In a typical HD wheel hub assembly, the locking nut is used to hold assembly together and also set the bearing end play (for conventional setups). There are many types of lock nuts in use. The most common ones include:
• Conventional Dowel Type (Double Nut)
• Single nut with separate keeper (Ex: Stemco’s Protorq)
• Integrated design Single nut (Ex: Stemco’s Ziptorq)
With a conventional wheel end setup requiring no spacers, TMC RP618 procedure can be used for adjusting bearings using dowel type double nut systems. If single nut systems are utilized, the procedure is similar to TMC. However, the actual torque and back-off values differ based upon nut manufacturer.
Conventional setups have several steps requiring torquing the bearing and then backing off. Spacer setups are simpler and require less steps compared to conventional setups. They maximize uptime by eliminating the need to manually adjust bearing setting. However, a major difference is that a spacer setup does not require backing off the nut. This is because nut torque does not set endplay for a spacer setup. Instead, the endplay is controlled by the tightly machined tolerances of the bearings and the spacer. Both single and double nuts can be utilized with a spacer setup. Torque specifications can vary depending upon nut type and manufacturer.
This technical tip was sponsored by Bower Heavy Duty Bearings by NTN.