DAF CF65, CF75, CF85 Series . Manual - part 1160

©

 200423

3-23

Inspection and adjustment

EXPLANATORY NOTES ON THE MAINTENANCE ACTIVITIES

ΧΦ75 series

5

Checking and adjusting load-sensing air-
suspension control valve
1.

Check that the correct valve has been fitted 

(see instruction plate).

2.

Connect pressure gauge (4) to the test 

connection close to connecting point 

 on 

the load-dependent control valve (input 

pressure).

3.

Connect a pressure gauge (2) to the test 

connection on one of the brake cylinders 

(service brake connection) of the rear axle.

4.

Connect a pressure gauge (43) with a 

pressure-reducing valve to the simulation 

connection near connections 41 and 42 of 

the load-sensing valve (= simulated 

adjustable bellows pressure).

5.

Make sure that the reservoir pressure is 

higher than 8.5 bar throughout the testing 

process.

6.

Set the simulated bellows pressure to its 

second lowest value, as indicated on the 

instruction plate.

7.

Depress the brake pedal until pressure 

gauge (4) indicates a pressure of 8 bar.

8.

Read the brake pressure of the rear axle on 

pressure gauge (2) and check that this brake 

pressure matches the one listed on the 

instruction plate in the table under "delivery 

pressure p2" to the rear axle.

9.

If the measured value is not correct, 

depressurise connection (43) and, using a 

special tool (DAF no. 1329464), turn the 

adjusting nut (s):

-

braking pressure too high: unscrew the 

adjusting nut

-

braking pressure too low: screw in the 

adjusting nut.

Note:

When depressurising the simulation 

connection (pressure gauge 43), the air hose 

must remain connected to prevent the 

(actual) bellows pressure from accidentally 

activating the valve.

The small socket head screw in the centre of 

the valve must not be adjusted.

10. Repeat the procedure described in point 6 

until the measured braking pressure value is 

within the tolerance limits.

43

1/4

4

2

2

R600473

1

41 42

r

s

R600478

EXPLANATORY NOTES ON THE MAINTENANCE ACTIVITIES

3-24

©

 200423

Inspection and adjustment

5

ΧΦ75 series

11. Set the simulated bellows pressure to its 

second highest value, as indicated on the 

instruction plate.

12. Depress the brake pedal until pressure 

gauge (4) indicates a pressure of 8 bar.

13. Read the pressure gauge (2) and check that 

this braking pressure matches the pressure 

indicated in the table on the instruction plate.

14. If the measured reading is not correct, 

depressurise connection (43) and turn the 

adjusting bolt (r) using a Torx screwdriver:

-

braking pressure too high: screw in the 

adjusting bolt

-

braking pressure too low: unscrew the 

adjusting bolt.

Note:

When depressurising the simulation 

connection (pressure gauge 43), the air hose 

must remain connected to prevent the 

(actual) bellows pressure from accidentally 

activating the valve.

The small socket head screw in the centre of 

the valve must not be adjusted.

15. If the adjusting bolt (r) has been turned, 

repeat the procedure from point 6.

©

 200423

3-25

Inspection and adjustment

EXPLANATORY NOTES ON THE MAINTENANCE ACTIVITIES

ΧΦ75 series

5

3.28 CHECKING AND ADJUSTING LOAD-SENSING LEAF-SPRING CONTROL 

VALVE

Explanatory notes on instruction plate
This plate is mounted on the rear door pillar on 

the left-hand side of the vehicle. The data on axle 

loads and delivery pressures are listed on the 

instruction plate in the sequence of the axles 

beneath the vehicle. Therefore, "1" refers to the 

(first) front axle, "2" to the next following axle, etc.

If the vehicle is fitted with a relay valve in the front 

axle brake circuit, the box beneath the valve 

illustration will be blank. Throughout the column, 

a value of 8.1 bar has been filled in for "delivery 

pressure p2" under axle "1".

If the vehicle is equipped with a control valve 

instead of the relay valve mentioned, the box will 

contain a pressure ratio, e.g."i = 1 : 1.5". The 

"delivery pressure p2" of axle "1" then indicates 

variable readings.

These values can be used to check the brake 

pressure values of the front axle and to carry out 

the inspection/adjustment below at the same 

time. To do this, connect a pressure gauge to the 

test connection of one of the front axle brake 

cylinders.

AUTOM. LASTAFHANKELIJKE REMKRACHTREGELING
AUTOM. LOAD SENSING DEVICE
AUTOM. LASTABHAENGIGE BREMSKRAFT REGELEINR.
DISPOSITIF DE CORRECTION AUTOM. DE FREINAGE
REGOLATORE AUTOM. DELLA FORZA FRENANTE
REGULADOR AUTOM. DEL ESFUERZO DE FRENANDA

TYPE   -  TIPO   :   FA

1425287

2

1.8

2.0

3.0

4.0

8.0

10.0

11.5

13.0

2

1.8

1.8

2.2

3.1

6.4

7.6

8.2

8.2

1

5.7

5.7

5.8

6.1

7.4

7.8

8.0

8.0

1

ASLAST                          G

AXLE LOAD

ACHSLAST

CHARGE SOUS ESSIEU

CARICO ASSE

CARGA EJE

    

x10

4

 N

UITGESTUURDE DRUK   p2

DELIVER

Y PRESSURE

AUSGESTEUER

TER DRUCK

PRESSION DELIVREE

PRESSIONE USCIT

A

PRESION DE SALIDA

                 bar

BALG DRUK                     p3

PRESSURE BELLOWS

BALG DRUCK

PRESSION COUSSIN

PRESS. CUSCINI ARIA

PRESION FUELLES

                  bar

±0.4

±0.2

W475 721 004 0

1396041

i  =  1  :  1.5

MEEREGEL

VENTIEL

EMPTY

-LOAD V

A

LV

E

LAST

-LEER VENTIEL 

V

A

LVE CHARGE-VIDE

V

A

LVOLA VUOTO-CARICO

V

A

LVULA V

ACIO-CARGA

p1 = > 8.5 bar

p4 = 8.0 bar

L = 140 mm

a = 15  ±2 

G=11.0

L

p1

p2

p4

R600479

EXPLANATORY NOTES ON THE MAINTENANCE ACTIVITIES

3-26

©

 200423

Inspection and adjustment

5

ΧΦ75 series

Checking and adjusting load-sensing leaf-
spring control valve
1.

Measure the weight plus load of the rear 

axle(s).

2.

Check the attachment of the control lever 

and its ease of operation.

3.

Check whether the correct valve and the 

correct springs have been fitted (for 

information, see the instruction plate).

4.

Check the length of the control lever (see "L" 

on the instruction plate).

5.

Connect pressure gauge (4) to the test 

connection close to connecting point 

 on 

the load-dependent control valve (input 

pressure).

6.

Connect pressure gauge (2) to the test 

connection on one of the brake cylinders 

(service brake connection) of the rear axle.

7.

Make sure that the reservoir pressure is 

higher than 8.5 bar throughout the testing 

process.

8.

Depress the brake pedal until gauge (4) 

indicates a reading of 8 bar.

9.

Read the brake pressure of the rear axle 

from the pressure gauge (2) and check that 

this value matches the one listed on the 

instruction plate in the table under "delivery 

pressure p2" to the rear axle.

1/4

4

2

2

R600562

1