DAF CF65, CF75, CF85 Series . Manual — part 934

©

200423

2-3

Inspection and adjustment

BRAKING PERFORMANCE AND BRAKE EQUALISATION

ΧΦ65/75/85 series

6

6

Activation of the test function
1.

Switch the vehicle ignition off.

2.

Apply the brake pedal. The test function will
now be activated if the condition has been
met.

Note:
-

If during application of the brake pedal
the contact is turned on, the test function
will remain active even if the brake pedal
is then released.

-

The test function will be automatically
switched off if the condition is no longer
met or if, when the contact is on,
the contact is switched off when the
brake pedal is not being applied.

BRAKING PERFORMANCE AND BRAKE EQUALISATION

2-4

©

200423

Inspection and adjustment

6

ΧΦ65/75/85 series

6

2.2 INSPECTING AND ADJUSTING BRAKE EQUALISATION OF NON-EBS

TRUCK WITH NON-EBS TRAILER VEHICLE

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

Take a test drive and evaluate the braking
behaviour.

2.

In the case of disc brakes, inspect the
mechanical condition of the brake calliper,
brake disc and brake pads. In the case of
drum brakes, inspect the mechanical
condition of the brake drums and brake
linings. Their condition may provide clues
to the settings that need to be made.

3.

Perform a brake equalisation test using a
brake dynamometer and fill in the "Brake
equalisation form for brake dynamometer".
See "General".

4.

Evaluate the brake equalisation of the
combination using the "EC band graph".
The combination is correctly balanced if the
braking performance at 2 - 3 bar for the truck
and the trailer vehicle are in a comparable
position in the appropriate EC band, i.e.
both in the upper part, both in the lower part
or both in the middle part.

Note:
On a tractor/drawn vehicle combination the
values for the drawn vehicle may be slightly
lower than those for the prime mover.
The deceleration values for the truck and the
drawn vehicle of a truck/trailer combination
should be the same. The reason for this lies
in the dynamic axle load displacement,
which on semi-trailers causes a transfer of
weight to the tractive unit, whereas on
trailers it does not cause a transfer of weight
to the tractive unit.

5.

Due to the adjustment of the brake pressure
advance on the truck and/or trailer vehicle
the deceleration lines in the "EC band graph"
can be affected.

Note:
For optimum interchangeability of vehicles,
the correct choice between these two
alternatives must be made.

6.

If the mechanical condition of the wheel
brakes, the results of the test drive and the
data obtained from the brake equalisation
test using the brake dynamometer give
cause for doing so, the brake pressure
advance of the trailer vehicle control valve
can be adjusted.

©

200423

2-5

Inspection and adjustment

BRAKING PERFORMANCE AND BRAKE EQUALISATION

ΧΦ65/75/85 series

6

6

Adjusting brake equalisation of non-EBS
truck with non-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:
Increasing the brake pressure advance on
the trailer vehicle reaction valve on the trailer
vehicle results in increased deceleration of
the trailer vehicle.

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)

}

BRAKING PERFORMANCE AND BRAKE EQUALISATION

2-6

©

200423

Inspection and adjustment

6

ΧΦ65/75/85 series

6

2.3 INSPECTING AND ADJUSTING BRAKE EQUALISATION OF NON-EBS

TRUCK WITH EBS TRAILER VEHICLE

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

Take a test drive and evaluate the braking
behaviour.

2.

In the case of disc brakes, inspect the
mechanical condition of the brake calliper,
brake disc and brake pads. In the case of
drum brakes, inspect the mechanical
condition of the brake drums and brake
linings. Their condition may provide clues to
the settings that need to be made.

3.

Perform a brake equalisation test using a
brake dynamometer and fill in the "Brake
equalisation form for brake dynamometer".
See "General".

Note:
The EBS trailer vehicle must be correctly
connected and the test function of the EBS
system must be activated.

4.

Evaluate the brake equalisation of the
combination using the "EC band graph".
The combination is correctly balanced if the
braking performance at 2 - 3 bar for the truck
and the trailer vehicle are in a comparable
position in the appropriate EC band, i.e.
both in the upper part, both in the lower part
or both in the middle part.

Note:
On a tractor/semi-trailer combination the
values for the drawn vehicle may be slightly
lower than those for the tractor. The
deceleration values for the truck and the
drawn vehicle of a truck/trailer combination
should be the same. The reason for this lies
in the dynamic axle load displacement,
which on semi-trailers causes a transfer of
weight to the tractive unit, whereas on
trailers it does not cause a transfer of weight
to the tractive unit.

5.

Due to the adjustment of the brake pressure
advance on the truck, the deceleration line in
the "EC band graph" can be affected.

6.

If the mechanical condition of the wheel
brakes, the results of the test drive and the
data obtained from the brake equalisation
test using the brake dynamometer give
cause for doing so, the brake pressure
advance of the trailer vehicle control valve
can be adjusted.