What is ABS, BAS, DOHC, etc... on a car

Whenever you noticed or somebody tell you this car has ABS, BAS, CVVT, DVVT, DOHC, and bla bla... I guess your mind will go blank or trying hard to expand to characters.


Lets have a look at some of the more common ones and see what there are doing:

ABS (Anti-lock Braking System) – a system to prevent wheels from locking up when the brake pedal is depressed fully for long periods of time. It works by pulsating the brake fluid pressure so that the wheels are momentarily (milliseconds) released. This enables the vehicle to be manoeuvred to avoid obstacles to get out of danger compared to a conventional brake system that causes the vehicle to plough straight on when all the wheels are locked up. It works exceptionally well on wet surfaces but actually increases stopping distance in the dry.

BAS (Brake Assist System) – a system that senses the need for faster stopping as in an emergency and at the same time, reduces the need for long periods of high pressure on the brake pedal. This works in tandem with ABS to shorten stopping distance in the dry.

EBD (Electronic Brakeforce Distribution) – a modern brake fluid distribution system that is activated electronically to ensure the right amount of hydraulic force is distributed to each wheel. Earlier systems were mechanical, employing springs and metallic balls which did not take into account that the brake force requirements of each wheel could be different over various road surfaces and under variable vehicle loads.

VSC (Vehicle Stability Control) – a system that uses an electronic processing unit combining the ABS, EBD, BAS, engine management system (ignition and fuel systems) and sensors on the steering wheel, speedometer and yaw (longitudinal and latitudinal movements) of the vehicle. When the system, based on preset feedbacks from the sensors and the pendulum, recognises the signs of an impending skid such as when the wheels are losing traction during cornering, it does a number of things to reduce vehicle speed automatically. It slows down the engine speed by instant fuel and ignition adjustments while at the same time, applies or releases brake pressure on the relevant wheels. Also known as ESP (Electronic Stability Programme).

ETC (Electronic Traction Control) – a system that automatically applies the brakes on the wheel that is spinning so that power can be diverted to the wheel with the best grip on the road surface. Also known as VTC (Vehicle Traction Control).

VVT (Variable Valve Timing) – a system that lengthens the inlet and/or exhaust valve opening periods to increase gas flow according to engine requirements. This system enables the engine to idle smoothly and consumes minimal fuel at low engine speeds and at the same time, provides large volumes of gas flow into and out of the combustion chambers at high engine speeds for exceptional performance. Also known as CVVT (Constantly Variable Valve Timing), VLTC (Variable Lift and Timing Control) or proprietary names like V-TEC.

CVT (Continuously Variable Transmission) – a revolutionary transmission system that uses a belt connected to a drive pulley and a driven pulley that change their respective diameters due to centrifugal forces. The pulley diameter change effects the change in “gear” ratios – like the system of gears of a racing bicycle but without the mechanical connections.

DOHC (Dual Overhead Camshafts) – a system where the inlet and exhaust camshafts (that open and close the valves) are located and driven separately. This system not only improves valve performance but enables the spark plugs to be placed centrally in the combustion chambers between the two banks of camshafts.

For more details goto star-motoring.com.