Patent ID: 7900715

Claim:
A variable speed tool comprising: a switch; a gearbox housing; a motor; an outputting shaft; a multistage transmitting gear train and a gearshift ring coupled to the motor and the outputting shaft; and a torque sensing ring, which is driven to rotate by the multistage transmitting gear train; and wherein the variable speed tool further comprises a gearshift fork coupled to the gearshift ring and a first spring member which drives the gearshift fork in an axial direction of the gearshift ring, a second spring member being arranged between the torque sensing ring and the housing, one of the torque sensing ring and the gearshift fork forming a sliding groove and the other one forming a guiding portion movably received in the sliding groove, whereby when a load of the outputting shaft reaches a predetermined value, the torque sensing ring overcomes a spring force of the second spring member and rotates so that the gearshift fork is driven by the first spring member to take axial movement thereby moving the gearshift ring between a first position and a second position.