Glossary of Automotive Technical Terms! The List of more than 200 Terms from which You will Upgrade your Technical Knowledge!

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The terminology of automotive technology is complex and difficult to understand because it is constantly updated. hereby we present our technical glossary with more than 200 automotive terms from which you can gain technical wisdom.

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A roof that supports the sides of the windshield.

Active Suspension

A controlled suspension systems that uses actuators to position the car wheels for good handling.

Aerodynamic drag 

A displacement of the air “hitting” your car while driving. The displacement is made by the moving vehicle in front. Pounds are used to measure the Aerodynamic drag.

Air Dam

A front shaped spoiler that lowers the amount of airflow underneath the car while driving. The Air Dam is placed beneath the bumper and can also be used to increase the air going to the radiators and reduce aerodynamic drag.


A front suspension that reduces the dive movement of the car while braking hard from high speeds.

Anti-Lock Braking System

A system that controls the breaking power to avoid brake-lock up. The ABS keeps the wheel rolling under heavy braking.

Anti-Roll Bar

A suspension controlling the body roll with resistance of unequal vertical movements between the pair of wheels. Some call it the sway bar.


The Anti-Squat is opposite of the Anti-Dive system. It induces force that prevents the car from leaning backwards under high speeds.


Small addition on road corners that allowing the car to maintain speed while turning.

Aspect Ratio

The cross-sectional profile of the tires; a low aspect ratio means wider, shorter tire.

Axle Tramp

It`s a wheel hop occurring with live axles that are caused by the axle rotating with the wheels and then springing back.


The support between the car`s rear side window and the front door window (if the car actually has one).

Balance Shaft 

A shaft which vibrating reduces the vibration of the engine, or cancels it. They are quite common when it comes to engine refinement.

Ball Joint 

A flexible joint in the front suspensions accommodating angular motion. It is constructed of a ball in a socket.

Beam Axle

A.K.A Dead Axle supports the non-driven wheels.


A running line around the body of the car that is formed by the bottom edges of the glass panels.

Bevel Gears

A gear set that allows nonparallel axes of the gears. They also transmit   motion through an angle.

Boost Pressure

The increase of atmospheric pressure made by the supercharger inside the intake manifold.

Brake Bias

The breaking power distribution to the rear and front of the car. During hard breaking, the cars traction should match the brake bias to achieve a shorter stopping distance.

Brake Modulation

A process controlling the pedal pressure under braking when the brakes are near lockup. A small reduction of the pressure that made them lock will cause the brakes to unlock.

Brake Torquing

A procedure in car tests with the goal to improve the off-the-line acceleration in automatic transmission cars.

Breathing (engine)

The ability for the engine to “inhale” air in its cylinders and then release the burned exhaust gases. The more air-fuel mixture is burned, the more power there is.


A suspension made out of two coaxial steel tubes that are bond to a sleeve of rubber between them to accommodate the limited rotary motion.


The roof support between the rear window if the car and the rearmost side window.

Cam Profile

The form of a every lobe on a camshaft.


The angle between a vertical line and the plane of a wheel`s circumference. They are measured in degrees and minutes. The negative tilts the wheels inward, and the positive tilt the wheels outward.


A shaft which lobes push the valve lifters to create a linear motion from a rotary one.    

Carbon Fiber

Pure carbon tread strands which are extremely strong and reasonably flexible. It is used to create a light but strong car`s body using vacuum and heat.


The angle between the steering axis and the vertical line when it is viewed from the side. The Caster is measured in degrees and minutes.

Catalytic Converter

A canister made of stainless-steel or a combination of palladium, rhodium or platinum, that is placed in the exhaust system of the car and contains a catalytic material able to sped to a large areas of inert supports.

Center Differential

A differential that distributes power to the rear and front differentials – it is used I the four-wheel-drive systems.


The structural frame of the car to which all the mechanical parts are attached.

Coil Spring

A spiral bar of resilient metal that can be extended or compressed with no deformation whatsoever.

Combustion Chamber

When the piston is at the top of the cylinder, the space in the cylinder is called a combustion chamber. The cavity in the cylinder head and the top of the piston form the combustion chamber. This is the space where the air-fuel mixture combustion takes place.


A resiliency in the suspension for absorbing bumps. This makes the wheel go slightly rearward when they hit a bump.


A material consisting of two or more components, where one is and adhesive binder and one or more are or high strength.

Compression Ratio

When the piston is at the bottom, the ratio between the combustion chamber and the combined volume of a cylinder with the top stroke of the piston is called a Compression Ratio.

Connecting Rod

The connection of a throw on a crankshaft with the piston is made with a meal rod called the Connecting Rod.

Constant-Velocity Joint

A joint made to prevent cyclic fluctuation between the output shafts and the speeds of its input.

Control Arm

A suspension with two joints at one end and one joint at the other end. It is also known as an A-arm or a wishbone.

Cornering Limit

The maximum car speed when driving on a curve.


A car with two doors and an interior volume of 33 cubic feet.


A coupled shafts that connect the rods to the pistons of the engine.


The cavity made of cast iron where the pistons move up and down.

Cylinder Head

The housing of the exhaust and intake ports, the valvetrain and the combustion chambers made of iron or aluminum casting.

Cylinder Liner

A circular housing where the piston moves when the cylinder is not integral part of the block.


A logarithmic measurement of decibels, pressure or sound density. The “A” in abbreviation stands for A-weight scale. With variable sound pressure, the A-weight scale will approximate the sensitivity of a human`s ear to different frequencies.

de Dion Suspension

A suspension system where the back driven wheels are bound to a lightweight, rigit and transverse member.

Dead Pedal

A footrest on the leftmost pedal that helps the driver to brace the left leg while taking hard corners.


A spontaneous explosion in the combustion chamber due to a spark that is fired in the unburned air-fuel mixture. This detonation is set off by the pressure and the heat of the air-fuel mixture.


A gearbox which splits and delivers the torque to two outputs. The differentials in the axles split the torque evenly , but a four-wheel-drive system results in an uneven differential since the torque is delivered to the rear and front axles.

Disc Brakes

A braking disk attached to the wheel which by rotating with wheel speed is able to provide efficient braking under wet conditions and high temperatures. A cliper is stranded to the brake disc near the periphery.


A dive maneuver of the car`s nose when under heavy braking. The weight of the car transfers from the rear to the front when the driver tries to quickly stop the car from high speeds.


A Double Overhead Camshaft with two camshafts – one operating the intake valves and the other actuating the exhaust valves.


A vertical force caused by the airflow around an car`s body.

Drag Coefficient

The measurement of the car`s aerodynamic sleekness.


An evaluation of the powertrain`s operating qualities, such as cold and hot starting, power delivery, throttle response, idle smoothness and altitude change tolerance.


A shaft transmitting power from the transmission to the differential.

Drum Brakes

An iron casting brake rotating with the wheel. It has a shape like a shallow drum. Braking is provided by the forced Curved brake shoes to the inner periphery of the drum.

Exhaust – Gas Recirculation

A method that reduces NOx exhaust emissions. This is done bay recalculation of the engine exhaust gas into the intake manifold. The exhaust gas absorbs the heat in the combustion process and then reduces the highest temperature that is reached.

Engine Control System

Also known as ECU – a computerized brain regulating the operation f the engine with monitoring certain characteristics, like coolant temperature, intake flow, rpm and etc. This is achieved through sensors and a control of key variables, like spark timing or fuel metering.

Exhaust Mainfold

A network that routs the exhaust gases from different exhaust ports toward the catalysts and the mufflers.

Exhaust Port

A passage from the cylinder head that goes from the exhaust valves to the exhaust maingold.

Feedback Fuel-Air-Ratio Control

A computer-controlled fuel system that uses a sensor to measure oxygen content in the exhaust. The guel-air ratio is kept to a close proportion to have a perfect chemical combustion.


A strong composite material consisting of small glass fibers.

Final-Drive Ratio

A reduction ration in the drivetrain`s gearshift which is removed from the engine.


A stamped metal part in the body of the car. It is assembled from several stampings forming the fixes dimensions of the external and structural panels of the car, as well as the floor. The floorpan is the largest as well as the most important metal part of the car.

Fluid Coupling

The transfer of fluid through any device, between its outputs and inputs. It consists of two fans in sealed housing, which is oil-filled.


Attached heavy disc to the crankshaft of the engine, used to increase the toraty inertia and smoothing the power flow.

Four Valves Per Cylinder

A four valve valvetrain in the combustion chamber; two exhausts and two intakes, allowing a closer location of the spark plug to the center of the combustion chamber and improved breathing.

Four-Wheel Drift

A term used to describe when all the flour tires operate at large slip angles while driving through corners.

Four-Wheel Steering

A system that steers the front wheels as well as the rear wheels for better maneuvering and handling.

Fuel Injection

A system that injects fuel to the engine measures the needs for fuel injecting and regulates the fuel flow by through a pump or injectors by mechanical or electronic means.


The unit to measure lateral acceleration, also known as “road-holding”.


Two or more gears used for transmitting power


The part of the car`s body that is above the beltline of the car.

Ground Effect

A downforce created by the airflow between the ground and a moving object.


A rotating shaft transmitting power to the wheel from the differential by the use of independent-suspension systems.


The way a driver controls the car on the road.


A technique when the driver uses all three pedals simultaneously of a manual transmission car. This is done by braking with the toe of the right foot while blipping the throttle with the heel and this raise the rpm of the engine with downshifting. The left, normally, controls the clutch.

Heim Joint

Also known as “spherical road-end” is a rigid articulating joint that is used for precise linkage.

Helical Gear

A gear which teeth have a slanting angle to the circumference of the gear.


An engine with hemispheric combustion chamber in the cylinder head is called a Hemi.


A measurement unit for engine power – 1 horsepower is 550 foot-pounds per second.

Hotchkiss Suspension

Live-axle rear suspension where the leaf springs handle the axle`s location and springing.

Hydraulic Lifter

A valve lifter that uses the engine`s oil pressure and simple valving to slightly adjust its length, therefore maintaining zero clearance in the valvetrain.

Independent Suspension

A suspension where the camber of wheel is not affected by the opposite wheel`s vertical motion.

Intake Charge

The mixture of air and fuel that goes into the engine.

Intake manifold

Passages that direct the air-fuel mixture or the direct air from the throttle body to the intake ports in the cylinder head.

Intake Port

The passage in the cylinder head from the intake manifold to the intake valve.


A heat exchanger that serves to cool the air which was heated by compression of supercharger. It resembles a house radiator system.


When the wheel compresses its suspension.

Jounce bumper

An elastic cushion that gradually stiffens the suspension as it reaches the end of the jounce travel.


An automatic transmission downshift as a result of depressing the throttle.

Knock Sensor

A sensor that detects high frequency vibrations as a result of detonation. A computerized engine-control system is able to allow the engine to work at the nearest point of detonation, which improves efficiency and power.

Lateral Link

A suspension link capable of resisting sideway motions of the wheel.

Leading Link

A suspension link, mounted in the chassis behind the wheel, capable of resisting longitudinal motions of the wheel.

Leaf spring

A spring steel that deflects with bending when forces act upon it. They are long, thin, flat and flexible, and can be made from different materials.


A vertical force due to airflow around a moving object.

Lift-Throttle Oversteer

When the rear tires lose cornering grip while the throttle is released under hard cornering.

Limited-Slip Differential

A differential limit in the torque and speed differences between two outputs.


The path through a corner for a vehicle to drive when it has high cornering speed,  has the opportunity to exit the corner in high speeds and is best for late braking points.


A suspension with single joints at both ends.

Live Axle

Rigid Axle incorporating axle shafts and differential for powering the two wheels that is supporting.


A lockup occurs when a tire, while under braking, starts to skid. Under maximum braking force at the verge of a lockup, the rear and front tires simultaneously lockup, which is hard to achieve under different conditions of traction and load.

Locking Differential

Two differential outputs lock together maximizing traction whli under slippery conditions.

Locking Torque Converter

A torque converter in the locking clutch that can eliminate the slip between the input and output o the torque convertor.


Also known as Oversteer.

Main Bearings

Bearings supporting the crankshaft in the engine block.


An engine that is positioned behind the passenger compartment in the chassis layout, but it is ahead of the rear axle.


A unitized construction delivering strength and rigidity from thin -- shaped joined panels.

Multileaf Spring

A several leaves spring bundled by steel bands.

Multilink Suspension

A four links rear suspension with no struts assigning specific wheel-locating duties to each element.  The provide flexibility for the handling and ride.

Neutral Steer

A neutral steer is when the rear and front slip angles are the same under cornering conditions.

On-Center Feel

The feel and responsiveness of the steering when the wheel is centered. The steering wheel returns to the center when it is slightly deflected.

Opposite Lock

When the steering wheel turning away from where the car is turning. This controls the car in conditions of oversteering.


When the output shaft of the gear set is faster in turning from the input shaft.

Overhead Cam

A valvetrain arrangement when the engine`s camshaft is in the cylinder head. The components of the valvetrain are lighter and stiffer when the camshaft is closely placed to the valves. The valves close and open rapidly and the engine develops higher rpms


When the bore of an engine is larger than the stroke


When the slip angles of the rear tires are grater than the front tires.

Panhard Rod

A lateral link, parallel to the axle, providing lateral location for a rigid axle.


A combustion chamber resembling a shallow peak roof on the upper surface.


A horizontal axis car rotation causing the tail or nose to bob up and down.

Planetary gears

A grouped gears in one plane of a gearset, like planters around the sun.

Plenum Chamber

A chamber between the runner of an intake manifold and the throttle body that is used to evenly distribute intake charge and enhance engine breathing.

Polar Moment of Inertia

When an object is resisting to a rotational acceleration. High polar moment of inertia is when a mass of an object is distributed far from the axis of rotation.

Port Fuel Injection

A fuel injection with one injector (at least) in the intake ports of each cylinder. This allows flexibility in the intake-manifold design and improves fuel distribution.


The measurement unit for torque.


A rate of performed work, proportional to torque and rpm measured in horsepower.

Power Band

An rpm range in which the engine delivers substantial fraction of top power. It extends from slightly below torque peak to slightly above the peak of power.


A combination of engine and transmission


A tire`s aspect ratio

Progressive-Rate Spring

A spring that becomes stiffer as springs are compressed. They have an increased spring constant.


A measurement unit for pressure (Pounds per square inch)


Also known as Understeer


A term used to describe a rod that transfers the force in compression.


A gear in mesh with a toothed bar steering mechanism. When the steering shaft rotates the gear, it moves the rack from side to side.


When the wheel extends the suspension with its motion. It is the opposite of jounce.


A mechanism where the steering shaft turns a worm gear causing a toothed metal block to move back and forth.


The maximum of revolutions per minute for an engine.

Ride height

The measurement between the ground and the car`s body.

Ride Steer

A condition when the wheel steers slightly as the suspension extends or compresses.

Rigid Axle

A non-independent suspension that consists of transverse member with bolted wheel hubs

Ring-and-Pinion Gear

A gearset with small gear that turns a large-diameter annular gear.


When the car is able to grip to the pavement.

Roal-Load Horsepower

The power a car needs to go down a road in a steady speed. This varies according to the aerodynamic drag, mechanical friction and car`s speed.


The car`s body rotation about a longitudinal axis, also called “a lean” or “a sway”.

Rubber-Isolated Crossmember

An aligned structural member that is attached to the car`s frame or body through vibration-absorbing rubber isolators.

SAE: Society of Automotive Engineers

A professional association of transportation-industry engineers.

Scrub Radius

The point from where the steering axis intersects the ground to the longitudinal line running through the center of the patch of the tire`s contact.


A car with four doors and a fixed-roof with 33 cubic feet of space.

Semi-Elliptic Leaf Springs

A leaf spring, slightly curved, attached to the body of the car at its ends and to a suspension component near the middle.

Semi-Trailing-Arm Suspension

Independent rear-suspension system where each wheel hub is located by a large triangular arm, pivoting at two points.

Series (Tire)

The tire`s Aspect Ratio numeric representation

Shift Gate

The mechanism controlling the gearshift leaver motion in transmission. It is usually an internal mechanism.

Shock Absorber

A device capable of converting motion into heat by forcing oil via small internal passages.

Single-Rate Spring

Spring with a constant spring rate.


A smooth, flat pavement on a large area that is used to test the car`s handling.

Slip Angle

The difference between the tires rolling direction and the plane of the wheel. It is caused by thread and the tire`s sidewall deflections while cornering.

Slush box

Automatic transmission (a slang)


Stands for: Single Overhead Camshaft that uses one camshaft in each cylinder head, operating the intake valves and the exhaust valves.

Space Frame

A tube frame consisting of short, small-diameter tubes welded together.


A devise used for changing direction of airflow to reduce the aerodynamic drag or lift, and also to improve the cooling of the engine.


It occurs when the rear of the car dips downward under hard acceleration.

Steering Axis

The line intersecting the lower and upper steering pivots on a steering wheel.

Steering Feel

The relationship between the handling and the forces at the steering wheel.

Steering Gain

 The relationship between the position and effort of the steering wheel and the yaw.

Steering Geometry

variables that are outside the steering mechanism affecting the steering, linkage arrangement, trail, scrub radius, toe-in, camber, caster and ride steer.

Steering Response

A term that combines the steering gain and the steering feel.

Steering-Line Tracking

When the car is able to run in a straight line and resist road irregularities with no steering corrections.


The distance between the extremes of the piston travel in the cylinder.


A suspension element where a shock absorber is used as a locating member for the wheel.


A space in the engine block, just below the crankshaft, where the oil drains from its various applications.


An air compressor that forces more air in the engine capable of inhaling on its own.


Removable-roof body style that incorporates a fixed, roll-bar-like structure. It runs from side to side behind the front seats.


A housing that with a valve regulates the airflow through the intake manifold.

Throttle-body Fuel Injection

Fuel injection when the injectors are at the engine`s throttle-body, which feeds fuel to more cylinders.

Toe-Control Link

A lateral link that controls the wheel`s direction when the suspension moves up and down.


The nonparallel, intentional orientation of opposite wheels. It is measured by subtracting the distance between the front edges of the pair of tires from the distance between the rear edges of the same pair of tires.

Toe Steer

The change in wheel direction without steering input. It can happen as a result of deflection in suspension components due  to acceleration, cornering or braking on bumpy and smooth roads.


The rotational equivalent of force.

Torque Converter

A fluid that is coupled with a third element which is added to the input and output turbine.

Torque Steer

When the car turns in a particular direction when power is applied. It is typical fro front-drive cars due to the forced reaction created in the half-shafts.

Traction Control

An electronic system that prevents wheelspin.


Braking before entering a turn, than the braking continues for easy entry.

Trailing Arm

A suspension that consists of longitudinal member pivoting from the body at the forward end and a wheel hub attached to the trailing end.

Trailing Link

An aligned suspension link capable of resisting longitudinal motions in a wheel.


A differential and transmission combined in one assembly.


Gearbox with selectable ratios that matches the engine`s torque and rpm.

Tread Squirm

 The flexibility of a tire tread between the tire carcass and the surface of the tread.

Tube Frame

A car frame constructed of rigid tubing that are welded together.


A convex curvature on the side of the car`s body.

Tuned Intake and Exhaust Systems

Exhaust and Intake systems that increase the intake charge flow out and into the combustion chamber.


An exhaust-driven turbine that powers the supercharger.

Turbo Lag

The delay between the depressed car accelerator and the time a large friction of the power developed by the turbocharger.

Turn –In

The transition between straight ahead driving and cornering.


When the slip angle of the front tires are greater than the ones one the rear tires.

Unitized Construction

A body construction that doesn`t need a separate frame for providing structural support or strength for the mechanical components of the car.

Universal Joint

A joint transmitting a rotary motion between two shafts that are not in a straight line.

Valve Float

An rpm engine condition where the valve lifters lose contact to the cam lobes due to the lack of strength of the valve springs to succumb the momentum of various valvetrain components.

Valve Lifter

A cylindrically shaped component pressing on the lobe of a camshaft and moves up and down while the cam lobe rotates.


The parts that allow the valves to operate. It includes all the related drive components and the camshaft components.

Viscous Coupling

A fluid coupling where the output and input shafts mate with alternately spaced discs in a cylindrical chamber.

Waste Gate

A valve that limits the turbocharger`s boost.

Wheel Hop

A suspension characteristic when the wheel violently moves up and down that it leaves the ground.


A rotation about the vertical axis which passes through the center of gravity of the car.

Zero-Offset Steering

A scrub radius of zero steering system which minimizes the steering effect while accelerating or braking in different traction surfaces.

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