INA KSR20BO12101516 Kettenspannräder (20x99,2x31)

As a track or cam roller, this component runs directly on a mating track or cam surface. The principal dimensions are 20x99.2x31 mm at a weight of 0.46 kg; the further technical details are listed in the specification table. Chain elongation, strand oscillation and start-up shocks all converge in this component. A chain tensioner sprocket holds the slack strand of a chain drive under tension and guides it along its path.

Its task is therefore a different one from that of a driving wheel: it transmits no drive torque but absorbs the force with which the tensioning mechanism presses it against the chain, together with the shocks arising from start-up, load changes and strand oscillation. The toothed rim has to match the pitch and form of the chain; a wheel with an unsuitable pitch does not mesh cleanly and accelerates wear on chain and wheel alike.

Chain elongation likewise belongs in the layout, since the travel of the tensioning mechanism must cover the amount by which the chain lengthens over its operating life. Two routes are available for the material of the sprocket. A toothed rim machined or formed from steel is tough and carries shock loading and alternating load better; a rim produced from sintered iron is formed close to final contour and with consistent dimensions in quantity, and is intended for evenly running, moderately loaded drives, but behaves more brittly under impact loading.

Which of the two is present is to be taken from the item data. For the bearing arrangement of the wheel, the speed, the permanently applied contact force and the ambient conditions are decisive; the alignment between the tensioner sprocket and the plane of the chain has to be checked during mounting, since a wheel standing at an angle loads the chain on one side.