DLT Step Double Diaphragm Coupling | Zero Backlash, 2-90 N·m, 10000 RPM

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DLT Aluminum Step Double Diaphragm Coupling – Zero Backlash for Servo & Stepper Motors

Model Number
Check below, custom

DLT-34×37.5
DLT-39×48
DLT-44×48
DLT-56×61
DLT-68×74
DLT-82×98

Product Description

DLT Aluminum Step Double Diaphragm Coupling – Zero Backhaul for Servo & Stepper Motors

The Apexcoupling DLT series is a high-precision aluminum double diaphragm coupling featuring a unique step (stepped) design that provides enhanced stress distribution and extended service life. Engineered for demanding motion control applications, this coupling delivers zero backlash torque transmission with high torsional rigidity and excellent misalignment compensation. The double diaphragm design provides superior compensation for angular, radial, and axial misalignment, while the step design creates additional space for the diaphragm to flex, dispersing concentrated stress and延缓 fatigue crack propagation. With clamping screw fastening, H7 precision bore, and maintenance-free operation, the DLT series is the ideal solution for servo motors, stepper motors, encoders, lead screws, and precision automation equipment.

✅ Zero backlash – no lost motion for precise positioning. Step (stepped) design – enhanced stress distribution and longer service life. Double 304 stainless steel diaphragm – superior misalignment compensation and fatigue resistance. Low inertia – ideal for high-speed operation up to 10000 RPM. Maintenance-free – no lubrication required. Specifically designed for servo and stepper motors.

Key Technical Specifications

Parameter	Value
Brand	Apexcoupling
Model Series	DLT (Step Double Diaphragm Coupling)
Type	Flexible / Disc / Diaphragm
Structure	Double diaphragm with step (stepped) design
Body Material	High-strength aluminum alloy
Diaphragm Material	304 stainless steel – excellent fatigue resistance
Surface Treatment	Anodized
Design	Two aluminum hubs + double 304 stainless steel diaphragms with step configuration
Backlash	Zero – no rotational clearance
Bore Tolerance	H7
Bore Diameter Range	6 – 30 mm (custom available)
Outer Diameter Range	34 – 82 mm
Length Range	37.5 – 98 mm
Rated Torque	2 – 90 N·m
Maximum Speed	8000 – 10000 RPM (varies by model)
Allowable Eccentricity	0.12 – 0.18 mm
Allowable Deflection Angle	1°
Allowable Axial Deviation	±0.18 to ±0.50 mm
Misalignment Compensation	Angular, radial (eccentricity), and axial
Fastening Method	Clamping screw
Maintenance	None required – maintenance-free
Operating Temperature	-30°C to +100°C
Customization	OEM – custom bores, keyways, and materials
Applicable Industries	Servo motors, stepper motors, encoders, lead screws, CNC machines, robotics, automation equipment
Place of Origin	Guangdong, China

🔧 Custom bores and keyways available. For keyway options, add “K” after the shaft diameter (e.g., DLT-39×48-8Kx9K). Contact us with your specifications.

DLT Series – Model Range & Specifications

Model	Outer Diameter (D) mm	Length (L) mm	Bore Range (d) mm	Rated Torque (N·m)	Max Speed (RPM)	Weight (g)
DLT-34×37.5	34	37.5	6,6.35,7,8,9,9.525,10	2	10000	49
DLT-39×48	39	48	8,9,9.525,10,11,12	4.5	10000	85
DLT-44×48	44	48	8,9,9.525,10,11,12,12.7,14,15,16	6.75	10000	107
DLT-56×61	56	61	12,14,15,16,17,19,20,22	20	10000	196
DLT-68×74	68	74	15,16,19,20,22,24,25	50	9000	374
DLT-82×98	82	98	20,22,24,28,30	90	8000	645

📐 Additional sizes and custom dimensions available upon request. Contact our engineering team for custom sizing.

Product Structure

Two Aluminum Hubs – High-strength aluminum alloy, precision-machined, anodized finish.
Double 304 Stainless Steel Diaphragms – Two diaphragm packs connected by a center spacer, providing superior misalignment compensation.
Step (Stepped) Design – Creates additional space for the diaphragm to flex, dispersing concentrated stress and延缓 fatigue crack propagation.
Center Spacer – Connects the two diaphragm packs.
Clamping Screw Fastening – Secure shaft fixation with even clamping force.

💡 How it works: The DLT coupling consists of two aluminum hubs connected by two 304 stainless steel diaphragms with a center spacer. The unique step (stepped) design creates additional space for the diaphragms to flex during operation, dispersing concentrated stress and延缓 the onset of fatigue cracks. The double diaphragm design provides superior compensation for angular, radial, and axial misalignment. Torque is transmitted through the diaphragms, which flex to accommodate misalignment while maintaining high torsional rigidity and zero backlash. The design provides zero backlash operation, which is crucial for precision control in servo systems and automated machinery.

Double Diaphragm vs Single Diaphragm – Key Differences

Feature	Double Diaphragm (DLT Series)	Single Diaphragm (DST Series)
Radial (parallel) misalignment	✅ Yes – superior compensation	❌ Cannot accommodate
Angular misalignment	✅ Yes – up to 1°	✅ Yes – up to 1°
Axial misalignment	✅ Yes – up to ±0.50mm	✅ Yes – up to ±0.50mm
Torsional rigidity	High	Higher
Space requirement	Longer (center spacer required)	Compact – saves space
Misalignment compensation	Superior	Good
Best for	Applications requiring full misalignment compensation	Space-limited, well-aligned applications

Selection guideline:

Choose double diaphragm (DLT) when radial (parallel) misalignment must be accommodated.
Choose single diaphragm (DST) when space is limited, high torsional rigidity is required, and shafts are well-aligned with no significant parallel misalignment.

Step (Stepped) Design – Key Advantage

The DLT series features a unique step (stepped) design that offers several advantages over standard flat diaphragm couplings:

Advantage	Benefit
Enhanced Stress Distribution	The step design creates additional space for the diaphragm to flex, dispersing concentrated stress and延缓 fatigue crack propagation
Extended Service Life	Reduced stress concentration significantly extends the service life of the diaphragm
Superior Misalignment Compensation	The step allows for smoother flexing, improving misalignment compensation
Reliable Performance	More consistent performance under repeated cyclic loads

💡 The step design is a key differentiator of the DLT series, providing longer service life compared to standard flat diaphragm couplings.

Product Features & Advantages

Advantage	Benefit
Zero Backlash	No rotational clearance – precise positioning for servo motors and encoders
Double 304 Stainless Steel Diaphragm	Superior misalignment compensation – accommodates angular, radial, and axial misalignment
Step (Stepped) Design	Enhanced stress distribution and extended service life
High Torsional Rigidity	Accurately controls shaft rotation – enables high-precision control
High-Strength Aluminum Alloy	Lightweight, low inertia – ideal for high-speed operation
Zero-Clearance Shaft Connection	Suitable for positive and negative rotation – identical clockwise and counterclockwise characteristics
Low Inertia	Lightweight design enables high-speed operation up to 10000 RPM
Clamping Screw Fastening	Even clamping force, no shaft damage – easy installation
H7 Precision Bore	High concentricity and accurate shaft fit – reduces vibration
Maintenance-Free	No lubrication required – reduces operating costs
Specifically for Servo/Stepper Motors	Designed for high-precision motion control applications
OEM Customization	Custom bores, keyways, and materials available

Applications

Servo Motors – High-precision motion control systems
Stepper Motors – Accurate positioning and step transmission
Encoders – Precision position feedback systems
Lead Screws – Precision linear motion systems
CNC Machines – Feed drives, positioning systems
Robotics – Joint drives, precision motion
Automation Equipment – Pick-and-place systems, indexing tables
Laser Cutting Equipment – Precision positioning
General Industrial Machinery – High-precision power transmission

Why Choose Apex Coupling for DLT Diaphragm Couplings?

Advantage	Description
Factory Direct	Competitive B2B pricing – no middlemen
Premium Materials	Aluminum alloy hubs + 304 stainless steel double diaphragm
Step Design	Enhanced stress distribution and extended service life
Zero Backlash	Precision performance for encoders, servo motors, and stepper motors
High Torsional Rigidity	Accurately controls shaft rotation – enables high-precision control
Superior Misalignment Compensation	Double diaphragm design accommodates angular, radial, and axial misalignment
Low Inertia	High-speed capability – up to 10000 RPM
Clamping Screw Fastening	Secure, even clamping force – no shaft damage
H7 Precision Bore	High concentricity and accurate shaft fit
Maintenance-Free	No lubrication required – reduces operating costs
OEM Customization	Custom bores, keyways, and materials available

FAQ

Q: What is the advantage of the step (stepped) design?
A: The step design creates additional space for the diaphragm to flex during operation, dispersing concentrated stress and延缓 fatigue crack propagation, significantly extending the service life of the coupling.

Q: What is a double diaphragm coupling?
A: A double diaphragm coupling consists of two aluminum hubs connected by two stainless steel diaphragms with a center spacer. It transmits torque while compensating for angular, radial, and axial misalignment with zero backlash and high torsional rigidity.

Q: What materials are used?
A: The hubs are made of high-strength aluminum alloy with anodized finish. The diaphragms are made of 304 stainless steel – offering excellent fatigue resistance and corrosion resistance.

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

Q: Is the coupling maintenance-free?
A: Yes. The DLT series is maintenance-free – no lubrication required.

Q: What are the common applications?
A: Servo motors, stepper motors, encoders, lead screws, CNC machines, robotics, and automation equipment.

Q: Can the coupling compensate for misalignment?
A: Yes. The double diaphragm design compensates for angular, radial (eccentricity), and axial misalignment.

Q: Can I get a custom coupling?
A: Yes. We offer OEM customization – custom bores, keyways, and materials available. For keyway options, add “K” after the shaft diameter (e.g., DLT-39×48-8K×9K).

Q: What is the maximum speed?
A: Maximum speed ranges from 8000 to 10000 RPM depending on the model.

Request a Quote

Send us your model (e.g., DLT-56×61), bore size, torque, speed, and application details. Our engineers will recommend the optimal model and provide a quotation within 24 hours.