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Swing link equalizes planet gear loading

Swing link equalizes planet gear loading

Ronkonkoma, NY-Engineers at Thomson Micron LLC developed a "swing-link" technology for its new Equalizer(TM)gearhead that improves performance measured against comparable fixed planetary designs at a reduced cost.

Rather than fixing planet gears to the carrier assembly as in most designs, Equalizer uses a pivoting link. The pivot allows dynamic radial position adjustments of the planet gear, offering two main benefits: reduced machining tolerances and equal load sharing between all three planet gears.

"Because the planet gear relocates itself during operation, manufacturing tolerances aren't as tight," explains Philip Shaw, Thomson Micron sales and marketing manager. "And equal load sharing lets us use less expensive methods to achieve the same or better wear characteristics."

The result, according to Shaw, is a line of lower-cost planetary gearheads that perform equal to-or better than-current available models. In fact, Thomson Micron documents Equalizer performance benefits compared to similar fixed-planet configurations with:

  • approximately 25% cost reduction

3-11% efficiency increase, for a 93% minimum

20% decrease in torque ripple

4 dBa noise decrease

25% torque increase

longer life

Shaw says that the most heavily loaded planet gear in some fixed planet designs carries more than 60% of the load. This unequal cyclic loading of the planet gear is caused when misalignment of the gearing creates a tight mesh between certain gear teeth, and a loose mesh between others. "Both are situations you want to stay away from," says Shaw. "Tightly meshed gear teeth wear faster, because of higher friction and heat generation that degrades lubricant. And a loose mesh generally causes backlash."

In contrast, Equalizer balances the load distribution between all three planet gears, eliminating rough spots that cause noise, vibration, and cyclic loading of the gearbox. With each planetary gear in the Equalizer handling one-third of the total load, vector analysis yields a resultant load on the input pinion of zero. "Equal load sharing extends motor-bearing life approximately 900 times that of old style, conventional spur, or hybrid gearheads," Shaw says. "That means reduced downtime and lower production cost."

Engineers borrowed a design concept from its more expensive UltraTrue(TM)helical gearhead family-incorporating the internal gears directly into the housing to reduce component count and increase reliability. "This one-piece construction increases torsional stiffness and creates a smoother transmission," Shaw notes.

Equalizer is offered in four frame sizes (40, 60, 90, and 115 mm) with three front- face mounting options (NEMA, metric, and C-Face). With these front-face options, the gearheads are said to be an easy drop-in replacement for parallel-shaft spur gearheads and planetary reducers on the market today. The gearbox reportedly mounts to any motor in less than five minutes using the company's RediMount(TM)motor-mounting system, and is targeted at motion control applications in Asia, Europe, and North America. With 18 arc-min of backlash, the new gearheads are available in exact ratios from 3:1 to 100:1.

Additional Details

Contact Philip Shaw, Thomson Micron LLC, 50 Alexander Ct., Ronkonkoma, NY 11779; Tel: (631) 467-8000; FAX: (631) 467-9814; E-mail: [email protected]

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