Zeromax ServoClass Couplings for High-Precision Servo Applications

Today’s servo applications are more demanding than ever, and the proper low-backlash coupling is crucial to maintaining position accuracy. The Zeromax ServoClass couplings are ideally suited for AC and DC servomotor applications that need precise positioning as well as the ability to handle high reverse loads. The very low runout couplings are available in 11 sizes, from 20mm (0.875”) to 35mm (1.378”), with an operating torque from 100 to 250 Nm (3937 to 9843 in-lb); additional sizes are available at 4mm (0.157”) bore and larger.

The couplings are available as single- and double-disc models, with the double-disc models providing the highest misalignment capability. The hubs and center members are manufactured from an aluminum alloy for high strength and low weight, and are treated to prevent oxidation; disc members are made from 304 stainless steel, and all couplings are precisely assembled using corrosion-resistant fasteners. This allows the coupling to operate from -22° - +212°F (-30° - +100°C)

The ServoClass couplings have several advantages over traditional servomotor couplings. These include:

Inertia and torsional stiffness are critical features of a superior servo motor coupling. The inertia should be low so as not to add significantly to overall inertia of the servo system. The lower the inertia, the less energy required by the servo motor to move the system and therefore, higher acceleration is possible. The torsional stiffness should be high enough to prevent the coupling from winding up during acceleration, deceleration or reversing conditions. The torsional stiffness of the Zero-Max Servo Motor coupling leads to a higher system resonant frequency, which in most cases, is far above the operating range.

Zero backlash is another key requirement of a high performance servo motor coupling. A servo motor coupling may be considered zero backlash and still have a large amount of windup. Zero backlash is the ability of the coupling to maintain the same relative relationship between the input and output shaft without lost motion. The windup of the coupling can be detrimental to the servo system. A coupling with a high amount of windup will cause positioning errors to the servo system. The Zero-Max Servo Motor coupling is a zero backlash coupling and it exhibits a very low amount of windup.

Misalignment capability of a coupling is also important in a servo motion control system. Usually, the alignment of a well manufactured servo system will be very good. Over time and under high load conditions, this alignment may deteriorate. The coupling should be capable of handling this change. Also, the coupling should accommodate any lack of concentricity in the connected shafts as well as the stack up of tolerances in the motion assembly. Another important benefit of a high misalignment capability is the dispersion of reaction loads on the bearings and bushings in the system. The Zero-Max servo motor coupling utilizes a design that provides adequate amounts of flexibility but does not sacrifice any of the torque capability or the torsional stiffness capability and therefore minimizes the reaction loads to the servo motor bearings.


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