Patent ID: 8313304

Claim:
A water pump assembly for an internal combustion engine, the pump assembly comprising: a bracket adapted to be fixed to the internal combustion engine; a drive shaft rotatably supported by the bracket; an input pulley being fixed for rotation with the drive shaft and adapted to be driven by the internal combustion engine; a drive pulley fixed for rotation with the drive shaft; a pump shaft rotatably supported by the bracket; a driven pulley fixed for rotation with the pump shaft; a pumping member fixed for rotation with the pump shaft such that rotation of the pump shaft and the pumping member causes a fluid flow; a flexible drive member including a surface contacting adjacent surfaces of the drive pulley and the driven pulley; a control mechanism for selectively switching the pump assembly between on and off modes of operation, wherein during the off mode of operation the control mechanism spaces a loading member apart from the flexible drive member and the flexible member transfers a minimum magnitude of torque between the drive pulley and the driven pulley as the flexible drive member surface slips relative to one of the adjacent pulley surfaces, in the on mode, the control mechanism engages the loading member with the flexible drive member to apply a load to the flexible member and transfer torque between the drive pulley and the driven pulley to drive the pumping member, wherein the control mechanism includes a spring biasing the loading member into engagement with the flexible drive member when the pump is operated in the on mode, the control mechanism also including an actuator operable to act against the spring and space the loading member apart from the flexible drive member.