When it comes to gearheads, any lost motion contributes to position error, can complicate control efforts, and can introduce magnified dynamic loading on components. Many reduction technologies try to minimize lost motion and its effects. When evaluating various reduction technologies it is usually not sufficient to consider just backlash. You must also think about all of the lost motion contributors, which would include the torsional stiffness of the gearhead.
For a pair of meshed gears, backlash is the amount by which a tooth space exceeds the thickness of an engaging tooth. For a gearhead, backlash is the amount of motion the meshed gears have when the input is held fixed. Torsional stiffness on the other hand may include such things as deflection of components, bearing support, etc.
Theoretically, perfect gears do not require backlash to operate satisfactorily. However, manufacturing tolerances, bearing dimensions, thermal considerations, and other practical considerations result in unavoidable backlash.
At Parker we measure the backlash of every Stealth gearhead by locking the input and applying to the output a torque of 2% of the gearheads rated torque. Measurements are taken at 6 points around an output revolution to ensure constant, low backlash throughout the entire cycle. Torsional stiffness is maximized with our high tooth to tooth contact ratio, and integral ring gear machined directly into the steel housing. The combination provides a well-balanced product that will minimize the lost motion of any application.
Article contributed by Jeff Nazzaro, Gearhead and Motor Product Manager, Electromechanical Automation North America. Originally published on ParkerMotion.com
Learn more about Parker options in Gearheads by downloading our Gearhead Catalog
Other posts about gearmotors and gearheads include: