BPW ECO Tronic EBS Operating And Installation Instructions page 61

5.1.3 Trailer Control Module TrCM +
Pressure loss in the supply line.
Effect on the service braking system (Fig. 105):
If the pressure in the supply line falls by at least 1 bar per second,
the automatic brakes of the trailer vehicle will come on before
the pressure in the supply line falls to 2 bar. This establishes a
direct connection between the supply reservoir (port 1-2) and
port 21. An automatic braking is carried out by the service brake
unit, and ABS remains in operable condition.
Effect on the service braking system supply reservoir and
the auxiliary devices:
If the supply line (red coupling head) is pulled off, loss of supply
air from the trailer vehicle's supply reservoir and the auxiliary
devices is prevented by the integrated low pressure check valve.
Effect on the spring braking system (Fig. 105):
The parking valve is pushed out automatically when the spring
braking system is released (red button pressed); the parking
brake actuator is kept released through the integrated double
check valve.
As a result, the pressure at ports 21, 2 and 1-2 is the same. If
the pressure in the supply reservoir falls further, ports 21 and
2 are vented at the same time; this automatically activates the
spring braking system and in that way prevents the trailer vehicle
from rolling away.
Pressure lost in the auxiliary devices,
effect on the service braking system supply reservoir:
If pressure is lost through an auxiliary device, a "safety pressure"
is maintained in the supply reservoir of the service brake
equipment by the integrated pressure protection valve.
Applying pressure through the service coupling,
supply reservoir not coupled:
If pressure is introduced through the service coupling (e.g.
when the tractor vehicle's parking brake is active) the braking
supply reservoir (and therefore the auxiliary devices as well) are
fi lled with a pressure that is reduced by the overfl ow loss.
Filling the auxiliary devices depends on reaching the pressure
at which the integrated pressure protection valve will open.
As a result of this, a braking system that is empty or only partially
pressurised is charged even before the palm coupling supply
is connected.
Caution Danger!
Before starting the journey, the spring brake cylinder
must be released manually using the parking valve.
5.1 Brake system
Manoeuvring when uncoupled
24 23 1-2
25
1
Fig. 106
Activating the parking brake
when coupled
24 23 1-2
25
1
Fig. 107
Releasing the parking brake
when uncoupled
24 23 1-2
25
1
Fig. 108
4 21 12
2
3
4 21 12
2
3
4 21 12
2
3
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