US Patent 8251158 Multi-speed power tool transmission with alternative ring gear configuration

A power tool with a housing, a transmission and a switch mechanism. The switch mechanism has an actuator, a rail, a switch and first and second springs. The actuator is non-rotatably but slidably coupled to the housing for movement along a longitudinal axis of the transmission between a plurality of positions to selectively engage one or more members of the transmission at each of the positions such that the transmission operates in one of a plurality of different overall speed ratios. The rail is fixedly coupled to the actuator and is received through the switch such that the switch is slidably mounted on the rail. The first and second springs are configured to bias the switch relative to the actuator in different directions.