Meritor WABCO® Electronic Braking System (EBS)

The Meritor WABCO® Electronic Braking System (EBS) is designed to continuously monitor and coordinate all aspects of service braking.

The EBS pairs an electronic control system with a pneumatic application system. Key braking data such as driver brake demand, wheel speed, and vehicle load is gathered by a network of electronic sensing devices (including load sensors, and signal generating tone wheels and sensors located in the wheel hubs of each sensing axle).

An electronic control unit, the central module, oversees the translation of electronic signals into pneumatic actuation. During a braking application, electronic-pneumatic modulators control the brake pressure of each wheel, as well as at the trailer coupling head. As a result, the same amount of vehicle deceleration will occur for a given brake pedal travel, regardless of vehicle load. During emergency stops (i.e. wheel lockup), the EBS also activates the Antilock Braking System (ABS).

The EBS includes a system check for all modulators, sensors, brake system electric circuits and data lines and is thereby able to detect malfunctions in the braking system. When a fault is detected, the central module will disable the affected part of the EBS. Under this safe status (i.e. fail-safe) mode, the nonaffected parts will continue to function. For example, in the case of a sensor malfunction, the system works without the sensor information but at a reduced performance level.

If a serious malfunction causes a total switch-off of one or more electronic braking circuits, a pure pneumatic backup system is available.

The following functions can be deactivated in the event of a malfunction:

• ABS can be deactivated at one individual wheel, at one axle, or for the whole vehicle.

• ATC control can be deactivated. If it is shut down, then both the brake control and the engine control will be shut down.

• If electrical control is lost, the affected axle is braked by means of the pneumatic redundancy pressure. The driver must compensate by exerting more force on the brake pedal to stop the vehicle.

This system has built-in diagnostics to ensure that all components are operating properly. Under normal conditions, the system performs a three second self-check when the ignition is turned on. The two warning lamps (EBS, ABS) and the information lamp (ATC) should illuminate for three seconds and then go out if all EBS components are working properly. If all three lamps do not switch on or if all three lamps do not switch off after three seconds, the system should be checked.