The coaxial-drive (Koaxdrive) KD 32 planetary gearhead from maxon precision motors inc., Fall River, Mass. (www.maxonmotorusa.com), uses plastic planetary wheels designed to handle relatively high-torque loads (6.5 Nm) and reduce noise. Quiet operation, compact size (32-mm diameter), and coaxial configuration, make the drives well suited for medical and dental hand tools and instruments used near patients’ ears. The drive operates at up to 8,000 rpm and has gear reductions ranging from 11:1 to 1,091:1.

The drive combines the best of worm and planetary gearing. A worm-formed motor pinion in the first stage drives three offset planetary wheels. These three wheels interlock with an internal gear which has straight-cut teeth. And a patented sliding mechanism removes the axial load from the motor shaft, which also helps reduce contact noise.

Edited by Stephen J. Mraz