Small cross universal joints (cardan joints) are essential for transmitting power between shafts that are not perfectly aligned. The WX/WXD series offers both single and double joint configurations, covering a torque range of 11.2 to 1120 N·m with angular capacity up to 45° per joint. Available in 40Cr alloy steel or 304/316 stainless steel with pin/block or needle roller bearings, this series provides maximum flexibility for a wide range of applications.

This guide explains the key differences between WX and WXD, how to select the right bearing type, and how to choose the optimal material for your application.

1. Single Joint (WXD) vs Double Joint (WX) – Which One Do You Need?

Rule of thumb:

• Use WXD (single joint) for applications with constant angular misalignment where speed fluctuation is acceptable.

• Use WX (double joint) for applications requiring parallel offset compensation or synchronous rotation between the driving and driven shafts.

💡 For synchronous rotation: When using a double joint (WX), ensure the following three conditions are met: (a) the angles between the intermediate shaft and the driving/driven shafts are equal; (b) the yoke planes at both ends of the intermediate shaft are aligned; and (c) the intermediate shaft and the driving/driven shafts are in the same plane .

2. Operating Angle – 30° Working vs 45° Limit

The WX/WXD series is designed for smooth operation up to 30° in continuous use. The absolute limit per joint is 45° .

Practical tip: For most applications, try to keep operating angles below 30° for continuous operation to maximize service life .

3. Bearing Selection – Pin/Block vs Needle Roller

The WX/WXD series offers two bearing options:

Recommendation:

• Choose pin/block bearing for heavy-duty, low-speed applications with shock loads.

• Choose needle roller bearing for high-speed applications (above 1000 RPM) where precision and low friction are priorities.

⚠️ Note: It is recommended to use the coupling at ≤50% of the maximum rated speed for optimal service life .

4. Material Selection – 40Cr Alloy Steel vs 304/316 Stainless Steel

Our recommendation:

• Choose 40Cr alloy steel for most industrial applications requiring high strength and durability .

• Choose 304/316 stainless steel for food & beverage, chemical, marine, or outdoor applications where corrosion resistance is critical .

5. Surface Finish Options – Protection & Appearance

6. Applications Where WX/WXD Couplings Excel

7. Real‑World Example – Woodworking Multi-Spindle Drill Upgrade

A woodworking equipment manufacturer was experiencing premature wear on standard universal joints used in multi-spindle drilling machines. The joints operated at 28° angles and 1200 RPM, causing frequent failures.

They switched to Apex Coupling WXD single universal joints (40Cr alloy steel, needle roller bearing, H7 bore, keyway). Results:

• Service life extended – needle roller bearing handled 1200 RPM smoothly

• Angle capacity – 28° well within the 30° recommended range

• Vibration reduced – H7 bore improved concentricity

• Less downtime – fewer replacements during production

8. Installation & Maintenance Tips

1. Check alignment – Keep operating angles ≤30° for continuous operation 

2. Lubricate pin/block bearings – Regular lubrication extends service life

3. Needle roller bearings – Sealed, low maintenance – inspect periodically

4. Check for wear – Inspect cross shaft and bearings periodically

5. Dynamic balancing – For speeds above 1000 RPM, ensure the joint is balanced

6. Bore fit – Use H7 shaft tolerance for best concentricity

7. Speed recommendation – Use at ≤50% of maximum rated speed for optimal life 

8. For synchronous rotation (WX) – Ensure equal angles and aligned yokes 

9. Selection Checklist

• Configuration: WXD (single) or WX (double)

• Bearing: Pin/block (1000 RPM) or Needle roller (4000 RPM) 

• Material: 40Cr alloy steel (standard) or 304/316 stainless steel 

• Finish: Black oxide, natural, nickel, chrome, or sandblasted 

• Torque: 11.2–1120 N·m – select based on your requirement 

• Angle: Up to 45° – keep ≤30° for continuous use 

• Bore type: Keyway, hexagon, square, or plain 

• Bore tolerance: H7 for precision shaft fit 

• Synchronous rotation: Required? → Choose WX double joint 

10. Conclusion

The WX/WXD small cross universal joint coupling from Apex Coupling offers the perfect combination of strength, flexibility, and precision for light to medium-duty industrial applications. With 11.2–1120 N·m torque capacity, 45° angular flexibility, H7 bore precision, multiple material options, and two bearing options, it is the ideal solution for packaging machinery, woodworking equipment, multi-spindle drills, metallurgy, and general industrial drives.

👉 Need a universal joint for your application? Contact us with your configuration, torque, speed, material, and bore requirements.