Universal joint, is part of the power transfer to realize variable Angle, used to need to change the location of the drive axis direction, it is the universal transmission device of car driving system of the "joint" part. 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.