How will a Harmonic Drive work? Why are they used?

Among the many advantages of a harmonic drive is the insufficient backlash because of the unique design. However, the fact that they are light-weight and extremely compact can be important.
High gear reduction ratios as high as 30 occasions that achieved with planetary gears are possible in the same space.
C W Musser designed strain wave gearing back in 1957 and by 1960 he was already selling licenses so that industry giants might use his patented product.
harmonic drive assembled The harmonic drive is a type of gear arrangement often referred to as a strain wave gear due to just how it works. It is a kind of reduction equipment mechanism comprising at the least three main elements. These components interact in a manner that allows for high precision decrease ratios that could otherwise require much more complex and voluminous mechanisms.

As something, the harmonic drive was invented by the American engineer Clarence Walton Musser in 1957, and it quickly conquered the industry with a variety of advantages that it brought to the desk. Musser discovered the potential of his invention at an early stage and in 1960 started offering licenses to producers so they might use his patented item. Currently, there are only a handful of manufacturers in the USA, Germany, and Japan who are holding the license to produce harmonic drives, doing so at their top-notch services and creating ultimate quality stress gears for your world.

harmonic drive exploded viewThe workings of a harmonic drive
The rotational motion comes from an input shaft that can be a servo electric motor axis for instance. This is linked to an component called “wave era” which includes an elliptical form and is certainly encircled by an elliptical ball bearing. As the shaft rotates, the edges switch position, so that it looks like it is generating a movement wave. This component is inserted inside a flex spline that’s made out of a torsionally stiff however flexible material. The material takes up this wavy movement by flexing according to the rotation of the insight shaft and in addition produces an elliptical form. The outer edge of the flex spline features equipment teeth that are ideal for transferring high loads without any issue. To transfer these loads, the flex spline is installed in the circular spline which is a round gear featuring internal tooth. This outer band is rigid and its internal size is marginally bigger than the major axis of the ellipse created by the flex spline. This means that the circular spline will not believe the elliptical form of the various other two elements, but rather, it basically meshes its internal teeth with those of the external flex spline part, leading to the rotation of the flex spline.

The rate of rotation would depend on the rotation of the input shaft and the difference in the amount of teeth between your flex spline and the circular spline. The flex spline has fewer teeth compared to the circular spline, so it can rotate at a much decreased ratio and in the contrary direction than that of the insight shaft. The decrease ration is distributed by: (number of flex spline tooth – amount of circular spline tooth) / quantity of flex spline teeth. So for example, if the harmonic driveflex spline offers 100 teeth and the circular spline offers 105, the reduction ratio is (100 – 105) / 100 = -0.05 which means that the flex spline ration is -5/100 (minus indicates the contrary direction of spin). The difference in the number of teeth could be changed to support different decrease ratios and therefore different specialized desires and requirements.

Achieving reduction ratios of 1/100 and up to even 1/300 by simply using such a compact light arrangement of gears can’t be matched simply by any various other gear type.
The harmonic drive is the only gear arrangement that doesn’t feature any backlash or recoil effect, or at least they are negligible in practice. That is mainly because of the elliptical bearing installed on the outer rim of the input shaft allowing the free rotation of the flex spline.
The positional accuracy of harmonic drives even at an extreme number of repetitions is extraordinary.
Harmonic drives can accommodate both ahead and backward rotation without the need to improve anything, and they retain the same positional accuracy on both spin directions.
The efficiency of a typical harmonic drive measured on real shaft to shaft tests by the producer rises to 90%. There are extremely few mechanical engineering elements that may claim this operational performance level.
Uses for a harmonic drive
In short a harmonic drive can be used “in virtually any gear reduction software where little size, low weight, zero backlash, high precision and high reliability are required”. Examples include aerospace applications, robotics, electric automobiles, medical x-ray and stereotactic machines, milling and lathe machines, flexo-printing devices, semiconductor gear, optical measuring machines, woodworking machines and camera head pans and tilt axes. The most known types of harmonic drive applications include the tires of the Apollo Lunar Rover and the winches of the Skylab space station.



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