Accumulating conveyor of the low pressure type

Claim 1

In an accumulating conveyor including a frame supporting a plurality of freely rotatable rollers defining a conveying surface for successive articles, an endless belt of a predetermined radial thickness mounted in the frame below said rollers and including an upper run adapted for frictional driving engagement with said rollers from below, and means for driving said belt, the combination of a plurality of individual assemblies for effecting controlled driving engagement of said belt with said rollers and disengagement of said belt from said rollers, each of said assemblies comprising: (a) a shaft mounted in said frame below and in substantially parallel alignment with one of said rollers by mounting means providing for movement of said shaft toward and away from said one roller, (b) a compound sheave rotatably mounted on said shaft and having therein a circumferential groove including a bottom wall proportioned to receive and support said upper run of said belt, (c) said groove wall being cylindrically curved about the central axis of said shaft over the major angular portion thereof but having a minor portion which is convexly curved to a contour in radial section of a radial dimension from said shaft axis that varies from a minimum at the center thereof to a maximum at each end thereof equal to the radius of said major portion of said groove wall, (d) yieldable means biasing said shaft toward said one roller to effect driving engagement of said belt run with said one roller, (e) said compound sheave also including means defining a convexly curved cam lobe adjacent and parallel with said groove and in axially centered relation with said minor portion of said groove wall, and (f) said cam lobe having an outer radial dimension from the rotational axis of said compound sheave which varies from a maximum, that coincides in angular position on said sheave with said minimum radial dimension of said minor portion of said groove wall and is greater than the sum of said belt thickness and said minimum radial dimension of said minor portion of said groove wall, to a minimum that is less than the sum of said belt thickness and the radius of said major portion of said groove wall, (g) whereby as said minor portion of said groove wall rotates through the 12 o'clock position thereof, said cam lobe will cause said belt to move out of and then back into engagement with said one roller.