Boston Gear's stem pinions feature small numbers of teeth that are cut integral to the steel shaft. Using a special, enlarged pitch diameter minimizes the undercutting of the teeth. When run with standard stock spur gears, stem pinions increase the ratios normally found in spur gear drives.

Please note: Stem pinions are not intended to be operated with each other, with internal gears, or with eleven-tooth spur gears. They will, however, run satisfactorily with all other standard 14 1/2° PA spur gears.

Many different gears with a variety of bore sizes, keyways, and setscrews are routinely in stock, but if the particular bore/keyway/setscrew combination needed is not readily available, our machining experts can alter any non-hardened gear and ship it within 24 hours. Just ask!