Bearings are what enable the gears to rotate effortlessly. They are usually designed outside of bronze or brass, they usually fit into races (or grooves) within the gearbox housing. Contaminants can enter your gearbox oil by means of vents or maybe the fill tube for the duration of checking/filling. Usually, https://emiliohdukb.onesmablog.com/not-known-facts-about-filter-gearbox-74708756