Ruland has introduced D-bore couplings designed to engage directly with D-profile shafting in compact motion-control assemblies.
The couplings are aimed at applications where shaft slippage can compromise performance, including semiconductor equipment, medical devices, factory automation, and warehouse automation systems. They are available in disc, jaw, bellows, and oldham styles, allowing the coupling type to be matched to misalignment, torsional stiffness, vibration, and maintenance requirements.
D-profile shafts are commonly used in smaller motion systems because the flat provides a defined contact surface without requiring a machined keyway. Conventional set screw couplings can be difficult to install reliably on small shafts, particularly where the screw does not seat cleanly on the D-profile or loosens under vibration.
Ruland’s D-bore design mates directly with the flat of the shaft profile, creating a mechanical engagement intended to improve torque transmission and reduce slip. The format is particularly suited to shafts below 7 mm, where standard keyways are often unavailable and secondary shaft machining adds cost, time, and assembly complexity.
The company is offering D-bore couplings with bore sizes from 3 mm to 10 mm. The couplings are manufactured from aluminium to reduce inertia in compact drive systems, with clamp and set screw hub configurations available depending on coupling style.
The range targets a persistent weak point in small-shaft assemblies: the interface between the drive component and the shaft. A more secure connection can help preserve positional accuracy, reduce loosening-related service issues, and improve repeatability in machinery where compact design leaves little tolerance for adjustment errors.
Ruland manufactures its couplings at its facility in Marlborough, Massachusetts, using North American bar stock and proprietary production processes. The company says the D-bore couplings are RoHS3-, REACH-, and Conflict Minerals-compliant, supporting use in regulated industrial and electronic equipment supply chains.
Complete specifications, CAD models, and ordering information are available through Ruland’s website.
The launch gives designers a standard coupling option for D-shaft assemblies rather than forcing a custom machining decision late in a machine build. In compact motion-control systems, that standardisation can reduce assembly variation without adding another precision-machined feature to the shaft.
