Shaft seals on both the input and output shafts keep lubrication inside the gearbox while keeping debris and solid particles out. For equipment used in demanding applications, harsh environments or requiring ingress protection certifications, additional protective elements can be used. 

Depending on temperature and rotation requirements, radial oil seals made of acrylonitrile butadiene rubber (NBR) or fluorocarbon rubber (FKM) are recommended as shaft seals, while V-Rings can be used as secondary seals to prevent the ingress of dirt and/or water. Static seals such as O-Rings, gaskets, bonded seals and molded parts can be found as sealing elements for lids, flange joints, threads and covers. For high-end gearboxes and speed reducers a cassette seal can also be used as a long-lasting single sealing element with heavy duty dust lips that grant longer service life and lower maintenance.

In some instances, speed reducers can benefit from Trelleborg’s Varilip PDR radial oil seal. Constructed from one or multiple Turcon PTFE-based sealing elements they are mechanically retained in a precision machined metal body. The metal body gives a robust static seal against the housing, preventing thermal cycling, while the Turcon sealing element provides positive dynamic sealing on the shaft, leading to excellent performance at high rotary speeds. Characterized by low friction and stick-slip-free running, the seal reduces temperature generation, permits higher peripheral speeds and lowers power consumption. This results in a long-service life, with maximized meantime between planned maintenance and greater productivity.