The so-called universal joint; Refers to the use of ball type and other devices to realize the different direction of output shaft power, it is also an important part of the car. Universal joint and combination of transmission, known as the universal joint transmission device. On the front engine rear wheel drive vehicles, universal transmission device installed in the gearbox output shaft and drive axle of the main reducer input shaft between; And front engine front-wheel drive vehicles omit the transmission shaft, universal joint is installed in the steering system is responsible for driving and responsible for between front axle and half axle and the wheel.