DAF CF65, Service Manual

Page: 240 / 352

ENGINE BRAKE, PE ENGINE
2-2
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200324
General
7
CF65/75/85 series
4
2.2 SYSTEM DESCRIPTION, EXHAUST BRAKE
Switching on the exhaust brake
The exhaust brake consists of an engine brake
operating switch fitted in the cab floor and an
operating cylinder (2) connected to the butterfly
valve in the exhaust pipe.
If the engine brake control switch is operated, a
signal is passed to the engine management
system's electronic unit. The engine
management system's electronic unit interrupts
the fuel supply to the various cylinders. The unit
also energises the exhaust brake valve, causing
compressed air to flow to the operating cylinder
(2). The cylinder closes the butterfly valve in the
butterfly valve housing. The exhaust pipe is then
almost completely closed off.
Controlled discharge of exhaust gases is still
possible through a calibrated hole in the butterfly
valve.
The engine now acts as a compressor, creating a
braking action.
The higher the engine speed, the greater the
braking action of the exhaust brake.
Switching off the exhaust brake
If the engine brake control switch is released, the
fuel supply to the various cylinders will be
re-instated and the butterfly valve will be
re-opened.
I400533
3
2
4
1
1. Butterfly valve operating cylinder
2. Exhaust brake valve
3. Supply pressure
4. Butterfly valve
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