Jake Brake

Jake brakes, sometimes called a decompression brake or engine brake, is a feature of some diesel engines that opens exhaust valves to the cylinders to release compressed and slow the vehicle.

The feature is mostly used on large trucks, but has been banned in many areas because of the loud noise that it produces during operation.

First, start with an engine. Suck, squeeze, bang, blow.

  • draw and into the engine
  • squeeze (compress) it
  • light it on fire which drives the piston down forcefully
  • push the remains out the exhaust

Now imagine an engine with the removed.

  • draw intake , without , in.
  • compress it
  • de-compress it (instead of blowing it up)
  • push it out the exhaust.

So without , you get some , the piston goes up, then it gets pushed back down. This is essentially an spring. The harder you squeeze the , the harder it pushes back. However, just like a spring, you can't use this as a brake because all the you add to the by compressing it comes right back when it pushes the piston back down.

A jake brake is a device that opens the exhaust valve prematurely, releasing the compressed before the piston starts going back down again. Now you've converted the engine into an compressor, which requires to operate (unlike the spring, whose net consumption is 0). The comes from the kinetic of the , and therefore the slows down.

Jake brakes work better on diesel engines because they don't have a throttle. engines have a throttle which is closed and won't allow to enter the engine. Newer electronic throttles and engine computers could allow a jake brake, but it would be a bit pointless.

Last Updated on 2 years by pinc