Four Point Contact B. SKF QJ312 MA/C3

The SKF QJ312 MA/C3 four-point bearing with a 60 mm bore accommodates high axial forces in both directions and saves axial installation space.

The QJ312 MA/C3 four-point bearing is a single-row angular contact ball bearing with a split inner ring, designed for axial loads acting in both directions. Thanks to its design, this rolling bearing supports shafts in the axial direction without the need for two separate individual bearings. The open design, without a retaining groove in the outer ring, is suitable for oil- or grease-lubricated assemblies in mechanical engineering and gearbox construction where compact dimensions – with an outer diameter of 130 mm and a width of 31 mm – are required.

What is the QJ312 MA/C3 four-point bearing suitable for in operation?

Design engineers prefer to use this design when predominantly axial forces are present and the axial installation space is limited. The bearing is often used purely as an axial bearing in combination with a separate radial bearing, for which the outer ring is fitted radially free in the housing. Thanks to the two-piece inner ring, the ball cage can be fitted with the outer ring separately from the inner ring halves, which simplifies handling during assembly and maintenance in mechanical engineering.

What do ‘brass cage’ and ‘C3 clearance’ mean in this design?

The suffix ‘MA’ denotes a solid brass cage that retains its dimensional stability even under vibration or rapid changes in rotational speed. The slightly increased radial clearance (C3) provides additional radial space between the balls and raceways. This enables the bearing to compensate for operational heating without causing internal stresses. The permissible temperature range is from –30 to +150 degrees Celsius, provided that tolerance class P0 is adhered to.