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Servo Couplings from Ruland



Servo couplings from Ruland are available in a wide variety of styles, sizes, and materials to match differing application requirements. Choosing the correct servo coupling can be a difficult process that involves many performance factors including: shaft misalignment, RPM, space requirements, torque, and others. Matching a shaft coupling with these factors is critical to system performance.

Ruland offers servo couplings in rigid, beam, bellows, curved jaw, disc, and oldham types allowing the user to select the coupling that best fits their application. All Ruland couplings are zero-backlash and manufactured in our Marlborough, MA factory. For more information about the differences between each coupling see below.

Rigid Couplings

  • It is the most precise coupling with almost zero windup.
  • Suitable for shaft support and demanding push-pull applications.
  • No misalignment capabilities or allowance for thermal expansion.
  • Bore sizes – 1/4" (6mm) to 2” (50mm), 4000 RPM
Servo Coupling

Beam Couplings

  • Large misalignment capabilities.
  • Various cut patterns and material options offer an array of performance.
  • Relatively low torque and torsional stiffness when compared to other servo couplings.
  • Bore sizes – 1/8” (3mm) to 3/4" (20mm), 6000 RPM
Servo Coupling

Bellows Couplings

  • Suitable for high torque applications requiring minimal position error.
  • Low inertia for responsiveness, balanced for high RPM capabilities.
  • No provision for impact loads and limited misalignment capabilities.
  • Bore sizes – 1/8” (3mm) to 1” (25mm), 10000 RPM
Servo Coupling

Disc Couplings

  • Suitable for delicate equipment requiring highly precise positioning.
  • Discs allow for misalignment while offering high torsional rigidity.
  • Some styles are not suitable for complex or parallel misalignment.
  • Bore sizes – 1/8” (3mm) to 1-1/4” (32mm), 10000 RPM
Servo Coupling

Oldham Couplings

  • Accommodates large amounts of parallel misalignment with low bearing loads while also being electrically isolating.
  • Forgiving coupling that is suitable for a wide variety of applications.
  • Both shafts must be fully supported and not suitable for push-pull applications.
  • Bore sizes – 1/8” (3mm) to 1-1/4” (30mm), 4500 RPM
Servo Coupling

Zero Backlash Jaw Couplings

  • Dampens impulse loads and is electrically isolating.
  • Multiple spider materials for a range of dampening and torque capacity.
  • Low misalignment capabilities due to high bearing loads.
  • Bore sizes – 1/8” (3mm) to 1-1/4” (32mm), 8000 RPM
Servo Coupling

Why Ruland?

  • Step-bore rigid couplingFull range of zero-backlash couplings to match different application requirements.
  • Precision honed bores on straight bore rigid couplings for superior fit and torque transmission and alignment.
  • Proprietary Nypatch® coating on rigid coupling hardware resists vibration and maintains holding power.
  • Flexible servo couplings have a balanced design leading to better performance, reduced vibration, and increased speed capabilities.
  • Ruland has designed flexible couplings to offer better torque and stiffness while still accommodating misalignment.
  • Raw materials are sourced from select North American mills to ensure product consistency.
  • All servo couplings are carefully made in our Marlborough, Massachusetts USA factory with large stocks for same day shipment.
  • Hardware is carefully selected and tested to ensure maximum torque capabilities.

Coupling Comparison Chart

Comparison of Ruland servo couplings on critical performance characteristics

Technical Articles

Ruland couplings

What to look for in a Servo Coupling

Selecting a coupling for a servo application can be a complex process. It involves many different performance factors, including: torque, shaft misalignment, stiffness, rpm, space requirements, and others, that all must be satisfied for the coupling to work properly. Before selecting a coupling, it is helpful to know the specifics of these issues for the application for which the coupling is to be used. Many different types of servo couplings exist with their own individual strong and weak points. This article is designed to introduce end users to the different types of couplings available for servo applications. It also helps the user select the proper coupling for their application by highlighting the factors that should be considered in the decision making process and how they relate to the different product offerings available.

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beam coupling failure

Technical Article

Avoiding Coupling Failure: Considerations in Design Selection

Mechanical couplings have a principal use in the connection of rotating shafts for the transfer of rotary motion and torque. As with all mechanical devices, a coupling must match its’ intended purpose and application parameters, including many different performance, environmental, use and service factors. All must be satisfied for the coupling to work properly. When selected with these design parameters in mind, and when installed and operating correctly, a coupling should have no failure issues over it’s’ lifetime. However, when one or more of these is not met a coupling can prematurely fail, resulting in either a small inconvenience or possibly serious financial loss or personal injury. This article provides a view of the primary reasons couplings fail, and the steps that can be taken to minimize the risk of failure.

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An assortment of Rigid Couplings

Rigid Couplings for Motion Control Applications

Rigid couplings, which are sometimes called sleeve or muff couplings, have been historically imprecise, inexpensive, and often home made components for simple shaft to shaft connections. In the past many people would not consider using a rigid coupling in any servo application. However, smaller sized rigid couplings, especially made of aluminium, are increasingly being used in motion control applications due to their high torque capacity, stiffness, and zero backlash.

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Ruland Shaft Collars

Shaft Collar

Rigid Coupling

Oldham Coupling

Beam Coupling

Bellows Coupling

Jaw Coupling

Disc Coupling

Shaft Collars Rigid Coupling Oldham Coupling Beam Coupling Bellows Couplings Jaw Couplings Disc Couplings