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My truck supports 2 types of engine brakes:

  1. Compression release brake

  2. Exhaust brake

Both can be selectively deactivated using switches.

What are the pro's and con's of each type of engine braking system?

(considering various factors like component lifetime, effectiveness of brake).

  • 5
    I'm not understanding something. If both compression and exhaust braking involve air handling (whether intake or exhaust) in the engine and how it slows the wheels, how can either one be effective at all if the engine has been disconnected from the wheels by depressing the clutch? What am I missing? I got my info on exhaust braking (and some on compression from here: bankspower.com/techarticles/show/17-How-An-Exhaust-Brake-Works – cdunn Jan 26 '16 at 16:13
  • What's your make/model/year? – DucatiKiller Jan 26 '16 at 16:36
  • Agree with cdunn ... I would think a smart system would shut down either type of braking while the clutch is depressed or it would kill the engine. – Pᴀᴜʟsᴛᴇʀ2 Jan 26 '16 at 17:03
  • Diesel box truck (some) and all semis I know of use these. Using the clutch petal deactivates the extra load on the motor and reinitiates upon clutch engagement. Any pressing of the gas pedal also deactivates it until pedal pressure is released. – Dee Jan 26 '16 at 19:00
  • Those switches are used to take the workload off the brakes so they don't catch fire under heavy loads usually going down hill. – Dee Jan 26 '16 at 19:01
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Attributes of Exhaust (Jake brake) and Compression Brakes

Compression (Jake) Brake

  • Jake brakes slow a vehicle by releasing pressure

  • Jake brakes are operated at the valve train.

  • Jake brakes open the exhaust valve at the top of the compression stroke.

  • Jake brakes use the compression of the compression stroke to provide gas compression resistance to slow the rear wheels of a vehicle.

  • Jake brakes are more efficient than exhaust brakes

  • Jake brakes have mechanisms to disable the braking upon use of the clutch or throttle

  • Jake brakes release exhaust pressure after TDC to prevent compressed gas expansion from acting upon the piston on the downstroke

Compression Brake

  • Exhaust brakes increase pressure to slow a vehicle

  • Exhaust brakes attach to the exhaust system at the manifold

  • Exhaust brakes block the exhaust gasses from escaping the exhaust manifold to slow a vehicle.

  • Exhaust brakes have mechanisms to disable them upon use of the clutch or throttle

Jake brakes are considered to be up to 80% more effective than exhaust brakes in creating resistance to slow a vehicle. In many communities in the US Jake brakes are illegal due to the high sound levels that are associated with their use.

Reliability

There are not reliable citations regarding the reliability of the two systems.

Effectiveness

Jake brakes are considered considerably more effective than exhaust brakes. Exhaust brakes have come into popularity as a fall back mechanism as the communities banned jake brakes due high levels of sound associated with them.

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