Bearings are what enable the gears to rotate smoothly. They are generally made away from bronze or brass, plus they match into races (or grooves) from the gearbox housing. Depending on the positioning, all automated transmission filters is usually divided into interior and exterior filters. External filters can be found https://filtergearbox84715.pointblog.net/an-unbiased-view-of-filter-gearbox-77922676