Before 1980s, most domestic engines used replaceable mechanical filters. The filter with this structure puts the filter element, spring, sealing ring and other parts into the metal shell, and connects the filter element of the shell with the metal filter seat through the pull rod. Replaceable machine filter has the advantage of low use cost, and only needs to maintain and replace the filter element regularly; The disadvantage is that there are too many sealing points, and the maintenance and replacement of the filter element may leak parts, which may easily lead to loopholes and trouble in replacement.
Since the early 1980s, rotary filters have been gradually recognized and selected by domestic OEMs. The rotary filter is characterized by one-way valve, bypass valve and only one sealing point, which are replaced integrally, greatly improving the sealing performance and being easy to replace. The filter element materials are mostly imported filter paper, which has high filtration efficiency, low flow resistance and long service life.