Patent ID: 7887624

Claim:
A system comprising: a source of rotary motive power; an air intake structure at least partially defining an air intake passage in fluid communication with said source of rotary motive power; a filter support structure having an inlet and an outlet in fluid communication with said air intake passage, said filter support structure being axially movable relative to said air intake passage; a filter mounted to said filter support structure and disposed between said inlet and said outlet; a resiliently compressible member disposed between said filter support structure and said air intake structure and biasing said filter support structure axially away from said air intake passage; a scale having indicia of a condition of said filter; and an indicator connected to said filter support structure and movable relative to said scale, wherein said filter support structure moves axially relative to said air intake passage in response to a change in a pressure differential across said filter and causes corresponding movement of said indicator relative to said scale to indicate said condition of said filter.