Jan 1, 2005 12:00 PM

The Hagelnut is an improved adaptation of the conventional three-piece jam nut used for years as the primary wheel end retention system in the tractor/trailer industry. The old three-piece design was recognized as being the most secure and reliable spindle nut system when installed in accordance with the TMC (Technology and Maintenance Council of the American Trucking Associations) Recommended Practice RP 618, Wheel End Adjustment Procedures. However, the old-style three-piece jam nut configurations were unable to be used for preload adjustment because the final jam-tightening operation of the outer nut would introduce excessive and uncontrollable preload. For that reason, the only assembly practice approved by most roller bearing manufacturers was limited to installing “end play”: a procedure unable to provide consistent results.

With the new SAE Standard J2535, it is now possible to assemble wheel end systems with controllable preload. The TMC recently published Recommended Practice RP 640, Alternate Wheel Bearing Adjustment Systems, which says in the section, “Adjustable Wheel End Systems” that “A nut fastener system is installed on the axle spindle to adjust the bearings either with limited end play or slight preload. Each fastener system manufacturer has definitive installation instructions.”

For more details, contact Rather Engineering, 414 S York, Dearborn MI 48124.