Filter with rotational end cap base retention

1. A filter comprising a filter element mounted to a base, said filter element comprising first and second end caps spaced axially along an axis, said second end cap having an axial flow opening therethrough, filter media extending axially between said end caps and extending in a closed-loop around a perimeter defining a hollow interior communicating with said axial flow opening, wherein fluid to be filtered flows laterally through said filter media and axially through said hollow interior and said axial flow opening, said filter element being mounted to said base by said second end cap in rotational relationship, and comprising a cover mounted to said first end cap independently of said second end cap, and wherein said second end cap is mounted to said base independently of said cover.

2. A filter comprising a filter element mounted to a base, said filter element comprising first and second end caps spaced axially along an axis, said second end cap having an axial flow opening therethrough, filter media extending axially between said end caps and extending in a closed-loop around a perimeter defining a hollow interior communicating with said axial flow opening, wherein fluid to be filtered flows laterally through said filter media and axially through said hollow interior and said axial flow opening, said filter element being mounted to said base by said second end cap in rotational relationship, said second end cap and said base are mounted to each other by a plurality of ears and slots, each slot having a pocket extending arcuately therefrom adjacent said perimeter, said filter having a first unlocked position with said ears axially aligned with and axially received in said slots, said filter having a second locked position with said second end cap rotated about said axis and said ears arcuately sliding into said pockets and retained thereby to prevent axial withdrawal of said filter element from said base, said pockets comprising arcuate tracks having leading edges at said slots and blocking axial withdrawal movement of said ears therepast, wherein said ears extend laterally outwardly from said second end cap and have an arcuately extending engagement surface facing axially toward said first end cap and spanning arcuately between a leading end and a trailing end, said engagement surface varying between said leading and trailing ends such that said engagement surface at said leading end is axially spaced from said first end cap by an axial distance which is greater than the axial spacing of said engagement surface at said trailing end from said first end cap, to facilitate entry of said leading end into said pocket.

3. The filter according to claim 2 wherein said engagement surface is tapered along a ramp from said leading end to said trailing end to provide increasing compressive axial engagement force upon said continued rotation of said second end cap.