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

20

30

40

50

60

70

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.

}

BRAKING PERFORMANCE AND BRAKE EQUALISATION

2-10

©

200423

Inspection and adjustment

6

ΧΦ65/75/85 series

6