Precision Gears from Harmonic Drive® The principle for these backlash free differential gears was patented under the name Harmonic Drive® in 1955. A compact design of the backlash free component set offers a space saving and integrated solution direct into the machine. The compact design of the gear component sets allows their integration in applications where a small envelope and light weight are required. Harmonic Drive offers a complete range of products for demanding applications:
Products Harmonic Drive Units consist of a gear component set, equipped with a high capacity output bearing, which are intended for integration into a machine.
The key element of Harmonic Drive gearboxes is a component set within a housing with a flange or shaft as output assembly.
The Harmonic Planetary Gears comprise three variants with different accuracy classes in order to fulfill the demands of applications requiring ratios smaller than 50:1.
Harmonic Drive servo motors, servo actuators and controllers a combination of precision gearboxes with specially developed AC or DC servo motors. Used in applications with demanding requirements they provide precision motion control, high torque capacity in a very compact package.
We offer customer-specific solutions in a variety of configurations for both linear and rotational motion.

» More info at Harmonic Drive website

Principle of operation

The Flexspline is slightly smaller in diameter than the Circular Spline resulting in it having two fewer teeth on its outer circumference. It is held in an elliptical shape by the Wave Generator and its teeth engage with the teeth on the Circular Spline across the major axis of the ellipse.

As soon as the Wave Generator starts to rotate clockwise, the zone of tooth engagement travels with the major elliptical axis.

When the Wave Generator has turned through 180 degrees clockwise the Flexspline has regressed by one tooth relative to the Circular Spline.

Each turn of the Wave Generator moves the Flexspline two teeth anti-clockwise relative to the Circular Spline.