WHAT ARE THE ADVANTAGES AND DISADVANTAGES OF UNIVERSAL COUPLINGS?

1. The structure of the cross axle universal coupling consists of a cross shaft, two universal joint forks, and four needle bearings; the rotation centers (axes) of all the rotating pairs of the universal-joint shaft coupling intersect at a point o, and the angle between the two shafts is α; it is a device (coupling) used to transmit the motion between two intersecting shafts with variable angles.

2. The working principle of the universal-joint shaft coupling: when shaft I rotates one circle, shaft II will also rotate one circle, that is, the average transmission ratio of the two shafts is 1; but the instantaneous transmission ratio of the two shafts is not always 1, but changes periodically; this characteristic of the universal Cardan shafts is called the unevenness of the instantaneous transmission ratio; for a single universal joint, when there is an angle between the input shaft and the output shaft, the angular velocities of the two shafts are not equal, that is, the cross axle universal coupling has non-uniform speed; the larger the angle α between the two shafts of the universal coupling, the more obvious the speed fluctuation of the driven shaft; therefore, α should be between 350 and 450. In order to prevent the angular velocities of the driving and driven shafts of the universal-joint shaft couplings from being unequal; in order to completely eliminate the disadvantages of the variable speed transmission of the driven shaft in the above-mentioned universal joint, they are often used in pairs.

3. Advantages of universal joint drive shafts: It has a large angular compensation capacity, compact structure, and high transmission efficiency;

4. Disadvantages of cross axle universal couplings: It will generate additional dynamic loads during transmission, and the speed should not be too high;

5. Application occasions of universal Cardan shafts: It is mainly used for transmission of two intersecting shafts, heavy load, medium load, light load and other medium and low speed occasions, such as machine tools and automobiles.

6. Conditions that double universal couplings should meet:

In order for the cross axle universal coupling to obtain a constant transmission ratio, the mechanism must meet the following three conditions:

(1) The three axes of the driving shaft, driven shaft, and intermediate shaft of the universal joint drive shaft should be located in the same plane.

(2) The inter-axial angles of the driving shaft, driven shaft and intermediate shaft of the universal coupling should be equal.

(3) The fork surfaces at both ends of the intermediate shaft of the cross axle universal coupling should be located in the same plane.