A cycloidal reducer is a kind of gear reducer. The basic operation is an input shaft connects to and drives an eccentric bearing. This bearing further drives a cycloidal disk (sometimes referred to as a cam) that connects to an output shaft.
cycloidal reducer
Standard cycloidal speed reducers, such as for example these Dojen series reducers from Onvio, offer zero backlash by 
combining a substance reduction cam with preloaded, complete compliment needle bearing cam followers.
The cycloidal disk (or cam) has lobes or teeth that build relationships some form of cam follower, typically a pin or needle bearings. The eccentric rotation of the cam is transformed into rotation of an result shaft at a lower life expectancy speed and a rise in torque.
The main advantage of cycloidal reducers is their property of zero or near-zero backlash, which results in high precision and high accuracy. That is especially in demand where highly specific and accurate positioning is necessary, for example in robotic applications, machine equipment, and similar applications. Cycloidal reducers also feature rolling instead of sliding contact, therefore experiencing less overall put on.