MAN Truck & Bus
Retarders are used to further improve the braking performance on commercial vehicles. Like engine brakes, they are wear-free continuous brakes. Retarders relieve the service brake and increase the active safety and cost-effectiveness of commercial vehicles. Retarders are installed in a commercial vehicle's drive train. They convert some of the vehicle's kinetic energy into heat. Subject to installation location, a distinction is made between primary retarders (depend on engine speed and installed between engine and transmission) and secondary retarders (speed-dependent and installed between transmission and drive axle). After operation and structure, a further distinction is made between hydrodynamic retarders (hydrodynamic brakes) and electrodynamic retarders. Hydrodynamic secondary retarders are normally used in modern forward control trucks. The braking effect depends on vehicle speed.