Torque limiting device for roller conveyor live roller

Claim 1

A live roller for a roller conveyor that comprises a pair of elongated, laterally spaced supporting elements by which said live roller and a plurality of other rollers are supported, with each of said rollers extending between said supporting elements and rotatable about a fixed axis that extends laterally to the supporting elements, said live roller being rotatably driven from drive means through clutch means so that an article resting on the rollers can be transported by them in a direction lengthwise of the supporting elements but said live roller is prevented from rotating if said article encounters a predetermined resistance to motion in said direction, said live roller being characterized by: A. a coaxial shaft for said live roller having (1) a circular cross-section, (2) a uniform diameter along substantially its entire length, (3) a screw threaded portion at one end thereof, and (4) a length to extend across the space between said supporting elements and to have said threaded portion spaced a substantial distance outwardly beyond one of them; B. bearing means cooperating with said shaft and each of said supporting elements to mount the shaft for rotation; C. said roller being tubular and having an inside diameter larger than the diameter of said shaft; D. a pair of annular bushings concentrically securing said roller to said shaft and cooperating with said bearing means to substantially confine the shaft against axial displacement relative to said supporting elements; E. axially inner and outer collar-like driven clutch members on said shaft, between its threaded end portion and said one supporting element, each having a flat friction surface which axially faces the friction surface on the other; F. a pin extending radially through the axially inner driven clutch member and transversely through the shaft to confine that clutch member against rotation and axial motion relative to the shaft; G. a second pin extending radially through the axially outer driven clutch member and through an axially elongated slot in the shaft to confine that clutch member against rotation relative to the shaft but allow it to have limited axial motion relative to the shaft; H. a coaxial driving clutch member rotatable and axially slidable on said shaft between said driven clutch members, said driving clutch member (1) having axially opposite flat friction surfaces which frictionally engage said friction surfaces on the respective driven clutch members, and (2) having a peripheral portion arranged for cooperation with said drive means to be rotat-ably driven thereby; I. a nut on said threaded end portion of the shaft; and J. a coiled expansion spring surrounding the shaft and reacting between said nut and said axially outer driven clutch member to maintain the respective friction surfaces on the driving and driven clutch members engaged under axial bias.