Heavy transportation, agricultural and construction equipment frequently rely on large diesel engines for power. It is important that clean air be delivered to these engines for combustion. Generally, one type of air cleaner for this purpose utilizes coaxial primary and secondary air filters, wherein the secondary air filter is nested within the primary air filter. Air is drawn from the atmosphere, radially through the primary and secondary filters and into the cylindrical space within the secondary filter. The filtered air then passes to the engine for mixture with fuel in the combustion chamber of the engine.
In order to ensure proper filtering of combustion air, the primary and secondary air filters are sealed within a housing by an arrangement of radial and axial sealing elements and gaskets. In one prior art approach, sealing of the filters is accomplished by compressing the outlet end of the filter against the end wall of the housing and by providing a gasket between the end of the filter and the end wall of the housing. This is accomplished by, for example, utilizing a yoke assembly which cooperates with a threaded wing nut, the nut being used to compress the filters against the end wall of the housing to prevent leakage of air around the filter elements. In the past, various other latches and clamping devices have been used to effect a positive clean air seal with such filter assemblies.
Axial compression techniques for sealing require filters and filter housings which are constructed so as not to collapse under compression. Since axially compressed filters tend to be more expensive than radially compressed filters because they are subjected to higher axial loads, radially sealed filters are being increasingly used. Since filter housings for both axially and radially sealed filter elements are on existing vehicles and equipment, confusion can occur as to which filter element should be used as a replacement when the original or prior replacement filter element is changed. Moreover, it is expensive and aggravating to produce two types of filters since the two types of filters require separation at some time during the production process and require separate marking and inventory control.