Principle: the principle of constant speed transmission is achieved according to the double cross shaft universal joint. When the universal joint fork swings within a certain angle range from the bearing fork of the universal joint mill, ensuring that the angular velocity of the two axles is close to the same, and the double-link fork is also driven to deflect the corresponding angle, so that the angle difference between the central line of the cross shaft of the two full-loaded roller bearings and the axis of the cross shaft of the two universal joint is very small, within the allowable range of the difference, the double-link. The universal joint has quasi isokinetic joint bearing property.

Advantages: allowing a larger angle between axles, reliable operation and simple structure. It is easy to manufacture, and the maximum angle of intersection can reach 50 &. Double universal joint used for steering drive axle, but it must be structurally ensure that the center of double universal joint is located at the intersection of the main pin axis and the half shaft axis, which can not have indexing mechanism to ensure constant speed transmission.