Ruland MJCC25-12-A Aluminum Flexible Jaw Coupling

Ruland MJCC25-12-A is a clamp-style, zero-backlash jaw coupling hub designed to join two shafts with a 12 mm bore. It uses a three-piece construction—two aluminum hubs and an elastomeric spider—providing a lightweight, low-inertia coupling that supports speeds up to 8,000 RPM. The hub measures 25.4 mm (1.000 in) on the outside, with a length of 35.3 mm, a 12 mm bore, and a 4 mm keyway to fit a keyed shaft. Machined from 2024-T351 aluminum and finished bright with no plating, it is RoHS3 and REACH compliant and manufactured in Marlborough, Massachusetts. The jaw coupling is balanced for reduced vibration at high speeds, and the spider inserts are offered in three durometers to tailor damping and misalignment tolerance. For installation, tighten the M3 screws on the first hub to the recommended seating torque of 2.1 Nm using a 2.5 mm hex torque wrench. This MJCC25-12-A hub is designed to work as part of a customizable family of clamp or set-screw hubs with inch, metric, keyed, and keyless bores, enabling precise alignment and straightforward assembly in servo and motion-control applications.