The component comprises a rigid wheel with inner teeth, a flexible wheel with radial elastic deformation and outer teeth when working, and a wave generator with oval shape and flexible rolling bearing on the outer ring inside the flexible wheel.The outer teeth of flexible wheel are less than the inner teeth of rigid wheel.When the wave generator is rotating, the external teeth of the flexible wheel corresponding to the direction of the long axis exactly penetrate into the inner teeth of the rigid wheel.In the direction of the short axis, the outer teeth all open the inner teeth.When the rigid wheel is fixed and the wave generator rotates, the outer teeth of the flexible wheel will successively bite in and out the inner teeth of the rigid wheel, and the radial displacement of any point on the flexible wheel tooth ring will be approximately sinusoidal waveform change, so this kind of transmission is called harmonic transmission.