Unsatisfactory equipment performance

CodeReason for conditionPractical solution
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 1). 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 2).
6Water, acids, paints or other corrosives are entering the bearing housing.Install a protective shield and/or flinger to guard against foreign matter (fig 3). Improve seals .
7
8
9
39
48
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.
10Chips, dirt etc. were not removed from housing before assembling the bearing unit.Carefully clean (fig 5), and apply fresh lubricant.
15Cross location.Insert shim between housing and cover flange to relieve axial preloading of bearing(fig 6).
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 7). 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.
17
18
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 8).
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).
21
49
Unbalanced load.
Housing bore is too large
Rebalance the machine (fig 10).
Replace the housing with one having the proper bore.
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.
23
24
Unequal load distribution on the bearing due to out-of-form of shaft seat or housing bore.Rework the shaft and/or housing seat to obtain the proper form and fit (fig 11). The application may require a new shaft or housing.
25Shaft is bending due to incorrect shoulder diameter.Remachine the shaft fillet to relieve stress (fig 12). The application may require a shoulder collar. Check that abutment dimension 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 13). Check that abutment dimension is in accordance with SKF recommendations. The application may require a shoulder collar.
29Shaft and inner ring are distorted.Remachine shaft fillet to obtain the proper support (fig 14).
30Housing and outer ring are distorted.Remachine the housing fillet to obtain the proper support (fig 15).
33
34
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 16).
37Washer prong is rubbing against the bearing.Remove the locking washer. Straighten the prong or replace with a new washer (fig 17).
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 18).
43Excessive clearance in the bearing is causing vibration.Use a bearing with recommended internal clearance (fig 19). 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 20). Rebalance the equipment.
45Shaft or housing shoulders or lock nut face out-of-square with the bearing seat.Remachine parts to obtain squareness (fig 21).
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 (fig 22). If regrinding is not possible change to bearing with larger radial clearance.
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 (fig 23). Machine the bushing bore to the correct size.
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 24). For standby equipment ball bearings are better suited than roller bearings to withstand vibration.
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