Bearings are what allow the gears to rotate easily. They are usually designed out of bronze or brass, and they suit into races (or grooves) inside the gearbox housing. Contaminants can enter your gearbox oil by means of vents or maybe the fill tube throughout checking/filling. More often than not, https://jaidenzulaq.ltfblog.com/33042417/a-review-of-filter-gearbox