Function of parking brake

D42.20-1105-06

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

9.01 Red illuminated indicator

10.01 Pressure switch
B66, B67, B118, B130, B131

14.01 Solo parking brake valve

16.01 Air admission relay valve

20.05 Pulling spring actuator

30.01 Safety valve

30.03 Pressure limiting valve with vent

36.03 Suction filter

38.02 Test connector

Ⅰ Electrical system

D42.60-1101-09

A Electric air compressor M57

B Air drier with heater

C1 Compressed air reservoir V2 (regeneration reservoir)

C2 Compressed air reservoir V3

C3 Compressed air reservoir V4

D1 Valve pressure limiting valve

D2 Safety valve

D3 Overflow valve

E5 Pressure switch B130
(green color coding)

F Check valve

G1 Spring actuator

G2 Spring actuator

H1-H3 Test connections

K Intake pipe

D4 Relay valve

D5 Parking brake valve

E1 Pressure switch B118

E2 Pressure switch B66

E3 Pressure switch B67
(yellow color coding)

E4 Pressure switch B131
(blue color coding)

Function of compressed air-operated parking brake

When the parking brake valves (D5) are 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 brake 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.