The Bendix+ E-10PR retarder control brake valve is used with retarder systems installed on automatic transmissions Automatic transmission retarders are used to retard forward motion of the vehicle above 5 mph Retarders are most popular in the transit -buses-coaches- industry and are used to extend the life of brake system components The retarder system is actuated early in the brake application, before air pressure is delivered Retarders can be installed either internally or externally on the automatic transmission and are generally electrically activated by devices such as the E-10PR valve Most retarders redirect the flow of hydraulic fluid through the torque converter while others use a small internal brake in the output section of the transmission The E-10PR valve is capable of controlling up to a threestage retarder -different levels of retardation- through the sequencing of its three electrical switches The sequencing of these switches is important to the proper operation of the retarder E-10PR retarder control brake valve is a floor mounted, treadle operated type brake valve with two separate supply and delivery circuits for service -primary and secondary- braking, which provides the driver with a graduated control for applying and releasing the vehicle brakes The E-10PR valve uses a metal coil spring housed in an upper body assembly The use of a metal coil spring -and the upper body assembly- provides greater treadle travel and, therefore, provides the driver with a less sensitive "feel" when making a brake application The E-10PR retarder control brake valve is generally used on buses, where smooth brake applications contribute to passenger comfort