Flexible couplings for rotating components

Coupling Design

ROCOM Precision Flexible Coupling Design

Rocom’s one piece, double taper, multi overlapping, helical curved beam flexible coupling is the patented result of years of testing. The helical curved beams are double tapered so that they are thick at the OD and thin at the ID in ratio to the circumferential lengths. They are thick at the hub end of the beam and thin at the circumferential center forcing the flexing to the center of their lengths, instead of the end where the highest stress would occur. The thick OD increases strength without sacrificing life.

The space between the beams is calculated and cut to allow the beams to flex without touching each other at their maximum misalignment rating. All thru bore couplings have an inside diameter relief in the flexible area. If the misalignment rating is not exceeded, the shaft cannot touch the flexible beams which otherwise could cause them to fail.

This design is continually self-compensating. When the coupling is in a misaligned condition, one set of three helical beams flex toward each other without touching, and are at their maximum load capability. On the other side of the coupling, the second set of beams are spread apart to their minimum load carrying capability. The second set of curved helical beams are 120° out of phase with the first set. This continually averages the torque load and velocity between all six beams and does not allow the coupling to have a sine wave output on each revolution. Tests by our customers show that when these couplings are installed correctly they have a constant velocity.

Triple start beam coupling cut-away
Cross section cut-away of a triple start beam coupling

Torque & Torsional Stiffness

The torque rating is based on the buckling point, not on the breaking point of the beam. Once the material exceeds its elastic limits (the buckling point) it will fatigue and fail. The beams are less than 360° long at the ID. Beam length, thickness and height (OD to ID), plus material determines the torque and torsional stiffness. The beam designs can be modified for special requirements.


The method of cutting six short overlapping double tapered helical curved flexible beams is complex and took many years to develop and perfect.  Our specialty-built machines are focused on the accurate and efficient production of a precise, quality, and high-performance flexible shaft coupling.

Prop. 65 Warning for California Residents

WARNING: These products may contain chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm.

Rocom Couplings Corporation

2727 Skyway Drive, Suite A
Santa Maria CA 93455

(805) 862-4424

Toll Free 1-800-952-FLEX

Newsletter Sign Up

Get the latest news from RoCom delivered to your inbox.