GEARS & GEARSETS
Miniature gearing and planetary gearing put to good use GEARS
function in an array of power-transmission applications. They are the natural complement to electric motors in industrial and consumer designs. Consider some examples: Amusement rides to consumer-grade home printers make use of spur gears. These roll through meshing for up to 98% or higher efficiency per reduction. The only caveat is that they exhibit tooth sliding and noise due to initial tooth-to-tooth contact and audible shock loads.
This subassembly is from a maxon GPX 22UP X-series 22-mm diameter planetary gearhead. Notice how the planet gears spin on precision needle bearings instead of higher-friction plain bearings. This and other features give the GPX UP planetary gearbox higher continuous and peak torque capabilities than comparable designs — for top efficiency, service life, and smoothness during back-driving … even in | courtesy of maxon multistage iterations.
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Helical gear reducers are costlier than spur sets but work in designs needing high horsepower and efficiency. Textile machinery, conveyor drives, rolling mills, and elevators all use helical gearing to engage gradually over tooth faces for smooth operation and high load capacity. The only caveat is that the machine setup must include framing or supports to resolve thrust loads originating from the gears. Non-parallel and right-angle gears go into motion applications for material handling, aerospace and defense, packaging equipment and food-processing machinery. Input and output shafts protrude in different directions; gear teeth are worm, hypoid, bevel (straight, spiral or zerol) as well as skew or crossed-axis helical. Common bevel gearsets often go into material-handling and packaging equipment. Hypoid gears (useful for high-toque applications) are like spiralbevel gearsets, but output and input shaft axes don’t intersect — and that simplifies integration of supports. Common in aerospace, zerol gearsets have curved teeth that align with the shaft to minimize thrust. Speed reducers work with an array of motors. These gearsets alter the torque of a motor — usually as an increase proportional to rpm reduction. Common in material-handling setups, shaft-mounted gear reducers come in designs that use special couplings to address reactionary torque. Other shaft-mounted reducers actually mount to the machine housing (especially in machine setups with surrounding enclosures) so the input shaft doesn’t support the reducer. 11 • 2020
DESIGN WORLD — MOTION
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