DBN56 Double Diaphragm Keyway Coupling – High Torque, Zero Backlash for Servo Motors

Factory direct | 45# high-quality round steel | 304 stainless steel dual diaphragm | Keyway connection | 420 N·m torque | 15000 RPM | H7 bore precision | Zero backlash | High sensitivity | OEM custom

The Apexcoupling DBN56 series is a high-performance double diaphragm keyway coupling specifically engineered for servo motor and stepper motor applications. Featuring 45# high-quality round steel hubs with keyway connection and a 304 stainless steel dual diaphragm, this coupling delivers exceptional torque capacity, high torsional rigidity, and zero backlash operation. The double diaphragm design provides superior compensation for radial, angular, and axial misalignment, while the keyway connection ensures secure, positive torque transmission. With H7 bore precision, high sensitivity, and identical clockwise and counterclockwise rotation characteristics, the DBN56 series is the ideal solution for CNC machine tools, machining centers, robotics, and precision automation equipment requiring reliable, maintenance-free power transmission.

✅ Zero backlash, high sensitivity, and large torque transmission – commonly used in servo motors, stepper motors, and precision motion control systems.

Key Technical Specifications

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

DBL56 Series – Model Range

📐 Non-standard lengths and outer diameters available upon request. Contact our engineering team for custom sizing.

Product Structure

1. Two 45# Steel Hubs – High-quality round steel, precision-machined with keyways, black oxide finish.

2. 304 Stainless Steel Dual Diaphragm – Two layers of stainless steel diaphragm connected by a center spacer – provides superior misalignment compensation.

3. Keyway Connection – Secure positive drive – transmits large torque without slipping.

💡 How it works: The double diaphragm coupling consists of two hubs connected by two stainless steel diaphragms with a center spacer. Torque is transmitted through the diaphragms, which flex to accommodate radial, angular, and axial misalignment. The keyway connection provides a secure, positive drive for high-torque applications. The double diaphragm design offers superior compensation for radial, angular, and axial deviations compared to single diaphragm designs.

Single Diaphragm vs Double Diaphragm – Key Differences

✅ Double diaphragm (DBN56) is the superior choice for applications requiring comprehensive misalignment compensation – ideal for servo motors, stepper motors, and precision motion control systems.

Product Features & Advantages

Why Double Diaphragm Couplings Are Ideal for Servo Motors

Double diaphragm couplings are specifically designed for servo motor applications due to their unique characteristics:

✅ The DBN56 series is specifically designed for servo motors and stepper motors – providing the high torque rigidity, zero backlash, and misalignment compensation required for demanding motion control applications.

Applications

• Servo Motors – High-precision motion control, zero backlash requirement

• Stepper Motors – Accurate positioning, no lost motion

• CNC Machine Tools – Spindle drives, feed axes, high-precision positioning

• Machining Centers – High-speed, high-accuracy drives

• Robotics – Joint drives, precision motion

• Packaging Machinery – Registration and indexing systems

• Printing Equipment – Register control, high-speed operation

• Semiconductor Equipment – Clean room compatible, high precision

• Medical Devices – Precision motion systems

• Automation Equipment – Pick-and-place systems, indexing tables

Why Choose Apex Coupling for DBN56 Double Diaphragm Couplings?

FAQ

Q: What is a double diaphragm coupling?
A: A double diaphragm coupling consists of two hubs connected by two stainless steel diaphragms with a center spacer. It transmits torque through the diaphragms while compensating for radial, angular, and axial misalignment. The double diaphragm design offers superior misalignment compensation compared to single diaphragm designs.

Q: What is the advantage of the keyway connection?
A: The keyway connection provides a secure, positive drive – ensuring reliable torque transmission without slipping, even under high loads.

Q: What materials are used?
A: The hubs are made of 45# high-quality round steel with black oxide finish. The diaphragms are made of 304 stainless steel – offering excellent corrosion resistance, fatigue resistance, and long service life.

Q: What is the torque and speed rating?
A: Rated torque is 420 N·m and maximum speed is 15000 RPM.

Q: What is the difference between single and double diaphragm?
A: A single diaphragm coupling compensates for angular and axial misalignment but cannot accommodate radial misalignment. A double diaphragm coupling compensates for radial, angular, and axial misalignment – providing superior compensation for demanding applications.

Q: Does the coupling have backlash?
A: No. The DBN56 series features zero backlash – no rotational clearance, ensuring precise positioning for servo and stepper motors.

Q: What are the rotation characteristics?
A: Clockwise and counterclockwise rotation characteristics are exactly the same.

Q: Is the coupling maintenance-free?
A: Yes. No lubrication required – reduces operating costs and maintenance schedules.

Q: What models are available?
A: The DBL56 series includes D56, D68, D82, D94, D104, D126, D144, D152, D178, and D190 – covering outer diameters from 56mm to 190mm.

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

Request a Quote

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