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In Production Lead Time: 0-2 Days
Ruland PCMR16-3-3-SS, 3mm x 3mm Four Beam Coupling, Stainless Steel, Clamp Style, 15.9mm OD, 20.3mm Length

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Ruland PCMR16-3-3-SS is a clamp style four beam coupling with 3mm x 3mm bores, 15.9mm OD, and 20.3mm length. It is machined from a single piece of material and feature two sets of two spiral cuts. This gives it higher torque capacity, lower windup, and larger body sizes than single beam couplings. PCMR16-3-3-SS is zero-backlash and has a balanced design for reduced vibration at high speeds of up to 6,000 RPM. This four beam spiral coupling is zero-backlash and has a balanced design for reduced vibration at high speeds of up to 6,000 RPM. All hardware is metric and tests beyond DIN 912 12.9 standards for maximum torque capabilities. PCMR16-3-3-SS is made from 303 stainless steel for increased torque capacity. It is machined from bar stock that is sourced exclusively from North American mills and RoHS3 and REACH compliant. PCMR16-3-3-SS is manufactured in our Marlborough, MA factory under strict controls using proprietary processes.



Bore (B1) Larger inner diameter. Should match nominal shaft diameter.

3 mm

Small Bore (B2) Smaller inner diameter. Should match nominal shaft diameter.

3 mm

B1 Max Shaft Penetration The maximum depth the shaft can penetrate into Bore B1.

9.6 mm

B2 Max Shaft Penetration The maximum depth the shaft can penetrate into Bore B2.

9.6 mm

Outer Diameter (OD)

15.9 mm

Bore Tolerance Variance in finished bore range before installation.

+0.025 mm / -0.000 mm

Length (L)

20.3 mm

Recommended Shaft Tolerance Acceptable variance in nominal shaft diameter before performance loss.

+0.000 mm / -0.013 mm

Fastening Hardware

Cap Screw Inch or metric socket head cap screw size.


Screw Material

Alloy Steel

Hex Wrench Size Wrench size that fits the screw head to tighten or loosen the screw.

1.5 mm

Screw Finish Surface finish and treatments on supplied hardware.

Black Oxide

Seating Torque Torque required to install supplied hardware. Use torque wrench for accurate seating torque.

0.6 Nm

Number of Screws

2 ea

Performance Specifications

Dynamic Torque Reversing Max torque when coupling reverses direction without stopping.

0.57 Nm

Angular Misalignment Max angle of the shaft axes relative to each other.


Dynamic Torque Non-Reversing Max torque for the coupling during quick changes in acceleration or deceleration.

1.13 Nm

Parallel Misalignment Shafts are parallel to each other, but not in-line with each other. They are offset.

0.20 mm

Static Torque Unidirectional constant max torque.

2.26 Nm

Axial Motion The amount shafts can move closer to or away from each other. This is meant for thermal expansion of the shafts. No axial force can be placed on the coupling.

0.13 mm

Torsional Stiffness Measures the rigidity of the coupling. The more rigid the coupling, the less windup it will have.

1.63 Deg/Nm

Moment of Inertia

0.878 x10-6 kg-m2

Maximum Speed

6,000 RPM

Full Bearing Support Required? Full bearing support is a bearing in close proximity to both sides of the coupling to prevent axial loads that could result in rapid coupling failure.


Zero-Backlash? Zero-backlash ensures there is no loss of motion during operation.


Balanced Design The balanced design allows for reduced vibration at high RPMs.


Recommended Installation Tools

Torque Wrench This torque wrench and bit combo is recommended to ensure proper installation. A torque wrench prevents the screw from being over torqued which can lead to product failure.


Recommended Hex Key This hex key set has the appropriate hex key for product installation. Trained and experienced assemblers can use a hex key in place of a torque wrench.

Metric Hex Keys

Additional Information

Material Specification

Type 303 Austenitic, Non-Magnetic Bar

Temperature Minimum and maximum operating temperature. Operating temperature includes ambient temperature plus or minus factors such as system heat generated during operation, washdown, vacuum, etc...

-40°F to 350°F (-40°C to 176°C)

Finish Specification Surface finish specifications.

Bright, No Plating


Ruland Manufacturing

Country of Origin


Weight (lbs)




Tariff Code


UNSPC Code used to identify products to standardize nomenclature around the world.


Product Notes

Note 1

Torque ratings are at maximum misalignment.

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 machined beams. Under normal/typical conditions the hubs are capable of holding up to the rated torque of the machined beams. 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 machined beams. Please consult technical support for more assistance.

Prop 65 Required for the US State of California only.

WARNING This product can expose you to chemicals including Ethylene Thiourea and Nickel (metallic), known to the State of California to cause cancer

ISO 9001:2015


Conflict Minerals






Installation Instructions

  1. Align the bores of the PCMR16-3-3-SS four beam coupling on the shafts that are to be joined and determine if the misalignment parameters are within the limits of the coupling. (Angular Misialignment: 3°, Parallel Misalignment: 0.20 mm, Axial Motion: 0.13 mm)
  2. Fully tighten the M2 screw on one hub to the recommended seating torque of 0.6 Nm using a 1.5 mm hex torque wrench.
  3. Before tightening the screws on the second hub, rotate the coupling by hand to allow it to reach its free length.
  4. Tighten the screws on the second hub to the recommended seating torque. Make sure the coupling remains axially relaxed and the misalignment angle remains centered along the length of the coupling.
  5. The shafts may extend into the relieved portion of the bore as long as it does not exceed the shaft penetration length of 9.6 mm.


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