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

21

1

22

a

2
3

5

4

6

8

7

9

10

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

2

7

3

4

5

6

1

3

2

a