The cycloidal principle:
How it works
Cycloidal gears
A proven technology in the drive world
If your machines had the choice, they would choose cycloidal gears developed by Sumitomo Drive Technologies. That’s because they’re compact, durable and superior to conventional gears on so many levels.
We invented the Cyclo principle and offer practical high-end designs that meet the most demanding requirements.
Talk to a Sumitomo Cyclo expert to discuss your application
Cycloidal gear working principle:
in simple terms
Although cycloidal gears seem complex at first glance, their design is actually remarkably straightforward. A cycloidal gear brings together the following five fundamental components in addition to other parts:
- High speed shaft with eccentric bearing
- Cycloidal disc(s)
- Ring gear housing with outer pins
- Driving pins with rollers
- Slow speed shaft
And here’s how it works:
As the eccentric bearing rotates, it rolls one or more cycloidal discs around the internal circumference of the stationary ring gear housing. The resulting action is similar to that of a disc rolling around the inside of a ring.
As the cycloidal discs travel in a clockwise path inside the ring gear housing, the discs themselves turn in an anticlockwise direction around their own axes. The lobes of the cycloidal discs engage successively with the pins of the ring gear housing, thus producing a reverse rotation at a reduced speed.
For each complete revolution of the high speed shaft, the cycloidal disc moves by one lobe. The reduction ratio is determined by the number of cycloidal lobes on the cycloidal disc.
There is at least one lobe fewer per cycloidal disc than there are pins in the ring gear housing, which results in the reduction ratio being numerically equal to the number of lobes on the cycloidal disc. The reduced rotation of the cycloidal discs is transmitted to the slow speed shaft via pins projecting through the holes in the cycloidal discs.
Normally, a kit comprising two cycloidal discs with a double eccentric bearing is used, which can increase the torque while still ensuring exceptionally quiet and vibration-free operation.
