Four Point Contact B. FAG QJ311 -MPA-C3

The FAG QJ311 -MPA-C3 four-point bearing, measuring 55 x 120 x 29 mm and featuring a brass cage, offers a compact solution for axial forces acting in both directions.

The FAG QJ311 -MPA-C3 four-point bearing has a single-row design and accommodates axial forces in both directions whilst requiring minimal axial installation space. With a bore of 55 mm, an outside diameter of 120 mm and a width of 29 mm, this design is suitable for gearboxes and industrial drives. The design with a split inner ring allows the rings to be fitted separately. The open rolling bearing operates without an integrated seal and covers a temperature range from –30 to +150 degrees.

What is the QJ311 -MPA-C3 four-point bearing suitable for in operation?

Design engineers typically choose this bearing type when axial forces from varying directions predominate, but the installation space does not permit a double-row bearing. The four-point bearing often functions as a pure axial bearing in combination with a separate radial bearing. Thanks to the split inner ring, the outer ring, together with the ball set, can be slid on separately from the inner ring halves. The outer ring has no groove, which ensures even contact in precisely fitted housing bores.

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

The suffix MPA denotes a robust brass cage that guides the rolling elements precisely and retains its dimensional stability even under vibration. This design also features a slightly increased radial clearance of C3. This bearing clearance ensures sufficient operating clearance when heat generated during operation causes the rings to expand or when tight shaft fits reduce the bearing clearance. Manufactured to the standard tolerance class P0/PN, the bearing meets common industrial tolerances for continuous operation.