Constant-velocity Joint - Tracta Joints

Tracta Joints

The Tracta joint works on the principle of the double tongue and groove joint. It comprises only four individual parts: the two forks (a.k.a. yokes, one driving and one driven) and the two semi-spherical sliding pieces (one called male or spigot swivel and another called female or slotted swivel) which interlock in a floating (movable) connection. Each yoke jaw engages a circular groove formed on the intermediate members. Both intermediate members are coupled together in turn by a swivel tongue and grooved joint. When the input and output shafts are inclined at some working angle to each other, the driving intermediate member accelerates and decelerates during each revolution. Since the central tongue and groove joint are a quarter of a revolution out of phase with the yoke jaws, the corresponding speed fluctuation of the driven intermediate and output jaw members exactly counteract and neutralize the speed variation of input half member. Thus the output speed change is identical to that of the input drive, providing constant velocity rotation.