Regular inspection and maintenance, according to Timken, can reduce Class 7-8 bearing damage in conventional wheel-ends and decrease long-term costs. Close inspections by the service tech as well as input from the driver can be invaluable in making sure wheels bearings are properly serviced.
Below are visual indications that the wheel needs to be service:
Bearing damage indicators:
• Hubcap sight glass discolored or burnt
• Low lube level in hubcap sight glass
• Lube leakage on wheel hub or tire, inboard and outboard sides
• Abnormal tire wear
• Smoking or extremely hot hubcap
Driver observations – bearing damage indicators:
• Wheel vibration
• Wheel wobble
• Wheel noise
• Smoke from a wheel end
• Decreased braking power
• Increased fuel consumption
• Abnormal side pull when braking
• Wheel lock-up/skidding
Wheel-End Disassembly Analysis
• Worn nut face (adjusting nut and lug nuts)
• Bearing noisy when rotated
• Rust or moisture
• Spindle wear (more wear on bottom half)
• Thread wear
• Hub shoulder wear
• Hub bore wear
• Loss of adjusting nut or jam nut torque
• Bearing dropped
• Worn out or damaged seals
Bearings must be replaced when:
• Dry, caked lube in hubcaps or other internal cavity
• Metal particles in lube, hubcaps, hubs, or bearings
• Heat discoloration on bearings or any other internal component (heat discoloration is a non-removable stain)
• Grooves on cone backface, bore or spindle
• Wear on any bearing surface
• Dents on bearing assembly cage
• Spalling (flaking away) of bearing material on races or roller bodies
• Any raised metal or dents on races or rollers
Proper maintenance and handling procedures are critical, Timken warns. Always follow installation instructions and maintain proper lubrication. Never spin a bearing with compressed air. The rollers may be forcefully expelled. Failure to replace bearings when they must be replaced can result in wheel separation.
