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Double Universal Cardan Joint
Assignment
Even though universal joints can transfer a great deal of torque, they have however, only one diffraction angle of maximum 25°. Moreover, with increasing diffraction angle, they transfer the rotary movement irregularly.
The problem is solved, e.g., on the front axle of an all-wheel-drive vehicle (figure 2) by using a double universal joint. It can transfer the high torque resulting particularly in utility vehicles at a maximum diffraction angle
of 47°.
Function
Two universal joints are connected through two cross pins by a ring with each other. This ring causes a difraction of the second joint to the first of 90°. This can be seen nicely in the above figure 1. A little irritating in
this case, is maybe, that both forks in the center piece are arranged in the same manner, apparently with 0° defraction. Nonetheless, the 90° refers, in each case to the power-delivery side. In reality, the left joint is
angled, in relation to the right joint, by 90°. This can sometimes still easily be seen in truck cardan shafts. On the center piece, both forks are arranged in the same direction.
Because the diffraction angles of both joint-sections are held the same, the Double universal cardan joint can be described as homo-kinetic if the shafts are parallel in front of, and behind the cardan shaft. Its only
disadvantage is the complex and heavy construction. In the motor car it was replaced by the ball joint. 03/09
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