Checking compressed-air system of spring-loaded parking brake

AR42.20-D-0580B

Checking compressed-air system of spring-loaded parking brake

23.1.04



Check

1

Fill out data sheet for spring brake compressed-air system

 Measure test values, record in written form and furnish data sheet with job.



OF42.20-D-3000-01B

2

Bleed spring-loaded parking brake system

3

Connect pressure gauge of test kit to test connection (H1)

 Before overflow valve (D3).



*360589002100

4

Connect pressure gauge of test kit to test connection (H2)

 After overflow valve (D3).



*360589002100

5

Check cutoff pressure of standby lamp "(!)" for proper operation

 Pressurize spring-loaded parking brake system. Check pressure at test connection (H1) when standby lamp "(!)" is extinguished and compare with specified value.

If cutoff pressure of pressure switch B130 (E2) and specified value are different:



*BE42.10-N-1016-10A

Install new pressure switch B130 (E2).



*BA42.20-N-1012-01A



*360589002100

6

Check cut-in pressure of standby lamp "(!)" for proper operation

Bleed spring-loaded parking brake system until standby lamp "(!)" comes on.

Check pressure at test connection (H1) when standby lamp "(!)" comes on and compare with specified value.

If cut-in pressure of pressure switch B130 (E2) and specified value are different:



*BE42.10-N-1015-10A

Install new pressure switch B130 (E2).



*BA42.20-N-1012-01A



*360589002100

7

Check setting of overflow valve (D3)

 Check the pressure at which the overflow valve (D3) opens and at which the compressed air reservoir V4 (C3) is filled.

If opening pressure differs from specified value:

*BE42.10-N-1012-10A

Adjust overflow valve (D3).



*360589002100

8

Connect pressure gauge from test kit to test connection (H3) at relay valve (D4)



*360589002100

9

Check parking lamp "P"

 Pressurize spring-loaded parking brake system. Check pressure at test connection H3 when parking lamp "P" is extinguished and compare with specified value.

If switch point of the pressure switch B118 (E1) differs from specified value:

*BE42.10-N-1009-10A

Install new pressure switch B118 (E1).

*BA42.20-N-1011-01A



*360589002100

10

Check cut-in and cutout points of air compressor (A)

 Check cutoff pressure of pressure regulator to determine cut-in and cutout point of air compressor (A).

AR42.20-D-0002B

11

Unplug air compressor connector, attach adapter cable to air compressor and connect to both vehicle ground and positive battery terminal

 Use 40A fuse for jumper

Contact cavity A = positive battery terminal

Contact cavity B = ground

 After bridging the air compressor operates continuously.



*220589009900



Adapter cable for electric air compressor

WF58.50-N-0580-01A

12

Check drain pressure of safety valve (D2) at test connection (H1)

 The air compressor must be in continuous operation during the test, although it may turn off intermittently depending on the temperature.

If the drain pressure of the safety valve (D2) differs from the specified value:

*BE42.10-N-1013-10A

Install new safety valve (D2).



*BA42.20-N-1009-01A



*360589002100

13

Check compressed air drier drain valve

 After the ignition is switched on and the air compressor switched off, the drain valve opens (audible hissing noise).

*BE42.10-N-1014-10A

*BE42.10-N-1018-10A

If the drain valve does not open: 

Check electrical actuation for drain valve, if OK:

Install new compressed air drier.

14

Disconnect pressure gauge of test kit from test connections (H1, H2, H3)



*360589002100

Number

Designation

Model 905

Model Series 905 from
R 465742

BE42.10-N-1009-10A

Cut-in/cutoff pressure of parking brake indicator lamp "(P)", pressure switch B118

bar

5.8 (0.3 )

-

BE42.10-N-1012-10A

Release pressure of overflow valve

bar

10.5 (-0.5 )

-

BE42.10-N-1013-10A

Opening pressure of safety valve

bar

13.8 (+1.2 )

-

BE42.10-N-1014-10A

Opening time of air drier purge valve

s

10

-

BE42.10-N-1015-10A

Activation pressure standby indicator lamp "(!)" Pressure switchB130

bar

-

5.5 (0.2 )

BE42.10-N-1016-10A

Cut-off pressure standby indicator lamp "(!)" Pressure switchB130

bar

-

8.4 (0.4 )

BE42.10-N-1018-10A

Deactivation pressure electric air compressor pressure switch B130

bar

-

12.5 (-0.4 )

Number

Designation

Model 905

BA42.20-N-1009-01A

Safety valve to air compressor screw-in fitting

Nm

50

BA42.20-N-1011-01A

Pressure switch (B118) to relay valve

Nm

27

BA42.20-N-1012-01A

Pressure switch (B130) on pressure limiting valve T-piece

Nm

15