Abstract: A conveyor travels in a helical path and is driven by a plurality of drive sprockets which are mounted on a common drive shaft. Each drive sprocket includes a yieldable portion which moves relative to a ring gear of the sprocket when the conveyor encounters an unyielding resistance. A sensor is activated in response to relative movement of the yieldable portion of the sprocket to provide an indication of which drive sprocket has sensed the resistance to conveyor travel.

Abstract: A conveyor installation comprises a framework having stationary guides with plastic contact surfaces. A conveyor belt is mounted for travel on the framework and includes plastic carriers mounted on plastic chain links. The carriers are supported for sliding contact with some of the guides which define vertical support rails. The carriers are connected to the links by upstanding coupling members. Plastic clip-on sleeves are mounted on the coupling members for engagement with some of the stationary guides to minimize wear of the chain, while assuring a low friction sliding contact between the chain and the guides. Snap-on pan guides are insertable into recesses of the carriers.