Universal joints that universal joints, the universal joint name, is to achieve variable angle power transmission of the machine, for the need to change the direction of the transmission axis position, which is the drive system of the universal drive "joint" components. Gimbal and drive shaft combination, known as universal joint drive. Gimbal structure and role a bit like a human body joints on the limbs, which allows the angle between the connected components within a certain range change. In order to meet the power transmission, to adapt to the steering and car running up and down the angle caused by the change, the front drive car drive axle, axle and axles commonly used between universal joints connected. However, due to the axial size constraints, the required declination is relatively large, a single universal joint can not make the output shaft and shaft into the shaft instantaneous angular velocity equal to easily lead to vibration, aggravate the mechanical damage, resulting in a lot of noise, So widely used a wide range of constant velocity joints. On the front drive vehicle, with two constant velocity joints per half axle, the gimbal near the transaxle is the half-axle inner joint and the axle near the axle is the outer half-joint. In rear-drive vehicles, the engine, clutch and transmission are mounted as a unit on the frame, while the transaxle is connected to the frame via a flexible suspension with a distance between the two that needs to be connected. Car running uneven road surface beating, load changes or assembly of the two assembly differences, will make the transmission output shaft and the drive shaft angle reducer input shaft and the distance between the change, so after driving the car Universal joint transmission forms are used double universal joints, that is, each end of the drive shaft has a universal joint, whose role is to make the angle between the two ends of the transmission shaft equal to ensure that the output shaft and shaft into the shaft instantaneous angular velocity is always the same. Gimbal is to achieve variable angle power transmission mechanism for the need to change the direction of the transmission axis position.