$134.85 ea
Quantity Price (USD)
1 $134.85 ea
10 $80.91 ea
25 $67.43 ea
50 $60.68 ea
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Built to Order Lead Time: 0-2 Days
Ruland BS16-6-6-A, 3/8" x 3/8" Bellows Coupling, Aluminum, Set Screw Style, 1.000" OD, 1.313" Length


Ruland BS16-6-6-A is a set screw bellows coupling with 3/8" x 3/8" bores, 1.000" OD, and 1.313" length. It is zero-backlash and has a balanced design for reduced vibration at high speeds. BS16-6-6-A is comprised of two anodized aluminum hubs and a stainless steel bellows. The bellows are able to flex while remaining rigid under torsional loads allowing for all types of misalignment to be accommodated. This bellows coupling is lightweight and has low inertia making it suitable 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 BS16-6-6-A to be torsionally rigid and an excellent fit for precise positioning stepper servo applications as well as encoders. It is machined from solid bar stock that is sourced exclusively from North American mills and RoHS2 and REACH compliant. BS16-6-6-A is carefully manufactured in our Marlborough, MA factory under strict controls using proprietary processes.



Large Bore B1

0.375 in

Small Bore B2

0.375 in

B1 Shaft Penetration

0.626 in

B2 Shaft Penetration

0.626 in

Outer Diameter OD

1.000 in

Bore Tolerance

+.001 in / -.000 in

Length L

1.313 in

Hub Width LH

0.467 in

Fastening Hardware

Forged Set Screw


Screw Material

Alloy Steel

Hex Wrench Size

2.0 mm

Screw Finish

Black Oxide

Seating Torque

2.2 Nm

Number of Screws

4 ea

Performance Specifications

Static Torque

60 lb-in

Angular Misalignment


Dynamic Torque Non-Reversing

30 lb-in

Parallel Misalignment

0.004 in

Dynamic Torque Reversing

15 lb-in

Axial Motion

0.012 in

Torsional Stiffness

244 lb-in/Deg

Maximum Speed

10,000 RPM

Additional Information

Material Specification

Hubs: 2024-T351 Aluminum Bar
Bellows: Type 321 Stainless Steel


-40°F to 200°F
-40°C to 93°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 metal bellows. Under normal/typical conditions the hubs are capable of holding up to the rated torque of the metal bellows. 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 metal bellows. 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 Bisphenol A 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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