Finished-Bore Sprockets are provided with standard keyway and 2 set screws. The keyway is for fixing your sprocket to the shaft to keep the sprocket from spinning. One set screw is located over the key and one is located 90 degrees to the key for locking onto the shaft. They have two set screws and a standard ANSI keyway, except 1/4", 3/8", and 1/2" bore sizes do not have a keyway. The keyway is American National Standard Institute (ANSI) standard, please be sure to double check your keyway before you order.
Roller chain sprockets, sometimes called single-strand sprockets, have a series of teeth around a central bore and are used in combination with roller chains to move conveyors and other industrial machinery. Fixed bore sprockets are designed to fit a specific shaft size and include a keyway and setscrew so they're ready to install. Plain bore sprockets are manufactured without a keyway or set screw. Keyways or set screws can be machined to the exact size required by the existing shaft and application. Bushed bores have more clamping area around the shaft to provide a secure fit for high torque or high-power applications when the shaft is at risk of slipping, such as paper milling and agricultural machinery.
Sprockets are of various designs, a maximum of efficiency being claimed for each by its originator. Sprockets typically do not have a flange. Some sprockets used with timing belts have flanges to keep the timing belt centered. Sprockets and chains are also used for power transmission from one shaft to another where slippage is not admissible, sprocket chains being used instead of belts or ropes and sprocket-wheels instead of pulleys. They can be run at high speed and some forms of chain are so constructed as to be noiseless even at high speed.