The variation law between the dynamic contact equivalent stress and time of helical gear is shown in the figure:

It can be seen from the figure that the contact equivalent stress of the helical gear is small when the speed slowly rises at the beginning, and the operation is relatively stable without large fluctuations. At 0.025s, the speed of the helical gear reaches the maximum, and the contact equivalent stress of the helical gear also rises to the maximum. As the helical gear continues to operate, the helical gear keeps the speed and applied torque unchanged, the helical gear basically operates smoothly, and the maximum contact equivalent stress does not fluctuate greatly.