Car Technical Glossary.

The leaning motion of a vehicle's body while turning into a corner. Also known as yaw angle.

The brake caliper looks almost like a normal measuring caliper and is part of the disc brake. When brakes are applied, hydraulic fluid forces the brake pads using one or several pistons in the calipers towards the discs, causing the discs to squeezed.

Any type of brake gets heated up after repeated or hard use. Apart from ceramic or any other ceramic alloy disc, all brakes diminish their effectiveness after they get heated up. This is called brake fade.

A normal differential is used in cars to help power the drive wheels while allowing them to spin independently of each other during cornering (same power, different rotational speeds). In vehicles with four-wheel drive, a center differential is required because during a tight turn all four wheels are rotating with different speeds. Receiving power from the engine through the transmission or the transfer box, the center differential regulates the power between the front and rear axles, thus allowing different rates of traveling.

A steel, aluminium or other similar material which connects the piston to the crankshaft in a combustion engine.

A coupe (or coupé) is a two or four-seater vehicle with a fixed roof and only two doors. There is no globally accepted official definition for the term though. According to SAE (Society of Automotive Engineers) standards, a coupe is a fixed-roof automobile which has less than 33 CuFt (approximately 934 liters) of interior volume. Any car with a greater interior volume is technically called a two-door sedan, not a coupe, even if it has only two doors.

The crankshaft is the part of the engine which translates the engine piston's linear motion into a more usable spinning motion. It is usually connected to a flywheel, in order to reduce the pulsating characteristic of the four-stroke cycle in the combustion engine and to the driveshaft consequently.

A crossover is a type of automobile which blends the main characteristics of at least two car segments. Most crossover cars nowadays bring together the versatility of a family car with that of an SUV.

In essence, a Continuously Variable Transmission (CVT) is a type of automatic gearbox with an infinite number of gears situated between two values (a maximum and a minimum). One of the most common types of CVT consists of a steel or rubber belt and two conical pulleys. Unlike a normal transmission, which effectively has to choose between a given number of planetary gears, the CVT just varies the diameter of the conical inner surfaces on which the steel/rubber belt rides. Most of them use either hydraulic pressure or spring tension to adjust the distance between the two pulleys. The main advantage of CVTs over conventional transmissions resides in their smoothness, since basically there is no interruption of power during the "shifting" maneuver. The main shortcoming is the amount of torque they can handle, which depends strictly to the material of which the belt is being made of. This can be neglected to a certain amount by designs which are using more complicated roller arrangements instead of belts and pulleys.

A differential is a device that can be used to do two mainly different things: either it can be used to transfer power from the transmission (or transfer gearbox in case of a 4WD vehicle) to the driving axle, or it can allow two wheels on the same axle to turn at different speeds, but using the same power.

Disc brakes are the most common and also most effective means of stopping a vehicle. This type of braking system usually consists of a disc that rotates at the same speed as the wheel to which it is attached, straddled by a brake caliper. The caliper contains brake pads which are operated by one or more small pistons that squeeze against the surface of the disc to slow it down or even stop it. Compared to the drum version, disc brakes operate much more efficiently at high temperatures and wet conditions, basically by having a more complete design.

DOHC is a valve train layout characterized by two camshafts within the cylinder head. This means that there are two separate camshafts for inlet and exhaust valves, unlike SOHC (Single Overhead Camshaft) layouts where a single camshaft operates both inlet and exhaust valves.

Downforce is the phenomenon when air pressure is pushing down on a vehicle at high speeds, thus enabling more stability and better traction. It is usually achieved by the use of spoilers and aerodynamic ground effects.

The driveshaft (also known as propeller shaft or propshaft) transmits power from the engine through the transmission (or transfer gearbox in case of 4WD vehicles) to the differential.

Also known as the powertrain, the drivetrain describes all of the vehicle's components which are used to produce and transmit power to the drive wheels. In short, the engine, transmission, driveshafts, differentials and axle shafts are all part of the drivetrain.

A drum brake is made of a drum-shaped housing (which is usually out of cast iron) that is attached to the wheel. Inside the drum there are usually two brake shoes curved around the interior that are forced into contact with the inner drum. The contact of the pads with the inner section of the drum housing provides braking. Drum brakes are very simple and generally very effective, except under heavy or hard use and under wet conditions, which is why they are less and less common on modern cars.

This is a numerical ratio of a series of gears in relation to each other, based on the number of turns of the input shaft, compared to turns of the output shaft. Gear ratios are determined by the number of teeth on each gear (and therefore the size of each gear).

Ground clearance is the measurement from the lowest-hanging point under a vehicle (usually a differential, part of the suspension or the exhaust system) towards the ground. A high ground clearance allows a vehicle to drive more easily off-road or through heavy snow without damaging the underbody.

A hatchback is a type of automobile layout, consisting of a passenger cabin which includes an integrated cargo space, accessed from behind by a hatch or a flip-up window - which is usually counted as a 3rd or 5th door. Hatchbacks are also often called three-doors (two entry doors and the hatch) or five-doors (four entry doors and the hatch) cars.

A measure of engine power.

The independent suspension is a system where each wheel can be moved on a vertical axis without influencing the other, and can react independently to bumps on the road.

The intercooler is a device used to cool the air coming into the combustion chamber on turbocharged and/or supercharged engines. This is done because cooler air produces more power, and charged engines tend to heat the intake air while it's being compressed, thus decreasing its burn and combustion chamber fill-up efficiency. Most intercoolers have an air-to-air system, air-to-liquid system, or sometimes combination of both.

ISOFIX is the name of standardized child seat anchorages used by most car manufacturers. It defines the standard attachment points to be built into cars, thus enabling manufacturer compliant child safety seats to be quickly and safely secured into the car's rear seats. On cars with a front passenger airbag deactivation option, the ISOFIX is also available for the front passenger seat.

Called "bubble cars" in the past, modern microcars are very small vehicles designed purely for city driving. Most of them have engines borrowed from scooters or use electric power, can only sit one or two passengers and are generally found in crowded cities.

The MPV (an acronym for Multi Purpose Vehicle) is a multi-passenger vehicle based on a car platform with maximized interior space. They are usually used by families and range in size from compact cars to almost van-like dimensions.

Power steering was developed in order to reduce the effort needed to steer the vehicle. In other words, the driver can change the vehicle's direction with the help of an external power source that can assist this operation. Most power steering systems employ hydraulic pressure and are operated using power from the engine, but in recent years, electro-hydraulic and even 100% electric systems have been introduced. Some modern steering systems can provide a variable amount of assist, depending on the speeds at which the vehicle is moving, while others are even using the "drive-by-wire" technology, with no direct linkage between the steering wheel and the the wheels.

Single Overhead Camshaft (SOHC) engines use one camshaft per each cylinder head to operate both the intake and the exhaust valves.

The supercharger (also known as a blower in some countries) is used to compress air into the cylinders of an internal combustion engine. It works just like the turbocharger (increasing volumetric efficiency in the cylinders) except it's not powered by the exhaust gases but by belt or chain-drive from the engine's crankshaft.

The supermini (keicar in Japan and sub-compact in the US) is a class of automobiles that covers the smallest cars. They usually have a hatchback configuration and are designed specifically for city driving.

The Sport Utility Vehicle (SUV) is a type of passenger vehicle which combines the carrying capacity of a station wagon or minivan with features like an increased ground clearance and all-wheel drive. At first they were derived from truck platforms but most of them are now using unibody construction for a lighter weight and better fuel economy.

The tongue weight is the actual force that is pressing down on the front axle of a vehicle and is strictly related to mass distribution between the axles.

Torque is rotational force, usually measured in newton-meters or pound-feet, and strongly affects acceleration and pulling power.

Designed to improve the volumetric efficiency of an internal combustion engine, the turbocharger is a forced induction device which can increase an engine's output. It is essentially a turbine driven by the exhaust gases which sucks in air and forces it into the cylinders, unlike the supercharger, which is mechanically driven by the engine's crankshaft.

Wheelbase is the distance between the front axle and the rear axle of a vehicle. Cars with a longer wheelbase are more stable at high speeds and provide better interior room, while cars with a shorter wheelbase have better city handling and are generally shorter.