A cycloidal reducer is a type of gear reducer. The basic operation is that an insight shaft connects to and drives an eccentric bearing. This bearing additional drives a cycloidal disk (sometimes known as a cam) that connects to an output shaft.
cycloidal reducer
Usual cycloidal speed reducers, such as for gear box for greenhouse example these Dojen series reducers from Onvio, provide zero backlash by combining a compound reduction cam with preloaded, full compliment needle bearing cam followers.
The cycloidal disk (or cam) has lobes or teeth that build 
relationships some type of cam follower, typically a pin or needle bearings. The eccentric rotation of the cam is certainly changed into rotation of an output shaft at a reduced speed and a rise in torque.
The main advantage of cycloidal reducers is their property of zero or near-zero backlash, which translates into high precision and high accuracy. This is especially in demand where highly precise and accurate positioning is required, for example in robotic applications, machine equipment, and similar applications. Cycloidal reducers also feature rolling instead of sliding contact, hence experiencing less overall wear.