Products
Four Point Contact Bearings
Product Overview
Four-Point Contact Ball Bearings are single-row angular contact ball bearings featuring specially designed raceways that enable each ball to establish four contact points under axial loading. This unique design allows a single bearing to support combined radial loads, bidirectional axial loads, and overturning moments simultaneously, providing a compact alternative to matched pairs of angular contact ball bearings while reducing axial installation space.
Available in QJ2 and QJ3 series, Four-Point Contact Ball Bearings are offered in a wide range of sizes and precision classes from P0 to P4/P2, meeting the requirements of both general industrial machinery and high-precision applications. Most designs feature a split inner ring for easy assembly and optimized load distribution.
Supplied primarily in open designs with steel, polyamide, or machined brass cages, Four-Point Contact Ball Bearings deliver excellent positioning accuracy, high rigidity, and reliable performance in applications such as machine tools, industrial gearboxes, robotics, pumps, and precision rotating equipment.
Technical Specifications
| Series | QJ2, QJ3 Series |
| Bore Diameter Range | 10mm – 500mm |
| Outer Diameter Range | 30mm – 870mm |
| Width Range | 9mm – 200mm |
| Cage Material Options | Steel stamped, machined brass, polyamide PA66 |
| Ring Structure Options | Split inner ring (full complement), one-piece ring with cage |
| Precision Grades | P0 standard, P6 high precision |
| Radial Clearance | CN normal, C3, C4 increased |
| Material Standard | Gcr15 / 52100 chrome steel, stainless steel SS440 |
| Temperature Range | -30°C to +150°C standard, up to +200°C high temperature |
| Lubrication | Grease standard, oil optional |
| Standards Met | ISO 9001, ISO 15, DIN 628 |
Key Features
- Bidirectional axial and moment load capacity in a single row – eliminates the need for paired bearing arrangements in many applications, reducing axial installation space
- Compact axial footprint – supports combined loading within a single-row width, comparable to or narrower than paired angular contact configurations
- Split-ring design options – allows full-complement ball loading for higher capacity, or caged designs for higher speed operation
- High rigidity under combined loading – well-suited for applications involving simultaneous radial, axial, and tilting moment loads
- Compatible with grease and oil lubrication, suitable for standard industrial and precision rotary applications
- Compliant with relevant ISO and DIN dimensional standards for slewing and four-point contact bearing series
Applications
Four Point Contact Bearings are widely used in robotics and rotary table applications, where compact axial space combined with the need to resist tilting moments makes this bearing type particularly effective.
In construction and material handling equipment, including crane slewing rings and excavator turntables, the series supports the combined radial, axial, and moment loading generated during rotation and load handling.
In machine tool rotary axes and indexing tables, Four Point Contact Bearings provide the rigidity and moment resistance required for precise rotational positioning under varying load conditions.
The series is also applied in medical imaging equipment, packaging machinery, and other rotary platforms, wherever combined load support within a compact single-row envelope is required.
Technical Resources
Whether you are an engineer, procurement manager, or equipment maintenance professional, here you will find in-depth content covering bearing operating principles, technical parameter interpretation, industry application analysis, and selection logic — helping you build a comprehensive understanding of bearing products and make more informed decisions in real-world applications.
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FAQs
What loads can deep groove ball bearings handle?
Deep groove ball bearings are primarily designed for radial loads, but they can also handle moderate axial (thrust) loads in both directions. They are not suitable for heavy axial loads or combined shock loads. In those cases, angular contact or tapered roller bearings are preferred.
How do I select the right bearing size for my application?
Selection should be based on bore diameter (shaft size), required load capacity (dynamic rating C and static rating C0), operating speed compared with the bearing limiting speed, available space (outer diameter and width), and required precision grade from P0 to P2. Always apply a safety factor and verify that the calculated L10 service life meets your requirements.
What is the difference between open, shielded (ZZ), and sealed (2RS) bearings?
Open: No built-in protection, requires external sealing, and is suitable for clean environments or oil bath lubrication.
ZZ metal shields: Protect against dust and debris with low friction, making them suitable for high-speed applications, but they are not waterproof.
2RS rubber seals: Provide strong protection against dust and moisture. They are pre-greased and ideal for contaminated environments, but generate slightly more friction.
How often should I lubricate or replace the grease?
For general industrial use, grease should be replenished or replaced every 3,000 to 10,000 operating hours depending on speed, temperature, and environmental conditions. Bearings running above 70 C or in contaminated environments require shorter intervals. Sealed 2RS bearings are pre-greased for life and do not require re-lubrication.
What are the common causes of premature bearing failure?
The most frequent causes include inadequate or improper lubrication, contamination by dirt, dust, or moisture, incorrect installation, misalignment, excessive force during fitting, overloading beyond the rated capacity, improper shaft or housing fits, and fatigue at the end of normal service life.
How is the rated service life (L10) of a bearing calculated?
The basic L10 life is calculated as L10 = (C / P)^3 x 10^6 revolutions, where C is the dynamic load rating in kN and P is the equivalent dynamic bearing load in kN. It represents the number of revolutions that 90% of identical bearings will complete without fatigue failure. In practice, ISO 281 modified life calculations also apply correction factors for lubrication, contamination, material, and reliability.
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