By Sejin Kim
Engine braking is generally used when the automobile is at a very small pace or while going downhill. This type of brake is used to slow the vehicle while running and not to stop the vehicle completely. Engine brakes are different from exhaust brakes. Engines brakes should also be used continuously. This will prevent the over use of a normal brake and avoid the wear and tear of it too early. Brake replacement costs a lot of money.
In engines, which run on petrol, engine braking is a process where the brakes are induced by giving a throttle to the vacuum in the petrol engine. There is some friction but main power of the engine brake comes from vacuum. The throttle is closed which reduces or completely stops the air flow. Due to reduced air flow, the braking effect is seen.
Engine brakes are often used while slowing down the vehicle on the road. We can hear a rattling sound when we apply the engine brake. Drivers often experience bad sound while applying engine brakes because of its mechanism.
Due to stopping the air flow and applying a vacuum like effect there is a loud sound heard which is also known as Jake Bark, wherein, the compressed air travels through valves in cylinder of engine.
The sound is normally around 10-13 decibel which is a little higher than sound of a normal conversation. Some states have banned the use of engine brakes due to noise pollution, but the work is going to address this problem.
Diesel engines also have a braking system, but it is not the same as that of petrol engines. Diesel engine mechanisms and flow of fluid is different from petrol engine systems. A diesel engine does not have the throttle engine mechanism. Diesel engines like those in trucks work on compression and release braking system or also known as Jake Brake system.
In this system, the throttle is opened to open the exhaust valve. This results in expansion of the compression air. The amount of air is very large and it is released outside in the environment. In diesel engines the compressed air like spring pushes back the cylinder, therefore, there is no engine braking in diesel engines.
When lots of air are released in the air, the springing action is lost, and to continue to work, the engine requires to pull back the cylinder, but due to lack of compression air, the engine loses energy and that is how the brake is applied.
There is a popping sound made when the compression air is lost in the surrounding. This sounds is similar to gunfire, therefore, engine braking is banned in many states. However, the use of engine brake does increase the life of normal brakes.
The engine brake in two stroke engines is very harmful for the vehicle. In two stroke engines along with the fuel, the engine lubricant, also flows through the engine. Therefore, when we put the engine brake, the flow of lubricant along with the fuel is stopped. Hence, if we use the engine brake many times, then due to lack of lubricant, there will be rapid wear and tear of the engine.
Engine braking application is to reduce the use of normal brakes, and to properly handle the vehicle on heavy roads when there is a stop and go traffic around. When we need to slow the speed while driving, engine braking is very advantageous. It is good on slopes. We need to use engine braking before the normal brake in order to maintain good speed. If we use the engine braking improperly, then the vehicle can skid on slippery and sloppy paths.
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