DAF LF45, LF55 Series. Manual - part 458

©

 200436

2-11

Inspection and adjustment

BRAKE SYSTEM AND COMPONENTS

ΛΦ45/55 series

6

4

2.8 INSPECTION AND ADJUSTMENT, ADVANCE IN TRAILER VEHICLE 

CONTROL VALVE

Inspection, brake pressure advance in drawn 
vehicle control valve, vehicles with empty/
load relay valve
1.

Connect a pressure gauge (1) to the test 

connection for the load-sensing valve and a 

pressure gauge (2) to the service coupling 

head.

2.

Simulate full load on the vehicle.

3.

Depress the brake pedal until the input 

pressure (measured at pressure gauge 1) 

is 3 bar. See "Technical data" for the 

pressure that should be indicated by 

pressure gauge 2.

4.

If the braking performance of the trailer 

vehicle (provided it is in good condition) is 

poorer than that of the prime mover, the 

advance may be increased by several tenths 

of a bar.

Inspection, brake pressure advance in drawn 
vehicle control valve, vehicles without empty/
load relay valve
1.

Connect a pressure gauge (1) to the 

measuring point on the front axle brake 

cylinder and a pressure gauge (2) to the 

service coupling head.

2.

Depress the brake pedal until the input 

pressure (measured at pressure gauge 1) 

is 3 bar. See "Technical data" for the 

pressure that should be indicated by 

pressure gauge 2.

3.

If the braking performance of the trailer 

vehicle (provided it is in good condition) is 

poorer than that of the prime mover, the 

advance may be increased by several tenths 

of a bar.

BRAKE SYSTEM AND COMPONENTS

2-12

©

 200436

Inspection and adjustment

4

ΛΦ45/55 series

6

Adjusting advance in trailer vehicle control 
valve

Note:

The pressure at which the readings are taken 

must always be built up. If the specified pressure 

is exceeded, bleed off sufficient air and once 

again allow the pressure to build up.

1.

Remove the plug.

Note:

Make sure that the valve is not operated 

when the advance is adjusted.

2.

Using a 6mm Allen key, turn the central 

section (7) anti-clockwise or clockwise to 

decrease or increase the advance 

respectively.

3.

Measure the advance again.

4.

Repeat these actions until the required 

advance is reached.

5.

Re-fit the plug.

41

42

3 bar

6 mm

43

11

12

+

_

22

R600341

©

 200436

2-13

Inspection and adjustment

BRAKE SYSTEM AND COMPONENTS

ΛΦ45/55 series

6

4

2.9 INSPECTION, PARKING BRAKE VALVE

Parking brake valve with trailer control

1.

Ensure there is sufficient system pressure.

2.

Using T-pieces, connect two pressure 

gauges to connecting point 43 of the drawn 

vehicle control valve and to connecting point 

42 of the relay valve.

Inspecting the driving position
1.

Place the parking brake valve in the driving 

position. Both pressure gauges must now 

indicate a pressure of approx. 8 bar. This is 

the limiting pressure of the air supply unit.

Inspecting the emergency brake
1.

Move the parking brake valve slowly towards 

the parking position. Both pressure gauges 

should now gradually fall to 0 bar (with the 

exception of the first 10

 angular 

displacement. See graph in "Technical 

data").

Inspecting the parking position
1.

In the parking position, both pressure 

gauges should read 0 bar.

Inspecting the test position
1.

Place the parking brake valve in the parking 

position, depress the handle, and move it to 

the test position. The pressure gauge on 

connection point 43 of the drawn vehicle 

control valve valve should read approx. 8 

bar. The pressure gauge at connecting point 

42 of the relay valve should read 0 bar.

2.

Ensure there is sufficient system pressure.

3

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22

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R600092

BRAKE SYSTEM AND COMPONENTS

2-14

©

 200436

Inspection and adjustment

4

ΛΦ45/55 series

6

Parking-brake valve with pressure limitation 

and without trailer control

1.

Connect a pressure gauge to point 42 of the 

relay valve, using a tee.

Inspecting the driving position
1.

Place the parking brake valve in the driving 

position. The pressure gauge must now 

indicate a pressure of approx. 8 bar. This is 

the limiting pressure of the air supply unit.

Inspecting the emergency brake
1.

Move the parking brake valve slowly towards 

the parking position. The pressure gauge 

should now gradually fall to 0 bar (with the 

exception of the first 10

 angular rotation - 

see graph).

Inspecting the parking position
1.

In the parking position, the pressure gauge 

should read 0 bar.

R600095

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2

a