Noisy 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.
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 2). 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.
5Dirt, sand, carbon, or other contaminants are entering the bearing housing.Clean the bearing housing. Replace worn seals or improve the seal design to obtain adequate bearing protection (fig 3).
6Water, acids, paints or other corrosives are entering the bearing housing.Install a protective shield and/or flinger to guard against foreign matter (fig 4). Improve seals.
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 5). 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.
10Chips, dirt etc. were not removed from housing before assembling the bearing unit.Carefully clean (fig 6), and apply fresh lubricant.
Rotating seals or flingers are rubbing against stationary parts.Check the running clearance of the rotating seal or flinger to eliminate rubbing (fig 7). Correct the alignment.
15Cross locationInsert shim between housing and cover flange to relieve axial preloading of bearing (fig 8).
16Two locating bearings on one shaft. Insufficient clearance in bearing caused by excessive shaft expansion.Move the covers in one of the housings outwards (fig 9). Use shims to obtain adequate clearance between the housing and the outer ring. Apply axial spring load on the outer ring, if possible, to reduce axial play of the shaft .
Shaft diameter is too small. Adapter is not sufficiently tightened.Metallise and regrind the shaft to obtain the proper fit. Retighten the adapter for a firm grip on shaft (fig 10).
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 11).
Unbalanced load.
Housing bore is too large
Rebalance the machine.
Replace the housing with one having the proper bore (fig 12).
22Flat spot on rolling element due to skidding. (Caused by fast starts).Visually check the rolling elements and replace the bearing if a rolling element has a flat spot. Make sure that the requisite minimum load is applied to the bearing.
25Shaft is bending due to incorrect shoulder diameter.Remachine the shaft fillet to relieve stress (fig 13). The application may require a shoulder collar. Check that abutment dimension is in accordance with SKF recommendations.
26Shaft shoulder is rubbing against bearing seals.Remachine the shaft shoulder to clear the seals (fig 14). Check that shoulder diameter is in accordance with SKF recommendations.
27Inadequate support in the housing is causing the outer ring to distort.Remachine the housing fillet to relieve stress (fig 15). Check that abutment dimension is in accordance with SKF recommendations. The application may require a shoulder collar.
28Distorted bearing seals.Remachine the housing shoulder to clear the seals (fig 16).
29Shaft and inner ring are distorted.Remachine shaft fillet to obtain the proper support (fig 17).
30Housing and outer ring are distorted.Remachine the housing fillet to obtain the proper support (fig 18).
37Washer prong is rubbing against the bearing.Remove the locking washer. Straighten the prong or replace with a new washer (fig 19).
40Incorrect mounting method. Hammer blows to bearing.Replace the bearing with a new one. Never hammer any part of a bearing when mounting. Always use a mounting dolly or sleeve (fig 20).
41Moving components in the machine are interfering with bearing operationCarefully check every moving component in the machine (fig 21). Clear whatever is interfering.
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 22).
43Excessive clearance in the bearing is causing vibration.Use a bearing with recommended internal clearance (fig 23). Apply spring load to the outer ring of the non-locating bearing to eliminate axial and radial play.
44Equipment is vibrating.Check the balance of the rotating parts (fig 24). Rebalance the equipment .
46Distortion of the shaft and other bearing arrangement components, probably due to heat.Use a torch to remove a bearing only under extreme circumstances, use a proper dismounting tool (fig 25). Avoid high heat concentration at any one point to prevent distortion. Replace discoloured bearings.
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 26).
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 27).
51Bearing is exposed to vibration while the machine is idle.Carefully examine the bearing for wear spots or indentations corresponding to the spacing of the rolling elements (fig 28). For standby equipment ball bearings are better suited than roller bearings to withstand vibration.
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