DAF CF65, CF75, CF85 Series . Manual — part 485
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200324
2-15
General
XE ENGINE, ENGINE BRAKE
CF65/75/85 series
4
10
2.6 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
XE ENGINE, ENGINE BRAKE
2-16
©
200324
General
10
CF65/75/85 series
4
©
200324
3-1
Inspection and adjustment
XE ENGINE, ENGINE BRAKE
CF65/75/85 series
4
10
3. INSPECTION AND ADJUSTMENT
3.1 INSPECTION AND ADJUSTMENT, DEB CLEARANCE
}
When the engine or parts thereof are
opened, it is possible for dirt to
penetrate which can result in serious
damage to the engine. Therefore, the
engine should be cleaned
thoroughly before any parts are
opened.
1.
Remove the valve covers.
2.
Tighten the DEB attachment bolts to the
specified torque. See "Technical data".
3.
Using the special tool (DAF no. 1310477),
crank the engine in the direction of rotation
until cylinder 1 has reached the top dead
centre (TDC) and the valves of cylinder 6 are
in overlap position.
4.
Use set screw B to set the DEB clearance (A)
of cylinders 1, 3 and 5. See "Technical data".
Tighten the lock nut to the specified torque.
See "Technical data".
5.
Using the special tool (DAF no. 1310477),
crank the engine in the direction of rotation
until cylinder 6 has reached the top dead
centre (TDC) and the valves of cylinder 1 are
in overlap position.
6.
Use set screw B to set the DEB clearance (A)
of cylinders 2, 4 and 6. See "Technical data".
7.
Tighten the lock nut to the specified torque.
See "Technical data".
8.
Fit the valve covers.
B
A
i 400166
XE ENGINE, ENGINE BRAKE
3-2
©
200324
Inspection and adjustment
10
CF65/75/85 series
4
3.2 FUNCTIONAL CHECK, DEB
Electrical inspection of DEB
1.
Disconnect both DEB connectors at the
valve cover.
2.
Check the solenoid valve for an open circuit
and for the correct resistance value using a
multimeter (set to the resistance value
position). See "Technical data".
3.
Check whether the solenoid valve is short-
circuited to the vehicle's earth.
4.
Connect a multimeter (set to the volt
measuring position) to the engine cable
harness.
5.
Start the engine and, using the accelerator
pedal, increase the engine speed to approx.
1500 rpm.
Activate the engine brake using the engine brake
control switch on the cab floor. The multimeter
should display a voltage reading. See "Technical
data".
Note:
As the electronic UPEC unit checks the activation
of the engine brake, it will disengage the engine
brake below a certain engine speed (see UPEC
system manual).
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