DAF CF65, CF75, CF85 Series . Manual - part 935

©

 200423

2-7

Inspection and adjustment

BRAKING PERFORMANCE AND BRAKE EQUALISATION

ΧΦ65/75/85 series

6

6

Inspecting brake equalisation of non-EBS 
truck with EBS trailer vehicle
1.

When the brake pressure advance in the 
trailer vehicle control valve on the truck is 
increased or decreased, the position of the 
curve for the trailer vehicle (B) in the graph 
will not be affected. This is because the 
reference pressures are measured at the 
yellow coupling head (= service line). 
For the same reason, however, the curve for 
the truck (A) will shift to the right or the left 
(will appear to be lower or higher 
respectively).
So the horizontal axis indicates how much 
the brake pressure advance has to be 
changed. Reducing the brake pressure 
advance results in increased deceleration 
of the truck. Increasing the brake pressure 
advance results in decreased deceleration 
of the truck.

Note:
Due to the operation of EBS on the trailer 
vehicle it is not possible to set the brake 
pressure advance on the trailer vehicle. 
The brake pressure advance is automatically 
adjusted electronically by the EBS.

Bear in mind that an increase in the 
brake pressure advance does not 
necessarily improve the braking 
performance of the trailer vehicle. 
It only means that the brake 
pressure balance between prime 
mover and trailer vehicle is changed. 
Moreover, in the event of an 
emergency stop the poorer braking 
performance of the trailer vehicle 
will again be noticeable, as the brake 
pressure advance is eliminated 
when the maximum brake pressure 
is used.

2.

So the horizontal axis indicates how much 
the brake pressure advance has to be 
changed.

3.

Take a test run, perform a brake equalisation 
test using a brake dynamometer and fill in 
the "Brake equalisation form for brake 
dynamometer". See "General". If desired or 
required, the setting of the trailer vehicle 
control valve can be adjusted again.

4.

If the desired brake equalisation cannot be 
achieved, the cause must be sought and 
remedied by means of the diagnostics table. 
See "Diagnostics".

R600774

0

10

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80

a

(%)

A

B

1

2

3

4

5

6

7

8

p(bar)

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BRAKING PERFORMANCE AND BRAKE EQUALISATION

2-8

©

 200423

Inspection and adjustment

6

ΧΦ65/75/85 series

6

2.4 INSPECTING AND ADJUSTING BRAKE EQUALISATION OF EBS TRUCK 

WITH NON-EBS TRAILER VEHICLE

Inspecting brake equalisation of EBS truck 
with non-EBS trailer vehicle
1.

Take a test drive and evaluate the braking 
behaviour.

2.

Check the mechanical condition of the 
braking system of the EBS truck with the help 
of the brake performance measurement, 
using a rolling testing device.

3.

Connect a pressure gauge to the yellow 
coupling head of the trailer. Activate the 
testing function of the EBS truck and 
gradually depress the brake pedal. 
Now you must gradually increase the 
pressure on the yellow coupling head 
and eventually exert a pressure value in 
excess of 8 bar.

4.

Evaluate the brake performance of the 
non-EBS trailer with the "EC band graph". 
The measured deceleration must be within 
the EC band graph.

5.

By adjusting the advance pressure in the 
trailer reaction valve of the non-EBS trailer, 
the deceleration line in the EC band graph 
can be influenced. Changing the advance 
pressure is only allowable if the mechanical 
condition of the brake system of the trailer 
allows for this.

Inspecting brake equalisation of EBS truck 
with non-EBS trailer vehicle
1.

If the advance pressure of the trailer reaction 
valve is increased or decreased, this will also 
result in an increase or decrease of the 
measured deceleration of the trailer vehicle.
 

©

 200423

2-9

Inspection and adjustment

BRAKING PERFORMANCE AND BRAKE EQUALISATION

ΧΦ65/75/85 series

6

6

Bear in mind that an increase in the 
brake pressure advance does not 
necessarily improve the braking 
performance of the trailer vehicle. 
It only means that the brake 
pressure balance between prime 
mover and trailer vehicle is changed. 
Moreover, in the event of an 
emergency stop the poorer braking 
performance of the trailer vehicle 
will again be noticeable, as the brake 
pressure advance is eliminated 
when the maximum brake pressure 
is used.

Note:
The EBS system on the truck has a system that 
automatically adjusts the brake pressures. 
It is not possible to adjust it. If the EBS system 
has not stored an error code and the brakes 
of the truck are in proper condition, the cause 
of the brake troubles must be sought in the 
condition and sizing of the brakes of the trailer 
vehicle. If an improvement of comfort (pulling 
or pushing) is desired for low brake 
decelerations, this is possible by changing 
the pressure pulse control of the trailer vehicle.

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BRAKING PERFORMANCE AND BRAKE EQUALISATION

2-10

©

 200423

Inspection and adjustment

6

ΧΦ65/75/85 series

6