78
Description and roadside assistance
Guidelines for Breakdown Services (Subject to technical modifications)
i
Brake system
General
In the basic version the service brake is a pneumatically controlled brake with antilock brake system (ABS). As
well as the basic version, the service brake is also available as the Telligent
®
brake system. The Telligent
®
brake
system features an electronic control system to control and monitor the brake system and incorporating the
following systems:
• Antilock brake system (ABS)
• Acceleration skid control (ASR)
• Hill holder
• Frequent-stop brake
To relieve the strain on the wheel brakes the Telligent
®
brake system can activate the vehicle's built-in
permanent brake depending on the load state of the vehicle and the weather conditions.
If there are any faults in the brake system, an appropriate message is shown in the display.
If the electronic system fails, the brake system is controlled pneumatically in two circuits. Braking behavior is
significantly different from that of the intact system. The ABS function is no longer available, the pedal travel is
longer and the pedal forces are higher.
While driving, the air compressor replenishment function prevents the trailer brake from responding.
Releasing the spring-loaded parking brake, see page 82.
Pressure table
Pressure
Circuit
Four-circuit
protection
valve
Pressure regulator cut-in/cutoff pressure
about 10.2/12.3 bar
Reservoir pressure, rear axle service brake
about 9.7–10.7 bar
1
21
Reservoir pressure, front axle service brake
about 9.7–10.7 bar
2
22
Reservoir pressure, parking brake and trailer brake
about 8.0–8.7 bar
3
23/25
Reservoir pressure, ancillary consumers
about 8.0–8.7 bar
4
24/26
Release pressure, spring-loaded parking brake
about 6.5 bar
Reservoir pressure, Telligent
®
level control
max. 12.3 bar
Air suspension system overflow valve
about 9.6–10 bar