Today we can observe them mainly in bicycles and motorcycles. In a slightly modified form, they also work under the hoods of some cars, being part of the camshaft. They are much more widely used in heavy industry, transmitting drive power in huge machines. The history of chain transmissions is longer than you might think. And thanks to increasingly advanced CNC machining methods they can be used in even more complex mechanisms.
Brief outline of the story
The first chain transmission report dates back to the 3rd century BC. This mechanism was an element of the repetitive crossbow, which was described by the famous Philon of Byzantium - an ancient mechanic, who is considered to be the constructor of the first catapult.
The chain transmission has probably been improved in China. It is known that during the Song Dynasty, or more precisely in the 11th century, such gears were used in the mechanism of a huge clock (they drove, among others, figurines hitting the chimes). The interesting thing is that the gearbox had to do a continuous work.
In modern times, chain transmissions with reels or primitive sprockets were used in various devices (e.g. port cranes). However, it was the present day that created the real demand for such mechanisms. At the end of the 19th century, they were used in the first bicycles, and several years later in automobiles.
How is a modern chain transmission built?
The chain transmission - in the modern sense - is made up of sprockets (usually two), which are bound by a string (chain). The manufacture of suitable components enables CNC machining. Computer programmed machines cut and shape individual components with great accuracy, thus ensuring optimal operation of the mechanism and avoiding problems that are troubling our ancestors, such as excessive wear of sprockets or deformation of links.
And how does the chain drive work? It's pretty simple. The pull pulley transfers the drive from the driven element to the passive element (both of which are usually sprockets), transferring energy and, depending on needs, changing the parameters of movement, its strength or speed.
Among the greatest advantages of chain transmissions are often mentioned constant speed (no slippage) and low loads on shafts and bearings (because the string mounted on sprockets does not have to be very tight). The disadvantages are, in turn, the need for lubrication and the loud work of certain types of it. What is more, the elements of the chain gears, especially the sprockets, are characterized by a complex construction. However, the answer to this is increasingly precise CNC machining.
Some examples of modern chain transmission applications
The closest and probably best known example of a chain transmission is the bike drive system. And it is in its context that technological progress can be most easily observed. After all, the components are getting closer and closer to perfection, which makes the performance of the bikes much higher than it was a few years ago, and the ride itself is more and more enjoyable.
Chain mechanisms are also used in valve train systems. It is worth remembering, however, that these are much more complicated constructions, which consist of sprockets (usually several) and strings of different lengths.
Other examples of application of chain transmissions can be various types of industrial machinery in which the transmissions act as the main or auxiliary drive, transferring the power generated by the engine.
Visit the website of JANUS - manufacturer of industrial chains >>
