Structure of Slewing Bearing

  • The single row ball type is an internal structure of the thrust angular contact ball bearings of four point contact type. And it is compact and the rating load is large because it can use a ball diameter that is bigger than the double row ball type.
slewbearing structure

①Inner Ring・②Outer Ring

Generally, S48C is used. SCM440 is used depending on a large-scale size and system requirements.

【Quenching depth in raceway(Left:S48C, Right:SCM440)】

③Steal Ball

The steel ball of various size is using according to the design. The basic static thrust load rating thrust is calculated by the size and the number of the used steel ball.


The separator is used between balls to maintain equalization of the load and a smooth rotation. The retainer is used instead of the separator when a high-velocity revolution use and a horizontal axis use.

【Left:Spacer, Right:Retainer】


The standard of the gear accuracy is the JIS7 class. Please consult when high accuracy is necessary.

【Left:One time quenching of teeth face and flank, Right:Quenching of teeth flank and bottom 】


The seal is a labyrinth structure for neither water nor the dust to enter the inside.

⑦Mounting Hole

A flange or a housing are unnecessary, because the inner ring and the outer ring have mounting holes. The structure can be simplified, the installation and uninstallation of bearing is easy and it leads to the laborsaving of maintenance.

Grease Nipple & Grease

The slewing bearing is a grease lubrication in general, grease can be easily replenished from the grease nipple installed in the inner or outer race. Generally, Alvania EP2 is used. Please consult when you use it in a special environment.


⑧Plug and “S”mark

The raceway surface of the plug position and the “s” mark position are the soft zone where quenching isn’t done, so you have to set there in the position where the load is least.