Torque responsive motor shutoff for power tool
AssigneeGardner-Denver Company
InventorWilliam Workman, Jr.
Life of this patent
Estimating the term…
Abstract
A pneumatic power tool for tightening threaded fasteners includes a planetary gear unit in which the ring gear is rotatable against the bias of a torsion coil spring to actuate a motor shutoff control valve at a predetermined torque reaction exerted on the ring gear. The torsion spring is in a substantially relaxed state during fastener rundown and before torque buildup on the fastener regardless of the torque setting at which motor shutoff is to occur. Adjustment of the motor shutoff torque setting is obtained by changing the positional relationship between a control valve pushrod and a cam surface on the ring gear member.
Claims11
A power tool for tightening threaded fasteners and the like comprising:
- housing means;
- a pressure fluid operated motor disposed in said housing means;
- valve means disposed in said housing means and operable to shut off the flow of pressure fluid through said motor;
- drive mechanism including a planetary gear unit connected to said motor for rotatably driving a threaded fastener;
- a first member disposed in said housing means and interposed in said drive mechanism, said first member comprising a rotatable ring gear of said planetary gear unit and a cam disposed on said first member and rotatable with said ring gear in response to a reaction torque imposed on said ring gear which is proportional to the torque exerted on said fastener;
- a cam follower disposed for engagement by said cam and responsive to the rotation of said ring gear to effect actuation of said valve means to shut off the flow of pressure fluid through said motor at a predetermined torque exerted on said fastener;
- and,
- a torsion coil spring disposed in said housing means and connected to said first member and being operable to be deflected from a substantially relaxed condition in response to rotation of said ring gear regardless of the predetermined torque at which motor shutoff is to be effected.
A power tool for tightening threaded fasteners and the like comprising:
- housing means;
- a motor disposed in said housing means and operable to produce rotary driving torque;
- means disposed in said housing means and operable to effect the stopping of said motor;
- drive mechanism including a planetary gear unit connected to said motor for rotatably driving a threaded fastener;
- a first member disposed in said housing means and interposed in said drive mechanism, said first member comprising a rotatable ring gear of said planetary gear unit and a cam disposed on said first member and rotatable with said ring gear in response to a reaction torque imposed on said ring gear which is proportional to the torque exerted on said fastener;
- a cam follower disposed for engagement by said cam and responsive to the rotation of said ring gear to effect actuation of said means to effect the stopping of said motor at a predetermined torque exerted on said fastener;
- and,
- a torsion coil spring disposed in said housing means and connected to said first member and being operable to be deflected from a substantially relaxed condition in response to rotation of said ring gear regardless of the predetermined torque at which the stopping of said motor is to be effected.
Dependencies are inferred from the claim text.