$282.79 ea
Quantity Price (USD)
1 $282.79 ea
10 $212.09 ea
25 $158.36 ea
50 $95.09 ea
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Built to Order Lead Time: 0-2 Days
Ruland MDSDE51-20-14-A, 20mm x 14mm Double Disc Coupling, Aluminum, Set Screw Style, Electrically Isolating, 50.8mm OD, 64.0mm Length


Ruland MDSDE51-20-14-A is an electrically isolating double disc coupling with 20mm x 14mm bores, 50.8mm OD, and 64.0mm length. It is zero-backlash and has a balanced design for reduced vibration at high speeds. The double disc design is comprised of two anodized aluminum hubs, two sets of thin stainless steel disc springs, and an acetal center spacer allowing each disc to bend individually and accommodate all types of misalignment. The acetal center spacer isolates the two hubs preventing the incidental transfer of current from the motor to the driven component or vice versa. MDSDE51-20-14-A is lightweight and has low inertia making it well suited for applications with speeds up to 10,000 RPM. Hardware is metric and tests beyond DIN 912 12.9 standards for maximum torque capabilities. Ruland manufactures MDSDE51-20-14-A to be torisionally rigid and an excellent fit for precise positioning stepper servo applications commonly found in semiconductor, solar, printing, machine tool, and test and measurement systems. It is machined from solid bar stock that is sourced exclusively from North American mills and RoHS2 and REACH compliant. MDSDE51-20-14-A is manufactured in our Marlborough, MA factory under strict controls using proprietary processes.



Large Bore B1

20 mm

Small Bore B2

14 mm

B1 Shaft Penetration

30.3 mm

B2 Shaft Penetration

30.3 mm

Outer Diameter OD

50.8 mm

Bore Tolerance

+.03 mm / -.00 mm

Length L

64.0 mm

Hub Width LH

20.6 mm

Fastening Hardware

Forged Set Screw


Screw Material

Alloy Steel

Hex Wrench Size

3.0 mm

Screw Finish

Black Oxide

Seating Torque

7.2 Nm

Number of Screws

4 ea

Performance Specifications

Static Torque

39.6 Nm

Angular Misalignment


Dynamic Torque Non-Reversing

19.80 Nm

Parallel Misalignment

0.30 mm

Dynamic Torque Reversing

9.90 Nm

Axial Motion

0.64 mm

Torsional Stiffness

67.2 Nm/Deg

Maximum Speed

10,000 RPM

Additional Information

Material Specification

Hubs: 2024-T351 Bar, Disc Springs: Type 302 Stainless Steel, Center Spacer: Acetal


-10°F to 150°F
-23°C to 65°C

Finish Specification

Sulfuric Anodized MIL-A-8625 Type II, Class 2 and ASTM B580 Type B Black Anodize


Ruland Manufacturing

Country of Origin


Weight (lbs.)




Product Notes

Note 1

Stainless steel hubs are available upon request.

Note 2

Torque ratings are at maximum misalignment.

Note 3

Performance ratings are for guidance only. The user must determine suitability for a particular application.

Note 4

Torque ratings for the couplings are based on the physical limitations/failure point of the disc springs. Under normal/typical conditions the hubs are capable of holding up to the rated torque of the disc springs. In some cases, especially when the smallest standard bores are used or where shafts are undersized, slippage on the shaft is possible below the rated torque of the disc springs. Keyways are available to provide additional torque capacity in the shaft/hub connection when required. Please consult technical support for more assistance.

Prop 65

WARNING This product can expose you to chemicals including Ethylene Thiourea and Nickel (metallic), known to the State of California to cause cancer, and Ethylene Thiourea known to the State of California to cause birth defects or other reproductive harm. For more information go to

ISO 9001:2015


Conflict Minerals






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