Among the many advantages of a harmonic drive may be the insufficient backlash because of the unique style. However, the fact that they are light-weight and intensely compact can be important.
High gear reduction ratios of up to 30 times that achieved with planetary gears are feasible in the same space.
C W Musser designed strain wave gearing back 1957 and by 1960 he was already selling licenses to ensure that industry giants might use his patented item.
harmonic drive assembled The harmonic drive is a kind of gear arrangement often referred to as a strain wave gear due to just how it works. It really is some sort of reduction gear mechanism consisting of a minimum of three main elements. These components interact in a way that allows for very high precision decrease ratios that could otherwise require much more complicated and voluminous mechanisms.

As a product, 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 taken to the table. Musser recognized the potential of his invention at an early on stage and in 1960 began selling licenses to producers so they might use his patented product. Today, there are only a handful of manufacturers in america, Germany, and Japan who are keeping the license to produce harmonic drives, doing this at their top-notch services and creating ultimate quality stress gears for the whole world.

harmonic drive exploded viewThe workings of a harmonic drive
The rotational movement comes from an input shaft which can be a servo engine axis for instance. This is connected to an component called “wave era” which includes an elliptical form and is normally encircled by an elliptical ball bearing. As the shaft rotates, the edges change position, so it appears like it really is generating a movement wave. This part is inserted inside a flex spline that is crafted from a torsionally stiff however flexible materials. The material occupies this wavy motion by flexing according to the rotation of the input shaft and in addition produces an elliptical form. The outer advantage of the flex spline features gear teeth that are ideal for transferring high loads with no problem. To transfer these loads, the flex spline is fitted in the circular spline which really is a round equipment featuring internal teeth. This outer band is definitely rigid and its internal diameter is marginally bigger than the major axis of the ellipse produced by the flex spline. This implies that the circular spline will not believe the elliptical form of the additional two parts, but instead, it just meshes its internal teeth with those of the outer flex spline aspect, resulting in the rotation of the flex spline.

The rate of rotation would depend on the rotation of the input shaft and the difference in the number of teeth between your flex spline and the circular spline. The flex spline provides fewer teeth compared to the circular spline, so that it can rotate at a much decreased ratio and in the contrary direction than that of the insight shaft. The reduction ration is given by: (number of flex spline teeth – amount of circular spline tooth) / number of flex spline teeth. So for example, if the flex spline provides 100 teeth and the circular spline provides 105, the reduction ratio is (100 – 105) / 100 = -0.05 which implies that the flex spline ration is -5/100 (minus indicates the opposite 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 or more to even 1/300 simply by using such a concise light set up of gears cannot be matched simply by any additional 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. That is mainly because of the elliptical bearing fitted on the external 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 forwards and backward rotation with no need to change anything, plus they retain the same positional accuracy on both spin directions.
The efficiency of the harmonic drive measured on real shaft to shaft studies by the producer goes up to 90%. There are extremely few mechanical engineering elements that may claim this operational effectiveness level.
Uses for a harmonic drive
In a nutshell a harmonic drive can be utilized “in virtually any gear reduction application where little size, low weight, zero backlash, high precision and high reliability are needed”. Examples include aerospace applications, robotics, electric vehicles, medical x-ray and stereotactic devices, milling and lathe devices, flexo-printing machines, semiconductor tools, optical measuring machines, woodworking devices and camera mind pans and tilt axes. The most notable examples of harmonic drive applications include the tires of the Apollo Lunar Rover and the winches of the Skylab space station.