초록

A drive rod apparatus and method generates a drive feed which is dependent on the speed change of the load. The apparatus and method, which is preferably embodied in a lifting jack, includes a slidable drive screw and nut set.

대표청구항 ▼

In a loading-lifting device, the combination of a drive rod including a forward portion being threaded in a first direction, a rearward portion being threaded in a second, opposite direction, and an intermediate, unthreaded portion therebetween, drive means for rotatably moving the drive rod in firs

In a loading-lifting device, the combination of a drive rod including a forward portion being threaded in a first direction, a rearward portion being threaded in a second, opposite direction, and an intermediate, unthreaded portion therebetween, drive means for rotatably moving the drive rod in first and second opposite directions, a driven member for supporting the load thereon, the driven member being driven in first and second opposite directions in response to the rotational movement of the drive rod for thereby lifting the load on the driven member, said driven member being connected to the respective forward and rearward portions of the drive rod by a pivotable linkage means, the linkage means including a drive sleeve threadably carried on the rearward portion of the drive rod, the drive sleeve having an outer periphery, the linkage means further including a linkage block in which at least partly disposed therein, the driven load supported by the member exerting a force on the linkage block through the linkage means, a positive screw nut structure on the forward portion of the drive rod between the drive rod and the linkage means, an adjustable pressure means carried by the linkage block and contacting the periphery of the drive sleeve for applying a pressure thereon, wherein when the pressure on the drive sleeve exceeds the force on the linkage block, the drive sleeve is maintained in a substantially stationary position relative to the rotary movement of the drive rod, and further wherein when the force on the linkage block exceeds the pressure on the drive sleeve, the drive sleeve rotates substantially in unison with the drive rod.