| 摘要 |
A screw-threaded device as for use in a vise or other clamping mechanism which includes a threaded shaft received in a partially threaded nut. The threaded shaft is axially movable under an axial actuating force at a rapid rate, and is incrementally advanced axially by a rotative force thereon, the screw threads of the shaft being automatically moved into or out of engagement with the partial threads of the nut upon rotation of the shaft in advancing or retracting direction. One spring coacts between the nut and a guide yoke on the shaft to guide the nut in and out of engagement with the shaft, while a second spring on the yoke bears against the shaft and tends to turn the yoke with the shaft. A second form of the invention uses the same, or essentially the same, partially threaded nut and guide yoke, but uses a positive pivot pin for guiding the partially threaded nut in and out of engagement with the threaded shaft.
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