$41.66 ea
Quantity Price (USD)
1 $41.66 ea
10 $25.00 ea
25 $20.83 ea
50 $18.75 ea
100 Request Quote
In stock
Registered users receive a 5% discount
Ruland OCT21-5-A, 5/16" Oldham Coupling Hub, Aluminum, Clamp Style, 1.313" OD, 0.590" Length


Ruland OCT21-5-A is an oldham coupling hub with 5/16" bore, 1.313" OD, and 0.590" length. It is a component of a three-piece design consisiting of two anodized aluminum hubs press fit onto a center disk. This three-piece design allows for a highly customizable coupling that easily combines clamp or set screw hubs with inch, metric, keyed, and keyless bores. Disks are available in acetal plastic for zero-backlash and high torsional stiffness, nylon for shock absorption and dampening, and PEEK for high temperature and cleanroom environments. OCT21-5-A can accommodate all forms of misalignment and are especially useful in applications with high parallel misalignment (up to 10% of the OD). It operates with low bearing loads protecting sensitive system components such as bearings and has a balanced design for reduced vibration at speeds up to 6,000 RPM. Hardware is metric and tests beyond DIN 912 12.9 standards for maximum torque capabilities. OCT21-5-A is machined from bar stock that is sourced exclusively from North American mills and is RoHS2 and REACH compliant. It is manufactured in our Marlborough, MA factory under strict controls using proprietary processes.



Bore B

0.313 in

Bore Tolerance

+.001 in / -.000 in

B1 Shaft Penetration

0.590 in

Outer Diameter OD

1.313 in

Length L

1.875 in

Hub Width LH

0.590 in

Fastening Hardware

Forged Clamp Screw


Number of Screws

1 ea

Screw Material

Alloy Steel

Screw Finish

Black Oxide

Seating Torque

2.1 Nm

Hex Wrench Size

2.5 mm

Performance Specifications

Angular Misalignment


Parallel Misalignment

0.008 in, 0.20 mm

Max Parallel Misalignment

0.131 in, 3.33 mm

Axial Motion

0.006 in, 0.15 mm

Maximum Speed

4,500 RPM

Additional Information



Country of Origin


Material Specification

2024-T351 Aluminum Bar


Black Anodized

Finish Specification

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


Ruland Manufacturing


Acetal Disk -10°F to 150°F
Acetal Disk -23°C to 65°C
Nylon Disk -10°F to 130°F
Nylon Disk -23°C to 54°C
PEEK Disk -10°F to 300°F
PEEK Disk -23°C to 148°C

Weight (lbs.)


Product Notes

Note 1

Stainless steel hubs are available upon request.

Note 2

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

Note 3

Torque ratings for the couplings are based on the physical limitations/failure point of the torque disks. Under normal/typical conditions the hubs are capable of holding up to the rated torque of the disks. 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 disks. 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 the chemical Ethylene Thiourea, known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

ISO 9001:2015


Conflict Minerals






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