a driveline retarder coupled to a vehicle driveline where a ball ramp actuator having a control plate and an activation plate separated by rolling elements is energized by an electrical coil is used to apply a clamping load on a clutch pack which frictionally couples a rotating shaft to a gerotor hydraulic pump which is used to absorb rotational energy to create a braking torque on the vehicle driveline to aid in vehicle braking . a coupling plate is electromagnetically attracted to the electrical coil thereby transferring a braking torque to the control plate through a flex plate .