Skeleton oil seal is a typical representative of oil seal, and generally speaking, oil seal refers to skeleton oil seal. The function of oil seals is generally to isolate the parts that need lubrication in the transmission components from the output components, so as not to allow lubricating oil to leak. The skeleton is like the steel bars inside the concrete components, which play a reinforcing role and enable the oil seal to maintain its shape and tension. According to the structural form, it can be divided into single lip skeleton oil seals and double lip skeleton oil seals. The secondary lip of the double lip skeleton oil seal plays a dust-proof role, preventing external dust, impurities, etc. from entering the interior of the machine. According to the skeleton type, it can be divided into internal skeleton oil seals, exposed skeleton oil seals, and prefabricated oil seals. According to working conditions, it can be divided into rotating skeleton oil seals and reciprocating skeleton oil seals. Used for gasoline engine crankshafts, diesel engine crankshafts, transmissions, differentials, shock absorbers, engines, axles, and other parts.