Parking brake, function

L42.20-0019-05

1.08 Air compressor

5.01 Single-chamber compressed air reservoir

6.01 Water separator

6.14 Air drier

7.01 Overflow valve with backflow

8.01 Check valve

9.01 Red indicator lamp

9.05 Yellow indicator lamp

10.01 Pressure switches
B5, B12, B13, B14, B74, B75

14.01 Solo parking brake valve

16.01 Ventilating relay valve

20.05 Pulling spring actuator

30.01 Safety valve

30.04 Pressure relief valve without vent

38.02 Test connection

I Electrical system

L42.60-0012-09

A Electric air compressor

B Air drier

C1 Compressed air reservoir

C2 Compressed air reservoir

D1 Pressure relief valve

D2 Safety valve

D3 Overflow valve

D4 Relay valve

D5 Parking brake valve

E6 Pressure switch B13
(color coded red)

F Check valve

G1 Spring actuator

G2 Spring actuator

H1-H3 Test connections

I1 Pipe 12x1.5 7.6m, 12x 1.5 7.9m (raised)

I2 Intake pipe

E1 Pressure switch B12
(yellow indicator lamp)

E2 Pressure switch B74
(color coded blue)

E3 Pressure switch B14
(color coded yellow)

E4 Pressure switch B75

E5 Pressure switch B5

Function of compressed air-operated parking brake

When the parking brake valve (D5) is actuated, the spring actuators (G1, G2) are vented. This leads to a pressure reduction in the spring actuator cylinder.
The pressure drop releases the stretched actuating spring

in the spring actuator cylinder, which pulls the actuator piston by the piston rod and the wheel brake is applied.
The brake is released by pressurizing the spring actuators.