Thin Section Four-Point Contact Ball Bearings
Type X Bearings for Radial, Bidirectional Axial and Moment LoadsBearing Type: Type X thin-section four-point contact ball bearing
Contact Geometry: Gothic-arch raceways with four potential contact points
Contact Angle: Dual load paths of approximately 30°
Model Family: HK-prefix open models and HJ-prefix sealed models
Open Series: KAA, KA, KB, KC, KD, KF and KG.
Sealed Series: JHA, JA, JB, JU and JG.
Technical Specifications
| Specification | Details |
|---|---|
| Bearing Type | Type X thin-section four-point contact ball bearing |
| Contact Geometry | Gothic-arch raceways with four potential contact points |
| Contact Angle | Dual load paths of approximately 30° |
| Cross-Section | Fixed cross-section within each series |
| Model Family | HK-prefix open models and HJ-prefix sealed models |
| Open Series | KAA, KA, KB, KC, KD, KF and KG |
| Sealed Series | JHA, JA, JB, JU and JG |
| Loads | Radial, bidirectional axial and moment loads |
| Materials | Bearing steel or stainless-steel rings; steel, stainless-steel or ceramic balls |
| Precision | P0 and P4 precision classes |
| Catalog Temperature | −50°C to +100°C; final limit depends on cage, seals and lubrication |
Thin Section Four-Point Contact Ball Bearings
Type X thin-section four-point contact ball bearings use gothic-arch raceways with two curvature centers on each side of the ball. This geometry creates four potential contact points, allowing one compact bearing to support radial, bidirectional axial and moment loads.
Under axial load in one direction, one diagonal pair of contact points carries the load along an approximately 30° path while the opposite pair is unloaded. Reversing the axial load transfers the load to the other diagonal pair, enabling stable two-direction thrust support.
Combined Load and Moment Capacity
The Type X raceway performs similarly to a back-to-back pair of angular-contact bearings while occupying the axial space of a single bearing. It is well suited to compact mechanisms that must carry reversing thrust and overturning moment.
- One bearing supports radial and bidirectional axial loads
- Moment-load capability in a compact cross-section
- Approximately 30° diagonal load paths
- Open and sealed configurations
Raceway, Clearance and Speed
Correct internal clearance and mounting rigidity are essential for smooth running and accurate positioning. At higher speed, suitable clearance and preload should maintain the intended two-point load path. Filling-slot versions can increase ball count, but the interrupted raceway may reduce load rating and allowable speed.
- Control clearance to avoid unintended four-point contact at speed
- Select lubrication for combined-load service
- Use sealed versions where contamination control is required
HK-prefix open models and HJ-prefix sealed models
Technical Specifications
| Model Family | Configuration | Selection |
|---|---|---|
| HK Prefix Models | Open: KAA, KA, KB, KC, KD, KF, KG | Cross-sections from 3/16 × 3/16 in to 1 × 1 in |
| HJ Prefix Models | Sealed: JHA, JA, JB, JU, JG | Protected cross-sections from 3/16 × 1/4 in to 1 × 1 in |
Performance Characteristics
The equal-section design reduces radial space and weight while retaining combined-load capability. Open HK-prefix models suit controlled environments and replenishable lubrication; sealed HJ-prefix models provide added protection where cleanliness is harder to maintain.
Model selection should consider cross-section, precision class, seal arrangement, working clearance, speed and the balance of radial, axial and moment loads.
Typical Applications
- Robot joints and articulated arms
- Radar and antenna positioning systems
- Precision turntables and rotary platforms
- Medical imaging and treatment equipment
- Aerospace gimbals and turrets
- Packaging, inspection and automation machinery
Available Models & Specifications
Click on any part number to view detailed CAD drawings and download PDF specifications.
