One way to stop a train

A new self-energizing electrohydraulic brake offers the advantages of hydraulic brake actuation without the disadvantages of a centralized hydraulic power supply.

The idea of a self-energizing electrohydraulic brake (SEHB) such as that being developed for trains by researchers at RWTH Aachen University is that the pressure needed for actuation of a hydraulic disc brake is gained from hydraulic support of the friction force. Unlike conventional brakes, where the brake caliper is fixed, in the SEHB concept it moves tangential to the friction contact. A hydraulic supporting cylinder connects the caliper to the bogie structure, thus fixing it between two columns of oil.

In case of braking, the friction force acts on the supporting cylinder, causing a pressure difference. Independent of which chamber is pressurized and which is released, a configuration of four check valves assures that the lower line has the higher pressure and the upper line is low pressure. A control valve connects high- and low-pressure sides with the chambers of the brake actuator.