DAF 95XF. Manual — part 783

9

REAR AXLE ALIGNMENT

Contents

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9

General

REAR AXLE ALIGNMENT

1-1

1. GENERAL

1.1 DESCRIPTION OF POSSIBLE CAUSES OF REAR AXLE MISALIGNMENT

2

1

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3

4

5

6

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W9 08 001

The drawing above shows several factors which
determine the position of the axle under the
vehicle:
1.

Difference in spring opening between the
spring assemblies on the left and right due
to the composition of the spring assemblies
or an unbalanced vehicle load.

2.

Play between the centre bolt and the spring
assembly.

3.

Location of the holes for attachment of the
spring bracket to the chassis.

4.

Dimensions of the spring bracket.

5.

Dimensions of the spring eye.

6.

Installation of spring assembly to the axle
housing.

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REAR AXLE ALIGNMENT

General

1-2

Points 2 to 6 are factors determined by the
manufacturer. Generally, the manufacturer will
ensure that the axle is positioned (within tight
tolerances) at an angle of 90

° in relation to the

centreline of the chassis.
Point 1, however, cannot always be controlled
by the manufacturer.
The difference in spring opening, which is
minimal for new spring assemblies, may
increase as a result of the “settling” of the spring
assembly.
Furthermore, the superstructure and vehicle
load may be the cause of a difference in spring
opening and, consequently, misalignment of the
axle.
During spring movement the axle moves
backwards. If the springs on one side deflect
more than on the other side because of an
unbalanced vehicle or superstructure, this side
of the axle will move further backwards than the
other. This may cause misalignment of the axle.

The misalignment of the rear axle(s) may result
in increased tyre wear.
In case of a combination (truck and trailer or a
tractor and semi-trailer), a misaligned trailer or
semi-trailer may cause increased tyre wear on
the drawing vehicle.

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Inspection and adjustment

REAR AXLE ALIGNMENT

2-1

2. INSPECTION AND ADJUSTMENT

2.1 INSPECTION AND ADJUSTMENT, AXLE POSITION

General
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Only use high-quality testing tools for
measurements. They must be calibrated
regularly and preferably be checked before
every measurement.

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Position the vehicle on a flat and level
surface during the measurement.

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Work with great accuracy.

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Check the position of each wheel in relation
to the centreline of the vehicle (twin wheels
are regarded as one wheel).

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The misalignment of a rear axle is equal to
the average of the individual misalignments
of the left and right wheels.

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In the case of a vehicle combination (truck
with trailer or tractor with semi-trailer) the
alignment of the combination as a whole
must be checked. A misaligned trailer or
semi-trailer may cause problems for the
tractor.

Inspection of axle position
1.

Make sure that the vehicle load is in
accordance with the vehicle’s normal load
conditions. The load must be at least 40%
of the permissible loading weight and be
evenly distributed over the vehicle.

2.

Drive the vehicle straight to the test location
to avoid stresses in the chassis or in the
axle suspension.

Note:

Avoid braking hard and do not put the
vehicle on the parking brake.

3.

Check the tyre pressure prior to the
measurement. Adjust if necessary.

4.

Check the spring opening of the spring
assembly and check the axle suspension
for play prior to the measurement. Any
defects should be repaired first.

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