Among the many advantages of a harmonic drive may be the lack of backlash due to the unique design. However, the fact they are light-weight and extremely compact is also important.
High gear reduction ratios of up to 30 moments that achieved with planetary gears are possible 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 could use his patented product.
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 equipment mechanism comprising at the least three main parts. These components interact in a manner that allows for very high precision decrease ratios that could otherwise require a lot 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 a variety of advantages that it brought to the table. Musser discovered the potential of his invention at an early on stage and in 1960 began offering licenses to producers so they could use his patented product. Currently, there are just 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 creating ultimate quality stress gears for your world.
harmonic drive exploded viewThe workings of a harmonic drive
The rotational movement comes from an input shaft which can be a servo electric motor axis for instance. This is connected to an element called “wave era” which includes an elliptical shape and can be encircled by an elliptical ball bearing. As the shaft rotates, the edges switch position, so that it appears like it is generating a motion wave. This part is inserted in the flex spline that’s crafted from a torsionally stiff yet flexible materials. The material occupies this wavy motion by flexing based on the rotation of the insight shaft and also creates an elliptical shape. The outer edge of this flex spline features gear tooth that are ideal for transferring high loads with no issue. To transfer these loads, the flex spline is installed in the circular spline which is a round gear featuring internal teeth. This outer ring can be rigid and its own internal size is marginally larger than the major axis of the ellipse formed by the flex spline. This means that the circular spline does not assume the elliptical shape of the additional two elements, but instead, it simply meshes its internal teeth with those of the external 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 has fewer teeth than the circular spline, so it can rotate at a much reduced ratio and in the opposite direction than that of the insight shaft. The reduction ration is distributed by: (quantity of flex spline tooth – amount of circular spline teeth) / quantity of flex spline tooth. So for instance, if the flex spline provides 100 teeth and the circular spline has 105, the decrease 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 amount of teeth could be changed to support different decrease ratios and thus different specialized demands 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 cannot be matched simply by any 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. This is mainly because of the elliptical bearing fitted on the external rim of the input shaft allowing 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, and they retain the same positional accuracy in both spin directions.
The efficiency of the harmonic drive measured on real shaft to shaft tests by the producer goes up to 90%. There are very few mechanical engineering components 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 software where little size, low weight, zero backlash, very high precision and high reliability are needed”. Examples include aerospace applications, robotics, electric automobiles, medical x-ray and stereotactic machines, milling and lathe devices, flexo-printing devices, semiconductor devices, optical measuring devices, woodworking devices and camera head pans and tilt axes. The most notable types of harmonic drive applications are the tires of the Apollo Lunar Rover and the winches of the Skylab space station.
