The degree of protection describes the extent to which housings are protected against solid objects (e.g. dust) and liquids (water). The aim is to maintain the operability of electronic components for various environmental conditions.
Rehfuss gears and motors are available in different types of protection, depending on your needs. The suitability of our gearboxes and motors is classified in IP codes.

More details you can find here.

“Revolving wheel gearboxes (or planetary gearboxes) are gear or friction wheel gearboxes which, in addition to fixed shafts, also have axles that revolve on circular paths in the frame. Accordingly, a distinction is made between the central or sun wheels mounted on the fixed axles and the revolving or planetary wheels mounted on the revolving axles. The wheels rotating on the revolving axles orbit a central wheel in a similar way to planets orbiting the sun. The bridge, which carries the rotating axles, in turn rotates around a fixed axle. Helical gearboxes are compact gearboxes with the special feature that the fixed axles (or shafts in the case of torque transmission) are aligned with each other. Another special feature is the generally used three-shaft operation (the third shaft carries the web, which can therefore also be the drive or output).”