Universal joint is a mechanical part that realizes variable Angle power transmission and is used for changing the direction of the transmission axis. It is the "joint" part of the universal transmission device of the automobile drive system. The combination of universal joint and drive shaft is called universal joint transmission device.
The so-called universal joint refers to the use of ball-type devices to realize the shaft power output mechanism in different directions. A bit like the joints on the limbs of the human body, it allows the angle between the connected parts to vary within a certain range.