Slewing Bearings are a kind of large bearing with special structure which can bear the large axial load, radial load and overturning moment at the same time.Construction machinery is the first and most widely used place of Slewing Bearings, such as earthmoving machinery, excavator, disintegrator, stockpiling and reclaimer, grader, roller, dynamic rammer, rock drilling machinery, roadheader, etc.
The Slewing ring is also called rotary support. It is linked by 2 structure, inner ring, and outer ring. Two rings rotate separately and transmit load. A connector simple equipped in slewing ring and can be linked with other structures fast and convenient. What’s more, 2 rings rotate become more smoothly. The slewing ring can be withstood single or multiple loading. There are loading, radial loading, axis loading, tilting moment and output torque.
All-round Load Capacity
The best part of using PSR bearings in any system is that they provide 360 degrees of joint support even when used for complex load-bearing systems. The bearings allow for a concurrent movement on multiple axes.
Shaftless Bearings
When these bearings get made, you will observe that they happen to be without a shaft/ spindle, which works as an advantage. The bearing is now an enhancement in the bearing motion and gives more space to the system’s other components.
Increase In Load Capacity
You will find an automatic increase in the bearings’ load-carrying capacity because of the design change. They are now capable of handling heavy loads during movement efficiently.
The Right Amount Of Stiffness
Precision slewing ring bearings can facilitate a wide range of motions because of the high material stiffness. It is the ideal amount that is ample enough to provide support for the rigid ball bearing applications
Lesser Friction
Since the components are fewer because there aren’t any shafts or spindles, you will find lesser friction that these ball bearings will impose on the movement even with heavy loads. The freedom of movement is another aspect that gives the upper hand in providing optimum efficiency. The life of the bearings gets comparatively increased because of the above factors and surrounding components.
More Service Life
The durability of such bearings increases due to the reduction in friction. The load-bearing capacity is adjusted to ensure that it reduces the stress on the bearings and the adjacent components. With the number of components decreasing, you will find that the system will last longer and have lesser maintenance issues.
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Internal Gear Type
It is a slewing bearing with a toothed inner ring. Gears and slewing bearings do not need to be equipped with safety covers, and the gears have better dust-proof performance. The filled lubricant maintains lubrication for a long time, and the internal gear meshing transmission contact stress is low, the wear is small, and the service life is long.
External Tooth Type
It is a slewing bearing with teeth on the outer ring. It is a large bearing that can withstand combined loads and can withstand large axial, radial and overturning moments. This structure is easy to process and can maximize the use of the limited space of the slewing bearing. If a failure occurs, diagnosis is easy, as is gear mesh inspection. Due to the larger pitch diameter of the ring gear, a larger transmission ratio can be obtained, and the circumferential force and torque on the pinion are greatly reduced.
Single Row Ball Slewing Bearing
Single row ball slewing bearing is a four-point contact bearing with only one row of steel balls. They can bear axial load, radial load and overturning moment at the same time. A row of four-point contact ball slewing bearings consists of two seats. It has compact structure and light weight. The steel balls contact the circular raceway at four points.
Single Row Crossed Roller Slew Bearing
Single row crossed roller slew bearings consist of two races. It has the characteristics of compact design, light weight, high precision and small fitting gap. Since the rollers are arranged laterally in a 1:1 ratio, they are suitable for high-precision installation and can withstand axial force, resultant moment and considerable radial force.
Double Volleyball Slewing Bearing
Double-row ball slewing bearings adopt a two-row steel ball structure, which has greater load-bearing capacity and a better safety factor than single-row slewing bearings. The double volleyball slewing bearing has three seats. Steel balls and limit blocks can be installed directly on the upper and lower raceways. The upper and lower rows of steel balls with different diameters are assembled according to the stress conditions.
Three-row Roller Slewing Bearing
Three-row roller slew bearings have three rows of raceways, and the rolling elements are steel rollers. This structure can withstand the heaviest loads compared to other structural load-bearing types.
Aerospace Industry
Slewing bearings have a wide range of applications in the aerospace industry, from aircraft landing gear to satellite dishes and telescopes.
Medical Equipment
Medical equipment such as CT scanners and X-ray machines often require rotating stands to ensure precise positioning and rotational motion.
Food And Packaging Industry
In food processing and packaging lines, slew bearings are used in rotating conveyor belts, sealing machines and packaging equipment.
Marine Engineering
In the field of marine engineering, slewing bearings are widely used in lifting equipment, offshore cranes and various underwater robots.
Scientific Research
In the field of scientific research, slewing bearings are used in astronomical telescopes, particle accelerators, microscopes and experimental devices.
Wind And Solar Power
Wind turbines and solar tracking systems require slewing bearings to ensure that the wind turbine or solar panel can rotate based on the wind direction or sun position to maximize the capture of wind or solar energy.
Mining And Heavy Machinery
In mining and construction heavy machinery, slew bearings are used in excavators, loaders, backhoes and other equipment.
Construction Work
In construction projects, slewing bearings are usually used on cranes, tower cranes, concrete pumps and other equipment. They allow these machines to rotate 360 degrees, making it easier to move and position materials and equipment.
Inner Ring Of Slewing Bearing (Upper Ring)
It can be toothed or toothless. It is made of precision raceways made of carbon steel that can transmit the load and relative motion of the two rings. The inner and outer rings are selectively hardened to the required surface and depth to transfer the high stresses exerted during equipment operation.
Slewing Bearing Outer Ring (lower Seat Ring)
It can also have teeth or be toothless. the inner ring, it is fixed to the rotary sleeve and housing through high-strength bolts. The rigidity of the outer ring is ensured by the chassis structure that supports it.
Slewing Bearing Rolling Elements
Rolling elements are the core components of slewing bearings. They roll between the inner and outer rings to help withstand and transfer loads. The rolling elements of the slewing bearing can be balls or rollers. The contact points between rolling elements and raceways experience fewer load cycles. When designing and calculating, the load-bearing capacity is mainly calculated to determine the maximum contact stress at the contact point between the rolling element and the raceway.
Slewing Bearing Cage
The cage of the slewing bearing is its key component, and it has different structural forms such as integral type, segmented type, and isolation block type.Overall cage and segmented cage These two types of cages are usually made of No. 20 steel or ZL102 cast aluminum alloy.isolation block cageThis type of cage is usually made of polyamide 1010 resin, ZL102 cast aluminum alloy and other materials.
Slewing Bearing Seal
The function of the seal is to protect the slewing bearing from external contaminants and prevent the loss of lubricant. The seal of the slewing bearing is an important component, mainly used to prevent the leakage of grease in the raceway and the intrusion of foreign matter such as mud, water, dust, etc. in the external environment into the raceway. It can protect the raceways, rolling elements and isolation bodies to a certain extent, thereby extending the service life of the slewing bearing.
Slewing Bearing Isolation Block
Lubrication devices are often used to provide lubricant to slewing bearings to reduce friction and wear. Mainly used to ensure the normal operation of the slewing bearing.
Materials for ferrules and rolling elements
Generally, the rolling elements of the slewing bearing are made of integrally hardened carbon-chromium bearing steel. The grade is made of GCr15 or GCr15SiMn steel; the slewing bearing ring is made of surface-hardened steel. When the user has no special requirements, it is generally made of 50Mn steel. However, sometimes in order to meet the needs of the host in some special applications, it can also be made according to the requirements provided by the user. For specific usage conditions, other grades of surface-hardened steel should be selected, such as 42CrMo, 5CrMnMo, etc.
Materials for cage
Cages for slewing bearings have structural forms such as integral type, segmented type, and isolation block type. The integral and segmented cages are made of No. 20 steel or ZL102 cast aluminum alloy. The isolation block type is made of polyamide 1010 resin, ZL102 cast aluminum alloy, etc. In recent years, with the continuous development of the material industry, nylon GRPA66.25 has also been promoted and applied in the design of segmented cages.
After the slewing bearing has been running for 100 hours, the pre-tightening force of the bolts should be checked. After that, sufficient pre-tightening force must be maintained every 500 hours of operation.
When the slewing bearing is in use, if noise, impact or sudden increase in power occurs, it should be stopped immediately for inspection, troubleshooting, and disassembly and inspection if necessary.
The slewing bearing raceway should be filled with grease regularly. Generally speaking, ball bearings should be refueled every 100 hours of operation, and roller bearings should be refueled every 50 hours of operation.
The tooth surface of the slewing bearing should be regularly cleaned of debris and coated with corresponding grease.
Every 10 shifts, the slewing bearing and the tooth surface of the slewing ring should be cleaned and re-lubricated.
Rotation Accuracy
Crossed roller slewing bearings are usually selected when the ability to accurately position the bearing is required.
Carrying Capacity
Bearing capacity is one of the factors that determine the size of the bearing. Generally, the four-point contact ball slewing bearing can withstand heavier radial loads and shock loads, so it is suitable for situations where heavier loads and the magnitude and direction of the loads may change.
Working Temperature
In most cases, the allowable operating temperature of a slewing bearing is mainly determined by grease, spacers and sealing materials. In general, the allowable operating temperature range for slewing bearings is -25 to +70°C.
Vibration
For applications involving vibration, preloaded four point contact ball slewing bearing rings and crossed cylindrical roller slewing rings are suitable.
Running Speed
The friction force generated by the four-point contact ball slewing ring is smaller than that of the crossed cylindrical roller slewing ring, and it has a higher limit speed.
Seal
Sealing is critical to the performance of the slewing ring. Qualified seals used in slewing bearings provide good protection against moisture and contamination, and ensure adequate grease levels in the bearing, thereby extending the service life of the bearing.
Two concentric rings make up the main structure of a slewing bearing. The outer ring usually lies flat against a motionless surface and is screwed into place via evenly spaced mounting holes. The inner ring is usually affixed to a turning object via an adapter plate or bracket. It usually moves in a rotational manner while the outer ring stays affixed to the mounting surface.Relative rotation between rings is facilitated either by rolling or sliding elements. For slewing rings that operate with ball bearings, parts that facilitate greasing of the system are included, such as seals, load plugs, grease fittings and taper pins. For slewing rings that are based on sliding elements, replaceable plastic liners lie between the inner and outer rings.Because slewing rings based on ball bearings have very small contact points (ball bearings touching the inner and outer ring surfaces), they are able to move with very low friction.Slewing rings that are based on plastic liners to facilitate movement (with a larger inner ring surface to better handle heavier loads) work better for flat, horizontal applications . Vertical applications are better suited for ball bearing-based slewing rings.
The mounting support of the slewing ring must have sufficient rigidity and the mounting surface should be flat. The support should be subjected to stress relief before assembling the slewing ring. The slewing bearing and slewing ring should be repaired and maintained to reduce the deformation of the slewing ring support. The support should be assembled during assembly. The contact surface with the slewing bearing must be cleaned.
When using slewing bearings and slewing bearings, attention should be paid to changes in noise and slewing resistance torque. If there is any abnormality in the maintenance of slewing bearings and slewing bearings, they should be disassembled for inspection. The slewing bearings must be hoisted or stored horizontally, not vertically. Lift or store to avoid deformation.
Before the bolts are tightened, the slewing bearing and slewing support should be checked for gear meshing. The meshing condition should meet the requirements of gear accuracy, that is, the contact spots distributed on the tooth surface after the gear pair runs under slight braking. The tooth height direction is not less than 25%, and the tooth length direction is not less than 30%.
Slewing bearing and slewing ring In order to ensure the reliability of bolt work and avoid the lack of bolt pre-tightening force, the slewing bearing and slewing ring should be checked for the pre-tightening torque of the bolts after 100 hours and 500 hours of operation of the slewing ring. The pre-tightening torque should be checked every 1000 hours of work.
Carrying Capacity
The first and most important factor to consider when selecting a slew bearing is load capacity. You need to determine the maximum load the bearing will bear during operation. This includes both static and dynamic loads. Static load is the weight of the machine, while dynamic load is the weight of the machine plus any additional loads that may be applied during operation. Be sure to select a slewing bearing that meets the maximum load capacity of your application.
Dimensions And Dimensions
The size and dimensions of the slewing bearing are also important factors to consider. You need to make sure the bearings are properly suited for your application and can handle the required loads. The size and dimensions of the bearings will depend on the size and weight of the machinery, as well as the space available for installation. Make sure to measure the available space and select the appropriate bearings.
Operating Conditions
The operating conditions of your application also play a role in selecting the appropriate slewing bearing. You need to consider factors such as temperature, humidity, and exposure to corrosive substances. Choose bearings designed to operate under the specific conditions of your application. For example, if your application is exposed to high temperatures, choose bearings that can withstand high temperatures.
Lubricating
Proper lubrication is essential for the smooth operation of slewing bearings. You need to choose bearings that are designed for proper lubrication. Consider the type of lubricant that will be used and how often it will need to be used. Choose bearings designed for use with the lubricant you plan to use.
Cost
Finally, you need to consider the cost of the slew bearing. While it may be tempting to choose cheaper options, it's important to remember that the quality of the bearings affects the performance and longevity of your machine. Choose bearings that are within your budget but meet your application requirements.
Rolling Element Material
Rolling elements generally use GCr15SiMn.
Ring Material
The slewing bearing ring is made of 50Mn, but sometimes 42CrMo is also used to meet the needs of the host in special applications.
Cage Material
The cage has different structural types such as integral type, segmented type, isolation block type, etc. The integral or segmented cage is made of 20# steel or ZL102 cast aluminum alloy. The isolation block bracket is made of polyamide 1010 resin, ZL102 cast aluminum alloy or QA110-3-1.
Sealing Ring Material
The slewing bearing should be made of oil-resistant rubber, fluorine rubber, oil-resistant nitrile rubber, etc. The clearance of the slew plate bearing is mainly used to compensate for the manufacturing errors and installation errors of the slew plate bearing supports and related host assembly parts to ensure the normal use of the bearings. According to the structural type/tolerance level of the slewing bearing and the indexing circle diameter of the rolling element group, the clearance value or interference amount of the slewing bearing is determined.
How to Install Slewing Bearings
Ensure That The Slewing Bearing Is Transported And Stored Correctly
When manufacturers prepare slewing ring bearings for shipment, they are lightly lubricated, packaged for shipping, and packaged in separate, dedicated containers.Upon receipt, store the device in a clean, dry place using the original packaging materials until installation. Make sure all areas around the slewing ring bearing are free of grit and dirt.
Frequently Check Whether The Fragments Are Deformed Or Interfered With
Every part of the slewing bearing must be clean, not blocked by the smallest foreign matter, and positioned accurately. Problems can occur during operation when friction or imbalance occurs. Loads can become concentrated in specific areas, causing failure or undue wear and tear.
Make Sure The Support Surface Is Level And Firm
Support surfaces must be machined smooth and perfectly level. They need to be strong enough to remain rigid during operation to eliminate vibration or bending that may occur due to imbalance.
Check The Roundness Of The Ring
It is crucial to protect all elements of the slewing ring bearing. If the roundness of the slewing bearing is damaged during transportation, loading and unloading, the slewing drive will not work properly. Slewing ring bearings should be transported and stored in special crates and always maintained in a horizontal position.Make sure the lifting equipment or slings used are strong enough to lift and secure the rings during installation. External gear teeth must be protected to prevent damage from collision with other surfaces.The storage time of slewing bearing equipment should not exceed six months. The raceways must always be lubricated and free of rust.
Proper Sealing And Lubrication
Installers should specify integral seals on the bearings in combination with guards to protect the gears and bearingsAs with most metal machine parts, proper lubrication is essential for smooth operation and long service life. This process is critical for slewing ring bearings and gears. The device will come with operating instructions, which will suggest the recommended frequency of lubrication. The lubrication schedule depends on the type of equipment and its use.
Gear Lubrication
Gears should be lubricated with a brush or spray immediately after assembly. It is recommended to lubricate gear oil at least every three months, depending on the severity of equipment use.
Carefully Check The Installation Instructions And Test Before Use
Please follow the manufacturer's installation instructions.When installing, the slew bearing should be rotated while tightening the bolts to determine whether there are tight spots. Also, recheck bolt torque to determine any changes due to settlement.
LUOYANG TEDIN BEARING CO., LTD. --owns core production technology of high-end rolling bearings, focusing on R & D high-end bearings, customized bearings, and specially designed precision bearings have been in a leading position of China.
TEDIN has a variety of automatic producing lines and supporting facilities for high-precision roller bearings. The precision grade of the precision bearings can reach P5, P4, P2. TEDIN serves a wide range of customers especially in precision machine tools, rolling mills, precision rotary tables, industrial robots, high-speed railway, track traffic, military Radar, helicopter gunship, wind power, and solar energy, etc.
