Abstract: Technologies for variable retarder control include a control valve for controlling operation of a hydraulic retarder. The control valve includes a valve body having a retarder valve including multiple ports and a valve bore extending through the ports. A valve spool is located in the valve bore and movable to selectively block or connect one or more of the ports. The ports include a retarder-out port and an exhaust port, which are fluidly coupled to each other via an exhaust passageway. In use, the exhaust passageway bleeds lubrication fluid from the retarder-out port to the exhaust port as the valve spool is moved from a fully-off position to a fully-on position. The exhaust passageway is shaped so as to provide a linear relationship between the positioning of the valve spool between the fully-off and fully-on positions and the power of the hydraulic retarder.

Abstract: Technologies for variable retarder control include a control valve for controlling operation of a hydraulic retarder. The control valve includes a valve body having a retarder valve including multiple ports and a valve bore extending through the ports. A valve spool is located in the valve bore and movable to selectively block or connect one or more of the ports. The ports include a retarder-out port and an exhaust port, which are fluidly coupled to each other via an exhaust passageway. In use, the exhaust passageway bleeds lubrication fluid from the retarder-out port to the exhaust port as the valve spool is moved from a fully-off position to a fully-on position. The exhaust passageway is shaped so as to provide a linear relationship between the positioning of the valve spool between the fully-off and fully-on positions and the power of the hydraulic retarder.

Abstract: A system has been developed for engaging a clutch pack using a hydraulic piston. The system can be used with an automatic transmission or another part of the drivetrain of a vehicle. The system includes a piston, a clutch pack, and a housing that contains the piston and clutch pack. To engage and disengage the piston against the clutch pack, the system is configured to fill and empty a hydraulic chamber on a hydraulic side of the piston such that the hydraulic fluid moves the piston towards and away from the clutch pack. The piston includes one or more pads or standoffs that form flow gaps. The piston is further configured to position seals on the piston closer to the hydraulic side.

Abstract: A system has been developed for engaging a clutch pack using a hydraulic piston. The system can be used with an automatic transmission or another part of the drivetrain of a vehicle. The system includes a piston, a clutch pack, and a housing that contains the piston and clutch pack. To engage and disengage the piston against the clutch pack, the system is configured to fill and empty a hydraulic chamber on a hydraulic side of the piston such that the hydraulic fluid moves the piston towards and away from the clutch pack. The piston includes one or more pads or standoffs that form flow gaps. The piston is further configured to position seals on the piston closer to the hydraulic side.