When the angle between the two shafts connected by the universal joint is greater than zero, the output shaft and the input shaft transmit motion at a variable instantaneous angular velocity ratio, but the average angular velocity is equal to the universal joint.
The cross shaft type rigid universal joint is composed of universal joint fork, cross shaft, needle bearing, oil seal, sleeve sleeve, bearing cover and other parts. The working principle is: one of the rotating forks drives the other fork to rotate through the cross shaft, and at the same time, it can swing in any direction around the center of the cross shaft. The needle roller in the needle roller bearing can rotate on its own during rotation to reduce friction. The shaft connected with the input power is called the input shaft (also called the driving shaft), and the shaft output through the universal joint is called the output shaft (also called the driven shaft). Working under the condition that there is an angle between the input and output shafts, the angular velocity of the two shafts is not equal, which will cause torsional vibration of the output shaft and the transmission components connected to it and affect the life of these components.