Slewing Bearing Components
What is a slewing bearing/turntable bearing made of? How to describe each components in the slewing bearing? And what is the function of each part in the slewing ring? This artical will help you find out.
Inner Ring and Outer Ring
Bearings are composed of two rings - inner ring and outer ring, each contains a precision raceway that is induction hardened on the surface to a specified depth. Usually the material is bearing steel(GCr15/100Cr6/52100), RIGIA also use special material such as stainless steel to meet different customers requirements. Raceways are constructed in a four-point contact configuration, with 45° contact angles as standard, other configurations such as crossed roller are available too. These other options are often considered in cases where very high loads or special stiffness requirements are needed.
Mounting Holes
Gear
Mounting holes are generally equally spaced around the end faces of the inner and outer ring along a uniform bolt circle. These holes can be through holes, tapped holes, blind tapped holes, counter-bored holes, etc. Sometimes bolt circle or spacing requirements need to be customized to meet the demands of a specific application.
Seals
Seals are provided on each side of the bearing, their primary functions are grease retention and prevention of some contamination such as dust and debris from entering the bearing. The seals are typically made from NBR, and there are also metallic ones, which called shield.
Slewing ring bearings include ungeared, outer geared or inner geared. Gears are typically a standard stub involute spur gear with backlash provisions and AGMA Q8 quality minimum. Gear datas for each bearing can be found in our catalogue, and drawings are available upon request. Custom gear configurations are also available.
Grease Fitting
At least one grease fitting is included in one of the rings. The quantity may increase with the diameter of the bearing. For bearings with gears, the grease fitting(s) are located on the ungeared ring. Custom quantities, locations and configurations for grease fittings are available.
Rolling Elements
Slewing bearing rolling elements including steel balls and cylindrical rollers, its function is to facilitate relative ring rotation between the inner and outer rings.
Spacers/Space Retainers & Separators
Spacers, also called space retainers or separators, typically made from a plastic material, are commonly used to separate balls or rollers to prevent them from rubbing directly against each other. Sometimes spacer balls are utilized instead of spacers, they are balls that are slightly smaller than the load carrying balls, placed between each load carrying ball.
Load Plug
Due to the nature of the race hardening process, there is a hardness gap on each race. In that location for the non-geared ring, or the outer ring for ungeared bearings, a hole is drilled for loading balls into the final slewing ring assembly. This hole is plugged and secured with a taper pin. Note that for the ring where a load plug is not present, an ‘S’ is stamped on the face of that ring at the location of the unhardened gap in the race (also known as the soft spot).
Taper Pin
Secures load plug to the inner or outer ring.
Part Numbers
Part numbers and serial numbers are etched on one of the faces of the bearing. RIGIA can mark customer's code if letter of authorization is provided.