Recognize Hubs, Bearings and Seals
- Identify the hub, bearing cones, bearing cups and seal.
- Distinguish conventional, drilled-spindle and sealed cartridge arrangements.
- Recognize inspection findings and select design-specific maintenance instructions.
- Inspection light — Illuminate the hub cavity, bearing surfaces and seal for identification and inspection.
- Parts-cleaning brush — Remove residue from serviceable conventional bearing components so surface damage is visible.
- Lint-free shop cloths — Wipe cleaned components without introducing loose fibers into the bearing cavity.
- Seal puller — Remove a seal without using the inner bearing as a driving tool or damaging the hub.
- Dial indicator with mounting base — Measure axial hub movement when required by the applicable bearing adjustment procedure.
The standard wheel-bearing arrangement described in the source places opposed tapered roller bearing cones and cups inside a machined hub. A small amount of axial end play is necessary for bearing life; the arrangement is not intended to be tightened without regard to its adjustment instructions.
Lubrication arrangements differ. Standard bearings may use packed grease or, on some larger applications, oil. A drilled-spindle lubrication arrangement directs grease to the inner bearing and then toward the outer bearing. The sealed cartridge arrangement described in the source is lubricated and sealed at the factory.
The hub seal retains lubricant in the bearing cavity. Whenever the hub is removed, the seal must be inspected for damage and sealing ability. A questionable seal should be replaced, and the inner bearing must not be used as a tool to drive the seal out.
Bearing inspection looks for pitting, spalling and corrosion. A bearing requiring replacement is replaced as a cone-and-cup set. Dexter specifies lubrication every 12 months or 12,000 miles in its grease-bearing maintenance section; values vary by maker and bearing arrangement, and this is not a universal instruction for sealed cartridges.
How It Works
Component identification and bearing adjustment
The conventional arrangement places opposed tapered roller bearing cones and cups inside a machined hub; the cones carry the rollers, and the cups provide their outer running surfaces. The opposed bearings support wheel loads and locate the hub along the spindle. A small amount of axial end play is necessary in the arrangement described, so tightening until all movement disappears is not a substitute for its adjustment instructions.
Lubrication depends on the arrangement
Standard bearings may use packed grease or, on some larger applications, oil; a drilled-spindle arrangement directs grease to the inner bearing and then toward the outer bearing. The sealed cartridge arrangement described is lubricated and sealed at the factory, so conventional greasing instructions must not be assumed to apply. Dexter specifies lubrication every 12 months or 12,000 miles in its grease-bearing maintenance section, but the applicable maker and wheel-end design determine the instructions to use.
Seal condition and bearing surface damage
The hub seal retains lubricant in the bearing cavity; inspect it whenever the hub is removed and replace it if its damage or sealing ability is questionable. Inspect cleaned bearings for pitting, spalling and corrosion, because damaged running surfaces disrupt smooth rolling contact and promote further wear. Replace a conventional bearing requiring replacement as a cone-and-cup set, and never spin a bearing with compressed air or use the inner bearing to drive out a seal.
Step-by-Step Procedure
0/7 doneDexter grease-bearing maintenance interval; values vary by maker and design
| Lubrication interval in the grease-bearing section | Every 12 months or 12,000 miles |
Diagnostic Chart
| Symptom | Check | Spec / Expected | Likely cause & fix |
|---|---|---|---|
| Axial movement is felt at a conventional hub. | Identify the bearing arrangement and check axial movement using its applicable adjustment procedure before deciding whether adjustment is needed. | A small amount of axial end play is necessary in the described arrangement; no adjustment value is supplied in this lesson. | Movement may be required operating clearance rather than a defect; incorrect adjustment can also produce unsuitable clearance. Basis: LDServiceOnline |
| The seal is damaged or its sealing ability is questionable after hub removal. | Inspect the seal whenever the hub is removed; use an appropriate seal-removal tool rather than the inner bearing. | Replace a questionable seal. | A damaged or ineffective seal may fail to retain lubricant in the bearing cavity. Basis: LDServiceOnline |
| Cleaned bearing surfaces show pitting, spalling or corrosion. | Inspect the cone and cup running surfaces for damage before returning the bearing to service. | Replace a conventional bearing requiring replacement as a cone-and-cup set. | Surface deterioration interrupts smooth rolling contact and can accelerate wear. Basis: LDServiceOnline |
| A grease-bearing interval is being applied to an unidentified wheel end. | Identify the maker, bearing design and lubrication arrangement, then select the matching maintenance instructions. | Every 12 months or 12,000 miles applies to the cited Dexter grease-bearing maintenance section, not universally to sealed cartridges. | Instructions for different lubrication arrangements have been treated as interchangeable. Basis: LDServiceOnline |
At the Bay: Diagnose the Case
CASE 1 / 4
Axial movement is felt at a conventional hub.
- Test
- Compare
- Correct
Select the next check
Basis: LDServiceOnline. A likely cause is a hypothesis; confirm it with the applicable service procedure before repair.
Common Bay Mistakes
- ✕ Tightening away all hub movement without following the adjustment instructions.
- ✕ Applying conventional lubrication instructions to a sealed cartridge.
- ✕ Using the inner bearing to drive the seal out.
- ✕ Spinning a bearing with compressed air.
Quick Check
Practice only — not scored.
Plan the Service Sequence
Planning practice only. Follow the applicable manufacturer's instructions, employer safety program and qualified supervision on real equipment.
Plan the first action. Compare the service steps with the bay mistakes.
Source: LDServiceOnline — 49-55