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56mm Flanged Light Series 20 (Internal Gear)

FIG Series (Flanged Internal Gear)

A popular "light" series of slewing rings used in a variety of simple mechanical handling devices where rotation is effected by the addition of an internal metric spur gear, which can be more aesthetic and safer than the similar external gear unit.

Similar bearings are made by other manufacturers which can generally be considered interchangeable. However there can be important differences and customers are urged to ask our Technical Department for advice.

This metric series is similar to the KAYDON RK6-N range which is manufactured in imperial dimensions and has an American involute stub gear. It is usually easy to change to the European bearing and use a stock metric pinion to achieve a similar speed ratio on the gear. 

Within the QCB® range we can offer:-

  • The widest size range on offer
  • Double or non standrad drilling patterns
  • High precision bearings with location diameters
  • Zinc plating, black oxide paint or Nylon coatings for corrosion resistance
  • A variety of separators for high temp. or high speed applications


Flanged Seried (Metric) catalogue from the Downloads page 


FIG 418 20   FIG 505 20   FIG 650 20   FIG 750 20   FIG 850 20   FIG 950 20  FIG 1050 20   FIG 1200 20 


Available on request 



" * " - suffices dependent on final bearing designation e.g. FIG 750 20 51 CC LM


From 2014 all QCB® gearted slewing rings are made in 42CrMo4

Other manufacturers typically use C45 steel (Europe) or 50Mn (China), roughly equivalent to BS 080M46

Grease points

Usually supplied with 4 grease points in the inner ring, DIN 71412A M8x1 equispaced. 

Load and bolt limit curves

If a combination radial and axial load act on the bearing these should be converted to a single equivalent load for graphical analysis. Bearings should operate within the prescribed triangular load area at all times.

The bolt limit curve is based on the use of Grade 8.8 bolts. An improvement to this can be achieved by using Grade 10.9 bolts, but only after approval by the NBC Technical Department.

If the load is suspended, or the axis of rotation is not vertical, refer application details to

Units: Y-Axis = Moment load in KN.m; X-Axis = Axial load in KN

Interchange information

This information offers generally accepted interchange numbers. However, variations exist and all queries should be referred to our Technical Department for analysis.

Dimensional equivalance does not always imply equal performance.

* - suffices dependent on final bearing specification. This information subject to change without notice.

Contact the NBC Slewing ring experts by phone on +44 (0)1952 222300, by fax on +44 (0)1952 242938 or e-mail

Whilst every effort has been made to ensure the accuracy of the information on this website, if you spot a mistake please inform the Thanks!