DAF CF65, CF75, CF85 Series . Manual - part 907

 

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DAF CF65, CF75, CF85 Series . Manual - part 907

 

 

©

 200423

2-13

Inspection and adjustment

BRAKE SYSTEM AND COMPONENTS

ΧΦ65/75/85 series

6

5

2.8 INSPECTING THE RELAY VALVE

Inspecting the relay valve
1.

Connect a pressure gauge to connecting 
point (4) of the relay valve.

2.

Connect a pressure gauge to connecting 
point (2) of the relay valve.

3.

Pressurise the system.

4.

Depending on the position of the relay valve 
in the brake system, slowly activate the 
service brake or parking brake.

5.

The pressure in the pressure gauge 
connected to connection point (4) must now 
increase to approx. 0.8 bar (the increased 
parking brake actuating pressure) or 0.5 bar 
(service brake), without there being any 
noticeable pressure on connection point (2). 
From this point, the pressures in both 
pressure gauges must increase identically. 
The pressure on the gauge connected 
to point (2) should not rise in jumps. 
Both gauges should indicate a value 
corresponding to the graph. See "Technical 
data".

R600490

2

1

6

4

A

5

3

7

BRAKE SYSTEM AND COMPONENTS

2-14

©

 200423

Inspection and adjustment

5

ΧΦ65/75/85 series

6

2.9 INSPECTION, TRAILER VEHICLE CONTROL VALVE

1.

Ensure there is sufficient system pressure.

2.

Check whether air is escaping via the bleed 
vent.

3.

Depress the brake pedal, and again check 
for leaks.

4.

Disconnect the pipe at connecting point (42) 
and plug off this pipe.

5.

Depress the brake pedal, and check 
for pressure build-up in the service pipe 
(see "Technical data").

6.

Reconnect the pipe.

7.

Repeat the last three points, but now for 
connecting point (41).

8.

Operate the parking brake: pressure should 
build up in the service pipe (see "Technical 
data").

9.

Operate the parking brake to the stop, 
and lock the lever: the service pipe should 
once again become pressureless.

10. Simulate a leak in the service pipe, 

and depress the brake pedal; within 
two seconds, the outflow of air from the leak 
should slow down considerably.

R600340

©

 200423

2-15

Inspection and adjustment

BRAKE SYSTEM AND COMPONENTS

ΧΦ65/75/85 series

6

5

2.10 INSPECTION AND ADJUSTMENT, ADVANCE IN TRAILER VEHICLE 

CONTROL VALVE

Inspection, braking pressure advance in 
trailer vehicle control valve

Note:
The pressure ratio between prime mover and 
drawn vehicle is 10 : 8 (10 bar system pressure 
for prime mover and 8 bar system pressure for 
drawn vehicle).

This means that if no braking pressure advance 
is applied, at an input pressure of 3 bar at 
connection point (41), the output pressure at 
connection point (2) is equal to (3 x 8): 10 = 2.4 
bar.

If a braking pressure advance of 0.6 bar is now 
applied, the output pressure at connection point 
(2) should be 2.4 + 0.6 = 3.0 bar.

1.

Connect a pressure gauge (1) to the test 
connection for the load sensing valve and 
a pressure gauge (2) to the service coupling 
head.

2.

Depress the brake pedal until the input 
pressure (measured at pressure gauge 1) 
is 3 bar. The reading at pressure gauge (2) 
should now be 3.0 bar. This equals 0.6 bar 
braking pressure advance.

3.

If the braking performance of the trailer 
vehicle (provided it is in good condition) 
is poorer than that of the prime mover, 
the advance may be increased by several 
tenths of a bar.

BRAKE SYSTEM AND COMPONENTS

2-16

©

 200423

Inspection and adjustment

5

ΧΦ65/75/85 series

6

Adjusting the advance in trailer vehicle 
control valve

Note:
The pressure at which the readings are taken 
must always be built up. If the specified pressure 
is exceeded, bleed off sufficient air, and once 
again allow the pressure to build up.

1.

Remove the plug.

Note:
Make sure that the valve is not operated 
when the advance is adjusted.

2.

Using a 6mm Allen key, turn the central 
section (7) anti-clockwise or clockwise 
to decrease or increase the advance 
respectively.

3.

Measure the advance again.

4.

Repeat these actions until the required 
advance is reached.

5.

Re-fit the plug.

41

42

3 bar

6 mm

43

11

12

+

_

22

R600341

 

 

 

 

 

 

 

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