Motor Grader Shaft Flange – Pilot, Bolt Circle and Runout Guide
A shaft flange joins rotating components and must centre the mating part while transmitting torque. Bolt count alone is not enough: the pilot, bolt-circle diameter, face offset and shaft connection must all match.
What should be measured?
| Flange feature | Required evidence |
|---|
| Mating face | Outside diameter, pilot diameter/depth and register type |
| Fasteners | Hole count, hole diameter, bolt-circle diameter and thread if tapped |
| Shaft side | Spline/key/taper details, bore, retention and seal land |
| Axial geometry | Overall length, face-to-shoulder offset and hub length |
Runout and damage checks
Inspect the pilot and bolt holes for fretting. Check the face for impact marks and the hub for cracks. If vibration or seal leakage prompted replacement, measure runout using the service method and inspect the shaft, bearings and mating flange before blaming this part alone.
Assembly practice
Clean both faces, seat the pilot fully and use the specified fasteners and tightening sequence. Do not pull a misaligned flange into position with bolts. After installation, confirm rotation without interference.
Related rotating parts
Use the shaft measurement guide and the rear drive shaft page to verify adjacent interfaces.
FAQ
Can two flanges with the same bolt count interchange?
No. Bolt circle, pilot, offset and shaft interface can differ.
Why is the pilot important?
The pilot centres the assembly; bolts should not be the only centring feature.
What may cause recurring runout?
Dirt, burrs, a bent shaft, bearing play or a damaged mating flange.
Compatibility note: Match both flange faces and the shaft connection before ordering.
