Overheated bearing

CodeReason for conditionPractical solution
1Grease or oil is breaking down because it is the wrong type for operating conditions.Consult lubricant manufacturer to determine proper type of lubricant. Check miscibility if grease or oil has been changed from one type to another.
2Low oil level. Lubricant is being lost through the seal.
Insufficient grease in the housing.
Oil level should be just below the centre of the lowest rolling element in the bearing (fig 1).
Fill housing 1/3 to 1/2 with grease.
3Housing is fully packed with grease, or the oil level is too high. This causes excessive lubricant churning, high operating temperature or oil leakage.Purge grease until the housing is 1/2 filled with grease.
For oil lubricated bearings, reduce the oil level to just below the centre of the lowest rolling element (fig 2).
4Bearing has inadequate internal clearance for conditions where external heat is conducted through the shaft. This causes the inner ring to expand excessively.Check whether overheated bearing had clearance according to original design specification (fig 3). If so, then change to bearing with increased radial clearance, i.e. Normal to C3 or C3 to C4. If not, order to specification. Check with SKF if the bearing designation has become illegible.
Housing bore is out-of-round. Housing is warped or distorted. Supporting surface uneven. Housing bore is undersized.Check and scrape the housing bore to relieve pinching of the bearing. If necessary turn the housing bore to the correct dimension. Ensure that the supporting surface is flat and that the shims cover the entire area of the housing base (fig 4). Housing bore is undersized if non-locating bearing is changed from separable to non-separable bearing, e.g. from cylindrical roller bearing to deep groove ball bearing.
12Contact seals are dried out or have excessive spring tension.Replace contact seals with seals having correct spring tension (fig 5). Lubricate seals.
Rotating seals or flingers are rubbing against stationary parts.Check the running clearance of the rotating seal or flinger to eliminate rubbing (fig 6). Correct the alignment.
14Oil return holes are blocked. Pumping action of the seals causes oil leakageClear the holes. Drain used oil and refill to the proper level with fresh lubricant (fig 7).
15Cross locationInsert shim between housing and cover flange to relieve axial preloading of bearing (fig).
16Two locating bearings on one shaft. Insufficient clearance in bearing caused by excessive shaft expansion.Move the covers in one of the housings outwards. Use shims to obtain adequate clearance between the housing and the outer ring (fig 8). Apply axial spring load on the outer ring, if possible, to reduce axial play of the shaft.
19Adapter sleeve is tightened excessively.Loosen the lock nut and sleeve assembly. Retighten it sufficiently to clamp the sleeve on to the shaft, but be sure the bearing turns freely (fig 9).
Unbalanced load.
Housing bore is too large
Rebalance the machine.
Replace the housing with one having the proper bore (fig 10).
26Shaft shoulder is rubbing against bearing seals.Remachine the shaft shoulder to clear the seals. Check that shoulder diameter is in accordance with SKF recommendations (fig 11).
32No lubricant in bearing due to incorrect oil level.Clear out the clogged oil hole to vent the oil gauge (fig 12).
Incorrect linear or angular alignment of two or more coupled shafts with two or more bearings.Correct alignment by shimming the housings. Ensure that the shafts are coupled in a straight line, especially when three or more bearings operate on one shaft. Be sure to use full support shims (fig 13).
Constant oil level cup is mounted too high or low.
The cup is located opposite to the bearing's direction of rotation.
The static oil level must not be higher than the centre of the lowest rolling element. Replace the constant level oiler with a sight gauge.
Locate cup with rotation of bearing. Sketch illustrates correct position of constant level oil cup with respect to rotation (fig 14).
37Washer prong is rubbing against the bearing.Remove the locking washer. Straighten the prong or replace with a new washer (fig 15).
42Contact seals are excessively worn, causing lubricant loss or permitting dirt to enter the bearing.Replace seals after thoroughly flushing bearing and refilling with fresh lubricant (fig 16).
47Bearing seat diameter is oversized, causing excessive inner ring expansion. This reduces bearing clearance.Grind shaft to get a proper fit between the shaft and the bearing inner ring. If regrinding is not possible change to bearing with larger radial clearance (fig 17).
50"Pounding out" or hammering out of housing bore due to too soft metal. The resulting enlarged bore causes the outer ring to spin in the housing.Rebore the housing and press a steel bushing in the bore. Machine the bushing bore to the correct size (fig 18).
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