DAF CF65, CF75, CF85 Series . Manual — part 484

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200324

2-11

General

XE ENGINE, ENGINE BRAKE

CF65/75/85 series

4

10

Disengaging the DEB

The solenoid valve (1) is no longer activated. The

spring pressure moves the control valve (2)

downwards, as the oil pressure under the control

valve (2) flows back into the engine through a

hole in the solenoid valve (1).

The oil from the high-pressure area of the DEB

can now escape through a cleared opening

above the control valve (2).

This is effected by the main piston (4) being

moved up by the rocker.

The spring plate (5) holds the main piston (4) in

its top position.

Hydraulic control of the exhaust valves
To open an exhaust valve hydraulically at the end

of a compression stroke, optimum use is made of

the valve diagram.

This means that the DEB uses an exhaust valve

rocker of one cylinder to open an exhaust valve

for another cylinder.

i 400177

7

6

3

2

10

1

4

A

9

5

8

B

XE ENGINE, ENGINE BRAKE

2-12

©

200324

General

10

CF65/75/85 series

4

Cylinders 1, 2, and 3
Exhaust valve rocker of cylinder 1 hydraulically

opens the exhaust valve of cylinder 3

Exhaust valve rocker of cylinder 2 hydraulically

opens the exhaust valve of cylinder 1

Exhaust valve rocker of cylinder 3 hydraulically

opens the exhaust valve of cylinder 2

Cylinders 4, 5, and 6
Exhaust valve rocker of cylinder 4 hydraulically

opens the exhaust valve of cylinder 5

Exhaust valve rocker of cylinder 5 hydraulically

opens the exhaust valve of cylinder 6

Exhaust valve rocker of cylinder 6 hydraulically

opens the exhaust valve of cylinder 4

1

3

2

4

6

5

i 400178

©

200324

2-13

General

XE ENGINE, ENGINE BRAKE

CF65/75/85 series

4

10

Preventing the exhaust valve from opening
too far
Inside the set screw (10) is a spring-loaded pin.

This pin protrudes approx. 2.7 mm from the set

screw (10).

The operating piston (3) has a hole which is

closed by the pin in the set screw (10).

If the operating piston (3) is hydraulically moved

too far down, the hole in the operating piston (3)

will no longer be closed. Oil in the high-pressure

area escapes via the hole in the operating piston

(3), preventing the exhaust valve from opening

any further.

Position A:
Operating piston inactive.

Position B:
Operating piston during regular operation.

Position C:
Operating piston hydraulically opened too far, oil

pressure is discharged via the operating piston.

A

B

C

i 400179

10

3

10

3

10

3

XE ENGINE, ENGINE BRAKE

2-14

©

200324

General

10

CF65/75/85 series

4

Protection against excessive lubricating oil
pressure
There are 2 springs above the control valve.

When the DEB is switched on, the control valve

will be moved upwards by the engine oil pressure

against the direction of the pressure of the inner

spring.

This clears the way for the lubricating oil to pass

to the high-pressure area of the DEB.

If the lubricating-oil pressure in the engine is too

high (

≥

8 bar), the control valve will be moved

upwards against the pressure of both springs.

The control valve will move up further than usual,

preventing the route to the high-pressure area of

the DEB from being cleared.

The DEB will not function in this case.

Note:

A pressure in excess of 8 bar may result from:

-

cold lubricating oil

-

defective lubricating-oil pressure-relief valve

Position A:
DEB disengaged

Position B:
DEB engaged

Lubricating oil pressure between 1.5 and 8 bar

Position C:
DEB engaged

Lubricating-oil pressure approx. 8 bar

i 400196

2

A

B

2

C

2