Precleaner arrangement for use in air filtration; method; and, air cleaner using same

A precleaner arrangement for use in separating a portion of entrained material in air from air entering an air cleaner, is provided. The precleaner arrangement includes a vane structure positioned to direct air into a circular or cyclonic pattern, to facilitate material separation. The vane structure includes one or more adjustable air deflection vanes. Each adjustable air deflection vane is constructed: to have a first position under no air flow or low air flow rate conditions; and, to deflect to import a more open, lower restriction, orientation under increased air flow rates. Preferred precleaner arrangement constructions, assemblies utilizing in the precleaner arrangement and methods are described.