaust stroke. This lowers the back pressure, and there is a sizable increase in horsepower above a traditional engine.

Exhaust Pipe: A stainless steel pipe usually located under the car and out the back or side that connects to the muffler and catalytic converter to get the exhaust fumes from underneath the car.

Fuel Injection: A system that injects fuel directly into the cylinders of an internal combustion engine to avoid the need for a carburetor.

Fuel Pump: The fuel pump delivers fuel to the engine. It must maintain proper pressure in the carburetor and pump so that the fuel doesn’t boil, and it helps to prevent vapor lock. Fuel pumps generally deliver a minimum of ten gallons of gasoline per hour.

Gas Pedal: The gas pedal is what the driver pushes with his foot to make the car go. It is connected to a throttle valve by a cable. When the driver pushes down on the pedal, the valve opens, and the engine speed increases. When the pedal is released, the car slows.

Gaskets: Gaskets are used along with seals to keep joints fit and tight. This keeps fluids and gasses in the engine from leaking.

Global positioning system (GPS): GPS units are installed in many vehicles to help drivers navigate from one destination to another. They employ satellites maintained by the U.S. Department of Defense to provide audible turn-by-turn directions for drivers as they travel. For those who do not have the devices installed in their vehicles, portable GPS units are also available, and these can be mounted on the dash.

Hazard Lights: Hazard lights are used when a car needs to pull over or park in an area that is not usually designated for parking. A knob or button causes all front and rear signal lamps to light and flash together.

Horsepower: Horsepower measures the rate of mechanical work by a particular device, often an engine. One horsepower (or hp) is the power needed to life 33,000 pounds one foot in one minute.

Hybrid Electric Car: A hybrid electric car gives a driver the gas economy of an electric car when driving in town and the performance and power of a gas-powered vehicle in a rural setting.

Independent Suspension: A suspension system in which each wheel reacts independently to bumps, each on a separate axle. This is opposed to a non-independent suspension system which uses a solid beam axle to connect the two wheels.

Manual Transmission: Manual transmission requires the driver of a vehicle to press a clutch in order to change the “speed” of the vehicle, or the speed of the engine in relation to the speed of the wheels. Varying these gears allows the right amount of power at the right speeds while driving.

Oil Filter: Oil filters strain dirt and grit out of the oil before it runs through the engine. This reduces the wear on engine parts and helps reduce the possibility of acids forming.

Oil Pump: The oil pump is used to pump oil to the engine. There are several types of oil pumps, but the most common are gear and rotary pumps.

Parking Brake: The parking brake is used when the vehicle will be in one place for a long period of time. Rather than utilizing hydraulic pressure, a mechanical linkage is used for the brake shoes, and a steel cable pulls the tension levers. This draws the brake shoes firmly against the drums. This will hold the brake continuously in the applied position.

Power Brakes: Vehicles use power brakes so that drivers do not have to exert as much pressure to stop the vehicle. There are four types of power brakes: vacuum-suspended, air-suspended, hydraulic booster, and electro-hydraulic booster. They work by allowing the pressure on the brake pedal to exert pressure onto a rod that is connected to the pistons of the two master cylinders which force fluid into the front and rear brake lines. Simultaneously, the brake-pedal positions the vacuum control valve to seal off half of the booster unit. This creates a low-pressure vacuum chamber. The atmospheric pressure in the control chamber applies more pressure on the pistons.

Radiator: The radiator dissipates the heat from the engine. It holds water in tubes, providing a large area in contact with the atmosphere. There is a core, tubes, a large cooling area, a receiving tank, and a dispensing tank.

Shock Absorbers: A shock absorber is used to smooth out the shock on a vehicle and disperse the energy when traveling over rough terrain.

Spark Plug: The spark plug, when inserted into an engine, provides an electrical spark to ignite the fuel in the cylinder. This is done with an insulated center electrode and a side electrode spaced to provide a gap for firing a high-voltage burst. When the spark jumps the gap from one electrode to the other, it ignites the fuel in the cylinder.

Spoiler: A spoiler is a wing that comes off a car’s back in a horizontal position. It is meant to provide high-speed stability, but its usefulness only comes into play when the car reaches a speed of 100 mph. In most cases, the spoiler is cosmetic.

Starter: The starter converts electricity into mechanical energy to start the engine of the vehicle. When a driver turns on the ignition switch, a small amount of power is released from the batter to the solenoid above the starter creating a magnetic field that begins the process that starts the motor spinning. When the motor beings to spin, the drive turns the gears to provide power to the crankshift. This prepares each cylinder for ignition. After the car starts, the driver releases the ignition switch, and the circuit is broken.

Sway Bar: A sway bar is a stabilizer present on some vehicles to steady the chassis against swaying on turns. This helps control front end roll by using upward force on the outer wheel to life on the inner wheel, which keeps the car level.

Tailpipe: A long metal pipe that attaches to the muffler to exhaust fumes from underneath the car to air outside.

Transmission: A gearbox with different ratios that match the engine’s rpm to various driving speeds and situations.