4
XE ENGINE BRAKE
General
95
XF series
2-16
Switching on the exhaust brake
The exhaust brake consists of an engine brake
control switch fitted in the cab floor, an engine
brake valve (2), an operating cylinder (1)
connected to the butterfly valve (4) in the
exhaust pipe.
If the engine brake control switch is operated, a
signal is passed to the CTE unit. This signal
activates the engine brake valve (2), causing
compressed air to flow to the operating
cylinder (1).
The latter cylinder closes the butterfly valve in
the butterfly valve housing. The exhaust pipe is
then almost entirely 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 engine stop valve will bleed the two
cylinders. The springs fitted in the cylinders
force the pistons back into in their starting
position, thus re-opening the butterfly valve and
restoring the fuel supply.
7
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