Rigid shaft couplings are available in one and two-piece designs, with and without keyways, in aluminum, carbon steel, and stainless steel. A large number of standard sizes are available in straight and step bore combinations to fit shafts ranging from 1/8" to 2" in the inch series and from 3mm to 50mm in the metric series. Inch to metric conversion couplings are also available by special order. Each rigid coupling is stamped with the Ruland name and the bore sizes for easy identification.
The one-piece rigid coupling wraps around the shaft, providing high torsional holding power without the shaft damage and fretting inherent when set screw style couplings are used. The two-piece rigid coupling has the additional benefit of allowing for disassembly and maintenance without removal of other components. The two-piece design also features opposing hardware for dynamic balancing.
Extra steps are taken in the manufacture of rigid couplings to provide important performance benefits. As one of these steps, the bores of Ruland straight bore rigid shaft couplings are precision honed. Honing of the bores provides several benefits that enhance the overall performance of the rigid coupling. Applications that require strict control of shaft alignment benefit greatly from honing, which assures both bores are collinear. Honing also corrects any residual distortions caused by stresses introduced during the manufacturing process, resulting in a round, precisely sized bore. Proper sizing and geometry assures a large percentage of shaft contact and greater torque transmission ability.
Rigid couplings come with Ruland's unique Nypatch® socket head cap screws for increased performance and reliability. Nypatch® is a proprietary process that involves depositing a 360 degree coating of Nylon on several threads of the socket head cap screws. This coating is designed to reduce screw vibration, which can cause the screws to loosen and torque transmission ability to diminish during the course of normal use. The Nylon also provides the necessary dissimilar material to reduce galling of the screw threads in stainless steel rigid couplings.
Double wide shaft collars are an excellent alternative to rigid shaft couplings in applications where space is limited. The double wide shaft collar has a reduced torque capability compared to the rigid coupling due to its use of a single socket head cap screw per shaft. However, the compact size of the collar reduces inertia making it ideal for motion control applications.
The benefits of using rigid shaft couplings include their economy, high torque capacity, and zero backlash. Rigid couplings are suitable for applications when misalignment is neither present nor desired, including connecting line-shafting or attaching a motor to a gearbox.
As a service to our customers, we offer our vast machining experience and talents to meet special needs with custom parts. Our shop is equipped with the machines and skilled people necessary to fill all of your special requirements. If you don't see what you are looking for in our standard line, please inquire about our custom fabrication service.
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.
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.
Ruland manufactures a diverse line of servo couplings to provide solutions for applications such as stepper/servo systems, linear actuators, ball screws, lead screws, encoders, and valve actuation. Industries including medical, printing, packaging, machine tools, linear motion, semiconductor, and solar benefit from having a variety of couplings to choose from. Each application has performance requirements that must be met for the system to function properly. Understanding the different characteristics of each coupling is critical when making a selection.
Ruland offers miniature rigid couplings for a wide variety of medical devices. Common applications include test and measurement systems, imaging, patient positioning, and liquid handling such as chromatography.
Ruland now offers miniature rigid couplings with bore sizes as small as 3 mm. Miniature rigid couplings are suitable for micro component applications where misalignment is neither present nor desired, including connecting line-shafts, attaching a motor to a gearbox, and servo applications. Offering high torque capacity, stiffness and zero backlash, Ruland's rigid couplings are increasingly being used in precision motion control applications where misalignment is tightly controlled.