How should I adjust excessive bearing clearance?

Guide to Adjusting Excessive Bearing Clearance

 

Excessive bearing clearance (radial or axial play) can cause abnormal noise, vibration, reduced accuracy, and shortened bearing life, requiring targeted adjustment.

 

I. Pre-Adjustment Preparation

Types of Bearings: Radial play (radial play between the inner and outer rings) is common in casters; axial play (axial play between the inner and outer rings) is common in thrust bearings.

Causes: Main causes are normal wear or improper installation (lack of preload, loose fit). Material defects (deformation, cracks) require replacement.

 

II. Adjustment Methods

Rolling Bearings (Most Common):

Shim Method (Deep Groove Ball Bearings): In bearing housings with end caps, add a thin metal shim between the end cap and the bearing outer ring to compress the bearing and reduce clearance.

 

Nut Method (Tapered Roller/Angular Contact Bearings): Loosen the lock washer and tighten the lock nut (gradually testing for rotational resistance). Tighten after eliminating any play.

Eccentric Sleeve Method: Rotate the eccentric sleeve to reposition the outer ring and lock it.

(The preload spring method is suitable for light loads and is omitted.)

 

Sliding Bearings (a few heavy loads):

Bearing Scraping: Scrape the inner surface to restore the contact area.

Shim Thinning: Reduce the thickness of the shim between the bearing and the seat.

 

III. Verification After Adjustment

Testing: Measure the radial clearance with a feeler gauge (≤ 0.1mm for small models, ≤ 0.3mm for large models) or manually test the bearing. Manual rotation should be smooth and free of any sticking or noise.

 

Running Test: Run the bearing at no load for 10-15 minutes. The temperature rise should be ≤ 20°C, with no abnormal noise or vibration.

Securing and Lubricating: Tighten all adjusting components (nut, end cap, eccentric sleeve) and prevent loosening. Clean out any old grease and refill with fresh grease.

 

IV. Conditions Where Replacement is Necessary: If the following conditions exist, adjustment cannot be performed and the bearing must be replaced immediately:

Inner and outer rings or balls are cracked, deformed, or severely corroded.

The raceway has noticeable pits, and the ball bearings are out of round (severe wear).

Still sticking or heating after adjustment (internal damage).

 

Core Principle: Precisely control clearance according to bearing type to avoid overtightening (heating) or overloosening (wobbling). If wear exceeds the specified limit or the bearing is damaged, replacement is the only safe option.