DAF CF65, CF75, CF85 Series . Manual — part 1063

©

200424

2-1

General

HYDRAULIC LIFTING GEAR

ΧΦ65/75/85 series

8

9

2. GENERAL

2.1 LOCATION OF COMPONENTS

Relays, diodes and fuse
The relay, diodes and fuse that have a bearing on

the lifting gear of the trailing axle are stored in a

watertight box.

This box is fitted on the inside of the chassis on

the chassis main member.

A

B

1

2

3

4

5

6

7

A8 00 247

1.

Pressure switch

2.

Pressure relief valve

3.

4/2 solenoid valve (lift trailing axle)

4.

2/2 solenoid valve (lower trailing axle)

5.

Built-in non-return valve

6.

+ connection point (D1E1)

7.

- connection point (D2E2)

A.

Line connection (delivery line while

lowering)

B.

Line connection (delivery line while lifting)

(The characters are imprinted on the

pump unit)

HYDRAULIC LIFTING GEAR

2-2

©

200424

General

9

ΧΦ65/75/85 series

8

2.2 SYSTEM DESCRIPTION, HYDRAULIC PART

The hydraulic part of the trailing axle load transfer

device is composed of a pump unit and two

parallel, double-acting cylinders. Both when lifting

and lowering the trailing axle, the pump will

deliver oil to the cylinders.

The pump unit is composed of a gear pump which

is driven by an electric motor, a plastic reservoir

and a valve block.

The valve block is equipped with the following

valves: a non-return valve (6), the pressure relief

valve (2), the 4/2 valve "lift trailing axle" (3) and

the 2/2 valve "lower trailing axle" (4).

The valve block is also equipped with a pressure

switch (1).

When the lifting gear is not being operated, both

solenoid valves (3) and (4) will be deactivated.

Lifting
-

When the lifting-gear control switch is placed

in the "lifting" position, the pump relay and

the 4/2 solenoid valve (3) are activated.

The activated solenoid valve (3) connects

the pump delivery side to the space behind

the pistons in the cylinders. The space in

front of the pistons is connected to the

reservoir.

-

The pump relay activates the pump, after

which oil is carried to the cylinders through

line connection B. Due to the pressure build-

up from the cylinders, the piston rods are

pushed from the cylinders, thus lifting the

trailing axle via the lever effect.

-

When the trailing axle is fully lifted, the

pressure in the system will build up until the

switching value of the pressure switch (1) is

reached. The pressure switch (1) will

deactivate the pump motor. When the control

switch is released, the 4/2 solenoid valve (3)

is deactivated.

-

The non-return valve built into the 2/2

solenoid valve (4) keeps the line pressurised

and the trailing axle lifted.

A

B

M

4

3

2

6

1

A8 00 257

A

B

M

4

3

2

6

1

A8 00 258

©

200424

2-3

General

HYDRAULIC LIFTING GEAR

ΧΦ65/75/85 series

8

9

Lowering
-

When the lifting-gear control switch is placed

in the "lowering" position, the pump relay and

the 2/2 solenoid valve (4) are activated.

-

The activated solenoid valve will connect the

space behind the pistons to the reservoir. In

its neutral position the 4/2 solenoid valve (4)

connects the pump delivery side to the space

in front of the pistons in the cylinders.

-

The pump relay activates the pump after

which oil is carried to the cylinders through

line connection A. Due to the pressure build-

up in the cylinders the piston rods are

retracted, thus lowering the trailing axle.

-

When the pistons are fully retracted into the

cylinders, the pressure in the system will

build up until the switching value of the

pressure switch is reached. The pressure

switch will deactivate the pump motor. The

2/2 solenoid valve (4) remains activated for

approx. 2.5 minutes.

-

The line connected to line connection B will

be pressureless after deactivating the pump.

-

The line connected to line connection A will

remain pressurised immediately after

deactivating the pump.

Due to minor internal leakage in the 4/2

solenoid valve (3) the pressure in the line will

be slowly reduced after the pump is

deactivated. After approx. 5 minutes the

pressure in the line will have been be

reduced to approx. 5 bar.

A

B

M

4

3

2

6

1

A8 00 259

HYDRAULIC LIFTING GEAR

2-4

©

200424

General

9

ΧΦ65/75/85 series

8

2.3 OVERVIEW DRAWING, PUMP UNIT

1
2
3

4

5

6

7
8
9

10

11

12

13

14

15

16
17
18

21

22

23

24

25

26

30

31

33

32

34

38

37

44

36

35

41

39

40

42

43

46

47

45

49 50

51

52

53

54

48

27

29

28

19 20

A8 00 277