There are many forms of universal joints (See Model Case II). The advantage of this form is that it is noiseless in its action. The leather disks are very flexible and keep changing position. It is necessary to use a universal joint as the engine shaft and drive shaft are always out of line and every vibration of car changes angle.
[Virginia Downward & William M. Clark, 1930]

[Editor’s Note: There are several other universal joint models (Clark 17, 18, 19) that are constructed of solid elements. In this model the two rotating shafts are connected with a flexible leather element. In recent years, so-called 'compliant' mechanisms have replaced rigid kinematic mechanisms in many areas of machine design. In the Reuleaux models, there is a 'P' Series that are rigid kinematic universal joints. FCM]

Francis Moon 2005-00-00