Rather Engineering’s Controlled Position Axle Nut (CPAN) system is an installation procedure designed to reduce the operational expense caused by excessive tightening of axle nuts. Over tightening may cause a significant increase of annual fuel cost because of the drag that increases proportionately with applied preload on the wheel bearings. The CPAN system is a jam nut system capable of installing a safe range of controlled preload. It is the only axle nut system manufactured for commercial trailer operations that will virtually eliminate end play within the wheel assembly that contributes to diminished service life of oil seals. By reducing inward or outward movement of the hub assembly on the axle spindle, oil leaks are less likely to occur.