Experimental investigation of link tension and roller-sprocket impact in roller chain drives

Abstract This paper presents the results from a recent experimental investigation into the dynamic behavior of roller chain drives. A strain gage mounted on a link side plate was used to determine chain tension during normal operation over a wide range of linear chain speeds and preloads. The test machine also included specially instrumented idler sprocket that allowed the measurement of the horizontal and vertical components of the bearing reaction force. The roller-sprocket impact force was then computed by an experimental transfer function approach facilitated by a Bruel & Kjaer 2032 dual channel spectrum analyser. Observations about the data include: • • As is typically assumed, under quasi-static conditions, dynamic effects can be neglected without introducing significant error. • • As chain speed increases, dynamic effects become increasingly important. • • As is the case for belt drives, the average tight side chain tension can be expressed in the classical form of the preload, the driven load, and the load due to centrifugal force with only modest error over a wide range of linear chain speeds. • • The tension in a chain link increases very rapidly as the link exits the driven sprocket. The increase from loose side to tight side average tension occurs over less than two sprocket teeth. • • The tension in a chain link decreases very rapidly as the link enters the drive sprocket. The decrease from tight side to average loose side tension occurs over less than two sprocket teeth. • • Transient spikes are present in the tension data at the point were the link exits the driven sprocket and at the point where the link enters the driven sprocket. • • Impact force tends to increase as chain tension increases, however the relationship is not monotonic. • • Impact force tends to increase as chain speed increases, however the relationship is not monotonic. • • For a chain traveling in the horizontal direction, the vertical component of the impact force is much larger than the horizontal component. • • The magnitude of the horizontal component of the impact force increases more rapidly than the magnitude of the vertical component as the chain speed increases, indicating that the angle of impact (as measured from a vertical line) increases as chain speed increases.