Installation & Maintenance of Slewing Bearing

1. Transportation and Storage

The slewing bearing has been sealedwith grease before leaving the factory and wrapped with a film. The anti-rust period of this kind of packaging is generally 3-6 months. The storage temperature should be 20 ± 10 ℃, and the relative humidity is not more than 60%. After the expiration date, it should be maintained in time. The slewing bearing stock should be filled with grease after one year and the flexibility of its slewing should be checked.

The slewing bearing is usually fixed on the pallet or packing box when leaving the factory. There are two forms of single-piece packaging and group packaging. The transportation and storage should be kept level, not collide and squeeze, not rain, and the storage place should be level. There should be smooth isolation between the stacked slewing bearings.

The slewing bearing generally has lifting holes, which can be screwed into the eyebolts for safe lifting.

2. Installation

First open the slewing bearing package, check the certificate and the label, and confirm that the slewing bearing model is correct.

A. Installation plane

The installation surface should be smooth and clean, to remove all excess substances such as paint residues, welding beads, burrs, etc. When cleaning, be careful not to let the solvent penetrate into the inside of the slewing bearing, and do not use solvents that damage the sealing material. The mounting surface should be dry and free of lubricants before assembly. Measures to protect workers and the environment should be taken.

The roughness of the mounting surface of the mounting support is not greater than Ra = 12.5, 6.3μm, and the flatness error of the mounting surface must be tested for circumferential and radial errors. The circumferential flatness tolerance value has a corresponding standard value range with the diameter of the slewing bearing raceway (refer to the relevant standards for specific details, the radial error is measured based on the actual width of the flange, and the radial plane tolerance value is half of the circumferential tolerance value) .

In order to avoid local overload of the slewing bearing caused by unevenness of the installation plane or deformation of the support, the circumferential flatness error can only have one wave undulation within any 180 degrees, and the change is smooth.

B. Stiffness of support

Standard slewing bearings and zero clearance slewing bearings have different requirements for the rigidity of the support. See the table below:

C, positioning

The inner and outer ring raceways of the slewing bearing have a soft belt, which should be placed on both sides of the main load plane. That is 90 degrees offset from the main load zone. There is a blockage or “S” mark on the soft tape.

In addition, the matching of the slewing bearing and the installation surface should be checked. Usually, feeler gauge is used to check. If the matching is not good, it must be filled with appropriate materials. After the slewing bearing is installed, welding operations on the support are prohibited.

D. Strong bolt

1. Selection of mounting bolts

The specified (size, quantity, strength grade, etc.) mounting bolts and washers should be used. Also note:

● Full-thread bolts cannot be used

● Do not use old bolts and washers

● Do not use open washers such as elastic washers, etc.

2. Selection of bolt pre-tightening torque

It is recommended to take 0.6-0.7 times the bolt yield strength of the common metric bolts. It is recommended to use hydraulic fastening devices for bolts larger than M27, and the pre-tightening force should not exceed 85% of the yield strength.

3. Fastening bolts

The slewing bearing should be installed under no-load conditions. note:

● Apply a little oil to the thread of the bolt to ensure the balance of frictional resistance. Do not use glue on the bolt lock.

● Pre-tightening bolts: The pre-tightening should be staggered in three steps.

E. Adjust the gear backlash

When installing a toothed slewing bearing, it is important to adjust the gear backlash correctly. It can be adjusted with a feeler gauge at the highest point of the radial runout of the gear. It can also be pressed lead wire or other suitable methods. If the backlash is not within the specified value, move the pinion to change the center distance. After adjustment, turn the slewing bearing at least one full turn to confirm that there is no other tooth jump high point, and then check the backlash fake backlash after the slewing bearing is finally fixed. The highest point of the radial runout of the gear is marked in the tooth groove with green paint.

F. First lubrication

1. Lubrication of raceway

To ensure adequate lubrication, the grease specified in the drawings or product manual should be refilled before the first use. Pay special attention to all the oil nozzles are filled with grease one by one. It is best to fill the oil while turning the slewing bearing until the grease is seen to squeeze out.

2. Gear lubrication

When the gear is lubricated, the tooth surface should be clean. It is recommended to use a clean brush to brush the grease on the gear.

3. Regular inspection and maintenance

● Check the bolt pre-tightening torque once for 100 working hours for the first time. If more than 10% of the bolts are loose, check again during the 200th working hour.

● Check every 500 working hours in the future; shorten the inspection interval in bad working conditions.

● After a total of 2000 hours of equipment work, if a bolt is found to be loose below 80% of the specified torque, the bolt and the two adjacent bolts must be replaced. If it is found that 20% of the bolts are loosened below 80% of the specified torque, all bolts should be replaced with new ones.

● After the equipment has worked for 14,000 hours in total, all bolts must be replaced with new ones.

● For equipment with high rotation speed or continuous rotation or frequent work, add oil every 100 working hours. In the case of bad working conditions, the time interval for adding grease should be further shortened