Cycloidal Gear Technology by Sumitomo Drive Technologies
Proven technology for your machines
Cycloidal drive working principle: in simple terms
Although cycloidal drives seem complex at first glance, their design is actually remarkably straightforward. A cycloidal drive 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.
Understanding Gear Ratio in Cycloidal Gear Boxes
The gear ratio of a cycloidal gearbox is the ratio between the input speed (rotations of the input shaft) and the output speed (rotations of the output shaft). It indicates how many times the input shaft must turn to achieve one full rotation of the output shaft.
In cycloidal gearboxes, the gear ratio is determined by the number of lobes on the cycloidal disc and the number of pins (or teeth) engaging with the disc, plus one. This formula reflects the unique way that they transfer motion, with the gear ratio being adjustable by changing the number of lobes on the cycloidal disc or the number of pins it interacts with.
Selection Criteria for Applications
Here are the most common selection criteria for selecting a unit from top Cycloidal gearbox manufacturers such as Sumitomo Drive Technologies.
| Selection Criteria | Importance | Description |
|---|---|---|
| Reduction Ratio | High | Essential for determining the output speed based on the required application |
| Torque Capacity | High | Must match or exceed the maximum load the application will impose |
| Backlash | Medium to High | Critical for applications requiring high precision |
| Size and Weight | Medium | Important for applications with limited space |
| Efficiency | Medium | Higher efficiency may be necessary for energy-sensitive applications |
The benefits of cycloidal gear technology
Sumitomo Cyclo gears outperform conventional gears. Due to their rolling
motion, cycloidal gears have a significant advantage over cogwheel gears.
Today, they’re considered a proven solution that should be favoured over other
gear types in a number of scenarios – for good reason.
Explore our products with Cyclo® Technology Inside
As the inventor of cycloidal gears, we provide a broad range of tried and tested products
- spanning traditional gearmotors like the Cyclo Drive 6000, robust and versatile products
such as the Cyclo Drive 6000 reducer and the mechanically backlash-free precision gears
in the Fine Cyclo® series.
Celebrating 100 years of the Cyclo® gear
