Double Row 8 Point Contact Ball Slew Bearings Essential Component for Heavy Duty Rotation

Double Row 8 Point Contact Ball Slew Bearings Essential Component for Heavy Duty Rotation

What is Double Row 8 Point Contact Ball Slew Bearings

Double Row 8 Point Contact Ball Slew Bearings are complex mechanical assemblies comprising an inner ring an outer ring two rows of rolling elements steel balls separators or cages and sealing systems. The raceways are typically designed with a Gothic arch (peach shaped groove) profile. These raceways undergo surface hardening via intermediate frequency induction hardening achieving a surface hardness of HRC 55-60 and a hardened case depth of 3-5 mm. Crucially each single raceway contacts its corresponding row of balls at four distinct points resulting in a total of eight contact points for the entire bearing under combined loading. The curvature radii of the raceways are meticulously calculated to ensure smooth rolling motion of the balls minimizing rolling resistance and subsequent energy loss. Both the inner and outer rings feature multiple mounting holes for secure fixation to machinery structures. The balls are guided and spaced by cages or spacers ensuring controlled rotation between the rings.

The Critical Importance of Angular Separation Between Two Raceways

A fundamental design feature governing the performance of Double Row 8 Point Contact Ball Slew Bearings is the precise angular separation between the two raceways. This angular offset is not arbitrary; it is a critical parameter meticulously engineered based on the intended load case – specifically the expected magnitude and direction of the dominant tilting moment the bearing must withstand. Correct angular separation ensures optimal load distribution across all eight contact points under the design load conditions. This optimization prevents localized stress concentrations that could lead to premature wear spalling or catastrophic failure. It directly influences bearing life stability under load and overall structural integrity. Precise machining and strict quality control during manufacturing are paramount to achieving and maintaining the specified angular separation guaranteeing the bearing performs as intended throughout its service life.

Energy Efficiency of Double Row 8 Point Contact Ball Slew Bearings

The Double Row 8 Point Contact Ball Slew Bearing design inherently promotes favorable energy consumption characteristics compared to alternative slew bearing types particularly under complex loading scenarios. The optimized Gothic arch raceway profile combined with the precise calculation of curvature radii minimizes friction during ball rolling. The eight point contact configuration efficiently distributes loads reducing slippage and sliding friction within the bearing under combined axial radial and moment loads. Furthermore the hardened raceway surfaces significantly reduce wear maintaining low friction characteristics over a longer operational lifespan. While starting torque can be marginally higher due to the multiple contact points the steady state running torque is typically very efficient. This translates to lower power requirements for the drive system motors over prolonged operation contributing to overall machine energy efficiency and reduced operational costs. The robust construction also minimizes energy losses associated with bearing deflection under heavy loads.

Distinctive Features of Double Row 8 Point Contact Ball Slew Bearings

These bearings possess several defining characteristics that set them apart

Exceptional Load Capacity: The double row design and eight point contact enable them to handle significantly higher axial loads radial loads and tilting moments simultaneously compared to single row four point contact bearings offering up to 70-80% higher capacity for the same installation dimensions.

High Rigidity and Stability: The dual load paths and optimized contact geometry provide superior rigidity minimizing deflection under heavy or uneven loads ensuring precise positioning and smooth operation.

Enhanced Safety Factor: The inherent redundancy of two rows and robust construction typically allows for a higher safety margin in critical applications.

Optimized Raceway Design: The Gothic arch profile and precise hardening ensure smooth rolling low friction and extended service life.

Versatile Configuration: Available in three primary variants to suit different drive mechanisms: without gear external gear (teeth on the outer ring) or internal gear (teeth on the inner ring).

Robust Construction: Manufactured from high quality alloy steels with hardened raceways and often utilizing sturdy cages or spacers.

Gear Options: Gear teeth can be hardened using various methods (scan hardening tooth flank and root hardening increased core hardness) tailored to application demands. Different pinion gears can be matched depending on torque requirements and operating conditions.

Primary Applications of Double Row 8 Point Contact Ball Slew Bearings

The superior load handling capacity and rigidity make these bearings indispensable in numerous heavy industries

Cranes: Tower cranes mobile cranes crawler cranes and offshore cranes slewing superstructures and boom bases.

Excavators: Heavy duty mining excavators and large hydraulic excavators for upper structure rotation.

Construction Machinery: Piling rigs drill rigs concrete pump booms and heavy lift equipment.

Mining Equipment: Bucket wheel excavators stackers reclaimers and material handling systems.

Wind Turbines: Yaw drives controlling nacelle orientation (often utilizing large diameter variants).

Industrial Robots and Positioners: Heavy duty robotic arms and welding positioners requiring high precision under load.

Radar and Satellite Antennas: Supporting and rotating large antenna structures.

Port Equipment: Ship loaders/unloaders and heavy duty container handling cranes.

Any Machinery: Requiring robust reliable rotation under significant combined loads and tilting moments.

Factors Influencing the Price of Double Row 8 Point Contact Ball Slew Bearings

The cost of these sophisticated components is influenced by numerous variables

Size and Dimensions: Larger diameter bearings require significantly more material and complex machining driving costs up substantially.

Material Quality: The grade and quality of the alloy steel used for rings balls and gears directly impact cost and performance.

Manufacturing Complexity: Precision machining of raceways gears mounting holes and achieving critical tolerances (like angular separation) requires advanced equipment and skilled labor. Gear hardening methods add complexity.

Gear Configuration: Bearings with external or internal gears are more complex and costly than ungrooved versions. Gear size module and hardening process affect price.

Heat Treatment: Intermediate frequency hardening depth consistency and quality control add significant cost. Special hardening for gears further increases it.

Precision Requirements: Tighter tolerances for raceway geometry roundness and gear accuracy demand more meticulous manufacturing increasing cost.

Sealing Systems: The type quality and quantity of seals needed for the operating environment (standard dust seals vs heavy duty or labyrinth seals) affect price.

Cage/Separator Type: Material and design of the ball cage or spacer (e.g., polyamide vs brass vs steel) influence cost.

Bearing Design Loads: Bearings engineered for higher dynamic and static load ratings require more robust designs and potentially higher quality materials.

Quantity: Economies of scale apply; larger order quantities typically reduce the unit cost.

Brand and Supplier: Reputable manufacturers with proven quality and reliability often command premium pricing.

Raw Material Market Fluctuations: Costs for steel alloys and heat treatment energy can vary.

Customization: Nonstandard sizes designs or special features (like unusual mounting holes or special coatings) significantly increase cost compared to catalog items.

Supplier of Double Row 8 Point Contact Ball Slew Bearings

LYRADRIVE stands as a prominent global manufacturer and supplier specializing in high performance slewing bearings including an extensive range of Double Row 8 Point Contact Ball Slew Bearings. Catering to the rigorous demands of industries like construction mining and heavy machinery LYRADRIVE leverages advanced manufacturing capabilities and stringent quality control processes adhering to international standards like ISO. They offer comprehensive solutions encompassing standard catalog bearings and custom engineered designs tailored to specific application requirements. LYRADRIVE provides bearings in all configurations – without gear external gear and internal gear – featuring precise raceway hardening optimized gear treatments and robust sealing options. Their focus on engineering excellence reliability and timely delivery makes them a trusted partner for critical rotation solutions worldwide.