DAF 95XF. Manual - part 434

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.

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95

XF series

Inspection and adjustment

XE ENGINE BRAKE

3-1

3.  INSPECTION AND ADJUSTMENT

3.1

INSPECTION AND ADJUSTMENT, DEB PLAY

When the engine is or parts thereof
are opened, it is possible for dirt to
penetrate which can result in
serious damage to the engine. You
should therefore clean the engine
before opening it.

1.

Remove the valve covers.

2.

Tighten the DEB fixing bolts to the specified
torque, see main group “Technical data”.

3.

Use special tool (DAF no. 1310477) to
crank the engine in the direction of rotation
until cylinder 1 has reached the top dead
centre (TDC) and the valves of cylinder 6
rock.

4.

Use set screw (B) to set the DEB play (A) of
cylinders 1, 3 and 5, see main group
“Technical data”.
Then tighten set screw (B) to the specified
tightening torque, see main group
“Technical data”.

5.

Use special tool (DAF no. 1310477) to
crank the engine in the direction of rotation
until cylinder 6 has reached the top dead
centre (TDC) and the valves of cylinder 1
rock.

6.

Use set screw (B) to set the DEB play (A) of
cylinders 2, 4 and 6, see main group
“Technical data”.
Then tighten set screw (B) to the specified
tightening torque, see main group
“Technical data”.

7.

Fit the valve covers.

B

A

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4

XE ENGINE BRAKE

Inspection and adjustment

95

XF series

3-2

3.2

FUNCTIONAL CHECK OF DEB

Electrical DEB check
1.

Disconnect both DEB connectors at the
valve cover.

2.

Check the magnetic valve for an open
circuit and for the correct resistance value
using a multimeter (set to the resistance
value position). See main group “Technical
data”.

3.

Check whether the magnetic valve is
short-circuited to the vehicle’s earth.

4.

Connect a multimeter (set to the volt
measuring position) to the connector of the
engine wiring harness.

5.

Start the engine and, using the throttle,
increase the engine speed to approx.
1500 rpm.

6.

Activate the engine brake by means of the
engine brake control switch on the cab floor.
The multimeter should display a reading.
See main group “Technical data”.

Note:
As the CTE checks the activation of the
engine brake, it will disengage the engine
brake below a certain engine speed (see
CTE systems manual).

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95

XF series

Inspection and adjustment

XE ENGINE BRAKE

3-3

Mechanical DEB check

When the engine is run without the
valve covers, hot lubricating oil may
escape from the engine. Make sure
you are adequately protected.

When the engine is or parts thereof
are opened, it is possible for dirt to
penetrate which can result in
serious damage to the engine. You
should therefore clean the engine
before opening it.

Note:
If the DEB has been removed, you must first
switch the DEB on and off several times with the
engine running. This is done to bleed the DEB
and fill it with lubricating oil.

1.

Remove the valve covers.

2.

Start the engine, and run it at idling speed.

3.

Note:
When the DEB is mechanically activated,
the fuel pump is not switched into the stop
position and continues to inject fuel. Each
DEB should therefore be activated for as
brief a period of time as possible.

Use a small screw driver to push the pin in
the centre of the magnetic valve
downwards. The DEB has now been
activated mechanically.

4.

Visually check whether the main and
operating pistons of the DEB move and/or
the exhaust valve is opened.

5.

When you switch off the DEB, check
whether lubricating oil is discharged from
the control valves.

6.

Fit the valve covers.

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