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Slew Rings

2016-07-07 17:03:05

  • Installation and Maintenance


  • Installation

  • -Handling

  • -Storage

  • -Preparation

  •   --Cleaning

  •   --Positioning the Slewing Ring

      --Securing the Slewing Ring with bolts

      --Determining the existing tilting clearance

      --Setting the backlash

      --Operating test

  • -Post Installation


  • Maintenance

  • -Checking mounting bolts

  • -Checking the tilting clearance

  • -Lubrication

  •    --Raceway system



       --Noise, Roughness and Vibration


       --Dismantling the bearing

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  • Detailed Procedures to Install and Mainten Slew Rings as Follows:
    Detailed Procedures to Install and Mainten Slew Rings as Follows:
    Detailed Procedures to Install and Mainten Slew Rings as Follows:

    Detailed Procedures to Install and Mainten Slew Rings as Follows



  • -Handing

  • Slewing ring bearings, like any other machine part, require careful handling. To reduce the risk of injury,Use of safe operating practices and observation of all relevant legal regulations when handling,cleaning, and transporting are required. It is recommended that gloves be used whenever handling the bearing.Also, use carrying and lifting tools that are specially suited for mounting such bearings.

    Slewing bearings should be transported and stored flat on a surface that extends over the whole side face of the bearing , preferably safely secured to shipping pallets or in a container. Eyebolts, for example, should only be subjected to a load in the direction of the shank axis. Also, keep in mind when using.Avoid any sudden acceleration or impact. If the bearing must be turned over, use nylon web slings or equivalent. Do not use chains or metallic mesh slings in contact with the bearing.

  • -Storage

  • Store only in horizontal position in closed rooms, if stacked there must be a stable intermediate layer. We recommend that you do not stack more than two high if the bearing is four feet or larger in diameter.The corrosion protection coating has a shelf-life of approx. 3 months in closed packaging. Longer storage periods require special protective measures. If the bearing is not installed within one year of receiving it, the grease should be purged and replaced with fresh grease.Outdoor storage is not recommended. External surfaces of slewing ring bearings, including the gear, are coated with a preservative oil to provide nominal protection during storage.

  • -Preparation-Cleaning

  • Installation of the bearing and gear assembly should be done in a clean, dry, well-lit area.

    Remove extraneous material from supporting surfaces and pilots of the housings (including paint residues, welding beads, burr formation).

    Clear corrosion protection coating from supporting surfaces of the Slewing Ring.Even "soft" material trapped between the mounting and bearing surfaces can result in high spots and affect bearing and bolt performance.  

    The purpose of cleaning material is that to stop penetrating into the Slewing Ring.

    Cleaning material that attacks the sealing material is not used.

    When this has been done, examine for and remove weld spatter, paint, nicks and burrs and wipe clean again.Mounting surfaces should be machined.

  • --Determining permissible flatness deviation perpendicularity deviation and permissible deformation of the mounting surface of the supporting structure

    --Lubricating the Slewing Ring

    Slewing Rings are supplied fully lubricated. They shall be greased again prior to initial operation.

    Inject grease into all grease nipples one after the other,while rotating the Slewing Ring, until a bead of grease forms at least on one sealing lip.

  • -Positioning the Slew Ring

  • If one ring has a pilot or dowel hole, it should be positioned and mounted first.Consider alignment of gear's minimum backlash on structure so any necessary adjustments can be made.

    Determine the main load-carrying zone.

    For all Slewing Rings the soft spot of the Slewing Ring raceway shall be placed at a 90 deg point to the maximum load zone. The soft spot is designated with a filling plug or a punched “S” mark.

    Do not expose the seal area or any other bearing opening to pressurized cleaning.

    Use only cleaning material that is compatible with the seal material and avoid getting debris or other material into the bearing. Visually inspect and confirm that there is no damage to the bearing, gear, seals, or grease fittings.

    Remove any minor burrs from mounting surfaces that may have occurred in shipping or handling. Use a hand file, taking care to remove only as much material as necessary to ensure full contact of bearing surface with equipment mounting surface. Make sure all surfaces are wiped clean.

    With a gauge, check whether the supporting surface of the Slewing Ring is fully supported by the mounting structure.

  • -Securing the Slew Ring with bolts

  • The Slewing Ring shall be mounted in the unloaded condition.

    First the toothless bearing ring is attached and then the gear bearing ring.

    For good load distribution and smooth, low torque operation, the bearing should be as round as possible when the bolts are tightened. The following procedure is provided as an aid in achieving that objective.

    The following procedure shall be followed in order to avoid deviations between the bolt tightening forces:

    1.Lightly lubricate bolt threads in order to ensure uniform frictional resistance (does not apply to bolt locking devices with adhesive).

    2.Preload the bolts, including washers, if required, crosswise in 3 steps with 30%,80%, 100% of the tightening torque or the hydraulically applied pretension force.

    3.Thereby rotate the unbolted ring several times. Repeat the procedure for the bearing ring which has not yet been bolted.

    When applying a hydraulic fastening device, the tightening forces for preloading shall not exceed 90% of yield stress.

    4.Using a gauge, verify the bearing fully supports the mating structure. If not, then determine cause and correct.

    5.Complete installation of all rotating components of significant weight, and check bearing for freedom of rotation. Excessive torque level, variation, or vibration is indicative of some unsatisfactory installation condition or component.

    6.As permitted, inspect seals again for any damage.

  • -Determining the existing tilting clearance

  • When the equipment has been completely assembled, and prior to testing, check bolt tension to ensure that it is in compliance with that specified by the designer. The equipment should be oriented to generate as little moment or radial load on the bearing as possible to avoid inaccuracy in readings. Document this orientation so it may be used for all future bolt inspections. Any loss of pretensioning must be determined and eliminated.

    The tilting clearance increases with raceway wear. To determine the increase in tilting clearance,it is necessary to take basic measurements after installation prior to putting the Slewing Ring into operation for the first time.Permanently designate the measuring point in the main load direction.

  • -Setting the backlash

  • In the case of geared Slewing Rings the backlash shall be set during the mounting procedure. The narrowest point of the gearing is marked in green for this purpose.


  • A gauge shall be used to measure the backlash. If deviations from the specified values are established the axis spacing shall be corrected by moving the pinion. Afterwards the Slewing Ring shall be rotated by one complete turn making sure that no narrow points occur.

  • -Operating test

  • If the mounting bolts are properly tightened, then the Slewing Ring shall rotate uniformly. Deviations of the mounting structure and the effect of external loads can strongly impact the friction torque.

  • 1.Rotate the mounted Slewing Ring several times.

    2.Check whether the Slewing Ring runs smoothly without jumping.

    3.Perform further test runs under full load.

  • After the operating test, recheck the tightening torques of the mounting bolts.

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  • Maintenance

  • -Checking mounting bolts

  • While SOCARE® slewing ring bearings require minimal attention, what little they are given will pay big dividends in long life, high performance, and trouble-free service.

    To compensate for possible settling, it is necessary to retighten the bolts to the prescribed torque. This shall be done after no more than 100 hours of operation and without external load applied to the bolt connection

    The inspection shall be repeated after every 700 hours in operation or at least every 6 months. The inspection period shall be reduced under special operating conditions. In case of loose bolts, nuts and washers, replace all bolts, nuts and washers with new ones.

  • -Checking the tilting clearance

  • Raceway wear leads to increased tilting clearance. It is therefore necessary to check the tilting clearance after 700 operating hours, or at the latest after 6 months.

  • -Lubrication

  • Lubrication of the bearing is recommended every 100 operating hours for relatively slow rotating or oscillating applications such as backhoes, excavators, and cranes or as specified by the designer. In more rapidly moving or continuously rotating machinery such as trenchers, borers, and material distributors, the bearing should be lubricated every day, or every 8 hours of round-the-clock service. 

  • -Raceway system

  • 1.Inject grease into all cleaned grease nipples one after the other while rotating the Slewing Ring, until a bead of fresh grease forms at least on one sealing lip or at the bearing gap.

  • 2.Ensure that old grease can flow out of the Slewing Ring freely.

    3.If possible continue to rotate the Slewing Ring.


  • -Gear

  • 1.Apply grease to the teeth of the Slewing Ring with a clean brush.Instead of a brush the grease can also be sprayed on, or applied by means of a suitable lubricating device (e.g. a lubricating pinion).

    2.Remove excess and used grease. Adhesive lubricants have proved to be particularly effective in open gearing.

  • -Seal

  • Within the course of maintenance work it is also essential to check the seals. but the interval should not exceed 6 months. Check for tears, breaks, or other signs of damage. Depending on the lubrication frequency and protection, it may be necessary to clean some areas to  conduct this inspection. Carefully remove any buildup of debris around the seal and lubricate the bearing. There should be a small bead of grease around the seal edge indicating the bearing is receiving sufficient lubrication. Damaged seals must be exchanged. To obtain replacement seals please contact SOCARE® and have the complete drawing number ready. The replacement seals can be cut to the required length and installed with simple tools.

  • -Noise,Roughness and vibration

  • Continued monitoring of equipment noise, roughness, and vibration during operation can assist in early detection of poor or unsafe components, structural failure, or poor bearing performance. 

  • The operator should be very familiar with the typical operating conditions generated by the equipment. Investigate and resolve any noted changes.

  • -Torque

  • Monitoring rotational torque and any variation can not only be used to determine a bearing's condition, but can also provide early indication to a gear, joint, or other structural problem. To determine any change in torque, it is first necessary to record an initial measurement best done after testing and prior to the equipment going into service. Check torque every 700 hours of operation or every 12 months, whichever occurs first, and resolve the cause for any changes.

  • -Dismantling the bearing

  • If it is found that the limits of tilting clearance (δk) have been exceeded during an inspection according to the following tilting clearance value, the Slewing Ring must be exchanged. It is thereby necessary to proceed in the general sense in the reverse order to that for installation. Slewing rings shall be disposed of according to the materials of the individual components and are not taken back by the manufacturer. The corresponding environmental regulations shall be strictly observed during their disposal.

  • “The value (m1) determined after installation of the Slewing Ring is considered as the basic value and is deducted from the measured value (mx). The difference between mx and m1 may not exceed 0.45 mm.

    δk =mx - m1≦δk perm

    δk perm=according to table 1

  • Table 1

  • Rolling element Dia (mm)













    Ball supporting clearance δk (mm)













    Roller supporting clearance δk (mm)













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