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.
Rigid couplings are increasingly used in precision motion control applications where components are properly aligned. Read the article "Rigid Couplings for Precision Motion Control Applications" to learn how a rigid shaft coupling can be used in servo applications.