DAF CF65, CF75, CF85 Series . Manual — part 905

©

200423

2-5

Inspection and adjustment

BRAKE SYSTEM AND COMPONENTS

ΧΦ65/75/85 series

6

5

2.4 INSPECTION AND ADJUSTMENT, FOOT BRAKE VALVE

Inspection, foot brake valve
1.

Connect a pressure gauge to a brake
chamber of the front axle (in front of the
empty/load valve, if present).

2.

Connect a pressure gauge in front of the load
sensing valve.

3.

Pressurise the system.

4.

Depress the brake pedal a few times,
alternately quickly and slowly, until the end
stop is reached. Check if there is a
discrepancy between both gauge readings
(discrepancy maximum 0.3 bar).

5.

When the brake pedal is gradually
depressed, both circuits should not show
larger pressure increases than 0.3 bar.

6.

When the foot brake valve is completely
depressed, both gauges should indicate the
reservoir pressure.

7.

When the brake pedal is not depressed,
the pressure gauges should not indicate any
pressure.

Adjusting the foot brake valve
1.

Check whether the brake pedal can be fully
depressed. When fully depressed, the pedal
should not touch the floor mat. This is
especially important if circuit 1 were to fail.
More pedal travel will then be needed
to achieve full pressure at circuit 2.

2.

The stop bolt should be adjusted in such
a manner that there is noticeable play
between bolt and pedal.

21

22

12

A

B
D

C

10

9

7

8

6

5

4

3

2

1

11

R600748

Fig.2

BRAKE SYSTEM AND COMPONENTS

2-6

©

200423

Inspection and adjustment

5

ΧΦ65/75/85 series

6

2.5 INSPECTION AND ADJUSTMENT, LOAD SENSING VALVE,

AIR SUSPENSION

Explanatory notes on instruction plate
This plate is mounted on the rear door pillar on
the left-hand side of the vehicle. The information
on the instruction plate relates to the axle loads,
the delivery pressures and bellows pressures,
following 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

1425289

2

1.8

2.5

4.0

5.0

6.0

10.0

11.5

13.0

2

2.0

2.1

2.8

3.5

4.3

7.3

8.3

8.3

3

1

5.7

5.8

6.0

6.3

6.6

7.7

8.1

8.1

12

0.2

0.5

1.3

1.8

2.3

4.2

4.9

5.6

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 p43

PRESSURE BELLOWS

BALG DRUCK

PRESSION COUSSIN

PRESS. CUSCINI ARIA

PRESION FUELLES

bar

±0.4

±0.2

W475 721 003 0

1 = 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

p1

p2

p4

p43

R600472

©

200423

2-7

Inspection and adjustment

BRAKE SYSTEM AND COMPONENTS

ΧΦ65/75/85 series

6

5

Inspection/adjustment
1.

Check that the correct valve has been fitted
(see instruction plate).

2.

Connect a pressure gauge (4) to the test
connection close to connection 1/4 on the
load sensing 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 the
special cam spanner (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.

11. Set the simulated bellows pressure to its

second highest value, as indicated on the
instruction plate.

43

1/4

4

2

2

R600473

1

41 42

r

s

R600478

BRAKE SYSTEM AND COMPONENTS

2-8

©

200423

Inspection and adjustment

5

ΧΦ65/75/85 series

6

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.