What is slew bearing?

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What is a Slew Ring Bearing?

A slew ring bearing, also known as a slewing ring or turntable bearing, is a rotational rolling-element bearing that typically supports a heavy but slow-turning or slow-oscillating load, often a horizontal platform such as a conventional crane, a swing yarder, or the wind-facing platform of a horizontal-axis windmill. It consists of an inner ring and an outer ring, one of which usually incorporates a gear. Together with attachment holes in both rings, they enable an optimized power transmission with a simple and quick connection between adjacent machine components.

Types of Slew Ring Bearings

Slew ring bearings are categorized mainly based on their design and the demands of the application:

Single-row Four-point Contact Ball Bearing – This type is the most common, characterized by a single row of balls with the contact angle that can support axial, radial, and moment loads.

Double-row Ball Bearing – Offers higher load capacity than a single-row, using two rows of balls.

Crossed Roller Bearing – Rollers are arranged at right angles to each other at intervals between inner and outer rings. This design offers high stability and accuracy, suitable for high axial and radial loads.

Three-row Roller Bearing – This type combines three rows of rollers to bear different loads separately, facilitating higher load capacity and rigidity.

Ball and Roller Combination Bearing – These bearings combine both rollers and balls in different rows to optimize load capacity and reduce material costs.

Features of Slew Ring Bearings

High Load Capacity: Designed to handle simultaneously acting radial, axial, and moment loads.

Compactness: They are relatively thin in section and are often made in diameters of a meter or more; thus, they save space compared to conventional bearings.

Rotation Accuracy: Provides precise rotation and positioning.

Ease of Mounting: Their design simplifies the structure of the installation equipment.

Integrated Gearing: Many slew bearings have internal or external gears, facilitating the integration into a system.

Applications of Slew Ring Bearings

Slew bearings are used in a variety of applications including:

Construction machinery like cranes and excavators.

Wind turbines.

Medical equipment, particularly in rotating tables and scanners.

Military applications, such as in radar and missile launchers.

Industrial turntables and manipulators.

Robotics and automation systems.

Price of Slew Ring Bearings

The price of slew ring bearings can vary widely depending on the size, type, material, and specific manufacturer requirements. Small, standard slew bearings might start around a few hundred US dollars, while large, custom-engineered bearings can cost several thousand or even tens of thousands of dollars.

How to Select Slew Ring Bearings?

Selecting the appropriate slew ring bearing involves several considerations:

Load Type and Magnitude: Determine the axial, radial, and moment loads the bearing will need to support.

Precision Requirements: Consider the required precision and rotational speed.

Environmental Conditions: Assess the operating environment, including temperature extremes and exposure to contaminants or corrosive elements.

Size and Space Constraints: Factor in the physical space available for the bearing.

Gear Requirements: Decide if internal or external gearing is necessary for your application.

Material and Coatings: Choose materials and coatings based on environmental and load conditions to enhance durability and performance.

Lifecycle and Maintenance: Consider the expected life and maintenance requirements, including lubrication and inspection intervals.

By understanding these factors, engineers can select the most appropriate slew ring bearing for their specific application, balancing performance, longevity, and cost.

LDB Bearing is a professional slewing bearing manufactuer offers high-quality, custom-tailored slew bearings, slewing drives and gears for your project.

What is excavator slew ring？

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An excavator slew ring, also known as a slewing bearing or turntable bearing, is a crucial component in the construction of excavators. It is a rotational rolling-element bearing that typically supports a heavy but slow-turning or slow-oscillating load, often a horizontal platform such as a conventional crane, a swing yarder, or the wind-facing platform of a horizontal-axis windmill.

Features of Excavator Slew Ring

  1. High Load Capacity: Slew rings are designed to withstand axial, radial, and moment loads, making them suitable for the heavy loads and complex load combinations experienced by excavators.
  2. 360-degree Rotation: They enable the excavator’s upper structure (including the cab and boom) to rotate fully relative to the undercarriage.
  3. Compact Design: Despite their load-bearing capabilities, slew rings are relatively compact and integrate seamlessly into the excavator’s design.
  4. Sealed and Lubricated: They are generally sealed to prevent dirt, debris, and water ingress and are pre-lubricated for long life and reduced maintenance.
  5. Durability and Reliability: Made from robust materials, slew rings are built to withstand harsh working environments and repetitive use.

Types of Excavator Slew Ring

  1. Single-row Ball Type: Features a single row of steel balls. It’s the most common type, suitable for light to medium loads and offers smooth rotation.
  2. Double-row Ball Type: Contains two rows of balls, which can handle larger loads than the single-row type and provide better stability and load distribution.
  3. Crossed Roller Type: Rollers are arranged in a crossed pattern to increase load capacity and rotational accuracy. Ideal for applications requiring high precision under high loads.
  4. Three-row Roller Type: This type has three rows of rollers, maximizing load capacity and stiffness. It’s used for very heavy-duty applications.

Standards of Excavator Slew Ring

Slew rings are manufactured according to various international standards to ensure quality, compatibility, and safety. Some common standards include:

  1. ISO 9001: Quality management systems standards that help ensure manufacturers meet the needs of customers and other stakeholders.
  2. ISO 14001: Pertains to effective environmental management systems.
  3. JIS (Japanese Industrial Standards) and DIN (Deutsches Institut für Normung): Specific standards that provide guidelines on dimensions, tolerances, load capacities, and material properties.

How to Select Slew Ring for Excavators？

Selecting the right slew ring for an excavator involves several considerations:

  1. Load Calculations: Understand the maximum loads the slew ring will need to support. This includes axial, radial, and moment loads.
  2. Size and Space Constraints: The size of the slew ring must fit within the excavator’s designated space without interfering with other components.
  3. Sealing and Lubrication: Depending on the operating environment, choose a slew ring with appropriate sealing and lubrication for optimal performance and durability.
  4. Material and Coatings: Select materials and coatings that can withstand the environmental conditions (e.g., corrosion-resistant coatings if used in marine environments).
  5. Manufacturer’s Reputation and Support: Choose a manufacturer known for quality and reliability, and ensure they offer adequate technical support and warranty.
  6. Rotation Requirements: Consider the required rotational speed and precision, which will affect the choice between ball and roller types.

By carefully considering these factors, you can ensure that the chosen slew ring will meet the operational demands of the excavator and provide long service life.

Excavator Slew Ring Manufacturer

LDB Bearings is a professional slew ring, slew bearing, and slew drive manufactuer provides high quality and cost effective slew rings for excavator, if you are looking for slewing ring for excavator, feel free to contact us.

Slewing Gear Ring Bearing Drive

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Slewing Gear Ring Bearing & Slewing Gear  Drive

Rotary gears are usually divided into two types, one is the rotary gear support bearing, the other is the rotary gear drive
Slewing gear support bearings are composed of an inner ring and an outer ring, usually one of which contains the gear. Together with the connecting holes on the two rings, they are easily and quickly wired through the adjacent link components for optimized power transmission. Slewing gear bearing raceways combined with rolling elements and cages are designed to withstand loads acting individually or in combination in any direction.
Rotary gears can be used in various industries such as aerospace, heavy equipment, industrial machinery, medical systems, mining, oil and gas, etc., and are the key to many industries and play a vital role.
The slewing gear support bearing is different from ordinary bearings, the difference is that it has a gear that can adjust the rotation. The machine transmits and adjusts the direction of the mechanical products fixed on the slewing bearing through the dynamic sensing system installed on the slewing gear bearing. and take advantage of special constructs:

It maintains the overall balance, effectively guarantees the radial force generated in the work, and ensures the balance.

The rotary gear drive is a kind of turntable fixed in the gear box, which can safely bear the radial and axial load force, and drives the rotation of the turntable through the rotation of the turbine. Rotary gear drive is a gearbox composed of gears, bearings, seals, casings and motors.
The rotary gear drive is a modification of the worm drive mechanism. It dates back to the Renaissance period, when the Greek mathematician Pappus devised a worm drive. Da Vinci also used the slewing gear drive trim in many of its machines.


The driving force of the rotary gear drive comes from the rotational force given by the motor to the worm, and the gear on the worm is adjusted by the gear on the electric turntable. This combination mode reduces the rotation speed of the turntable, increases the torque, and can drive heavier objects.
Slewing gear drives can be applied to solar trackers, wind turbines, elevators, hydraulic machinery, telescopic arms, cranes and other equipment.

Slewing Bearing Installation Surface

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Mechanical machining of the bearing connection surfaces on the connecting structure is required . The mounting position of slewing bearings must correspond to that shown in the drawing. If a transporting cross was delivered, it has to be removed before installation.

The corrosion protection can be removed with an alkaline cleaner. Cleaner must be prevented from coming into contact with the seals or the raceway. Remove the protective coating from the upper and the lower mounting surfaces of the slewing bearing as well as from the gear.

The corrosion protection can easily be removed, for example, using a biodegradable alkaline cleaner.

Rapid removal of the corrosion protection and low environmental impact.

The unhardened zone between the beginning and the end of the hardened region of the raceway is marked with an “S” on the inner or outer diameter of each bearing ring. On the gear ring, the hardness gap is marked on the axial surface. Wherever possible, the hardness gap “S” must be positioned outside the main load-carrying areas. If the main working area for the application is known, then the hardness gap of the ring loaded on the circum-ference must also be positioned outside the main load-carrying area.

The bearing must be completely screwed on for commissionings and test runs. Sufficient load / moment loan must be applied to avoid a slip-stick effect on the anti-friction bearing bodies.

Gearing

Entanglement hazard due to exposed gear

  • Keep hands away from moving parts

The backlash is adjusted relative to the three gear teeth marked in green and should be 0.03 – 0.04 x module.After the final tightening of the bearing,the backlash should be rechecked over the entire circumference. A tip edge radius and a tip relief must be provided on the pinion.

How to maintain the slewing bearing during use?

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We know that the quality of the slewing bearing itself is the main factor affecting the service life of the bearing, but no, because in addition to the quality of the bearing, there is also a very important issue, that is, the maintenance and maintenance of the bearing during its use, but, How to maintain the slewing bearing during use?

Lubrication of slewing bearing

Slewing Bearings

1. Lubrication

(1) Reduce friction and wear. In the mutual contact parts of the rings, rolling elements and cages that constitute the bearing, metal contact is prevented, and friction and wear are reduced.

(2) Extend the fatigue life. The rolling fatigue life of the bearing is extended when the rolling contact surface is well lubricated during rotation. Conversely, if the oil viscosity is low and the lubricating oil film thickness is not good, it will be shortened.

(3) Discharge frictional heat and cooling. The oil circulation method, etc., can use oil to discharge heat generated by friction or heat from the outside, and cool it. Prevent the bearing from overheating and prevent the aging of the lubricating oil itself.

(4) Others. It also has the effect of preventing foreign matter from entering the inside of the bearing, or preventing rust and corrosion.

2. Lubrication method

Bearing lubrication methods are divided into grease lubrication and oil lubrication. In order to make the bearing function well, first of all, it is necessary to select a lubrication method suitable for the conditions of use and the purpose of use. If only lubrication is considered, the lubricity of oil lubrication is dominant. However, grease lubrication has the advantage of simplifying the structure around the bearing. Compare the advantages and disadvantages of grease lubrication and oil lubrication.

Cleaning of slewing bearing

1. Selection of cleaning materials

As the cleaning agent, cleaning agent and kerosene are generally used. In addition, pay attention to sealing the cleaning agent when not in use to avoid the entry of external magazines and contaminating the cleaning agent. In the case of inattentiveness, cleaning the bearing with the contaminated cleaning agent will not only not have a cleaning effect, but will contaminate the bearing and cause the bearing to be polluted. Running brings stress.

2. Cleaning precautions

(1) The disassembled bearing is cleaned, divided into coarse cleaning and fine cleaning, and placed in the container respectively, first put on the bottom of the metal mesh, so that the bearing does not directly contact the dirt of the container.

(2) During rough cleaning, if the bearing is rotated with dirt, it will damage the rolling surface of the bearing, so be careful. In the rough cleaning oil, use a brush to remove grease and adhesions. After it is roughly clean, transfer to the fine cleaning.

(3) Fine cleaning is to carefully clean the bearing while rotating in the cleaning oil.

slewing bearings

Maintenance of slewing bearing

1. Maintenance method

(1) Check the state of the raceway surface, rolling surface, and mating surface, the wear of the cage, the increase of bearing clearance, and the damage and abnormality irrelevant to the decrease of dimensional accuracy.

(2) For small ball bearings, support the inner ring horizontally with one hand, and rotate the outer ring to check whether it is smooth. For separable bearings such as tapered roller bearings, the rolling elements and the raceway surface of the outer ring can be inspected separately.

2. Maintenance precautions

(1) In order to judge whether the disassembled bearing can be used, it should be checked after the bearing is cleaned.

(2) Special tools and disassembly steps and techniques should be used for bearing disassembly to avoid damage to the bearing due to the disassembly of the bearing for maintenance, which is not worth the loss.

(3) Since large bearings cannot be rotated by hand, pay attention to checking the appearance of rolling elements, raceway surfaces, cages, rib surfaces, etc. The higher the importance of the bearing, the more careful inspection is required.

The above is the summary of how to maintain and maintain the slewing bearing during the use of the slewing bearing. It can be seen that the maintenance skills in the use of the slewing bearing include lubrication, cleaning, and maintenance.

Bearing lubrication should pay attention to the selection of appropriate lubricants, pay attention to the distinction between coarse and fine washing when cleaning, and pay attention to disassembly, rotation and other issues when overhauling.

Material handling Cranes slewing bearing

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Material handling Cranes slewing bearing

Dockside and deck cranes are moving heavier loads, faster than ever before.

Drawing on deep application knowledge and using advanced FEM calculations to optimize designs,LDB slewing bearings for cranes increase reliability and bearing service life, while reducing maintenance costs.

Integrating LDB’s advanced condition monitoring technologies also boost uptime and productivity.

“To solve my technical issue, LDB signiicantly increased the slewing bearing’s service life thanks to advanced calculations and specially developed technical solutions.”- Material handling customer.

Wind Turbine Bearings

Tunnel Boring Slewing Bearing

Scrap standard and service life of tower crane slewing bearing

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All machines will experience wear and tear after a long period of use. When the parts exceed the service life or are damaged beyond repair, they should be scrapped and replaced. The tower crane slewing bearing is prone to failure and damage in the long-term outdoor harsh environment and high-load operation, so to what extent does it meet the scrapping standard of the tower crane slewing bearing?

Scrap standard of tower crane slewing bearing

slewing bearing

1. Slewing bearing raceway ring and rolling element wear and scrap

The wear of raceway rings and rolling elements is one of the common forms of scrapped slewing bearings. When there is raceway pitting on the surface of the slewing bearing, surface metal peeling and overall wear, abnormal noise, rolling element jamming and excessive clearance between the raceway rings will occur in the tower crane during operation, resulting in vibration and local impact. With the development of the state, the slewing resistance will continue to increase and the slewing function will be lost.

2. The slewing bearing cage is damaged and scrapped

In order to avoid mutual friction between the rolling elements, the tower crane slewing bearing usually adds a spacer cage between the rolling elements. The material of the cage is generally copper, plastic, powder metallurgy or mild steel. During the working process of the bearing, the cage does not transmit the load, but it moves with the rolling elements. When the cage is damaged or broken, there will be a sharp and ear-piercing abnormal sound. As the broken body of the cage is pushed and rolled by the rotating rolling body, it will cause serious damage to the raceway ring and the rolling body. At this time, the slewing bearing meets the scrap standard and can be replaced.

3. The slewing bearing gear teeth are damaged and scrapped

The gear meshing methods of tower crane slewing bearing include external tooth meshing and internal tooth meshing. When the surface of the gear teeth is excessively worn, cracks and broken teeth occur. The tooth side clearance of the tower crane slewing bearing gear teeth increases, causing the slewing bearing to lose its function immediately when the tooth is broken, and it cannot be repaired. At this time, the scrapping standard of the tower crane slewing bearing is reached.

4. The connecting bolts of the slewing bearing are damaged and scrapped

Although the connecting bolt of the slewing bearing is not the bearing body, the failure of the bolt will also cause the slewing bearing to fail to work. The damage of connecting bolts in tower crane work is also a common phenomenon. When a slewing bearing connecting bolt loosens or breaks, it often brings about a chain reaction of loosening and breaking of other bolts. At this time, the slewing bearing also needs to be replaced.

5. The slewing bearing is scrapped due to corrosion and burn damage

Due to the complex working environment of the tower crane slewing bearing, the situation that the bearing may encounter is also unpredictable. If it is corroded by corrosive substances such as acid and alkali during operation, it will damage the internal components of the bearing and cause the bearing to be scrapped.

Service life of tower crane slewing bearing

Slewing Bearings

Under a certain load, the number of revolutions or hours that a bearing experiences before pitting occurs is called bearing life. The service life of tower crane slewing bearing is affected by rotational speed, radial load, basic rated load, equivalent compliance, speed coefficient, and fatigue life coefficient.

1. Calculation formula of bearing life

L10–When the bearing load is P, the basic rating life (106 revolutions)

C–Basic dynamic load rating N

ε–index

Ball bearing: ε=3

Roller bearing: ε=10/3

P–equivalent dynamic load (N)

The load on the bearing under actual conditions: A, R, converted into the load under the experimental conditions is called the equivalent dynamic load. For the bearing components, this load is variable. During the experimental study, the bearing life is 106 turns to The unit is more convenient (counter), but in actual production, the general life is expressed in hours, so it is necessary to convert L10×106=Lh×60n.

Slewing Bearings

2. Calculation method of tower crane slewing bearing life

(1) Knowing the bearing type, load and shaft speed, calculate Lh;

(2) Knowing the load, speed and life expectancy, calculate C, and select the bearing model.

Usually, the medium repair or overhaul limit of the machine is taken as the design life of the bearing, generally Lh’=5000, and the temperature coefficient ft should be introduced for the bearing working at high temperature

Ct=ftC

t≤120 125 150 200 300

ft 1 0.95 0.90 0.80 0.60

The above is the relevant content about the scrapping standard of the tower crane slewing bearing. The tower crane may affect its service life due to its complex use environment. At the same time, good maintenance and repair can also prolong the service life of the tower crane slewing bearing.

Is the surface roughness of the slewing bearing as small as possible? How to choose?

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Is the surface roughness of the slewing bearing as small as possible? Surface roughness refers to the small spacing and the unevenness of small peaks and valleys that the machined surface has. The roughness of the bearing surface may affect the wear resistance, stability, fatigue strength, stability and other properties of the bearing. Generally speaking, the smaller the roughness of the bearing surface, the better, but it should be determined according to the equipment use requirements and process accuracy.

The surface roughness of the slewing bearing is not as small as possible

Slewing Bearings

Is the surface roughness of the slewing bearing as small as possible? It can be analyzed from the following aspects:

1. Physical properties of materials

The surface roughness of the bearing is often represented by Ra. Generally speaking, from the working principle, we hope that the smaller the surface roughness of the slewing bearing, the better. Generally, the higher the bearing tolerance accuracy level, the better the surface quality and the finer the workmanship. However, two surfaces that are too smooth are prone to gluing (exchange between the same or similar materials, which is similar to the “dyeing phenomenon” in our life, but it belongs to the exchange of metal substances here), while the surfaces that are too rough are prone to gluing. Under the action of force, the surface is prone to peeling off (that is, what we often call wear).

2. Processing cost

Theoretically, the smaller the value of the surface roughness of the slewing bearing, the better, the smaller the roughness, the smoother the surface and the more beautiful the appearance. However, the size of the roughness is determined by the machining process and other factors, such as the friction between the tool and the bearing surface, cutting, and high-frequency vibration in the process.

However, the smaller the surface roughness, the higher the processing cost. Whether the use cost of the part matches the consumption speed and the profit of the equipment production output value. These all need to be considered. Some spare parts do not have high requirements on the roughness of the bearing surface. Excessive pursuit of the surface roughness will affect the economy of processing.

Selection principle of surface roughness of slewing bearing

slewing bearing

1. Economic perspective：

From an economic point of view, on the basis of meeting the performance requirements of the slewing bearing, the lower the accuracy, the better. This allows for lower production costs.

2. Use function:

(1) The roughness value of the working surface is smaller than that of the non-working surface.

(2) The roughness value of the friction surface is smaller than that of the non-friction surface.

(3) The roughness value of the clearance fit is smaller than that of the interference fit.

(4) The roughness of the mating surface should be equivalent to its dimensional accuracy requirements. The smaller the size, the smaller the roughness value should be.

(5) The roughness value of the surface subjected to cyclic load and the inner fillet and concave part where stress concentration may occur should be small.

Is the surface roughness of the slewing bearing as small as possible? I believe everyone is clear. The actual selection of bearing accuracy and surface roughness needs to be determined according to actual needs. In the case of ensuring bearing performance, cost control is also very important.

Slewing Bearing Comes In Many Sizes

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Slewing bearing comes in many sizes

LDB Slewing Bearing Manufacturer custom designed and manufactured a segmented, 3-row roller bearing almost 14 m in diameter. It weighed 70 tons.LDB Slewing Bearing Manufacturer also produces a range of smaller slewing bearings for special machinery,high-tech applications and more.

For more than a half century, LDB Slewing Bearing Manufacturer has been designing and manufacturing many types and sizes of high-performance slewing bearings to meet the speciic needs of customers worldwide. Combining decades of application knowledge and unmatched manufacturing expertise, LDB Slewing Bearing Manufacturer provides customised slewing bearings with outer diameters from 0,1 m to 14 m.

Unlike other providers of slewing bearings, LDB Slewing Bearing Manufacturer can offer fully tailored slewing bearing solutions with integrated advanced monitoring, lubrication and sealing systems for higher reliability and longer service life. Our breadth of engineering knowledge, global presence and design lexibility allow us to deliver the right solution for your project, no matter how large or complex.

High-performance slewing bearings

For a wide range of applications:

  • Wind turbines
  • Tunnel boring machines
  • Excavators
  • Forestry vehicles
  • Rail vehicles
  • Dockside and deck cranes
  • Mobile cranes
  • Water treatment equipment
  • Bottle illing systems
  • Metals
  • Material handling
  • Marine pods
  • Offshore buoys
  • Stacker reclaimers

Model parameters of externally toothed three-row cylindrical roller slewing bearings

Slewing bearing design types:

  • Double row ball bearings
  • 4point

Contact bearings

  • Crossed roller bearings
  • Wire race bearings
  • 3row

and double row cylindrical roller bearings

  • Cylindrical roller and ball bearings
  • Special bearings

How is the slewing bearing soft belt produced? The installation position of the flexible belt

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The raceway of the slewing bearing generally needs to be heat treated. In the heat treatment process, because the diameter of the raceway circle of the slewing bearing is relatively large, flame surface quenching is usually used. The method is to use acetylene to heat the surface of the workpiece to be hardened and then add water to cool it. , this process is completed continuously.

1. How is the slewing bearing soft belt produced?

During the production and processing of the slewing bearing, the raceway of the device generally needs to be heat treated. The usual processes are: forging → rough machining → quenching and tempering treatment → finishing → raceway surface flame surface quenching → raceway surface grinding and other processes . One of the raceway surfaces is flame quenched to form a soft band.
The so-called soft belt is the area that has not been heat treated. The formation of the soft band is necessary for the heat treatment process. In the heat treatment process of the slewing bearing, because the diameter of the raceway circle of the slewing bearing is relatively large, flame surface quenching is usually used. The method is to use acetylene to heat the surface of the workpiece to be hardened and then add water to cool it.

Slewing Bearings

The heated flame spray gun and water gun are mounted together while making a circular motion along the circle of the workpiece. When the movement is close to 360 degrees, the heating and water spray are stopped immediately. That is, the circular areas of heating and water spray do not overlap. Cracks in the workpiece can occur if the circle areas where the heating and water spray occur overlap (heat treatment at an angle greater than 360 degrees on the circle). The tangential width of the unheated area is typically 15 mm. This 15 mm area is called the soft belt in the slewing bearing, that is, the so-called soft belt is the area without heat treatment. The formation of the soft band is essential to the heat treatment process.
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Under normal circumstances, the steel character “S” is marked on the position where the soft belt exists in the workpiece to indicate the specific soft belt position. The installation position of the soft belt is essentially to improve the life of the bearing. From the perspective of the user and the manufacturer, it is still a reasonable position to install the upper and lower ring soft belts of the slewing bearing. Therefore, the manufacturer of the slewing bearing should accurately mark the position of the soft belt of the slewing bearing, and the manufacturer and installer should reasonably install the position of the soft belt of the slewing bearing as needed.

2. The installation position of the soft belt

Slewing Bearings

Usually the upper loop flexible belt of the slewing device is installed at a position perpendicular to the projection line of the pitching rotation plane. For example, the upper loop flexible belt of the slewing device of a ship loader or stacker-reclaimer should be installed at a position perpendicular to the center line of the cantilever and cut through the center of rotation , that is, standing at a 90-degree position facing the left or right side of the cantilever on the center of rotation. In the usual mechanical design, the soft belt does not have the stress state of the support roller of the slewing bearing device at this position.

The installation position of the lower ring soft belt of the slewing device should be determined according to the center of gravity of the equipment and the range of the slewing angle. If the rotation angle is 100 degrees left and right, and the center of gravity of the upper part of the rotation is in the front, it is recommended to install the lower ring soft belt at the rear, that is, at a position of 180 degrees. If the change position of the center of gravity of the upper part of the rotation is the same in the front and rear positions, the angular position of the lower ring soft belt can be installed arbitrarily.
​​
Because of the inevitability of the soft belt on the slewing bearing device, it is required that the user who uses and selects the slewing bearing device should install the position of the soft belt reasonably, so as to improve the service life of the bearing. The general principle is to try to install the soft belt in a position where the soft belt is under less pressure during the load change.