In practical application

especially under small torque

total output torsional stiffness of precision harmonic gear is much less than its nominal value.To find out the reason

a set of precision torsional stiffness test system on output shaft of harmonic gear is designed.The input shaft of the harmonic gear is fixed

bi-directional gradual change force couple is applied to the output shaft through a torque plate.A photoelectric autocollimator is used to measure the tiny rotation angle of the output shaft.Then precision torsional stiffness of the output shaft can be calculated out.Torsional stiffness tests of a certain type of precision harmonic gear in 6 different working positions are carried out.Test results show that the angle-torque characteristics of the measured harmonic gear are different when it’s in different working positions

the torsional stiffness of the output shaft is high enough and it will not lead to the insufficient stiffness of the harmonic gear.