Donaldson Comapny, Inc.

Thomas A Boeckermann

Larry R Nepsund

James K Elfstrand

Kathleen A Abrahamson

Steven Scott Gieseke

John D Sandkamp

A filter arrangement is provided. The filter arrangement generally includes an air filter having an upstream surface with a prefilter positioned thereon. The prefilter preferably include at least two layers of depth media. In preferred systems, the prefilter includes two layers of depth media secured to one another by stitching. In certain preferred arrangements disclosed, the prefilter include an upstream layer of fibrous depth media and a downstream layer of foam depth media, with the two layers stitched to one another along peripheral edges. The invention also concerns provision of prefilters, and also air filter arrangements which include housings having air filters with prefilters according to the present invention operably positioned therein. Methods of construction and use are also provided.

Method of servicing an air cleaner and of filtering engine intake air

Filter element having circular sleeve

Filter sleeve

A filter arrangement is provided. The filter arrangement generally includes an air filter having an upstream surface with a prefilter positioned thereon. The prefilter preferably includes at least two layers of depth media. In preferred systems, the prefilter includes two layers of depth media secured to one another by stitching. In certain preferred arrangements disclosed, the prefilter includes an upstream layer of fibrous depth media and a downstream layer of foam depth media, with the two layers stitched to one another along peripheral edges. The invention also concerns provision of prefilters, and also air filter arrangements which include housings having air filters with prefilters according to the present invention operably positioned therein. Methods of construction and use are also provided.

Filter arrangement including removable filter with first and second

Panel filter construction

Air conduit construction is provided. The construction generally comprises a conduit section having an open end; and, a support member positioned inside of the conduit section open end. In preferred arrangements, the conduit construction has two open ends, with a reinforcing member in each of the open ends. In preferred arrangements, the reinforcing member includes a friction fit construction on an outer surface thereof. In typical and preferred embodiments, the friction fit construction includes a bead on the reinforcing member. A method of preparing air conduit constructions is also provided.

Reinforcing structure for conduit; and method

An air cleaner with an integrated nozzle element comprised of a perforated portion at one end, a generally centrally located throat and a noise suppressing portion from the second end to the throat. The nozzle element is located within the inner opening of the air cleaner's tubular filter element. The perforated portion is arranged and configured to be the same size and shape as the inner opening to provide support for the tubular filter element, the throat is arranged and configured to provide the required restriction to create a specified negative engine crankcase pressure, and the noise suppressing portion is arranged and configured to provide the required attenuation of engine intake noise passing through the air cleaner.

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Lakeville, MN, United States of America

Thomas A Boeckermann