Endless conveyor

Abstract

A conveyor and method for preventing stick-slip friction conditions from exciting the conveyor into surging and for preventing surging vibration from adversely affecting operation of the conveyor. The conveyor has a pair of endless, flexible roller chains that are laterally spaced apart and carried on sprockets keyed to a drive shaft that is in communication with a drive at one end of the frame and sprockets keyed to a take-up shaft at the opposite end of the frame. Preferably, the take-up shaft is split into two shaft sections rotatively secured adjacent their ends by a pair of bearings on a mounting block to permit each conveyor chain to move on its idle sprocket independently of the other chain. The conveyor components are selected to provide a combination of chain stiffness and conveyor mass moment of inertia at maximum payload that produces a conveyor having a high enough natural frequency to prevent stick-slip friction conditions from exciting the conveyor chains into surging. Should a conveyor possess a natural frequency falling within the range of natural frequencies causing the conveyor to be susceptible to surging, a dampener that includes a flywheel disc coupled to the conveyor take-up shaft by a spring is attached to one or preferably both ends of the take-up shaft of the conveyor for preventing stick-slip from exciting the conveyor chains into surging and reducing the amplitude of any surging vibrations which might occur so they do not adversely affect operation of the conveyor.