Torque limiter

Abstract

A torque limiter includes a rotational driving member and a driven member aligned along the common axis. A plurality of axially extended arcuate recesses are formed on the outer periphery of an interlocking ferrule fitted over a rotational driving member, and also a plurality of radially extended grooves, matched with the arcuate recesses of the interlocking ferrule, are formed on the inner periphery of an interlocking ferrule fitted over a driven member opposed to the driving member. In each of the radial grooves, there is fitted a torque-transmitting steel ball in such a manner that it can only move radially and rotate about its own axis while it is confined in motion in the revolving and axial directions. As long as they transmit torque less than a preset critical level, these balls are biased diametrally inward by an elastic pressure means so that the rotational driving member and the driven member are integrally driven together. If any amount of torque exceeding the critical level is applied between the two members, the torque-transmitting steel balls being pressed against the arcuate recesses of the driving member and the radial grooves of the driven member will overcome the action of the elastic pressure means and will move radially outward along the radial grooves, thus allowing the driving and driven members to rotate relative to each other.