Abstract: An air precleaner for internal combustion engines having a central conduit for conducting precleaned air to the air intake of the engine. A housing is disposed around the central conduit and forms an air intake opening, an arcuate wall spaced radially outwardly from the conduit and substantially concentric therewith for conducting the incoming air stream from the intake opening around the conduit so that any dust in the air stream is collected along the housing wall by centrifugal action, and a dust outlet for discharging dust from the housing at the downstream end of the arcuate wall. The conduit forms clean air port near the downstream end of the arcuate wall for discharging clean air from the inner region of the space between the arcuate wall and the conduit. An internal baffle integral with one side of the intake opening extends between the arcuate wall and the conduit and forms a restricted passageway that increases the velocity of the incoming air at the upstream end of the arcuate wall.

Abstract: A two-stage fluid filter such as an automotive oil filter. The two-stages of filtering media are mounted inside a conventional cylindrical housing forming fluid inlet and outlet ports in one end thereof. One stage of the filtering media comprises an annular depth type filtering medium having a radially outer surface in fluid communication with the inlet port, and a radially inner surface in fluid communication with the outlet port so that fluid can flow from the inlet port to the outlet port by flowing radially through the depth type medium. The second stage of the filtering media comprises a spirally wound surface type filtering medium, such as filter paper, with alternate pairs of opposed surfaces of the spiral winding bonded to each other along the circumferential edges at one longitudinal end of the spiral winding.