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Motion System Design

Peaceful planetaries

Planetary gearing offers distinct advantages over parallel gear arrangements, including lower backlash, higher strength and torque, and greater torsional stiffness. Because forces are evenly distributed across several gears, the gearhead delivers greater torque than other designs without sustaining damage.

Highly efficient torque transmission in a compact package makes planetary gearheads suitable for space-constrained applications. However, one disadvantage of traditional planetary arrangements is the potential for noise — especially in the first gear stage where the greatest peripheral speeds occur. Where silence is golden, such as in medical hand tools, traditional planetary designs can be too loud.

A new coaxial-drive planetary gearhead (Koaxdrive KD 32) combines the best of two gearing technologies, worm and planetary, to achieve near-silent operation even at high loads. The hybrid design looks like a typical planetary gearhead on the outside, but uses a worm-shaped motor pinion to drive three offset planetary wheels that interlock with an internal straight gear. Plastic planetary wheels greatly reduce noise levels, as does the use of a worm gearing stage combined with fewer planetary stages.


On display: Koaxdrive KD 32 planetary gearhead

Key features: Combines worm and planetary gearing in a hybrid design; 32 mm OD and a coaxial arrangement on drive and output shaft fit tight spaces.

What it means to you: Quiet operation in noise-sensitive applications, such as medical hand tools, security and surveillance, robotics, and aerospace designs for seat and headrest actuation.

What else: Higher torque (6.5 Nm) and lower backlash compared to other designs; remains quiet, even at input speeds to 8,000 rpm; high reduction ratios in one planetary stage.

Innovator: maxon motor, Fall River, Mass.

(508) 677-0520 •

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