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