Technical Supporting

Technical informaton

Slewing ring bearings are large-sized bearings with compositive larege loads carrying capability, which can accommodate asxial load, radial load and tilting torque simultaneously. These bearings normally have mounting holes, internal gears or external gears, lubricating holes and sealing installations. They are featured by compact configuration, light weight, good rigidity, smoothly running, high precision and reliable safety. Applications of the bearings are found in the industries such as engineering/project, metallurgy, mining, oil, chemistry, light industry, aviation, harbor/quay, vessels, military industry, instruments and meters etc.
Our slewing bearing according different requirement has different configuration: single-row four point contact ball slewing ring bearing, double-row angular contact thrust ball slewing ring beairng, cross cylindrical roller bearings, cross tapered roller bearings and three-row cylindrical combination slewing ring bearing. These bearings also can be divided according to whether have gear and distribution of the gear: no gear, external gear and internal gear.

1. Function
2. Load distribution
3. Material
4. Clearance
5. Heat treatment
6. Lubrication
7. Sealing
8. Operating temperature
9. Service Life
10. Transport, handling and storage
11. Installation

1, Function

Construction and function of a Slewing Ring
Slewing Rings consist of an internal and external ring and with an integrated raceway system and optional internal or external toothing . A functional seal protects the raceway system on the upper and lower sides. Slewing Rings and designed for grease lubrication which is carried out grease inpples In Slewing Rings, the rolling elements carry the loads between the inner and outer ring. The load capacity of the raceway system is determined predominantly by the raceway design, the hardening depth, and the number and size of the rolling elements and minimise friction and wear. The rolling elements are inserted during manufacture through the filling plug hole retained by the filling plug which is then secured by a pin The force is transmitted to the mounting structure by bolts. Through holes or threaded holes can be provided in the inner and outer rings for these bolts.

2, Load distribution

Depending on external load, the load distribution and the contact angle around the rolling elements will vary.

• In the case of axial load, all rolling elements are loaded in the same direction
• In the case of radial load, a segment of the rolling elements carries the load.
• In the case of tilting moment load, a segment on one side and a segment on the opposite side of the raceway carry the load.
• Mostly, a combination of axial, radial and tilting moment loads occur.

Static load capacity of raceway

Static load capacity of the Slewing Ring is determined by:

• Hardening depth of the raceway
• Number and size of the rolling elements
• Slewing Ring design
• Raceway geometry

3, Material

Proper design and chosing material is important to ensure high technical capability and reliability.

Ring and Rolling element

Normally the roller element for the slewing ring bearing is the whole hardened chrome steel, China number is GCr15 or GCr15SiMn. Ring for the slewing ring bearing is case hardened steel, when no special requirement, we may choose Steel 50Mn. When have special application, or required by customers, we may choose other steel, like 42CrMo, 5CrMnMo, etc.

Cage

Cage for the slewing ring have integral cage, subsectional cage or isolation block cage. For most cages we use 20# Steel or aluminium alloy which adopt polyamide 1010 resin, cast aluminum alloy ZL102 or aluminum bronze QA110-3-1.5 manufacturing. And also with developing of material industry, Nylon GRPA66.25 also applied much now.

Seals

Material of sleiwng ring bearing seals are made by oil resistant Buna-N rubber.

4, Clearance

Clearance of slewing ring primarily compensate the erro between bearing supporting accessories and related assembling parts, and the mounting erro to ensure normal using of the bearings.

Normally exact data of the clearance of the beairng according to the dimension of the bearings. We also can adust the data according to the requirement of the customers, preload bearings also can be done with the bearings.

Single-row four point contact ball slewing ring bearing µm

Double-row ball slewing ring bearing µm

Cross roller bearing µm

Three-row cylindrical roller slewing ring bearing µm

5, Heat treatment

Inner and outer ring
Case hardened should to reach HRC55-62, depth should be follow the below table.

Ring and Race available hardened depth mm

Gear available hardened depth mm

6, Lubrication

To ensure flawless operation and long usable life, adequate and regular lubrication is necessary. The grease fulfills the following fuctions:

For the receway:

Reduction of friction and wear in the rolling contacts
Corrosion protection
Lubrication of seals
Additional sealing effect of grease collar
Low friction torque

For the gears:

Smoother running
Lower wear
Reduced operationg noise
Longer useful life
Lower heat development

Initial greasing

RTR Slewing ring are supplied pre-lubricated. High-quality lithium-complex grease.

7, Sealing

Polymer seals protect the Slewing Rings from normal dirt penetration, dust and light sprayed water. For very dirty and wet environments, the seals shall be protected by pre-mounted labyrinth or additional seals on the mounting structure. Performance and service life of the Slewing Ring depends strongly on preventing ingress of contaminents into the Slewing Ring.

8, Operating temperature

Standard RTR Slewing Ring can be used in ambient temperatures form -25 to up +70℃, please contact us in the case of higher or lower operating temperatures.

9, Service Life

The service life of the gear depends on the operating conditions.
The following factors are key:

• Torque
• Output speed
• Duty factor
• Ambient temperature
• Lubrication etc.

10, Transport, handling and storage

Transport only in horizontal position. Impact shall be avoided.

Wear work gloves when handling the slewing rings.

Slewing rings are generally provided with threaded holes in which eye bolts can befixed.

his enables safe handling on a hoisting device. Please observe the relevant legal regulations when doing this.

Slewing ring must be transforted with the hoistiong device connected to three uniformly distributed lifting points around the perimeter. Internal factory transport and installation shall only take place in a horizontal position. Transport crosses must be left in the slewing ring until it is properly installed.

Store only in horizontal position in closed rooms, if stacked there must be a stable inermediate layer. The corrosion protection coating has a shelf-life of approx. 3 months in closed packaging. Longer storage periods require special protective measures.

11, Installation

1, Cleaning the slewing ring and the mounting structure.
2, Determining permissible deviations and deformations of mounting structure
3, Lubricating of slewing ring.
4, Choice of mounting bolts.
5, Choice of tightening torques.
6, Tightening the bolts with a hydraulic tightening device.
7, Positioning the slewing ring.
8, Securing the slewing ring with bolts.
9, Determining the existing tilting clearance.
10, Setting the backlash
11, Operating test.