GF42.25-W-2000A | Electropneumatic 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
W42.25-0023-06
5.01 Single-chamber compressed air reservoir
12.07 Brake wear sensor
12.08 Rpm sensor
13.05 Brake value sensor
16.07 Proportioning relay valve
18.07 Trailer control valve
20.02 Single-circuit diaphragm brake cylinder
22.01 Combination brake cylinder
31.08 Drive axle axle modulator
33.06 Redundancy valve
45.01 ABS solenoid valve
A11 BS/EPB control unit
V1 Supply, circuit 1
V2 Supply, circuit 2
V3 Supply, circuit 3
E Electrical system
P Pneumatics
The BS/EPB control unit (A11) uses the signals from the sensors in the brake value sensor (13.05) to calculate the specified deceleration for the front and rear axle.
The BS/EPB control unit (A11) uses the signal for the specified deceleration to actuate the drive axle axle modulator (31.08) via the CAN data bus and causes the modulator to apply the brake pressure at the rear axle.
Application of the brake pressure at the front axle is regulated directly by the BS/EPB control unit (A11) via the proportioning relay valve (16.07).
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To calculate the actual deceleration and the wheel slip, the BS/EPB control unit (A11) evaluates the signals from the rpm sensors (12.08) at the wheels and from the pressure sensors integrated in the drive axle axle modulator (31.08) and in the proportioning relay valve (16.07) throughout the entire braking operation.
If the actual deceleration deviates from the specified deceleration, the BS/EPB control unit (A11) causes the drive axle axle modulator (31.08) or the proportioning relay valve (16.07) to reduce or increase the brake pressure.
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Trailer control
Trailer control is effected via the dual-circuit electropneumatic trailer control valve (18.07) which is actuated with top priority by the BS/EPB control unit (A11).
The specified deceleration predetermined by the brake value sensor (13.05) causes the trailer control valve (18.07) at the brake coupling head to apply a brake pressure adapted to the middle of the EC compatibility band.
Thus if both the trailer and the towing vehicle are at the center of the band simultaneously, there are no coupling forces.
If the trailer deviates from its legally required braking effect, the brake pressure at the brake coupling head is readjusted accordingly, but without violating the limits defined in the EC compatibility band.
Trailers equipped with an electropneumatic brake can also be braked via an electrical interface according to ISO 11992.
Control of individual axles
Vehicle version | 4-channel (BS) brake control | BS-controlled axles | Simultaneously controlled axles |
4x2 | X | Front axle+drive axle | |
6x2 | X | Front axle+drive axle | Trailing axle (simultaneously controlled by drive axle) |
6x2/4 | X | Front axle+drive axle | Leading axle (simultaneously controlled by drive axle) |
6x4 | X | Front axle+2nd drive axle | 1st drive axle (simultaneously controlled by 2nd drive axle) |
8x4/4 | X | 2nd front axle+2nd drive axle | 1st front axle (simultaneously controlled by 2nd front axle) and 1st drive axle (simultaneously controlled by 2nd drive axle) |