Strain wave reducer was invented or created by American inventor Mr. C. Walt Musser in the mid 1950s.
I.Composition of strain wave reducer device
strain wave reducer mainly consists of three basic parts, i.e. wave generator, flexspline and rigid spline.
Wave generator：It is composed of flexible bearing and oval cam. Wave generator is generally equipped at the input end of reducer with internal circle of flexible bearing fixed on the cam and elastic deformation of external circle to oval shape realized by means of roll balls.
Flexspline：It is a part of thin-walled elastomer carrying external tooth circle，which is generally equipped at output end of reducer.
Circular spline：It is a part of rigid round ring carrying internal tooth circle, in general, it holds 2 more gear teeth than those of flexspline. The rigid spline is usually fixed on the body of reducer machine.
II.Strain wave reducer principle
When strain wave wave is used as a speed reducer, wave generator is active, Circular spline is fixed, and flexspline takes output form.
When wave generator is loaded into internal circle of flexspline, flexspline is deformed to oval shape due to elasticity, then flexspline teeth at long axis place are inserted into rigid spline thoroughly, thus complete meshing status is realized. At this time, two wheels of gear teeth at short axis place do not contact completely, in other words, at the disconnected position. In the process from meshing to disconnection, the strain wave reducer is at the status of meshing out or meshing in.
When wave generator rotates continuously, flexspline is deformed unceasingly, two wheels of gear teeth will change their own working status from meshing in, meshing, meshing out to disconnection, thus the so-called staggered movement happens, finally movement transmission from active wave generator to flexspline is achieved.
III.Characteristics of strain wave reducer
High precision：Multiple teeth simultaneously mesh at two symmetry positions of 180°, hence, error of gear teeth space and accumulated error of teeth space impact evenly on rotation precision, therefore, extremely high position and rotation precision can be obtained.
Big transmission ratio：Single transmission ratio of strain wave reducer can reach i=30～500, furthermore, the structure is very simple, and three fundamental parts on the same axis can easily achieve high reduction ratio.
High bearing capacity：During strain wave reducer, teeth meshing belongs to surface contact, furthermore, comparatively more teeth can mesh together simultaneously, therefore, unit area bears small load, and load capacity is higher than that of other transmission forms.
Small size and light weight：Compared with ordinary gear device, strain wave reducer can significantly reduce size and weight, thus, miniaturization and light weight can be achieved in production..
High transmission efficiency and long life.
Smooth transmission, free shock and little noise.