The flexing capacity of the HELI-CAL Flexure compensates correctly for a variety of misalignments, including parallel, angular and skewed (three-dimensional) misalignment. The Flexure solutions for these misalignment situations are shown in the adjacent photographs.

Parallel		Angular		Skewed
Parallel misalignment is the most difficult form of misalignment for couplings to absorb. It can also be the most damaging to shafts, bearings and motors. The HELI-CAL Flexure, through lateral displacement, transforms an application’s parallel misalignment problems into angular displacement within the coupling. The center coils of the HELI-CAL Flexure can become an intermediate shaft that can allow 10, 20 or 30 thousandths of an inch of parallel offset or more.		Angular misalignment is the easiest form of misalignment for most couplings to accept, and thus one of the most practical applications of a flexible coupling. Allowing only enough space between coils to partially close the gap during bending, the HELI-CAL Flexure can accept an angular misalignment of 20 degrees or more (and even up to 90 degrees in special U-joint applications).		When shafts are not in the same plane (skewed), the HELI-CAL Flexure’s abilities to compensate are the same as with either parallel or angular misalignment – but in the third dimension. A Flexure designed with more coils in a series can compensate for as much three-dimensional misalignment as your application requires.

The basic requirement of a flexible coupling is to transmit torque loads without permanent distortion or damage and without imposing undue bending or radial loads upon the driver or driven components. Once the working torque rating of a HELI-CAL Flexure coupling is established—based on misalignment and design criteria, material specifications and service factors supplied during the design process—its operational life is virtually infinite.

Some torsional elasticity is present in every flexible shaft coupling, and the HELI-CAL Flexure’s torsional stiffness can be altered to the degree of rotational precision required. Torsional windup reflects the amount of twist in a system; torsional stiffness, the degree of resistance against twist

Bearing loads—primarily generated from irregular side loads, and end thrust resistance to this displacement—are among the most destructive forces imposed on an apparatus and its rotational components. The HELI-CAL Flexure is able to maintain a constant radial load at all points of rotation, producing some of the most uniform bearing loads in the entire coupling industry.

In a rotating system, constant velocity refers to the angular accuracy. At every point during rotation, the driven half of the coupling turns exactly the same amount and at the same rate as the driving half. In any mechanical system, however, various factors—backlash, angular misalignment, torsional stiffness and lack of concentricity—tend to inhibit constant velocity. The HELI-CAL Flexure design concept alleviates these conditions thusly:

• Backlash: the HELI-CAL Flexure has zero backlash, because of its one-piece construction.
• Angular misalignment, which can induce large fluctuations in rotational velocity in many other coupling designs, is corrected by the HELI-CAL Flexure’s constant spring rate at all points of rotation.
• Torsional variations, which can induce differences in hub-to-hub velocity when subjected to dynamic loading, are minimal in steady-state applications of the HELI-CAL Flexure.

Concentricity, when there is a lack of it—particularly in the case of couplings with backlash or where production variation is difficult to prevent—the HELI-CAL Flexure’s one-piece integrity minimizes sinusoidal variations.

The ability to adapt to high– and low–speed applications is another inherent benefit of the HELI-CAL Flexure’s design. The Flexure transmits motion throughout its length and cross section in a continuous helix from end to end. Torsional loading tends to make the HELI-CAL Flexure draw toward its centerline, reducing the chance of whipping action normally associated with rotating components. Consequently, vibrations are kept to a minimum at all rotating points.

Axial movement is inherent in any rotating componentry, such as the rotor assembly in a motor. Through internal displacement, the HELI-CAL Flexure absorbs and compensates for axial movement or end play. The curved-beam structure of the HELI-CAL Flexure operates naturally in this axial compensation mode, and special designs can accommodate for even large displacement applications.