SKF Cooper split roller bearings and bearing units

1 Overview, selection and application recommendations Design considerations Specifications for shafts and housing support surfaces Shaft bearing seat SKF recommends the following shaft diame- ter tolerance classes ( table 4 ) for the bearing seat for: • split cylindrical roller bearings: – h7 � , for typical applications – h6 � , for dn 1) > 150 000 mm/min – h6 � , for bearings with C2 clearance – h9 � , for light loads and low speeds • split tapered roller bearings: – h6 � , for all applications The geometrical tolerance of the shaft should be to IT6. The surface roughness Ra of the bearing seat should be: • < 3,2 μm, for an h7 � tolerance class • < 1,6 μm for an h6 � tolerance class Seal seat or counterface If a stepped shaft is used: • the dimensional tolerance of the shaft under the seals should be h9 � • the cylindricity should be to at least IT6 Housing support surface • flatness: tolerance grade IT7 in accordance with ISO 1101 • surface roughness Ra: ≤ 12, 5 μm Table 4 Shaft tolerances and resultant fits Shaft Shaft diameter deviations, resultant fits Nominal diameter Tolerance classes 1) d a h6 h7 h9 IT6 > ≤ mm μm – 50 0 –16 0 –25 0 –62 16 50 80 0 –19 0 –30 0 –74 19 80 120 0 –22 0 –35 0 –87 22 120 180 0 –25 0 –40 0 –100 25 180 250 0 –29 0 –46 0 –115 29 250 315 0 –32 0 –52 0 –130 32 315 400 0 –36 0 –57 0 –140 36 400 500 0 –40 0 –63 0 –155 40 500 630 0 –44 0 –70 0 –175 44 1) The envelope requirement ( � from ISO 14405-1) is not shown but applies to all tolerance classes. 1) Speed factor dn [mm/min] = bearing bore [mm] x rotational speed [r/min] 14