Universal joint is universal joint, English name universal joint, is to achieve variable Angle power transmission parts, for the need to change the direction of the transmission axis position, it is the automotive drive system of the universal transmission device "joint" parts. The combination of universal joint and transmission shaft is called universal joint transmission device. In the front engine rear-wheel drive vehicle, the universal joint transmission device is installed between the transmission output shaft and the drive axle main reducer input shaft; In front-engine, front-wheel-drive vehicles, the drive shaft is omitted and the universal joint is mounted between the front axle axle, which is responsible for both driving and steering, and the wheels.