Replacements are too frequent

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.
11Air flowing over the bearing is causing an oil leak. (Example: Forced draft fan with air inlet over the bearing.)Install baffles to divert the air flow (fig 7). Avoid pressure difference over the bearing. Use grease lubrication if possible.
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).
20Oil is leaking at the housing split. Excessive loss of lubricant.A thin layer of gasket cement will stop minor leaks (fig 12). Do not use shims. Replace the housing if necessary.
Unbalanced load.
Housing bore is too large
Rebalance the machine (fig 12).
Replace the housing with one having the proper bore.
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 13). 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 14). 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 15). 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 16). 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 17).
29Shaft and inner ring are distorted.Remachine shaft fillet to obtain the proper support (fig 18).
30Housing and outer ring are distorted.Remachine the housing fillet to obtain the proper support (fig 19).
Rotating seals or flingers are rubbing against stationary parts.Check the running clearance of the rotating seal or flinger to eliminate rubbing (fig 20). Correct the alignment.
32No lubricant in bearing due to incorrect oil level.Clear out the clogged oil hole to vent the oil gauge (fig 21).
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 22).
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. The fig 23 illustrates correct position of constant level oil cup with respect to rotation .
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 24).
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 25).
45Shaft or housing shoulders or lock nut face out-of-square with the bearing seat.Remachine parts to obtain squareness (fig 26).
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 27).
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 28). Machine the bushing bore to the correct size.
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