GF42.25-W-2003A | Pneumatic trailer brake circuit, function | 18.6.07 |
MODEL 944, 950.5 /6, 952.5 /6, 953.6, 954.5
with CODE (BB1) Brake control (BS)
except CODE (ZX2) EPB II
MODEL 944, 950.5 /6, 952.5 /6, 953.6, 954.5
with CODE (BB8) Brake control (BS) with ASR
except CODE (ZX2) EPB II
MODEL 950.0 /1 /2 /3, 952.0 /1 /2 /3, 953.1 /3, 954.0 /1 /2 with CODE (BB1) Brake control (BS)
MODEL 950.0 /1 /2 /3, 952.0 /1 /2 /3, 953.1 /3, 954.0 /1 /2 with CODE (BB8) Brake control (BS) with ASR
W42.25-0013-12
1.1 Proportioning valve
1.2 Pressure sensor
1.3 Relay valve
13.05 Brake value sensor
14.02 Parking brake valve with trailer control
16.07 Proportioning relay valve
18.07 Trailer control valve
33.06 Redundancy valve
35.02 Coupling head for supply
35.03 Coupling head for brake
V1 Supply, circuit 1
V2 Supply, circuit 2
V3 Supply, circuit 3
a Supply pressure (V1, V2 and V3)
b Redundancy circuit (pneumatic control pressure)
c Brake pressure
Trailer control is effected via a dual-circuit electropneumatic trailer control valve (18.07) which is actuated by the BS/EPB control unit. The trailer control valve (18.07) consists of a pneumatic and an electropneumatic component.
When the brake value sensor (13.05) is operated, the trailer control valve (18.07) is actuated electrically by the BS/EPB control unit and regulates pressure to the brake coupling head (35.03) according to the defined specification. Simultaneously, the redundancy-circuit pneumatic control pressure modulated by the brake value sensor (13.05) is also present at connection 42 of the trailer control valve (18.07).
Electropneumatic brake pressure regulation has priority over the pneumatic control pressure of the redundancy circuit.
The pneumatic control pressure of the redundancy circuit only takes over brake pressure regulation if electropneumatic brake pressure regulation fails.