NKE Hauptkatalog / General Catalogue 2011

Handling, Mounting andDismounting Rolling BearingsThe thickest feeler gauge that can be insertedindicates the actual amount of initial bearingclearance.The remaining bearing clearance should befrequently checked during the mounting.Because of the fact the bearing already sits on itsshaft at this stage of mounting, the actual bearingclearance is determined by measuring the finalgap between the roller and the outer raceway ona fi xed radial centreline (fi g. 10.16b).The minimum values of final bearing clearance(R 2 ) stated in table 10.2 are based on clearancevalues that lie on their lower limits.In this way volume production mounting may beorganised in a very efficient and economic wayby using the recommendations in tables 10.1 and10.2. It must also be considered, however, thatthese values apply to solid steel shafts only. Themounted bearing has to allow for easy rotationand skewing of the outer ring in all cases.Mounting Bearings byUsing Oil Injection MethodLarger and very large rolling bearings may bemounted in a much simpler way by using oil toforce the bearing either on or off its seat.To fi t bearings by the oil injection method, called“hydraulic nuts”, (fi g. 10.18), are used.The minimum values listed in table 10.2 must notbe undercut.In many cases a reliable measurement of theremaining bearing clearance using the aboveprocedure may cause some diffi culties.Furthermore, under certain conditions of mountingthis procedure may be time-consuming andimpractical.In such cases the remaining final bearing clearance(R 2 ) may be determined using the indirectmethod (i.e. axial displacement measurement “a”).Fig. 10.18They consist of a solid body piece (1) that featuresappropriate threads (6). The body piecehas a circular groove in one face that accepts anannular piston ring (3).The actual distance of displacement “a” is measuredusing effective measuring instruments such as dialgauges, depth gauges or even simple calliper rulers.This may depend on the particular application.Via the connecting threads (4) and oil ducts (5)oil is injected into the groove at a high pressureforcing the piston outwards. Two O-rings, (2)sitting in circumferential grooves on the pistoneffect the sealing of the oil groove against theabutting surfaces.354www.nke.at