Cardan joints are key components in various mechanical systems, playing a significant role in the transmission of rotary motion and power between two non-collinear shafts. They are found in many automotive, industrial and agricultural machines. The term "universal joint", which is widely used in the English-speaking world, first appeared in one of Henry Ford's patents at the end of the 19th century.
What is a cardan joint?
A cardan joint is a mechanical connection between two rotating shafts, usually at an angle to each other.
It allows the shafts to move freely, but prevents them from twisting relative to each other, thus enabling torque to be transferred from one shaft to the other.
Its main function is therefore to transmit rotary motion and torque, even when the shafts are not perfectly aligned. This capability makes the cardan joint indispensable in drive chains where the shafts have to accommodate angular misalignments.
How does it work?
The cardan joint The central element is the so-called cardan cross., which essentially consists of two pairs of perpendicular pins connected to forks mounted at the ends of the axles or formed from a single piece with them. bearings through. Each joint is connected to an axle, allowing the axles to rotate around the axle pin.
When one shaft rotates, the joint mechanism allows the other shaft to rotate as well, regardless of the angle between the shafts.
Its history
The principle of the cardan joint arose from the use of cardan suspension, which has been known since ancient times. One of its first applications was in the operation of the ballista, a siege engine invented by the ancient Greeks.
In 1545, Italian mathematician Gerolamo Cardano was the first to propose the use of the cardan joint for propulsion., However, it is doubtful whether he ever tried out his theory in practice.
Later Christopher Polhem Swedish scientist and entrepreneur also invented it, In 1676, Robert Hooke created a working model.
Did you know? Polhem is referred to as the father of Swedish mechanics. His work is exhibited in a museum set up in his laboratory, and his portrait adorned the old Swedish 500 krona banknote.
Cardan joints are crucial in mechanical engineering, as they provide the flexibility needed to transmit power across angular misalignments. Their robust and simple design makes them invaluable in a wide range of applications, from automotive drive shafts to industrial machines.
The image shows Polhem's portrait on a Swedish banknote that is no longer in circulation. Image source: sedelmynt.se.
