DB Aluminum Alloy 8-Shaped Double Loop Flexible Coupling – Encoder Series, Zero Backlash, PU Elastomer

Factory direct | High-strength aluminum alloy hubs | Polyurethane elastomer | Oil & oxidation resistant | Zero backlash | 3000 RPM | 3–13mm bore range | Set screw fastening | OEM customization

The Apexcoupling DB series is an 8-shaped (figure-8) double loop flexible coupling specifically engineered for encoder applications. Featuring high-strength aluminum alloy hubs and a polyurethane (PU) elastomer element, this coupling delivers excellent flexibility, zero backlash, and reliable torque transmission. The unique double loop (8-shaped) design provides exceptional flexibility while resisting twisting or breaking, making it ideal for connecting encoders to motors, servo systems, stepper motors, and precision positioning equipment. The PU elastomer offers outstanding oil resistance and oxidation resistance, ensuring long service life in demanding industrial environments.

✅ Specifically designed for encoders – zero backlash, high flexibility, oil & oxidation resistant, easy installation.

Key Technical Specifications

🔧 Custom bores, outer diameters, and special elastomer materials available. Contact us with your specifications.

Product Structure

1. Two Aluminum Hubs – High-strength aluminum alloy, anodized finish, precision-machined with set screw holes.

2. 8-Shaped Double Loop Elastomer – Polyurethane (PU) element in a figure-8 configuration, providing flexibility and misalignment compensation.

3. Set Screws – Secure shaft fastening (socket head cap screws).

💡 How it works: The unique 8-shaped (double loop) design allows the coupling to flex in multiple directions while maintaining torsional stiffness. This provides excellent compensation for angular, radial, and axial misalignment without imposing excessive stress on the encoder or motor shafts. The PU elastomer’s oil and oxidation resistance ensures reliable performance even in harsh environments.

Product Features & Advantages

Why Encoders Need Specialized Couplings

Encoders require high-precision couplings to ensure accurate position feedback. Key requirements include:

• Zero backlash – No lost motion between motor and encoder

• Low inertia – Minimizes loading on the encoder

• Misalignment compensation – Protects encoder bearings from stress

• Electrical isolation – Prevents ground loops (PU elastomer provides insulation)

• Reliability – Long service life without maintenance

✅ The DB series meets all these requirements – making it the ideal choice for encoder applications.

Applications

• Encoders – Rotary encoders, absolute encoders, incremental encoders

• Servo Motors – Precision motion control systems

• Stepper Motors – Accurate positioning applications

• 3D Printers – Precision filament drive and positioning

• CNC Machines – Position feedback systems

• Packaging Machinery – Registration and indexing systems

• Printing Equipment – Register control

• Textile Machinery – Precision drives

• Medical Devices – Precision motion systems

• Automation Equipment – Pick-and-place systems, robotics

• Food & Beverage Processing – Hygienic, reliable drives

• Linear Screw Modules – Precision linear motion systems

Why Choose Apex Coupling for DB Encoder Couplings?

FAQ

Q: What is an 8-shaped double loop coupling?
A: An 8-shaped double loop coupling (also called a figure-8 coupling) features two aluminum hubs connected by a polyurethane elastomer element shaped like a figure-8. This design provides exceptional flexibility for misalignment compensation while maintaining torsional stiffness.

Q: Why is this coupling specifically designed for encoders?
A: Encoders require zero backlash for accurate position feedback, low inertia to minimize loading, and misalignment compensation to protect encoder bearings. The DB series is engineered to meet all these requirements.

Q: What materials are used?
A: The hubs are made of high-strength aluminum alloy with an anodized finish. The elastomer element is made of polyurethane (PU) – offering excellent oil resistance, oxidation resistance, and flexibility.

Q: What is the bore diameter range?
A: Standard bore diameters include 3mm, 4mm, 5mm, 6mm, 6.35mm (1/4″), 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, and 13mm. Custom bores are available on request.

Q: What is the torque and speed rating?
A: Rated torque ranges from 0.15 N·m to 1.3 N·m depending on the model. Maximum speed is 3000 RPM (8000 RPM available for select models).

Q: Does the coupling have backlash?
A: No. The DB series features zero backlash – no rotational clearance, ensuring accurate position feedback for encoders.

Q: Can the coupling compensate for misalignment?
A: Yes. The 8-shaped double loop design compensates for angular, radial, and axial misalignment.

Q: What is the operating temperature range?
A: The working temperature range is -20°C to +80°C.

Q: Is the coupling oil-resistant?
A: Yes. The PU elastomer is oil-resistant and oxidation-resistant – suitable for demanding industrial environments.

Q: Can I get a custom coupling?
A: Yes. We offer OEM customization – custom bores, outer diameters, and elastomer materials available.

Request a Quote

Send us your bore size, torque, speed, and application details. Our engineers will recommend the optimal model and provide a quotation within 24 hours.