to 5 shafts arranged in the same circular pattern as the output rollers of the most basic design. The shafts are driven through planetary-like gears by a central input shaft. Since these shafts are always aligned by the input gears this allows the output to be transmitted through roller bearings rather than intermittent surface contact. Due to the planetary input this is effectively a two-stage drive and may be designed to be directly driven by a high speed brushless motor. This type is often used in robot actuators. Disadvantages Due to the eccentric nature of the drive, if the cycloidal disk is not balanced by a second disk or a counterweight, it will generate vibrations which propagate through the driven shafts and the body. This increases wear on the exterior teeth of the cycloidal disk and the component bearings. With two discs the static imbalance is corrected but a small dynamic imbalance remains. This is generally considered acceptable for most applications. To reduce vibration, high-speed drives use three or more discs to correct the imbalance; the outer discs move in unison, in opposition to the middle one, which is twice as massive. Advantages Cycloidal drives can feature zero backlash and high torque capacity while being compact in size, unlike Involute gearboxes. They are useful in situations where low speed with high torque is required. Cycloidal drives may be designed with significantly higher contact areas for their size than any gear-based transmission such as epicyclic gearing. They apply force through many of the teeth at once, allowing very high torque output relative to size at the cost of requiring sliding contact. See also Epicyclic gearing Cycloid gear – A gear tooth shape based on the cycloid Harmonic drive References External links Darali Cycloid Reducers Gears