Abstract: A filter element useful for filtering intake air for internal combustion engines includes a first filter media separated by an air space from a second filter media. The second filter media has a greater air permeability than the first filter media, but is electrostatically charged. As a result of this arrangement, the capacity of the filter element is enhanced because large particles are trapped by the first filter media and smaller particles are trapped by the second filter media. As a result, the filter element has a longer life because, for a given contaminant condition of an air stream, unacceptable clogging of the filter element takes longer.

Abstract: An interlocking dual filter includes a first filter element having a filter media enclosed by a frame and a sealing gasket disposed around the frame. The frame of the first filter element has a depending flange which defines a space for receiving a second filter element having a different filter media. The flange includes a plurality of recesses which form a first latching arrangement. The first recesses are aligned with latching tabs which extend laterally from the frame of the second filter element so that when the second filter element is placed within the frame, the second filter element latches with the first filter element. In accordance with one embodiment, the filter media of the first and second filter elements are different so that the filter assembly may be customized to accommodate various air stream conditions and utilizations.

Abstract: A replaceable filter element is installed in a filter assembly including a filter housing. There is a substantially annular space between the filter element and the housing and an air inlet for introducing inlet air tangentially with respect to the annular space. The filter element employed has a closed top and an open bottom communicating with a hollow core. An annular filter media is included in the filter element, the filter media having a top end and a bottom end with an outwardly projecting flange at the bottom end. The outwardly projecting flange has an annular rib thereon, spaced from the filter media, to define a trough between the annular rib and the filter media for retaining debris thereon. When the filter element is removed for replacement, debris accumulated on the flange is retained in the trough.

Abstract: An air pre-cleaner without moving parts including a housing having an inlet end for entrant air, an outlet end and a receiving chamber in between, wherein a feeder screw centrifuges the entrant air and moves it into a settling chamber where the dirt particles settle while the lighter air mass is directed to the outlet.