Oldham couplings (also known as cross slider couplings or sliding disc couplings) are essential for precision power transmission in applications requiring zero backlash, low inertia, and high parallel misalignment compensation. With a simple three-component design – two aluminum hubs and a center slider – they offer an excellent balance of performance, reliability, and ease of maintenance.

This guide explains how Oldham couplings work, why they are ideal for servo motors and encoders, and how to select the right DGHC model for your application.

1. What Is an Oldham Coupling?

An Oldham coupling consists of:

• Two hubs – typically aluminum alloy, with axial grooves on their inner faces

• A center slider – engineering plastic (PA66) with matching slots at 90° on each side

As the coupling rotates, the center slider slides within the grooves of the hubs, accommodating radial (eccentricity) and angular misalignment while transmitting torque. The clamping screw design provides even clamping force without damaging shafts.

2. Key Advantages of Oldham Couplings

3. Why Oldham Couplings Are Ideal for Servo Motors

Oldham couplings are commonly used in servo-driven systems that require precise motion control and a low inertia, balanced design:

• Zero backlash – Ensures accurate positioning for servo motors

• Low inertia – Enables rapid acceleration and deceleration

• High misalignment capacity – Accommodates installation errors without stressing servo bearings

• Electrical isolation – Prevents ground loops that can corrupt encoder signals

• Vibration absorption – Reduces vibration transmission to sensitive components

✅ Oldham couplings are widely used in digital servo equipment, robots, XY tables, and measuring instruments.

4. Single vs Double Disk – Why Oldham Design Wins for Misalignment

Oldham couplings offer distinct advantages over other coupling types:

Key takeaway: Oldham couplings offer the best combination of zero backlash, high parallel misalignment capacity, and electrical isolation – making them the preferred choice for servo motors, encoders, and precision motion control systems.

5. Material Selection – Aluminum Hubs + PA66 Slider

✅ The combination of aluminum hubs and PA66 slider provides the perfect balance of strength, low inertia, and long service life for precision motion control applications.

6. Short Clamping Design – Low Inertia Advantage

The DGHC series features a short clamping design that provides:

• Low moment of inertia – Enables rapid acceleration and deceleration

• Compact length – Saves space in tight installations

• Clamping screw fastening – Secure shaft connection, easy installation, no shaft damage

7. Zero Backlash – Why It Matters for Servo Motors

Backlash (rotational clearance) in a coupling causes:

• Position errors – Inaccurate feedback in servo systems

• Reduced accuracy – Poor system performance

• Control instability – Oscillations in motion control

• Reduced repeatability – Inconsistent positioning

✅ A zero backlash coupling like the DGHC series ensures accurate positioning – every time.

8. Applications Where Oldham Couplings Excel

9. Real‑World Example – Servo Motor Encoder Upgrade

A machine builder was experiencing position errors on a servo-driven indexing table. The encoder coupling had measurable backlash, causing the encoder to report incorrect positions.

They switched to Apex Coupling DGHC aluminum Oldham coupling (zero backlash, PA66 slider, clamping design). Results:

• Position errors eliminated – zero backlash

• Encoder accuracy improved – precise position feedback

• Electrical isolation – PA66 slider prevented ground loops

• Maintenance eliminated – no lubrication required

• Easy installation – clamping screw design

10. Installation & Maintenance Tips

1. Clean shafts and bores – Remove oil, grease, and debris

2. Check alignment – Even with misalignment compensation, keep within recommended limits

3. Tighten clamping screws evenly – Use a torque wrench in a star pattern – provides even clamping force without shaft damage

4. No lubrication required – PA66 slider is self-lubricating

5. Inspect slider periodically – Replace if worn or damaged

6. Detachable design – Replace slider without moving hubs

11. Selection Checklist

• Type: DGHC (Oldham) – zero backlash, high parallel misalignment capacity

• Bore size: 4–38mm – match your shaft diameters

• Torque: 0.7–56 N·m – select based on your requirement

• Speed: 0–9000 RPM – match your motor speed

• Material: Aluminum hubs + PA66 slider – lightweight, corrosion-resistant, electrically insulating

• Fastening: Clamping screw – no shaft damage, even clamping force

• Application: Servo motors, stepper motors, encoders, XY tables, robotics

12. Conclusion

The DGHC aluminum alloy Oldham coupling from Apex Coupling offers the perfect combination of zero backlash, low inertia, high parallel misalignment capacity, and electrical isolation for servo motor, stepper motor, and encoder applications. With aluminum alloy hubs, imported PA66 slider, short clamping design, and 11 models covering 4–38mm bores, it is the ideal solution for precision motion control systems.

👉 Need an Oldham coupling for your servo motor or encoder? Contact us with your bore size, torque, and speed requirements.