100 % Low-Floor Vehicles, System Variant Urbos

The 7-part multi-articulated vehicle has 3 motor bogies and one trailer bogie. 

The motor bogie has a spring-applied actuator HYS 252 on each drive wheel, which is controlled by a hydraulic power unit HZY K140-PR-NL with external pressure accumulator. The spring-applied actuators have two independent hydraulic circuits: the service circuit and the auxiliary release circuit. The hydraulic power unit supplies the proportional pressure for the service circuit, and also the pressure for the auxiliary release circuit via which all 4 spring-applied actuators of the bogie concerned can be released in the event of a malfunction. The HEY-C brake control unit ensures proportional activation of the hydraulic power unit and error monitoring.

Each wheel of the trailer bogie has a spring-applied actuator of type HYS 258. Here, too, the four spring-applied actuators are proportionately controlled by a hydraulic power unit HZY K140-PR-NL with external pressure accumulator. In interaction with 4 speed sensors, brake control unit HEY 2P/4G implements the necessary slide protection.

In the event of a malfunction, the spring-applied actuators can be released using a hand pump which is operated from the inside of the car via the independent auxiliary release circuit. A mechanical release possibility allows opening of the spring-applied actuator for workshop purposes. 

Two track brakes per bogie round off the braking system.