EXPERIMENTAL INVESTIGATION OF LINK TENSION AND ROLLER-SPROCKET IMPACTIN ROLLER CHAIN DRIVES

This paper presents the results from a recent experimental investigati on into the dynamic behavior of roller chain drives. A strain gage mou nted on a link side plate was used to determine chain tension during n ormal 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 t hen 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 co nditions, dynamic effects can be neglected without introducing signifi cant error. As chain speed increases, dynamic effects become increasin gly important. As is the case for belt drives, the average tight side chain tension can be expressed in the classical form of the preload, t he 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 chai n link increases very rapidly as the link exits the driven sprocket. T he increase from loose side to tight side average tension occurs over less than two sprocket teeth. The tension in a chain link decreases ve ry rapidly as the link enters the drive sprocket. The decrease from ti ght side to average loose side tension occurs over less than two sproc ket teeth. Transient spikes are present in the tension data at the poi nt were the link exits the driven sprocket and at the point where the link enters the driven sprocket. Impact force tends to increase as cha in tension increases, however the relationship is not monotonic. Impac t force tends to increase as chain speed increases, however the relati onship is not monotonic. For a chain traveling in the horizontal direc tion, the vertical component of the impact force is much larger than t he horizontal component. The magnitude of the horizontal component of the impact force increases more rapidly than the magnitude of the vert ical component as the chain speed increases, indicating that the angle of impact (as measured from a vertical line) increases as chain speed increases.