DAF CF65, CF75, CF85 Series . Manual — part 1087

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200448

1

Contents

SHOCK ABSORBERS

ΧΦ65/75/85 series

9

3

3 Shock absorbers

CONTENTS

Page

Date

1.

GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200448
1.1

Operation of shock absorber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200448

2.

REMOVAL AND INSTALLATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 . . . . . 200448
2.1

Removal and installation, shock absorber . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 . . . . . 200448

SHOCK ABSORBERS

2

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200448

Contents

3

ΧΦ65/75/85 series

9

©

200448

1-1

General

SHOCK ABSORBERS

ΧΦ65/75/85 series

9

3

1. GENERAL

1.1 OPERATION OF SHOCK ABSORBER

The function of the shock absorber is twofold:

-

to control the movements of chassis and

superstructure in relation to the axle.

Optimum comfort is achieved when the

chassis and superstructure remain truly

horizontal and are not subjected to any

vertical accelerations when moving;

-

to control the movements of the wheels on

the road. Optimum handling is achieved

when all wheels remain in constant contact

with the road surface.

The rate of the above-mentioned movements

depends on the available spring travel. The

available spring travel is the difference in height

between an unloaded spring and a fully loaded

spring.

A well-functioning shock absorber with

characteristics appropriate to the operating

conditions will be the best possible compromise

to fulfil the above-mentioned functions.

DAF only uses double-acting type shock

absorbers.

On vehicles with air suspension, hydraulic stroke

limitation is used.

The shock absorber consists of:

-

an operating cylinder, in which the actual

damping is done by a piston with piston rod

of which the valve unit damps the rebound

stroke;

-

a bottom valve which, in combination with

the piston valve unit, damps the bump

stroke.

-

a reservoir tube which draws in oil surplus

(result of the volume taken up by the piston

rod) via the bottom valve;

-

a dust cover, attached to the piston rod.

SHOCK ABSORBERS

1-2

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200448

General

3

ΧΦ65/75/85 series

9

Double-acting shock absorbers
The operation of the shock absorber is as follows:

The bump stroke moves the piston (1) down in

relation to the operating cylinder (2).

Subsequently, oil flows from the bottom chamber

of the piston (1) through the piston holes and

valves to the top chamber where the volume

increases. The oil pressure is equal on either side

of the piston (1).

To compensate for the volume taken up by piston

rod (3), oil flows from under the piston (1), via the

bottom valve (4), to the reservoir tube (5).

The resistance met by the oil during this

movement dampens the bump stroke of the

shock absorber.

The rebound stroke moves the piston (1) up in

relation to the operating cylinder (2).

Subsequently, pressure is exerted on the oil in

the upper chamber of the piston (1) causing the

oil to flow through the piston holes and valves to

the bottom chamber under piston (1).

The resistance met by the oil during this

movement dampens the rebound stroke of the

shock absorber.

To compensate for the volume taken up by the

piston rod (3) in the upper chamber, oil flows via

bottom valve (4) from the reservoir tube (5) to the

bottom chamber under the piston (1).

3

1

5

2

4

W9 02 001