What is the difference between a three-row cylindrical roller slewing ring and a double-row cylindrical roller slewing ring?

What is three-row cylindrical roller slewing ring?

Three-row cylindrical roller slewing bearings are a type of bearing used in heavy machinery, especially cranes, excavators, and other large rotating equipment. The design of this bearing includes three rows of cylindrical rollers, which enhances its load carrying capacity and provides better stability.

Features of internal gear slewing rings

High load capacity: The three-row design allows for simultaneous handling of combinations of axial, radial, and moment loads. This significantly increases the load carrying capacity compared to single-row slewing bearings.

Compact: Despite the high load-bearing capacity, the three-row cylindrical roller slewing rings maintain a relatively compact structure, making them suitable for space-constrained applications.

Optimized load distribution: The arrangement of the three rows of rollers ensures a more even distribution of loads, which improves stability and helps to manage stresses more effectively.

Durability and service life: The rugged design of this bearing type allows it to withstand harsh operating conditions and heavy-duty applications, resulting in a long service life.

Superior Rotational Accuracy: This bearing type ensures smooth and precise rotation even under heavy loads, making it ideal for applications that require high-precision motion.

Self-aligning capability: The three-row design can accommodate some misalignment between rotating and stationary components, providing greater tolerance for mechanical errors or distortions in the system.

Versatile Performance: Capable of operating in both high- and low-speed environments, this bearing provides versatility in a variety of mechanical systems.

Enhanced stiffness: Multiple rows of cylindrical rollers provide excellent stiffness, which is important for applications that require precise motion control and stability under varying loads.

Application of three-row cylindrical roller slewing rings

Cranes: Used for mobile cranes and tower cranes, they help to rotate the boom or jib of the crane under heavy lifting loads.

Excavators: Used in excavators to support the rotation of the superstructure relative to the lower chassis, especially in heavy-duty excavators handling large, difficult workloads.

Offshore Oil Rigs: Rotating equipment used on offshore platforms where reliability under adverse weather conditions and heavy moment loads is critical.

Wind turbines: In wind turbines, these bearings are used to allow turbine blades and nacelles to rotate smoothly, providing high load-bearing capacity while being subjected to enormous stresses.

Mining equipment: Heavy mining machinery, such as rotary drill rigs, utilize these bearings to ensure reliable rotation of large heavy components in extreme conditions.

Construction machinery: These bearings are used in construction equipment such as pile drivers, concrete mixers, and other machinery that needs to rotate large components under heavy loads.

Railway turntable: Used in railway turntable, it provides smooth rotation and high load support for rotating railway tracks or vehicles.

Aerial Work Platform (AWP): A slewing mechanism used on an aerial work platform or boom lift to ensure smooth rotation of the lifting arm.

Military and aerospace applications: In military vehicles and aerospace equipment, three-row cylindrical roller slewing bearings are able to support high axial and radial loads, so they can be used in turrets, radar systems, and other rotating mechanisms.

Robotic Arms: In industrial robots, especially those used for heavy material handling, these bearings are used to provide smooth and precise movement of the arm joints under heavy loads.

What is the difference between a three-row cylindrical roller slewing ring and a double-row cylindrical roller slewing ring?

The core differences between three-row cylindrical roller and double-row cylindrical roller slewing bearings are reflected in the structural design, bearing performance and applicable scenarios. From the structural point of view, the three rows adopt three independent raceways, the middle row vertically bears the axial force and overturning moment, and the rollers inclined at 45° on both sides share the two-way radial force, requiring three independent seat rings and high-strength cages; The double row is mostly two rows of rollers sharing the seat ring, the cylindrical rollers are arranged in parallel to mainly bear the radial load, and some of them have unidirectional axial load capacity through the flange design.

In terms of bearing performance, due to the three-dimensional force distribution, the composite bearing capacity of the three-row structure is increased by 30%-50% and the rigidity is increased by 2-3 times, which can adapt to high-speed operation above 100rpm, and the vibration and noise control is better. For example, a 310 series three-row bearing with an outer diameter of 2500mm has an axial load of 8MN, a radial load of 6MN, and an overturning moment of 12MN・m. The two-row model NN3040 can only withstand a radial force of 3.2MN and has no axial load capacity.

In terms of application scenarios, the three trains are mostly used for heavy equipment that needs to be compounded such as wind power (3-5MW wind turbines), port machinery (250t cranes) and shield machines, with a service life of up to 15-20 years; The double row is more suitable for small and medium-sized machinery with radial load, such as 50t gantry cranes, agricultural machinery, etc., and the cost is 20%-30% lower than that of the three rows, but the maintenance frequency is higher. When selecting the model, it is necessary to consider the load characteristics, accuracy requirements and budget of the equipment, and it is recommended to verify the finite element analysis for complex working conditions.

In terms of manufacturing process and accuracy, the three-row bearing has higher requirements for machining accuracy due to the multi-raceway structure, so it is necessary to use a CNC grinding machine to ensure the coaxiality and surface roughness of the three raceways (Ra≤0.4μm), and the heat treatment process needs to take into account the hardness matching of rollers and housing rings (HRC58-62). The manufacturing tolerances of the double row bearings are relatively loose, and the raceway parallelism error is more allowable, which is suitable for scenarios with moderate precision requirements.

In terms of lubrication and sealing, due to the concentrated contact stress between the rollers and the raceway, the three-row bearing needs to adopt a high-pressure lubrication system (pressure ≥10MPa), with lithium grease or synthetic oil to achieve circulating lubrication, and the sealing structure mostly adopts double-lip contact sealing rings, and the protection level can reach IP67. Double row bearings are usually lubricated with ordinary grease, and the open design has a high percentage, and regular grease is required for maintenance.

Supplier of three-row cylindrical roller slewing rings

LTZC Bearings is a professional manufacturer of slewing bearings, slewing rings, slewing drives, and bearing components, providing high-quality and advanced solutions to customers worldwide. If you are seeking three-row cylindrical roller slewing bearings for your project, please feel free to contact us.