This always-active retarder delivers continuous braking pressure to rail cars as they enter the unit. The spring design does not require air, hydraulics or electricity to operate. A shim adjusting system simplifies maintenance of the unit.

Adding a hydraulic package turns the AR2 into an operable fail-safe unit. In the event of a power failure the spring force closes the retarder making it possible to stop any rolling rail cars, bogies, or wagons