Torque-adjustable screwdriver
Patent 4517865 Issued on May 21, 1985. Estimated Expiration Date: 
January 6, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
January 6, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References2797564 InventorApplicationNo. 06/568681 filed on 01/06/1984US Classes:81/475Having complementary formationsExaminersPrimary: Jones, James L. Jr.Attorney, Agent or FirmInternational ClassesB25B 15/02 (20060101)B25B 23/142 (20060101) B25B 23/14 (20060101) B25B 15/00 (20060101) AbstractThis invention relates a screwdriver capable of exerting a preset twisting force and characterized by comprising a tubular handle, a twisting rod, an adjusting thimble and a spiral spring. The said twisting rod has circular toothing on its projecting part to be engaged with the corresponding toothing on the block serving as a plug in the handle opening. The said spring fitted over the twisting rod between the projecting part of the rod and the projecting part of the adjusting thimble makes the said toothings engaged tightly. The degrees of engagement is used as measurements of twisting force. When the resistance of turning exceeds the preset twisting force the handle will slide on the said toothings and turn idly. This and the sound produced at this moment will remind the operator that the required torque has reached.Other References
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