One of the many advantages of a harmonic drive may be the insufficient backlash due to the unique style. However, the actual fact they are light-weight and extremely compact is also important.
High gear reduction ratios as high as 30 instances that achieved with planetary gears are feasible 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 because of just how it works. It is some sort of reduction gear mechanism consisting of at the least three main parts. These parts interact in a manner that allows for very high precision reduction ratios that could otherwise require a lot 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 the countless advantages that it brought to the desk. Musser determined the potential of his invention at an early on stage and in 1960 started offering licenses to manufacturers so they might use his patented product. Currently, there are only a small number of manufacturers in the USA, Germany, and Japan who are keeping the license to produce harmonic drives, doing this at their top-notch services and making ultimate quality stress gears for your world.

harmonic drive exploded viewThe workings of a harmonic drive
The rotational motion comes from an input shaft which can be a servo electric motor axis for instance. This is linked to an element called “wave generation” which includes an elliptical form and can be encircled by an elliptical ball bearing. As the shaft rotates, the edges modification position, so it looks like it is generating a movement wave. This component is inserted in the flex spline that’s crafted from a torsionally stiff yet flexible material. The material occupies this wavy movement by flexing according to the rotation of the input shaft and in addition produces an elliptical form. The outer edge of the flex spline features gear teeth that are suitable for transferring high loads with no problem. To transfer these loads, the flex spline is installed within the circular spline which is a round equipment featuring internal tooth. This outer band can be rigid and its internal diameter is marginally bigger than the major axis of the ellipse created by the flex spline. This implies that the circular spline does not believe the elliptical shape of the additional two elements, but rather, it basically meshes its inner tooth with those of the external flex spline side, leading to the rotation of the flex spline.

The rate of rotation is dependent on the rotation of the input shaft and the difference in the number of teeth between the flex spline and the circular spline. The flex spline offers fewer teeth compared to the circular spline, so that it can rotate at a much reduced ratio and in the opposite path than that of the input shaft. The decrease ration is given by: (amount of flex spline teeth – quantity of circular spline tooth) / quantity of flex spline tooth. So for instance, if the flex spline provides 100 tooth and the circular spline provides 105, the decrease ratio is (100 – 105) / 100 = -0.05 which implies 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 accommodate different decrease ratios and therefore different specialized desires and requirements.

Advantages
Achieving decrease ratios of 1/100 and up to even 1/300 simply by using such a compact light arrangement of gears can’t be matched simply by any other gear type.
The harmonic drive may be the only gear arrangement that doesn’t feature any backlash or recoil effect, or at least they are negligible used. This is mainly thanks to the elliptical bearing installed on the external rim of the insight shaft permitting the free of charge 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 necessity to improve anything, plus they wthhold the same positional accuracy about both spin directions.
The efficiency of the harmonic drive measured on real shaft to shaft tests by the producer rises to 90%. There are extremely few mechanical engineering elements that can claim this operational performance level.
Uses for a harmonic drive
In short a harmonic drive can be utilized “in any gear reduction program where little size, low weight, zero backlash, very high precision and high reliability are required”. Examples include aerospace applications, robotics, electric automobiles, medical x-ray and stereotactic devices, milling and lathe devices, flexo-printing machines, semiconductor tools, optical measuring devices, woodworking machines and camera mind pans and tilt axes. The most known examples of harmonic drive applications include the wheels of the Apollo Lunar Rover and the winches of the Skylab space station.