Desmodromic distribution system, that great invention that Ducati engines wear almost exclusively, and which the engineer patented Fabio Taglioni in the fifties (the patent is from 1956) it is also a word that is on the lips of many, but only a few are able to say what it is and how it works. In any case, to make an educational effort, at the Italian museum of "Valle dell’Idice" we will be able to enjoy from next Sunday April 28 until November of this year an exhibition dedicated exclusively to the desmodromic distribution system.
The technical base is relatively simple (like almost all great ideas) since to avoid the problems that come with the springs in the valves of a four-stroke engine, these are replaced by a double rocker system in which one is responsible for opening the valve while the other is responsible for closing it. This way it is possible to specify when and how much a valve opens and it is guaranteed that it always closes at the exact moment.
The springs do not guarantee this at high revolutions, since they may not return to the initial position with the valve closed, which may cause a gas escape through that partially open valve or even that the valve collides with the piston head and cause a mechanical catastrophe. The solution is not to mount harder springs either, since then the engine would need a lot of force to open these valves with the consequent loss of power and performance.
Over time we have seen that in some competition engines the springs have been replaced by pressurized gas systems to guarantee closure and prevent the valves from floating at high revs. But this system makes the maintenance of the engines very expensive in addition to increasing their weight due to all the accessories it needs to function. The genius of the patent for Fabio Taglioni's invention is that it is a completely mechanical system, very reliable and that only slightly increases the weight of the camshafts, which instead of having a single cam have two. Although the first solutions had three camshafts (trialbero) two to open the valves and one to close them. This system is still superior to any other.
The downside is that the desmodromic distribution system is heavily protected by patents Ducati, so if someone wants to use it they have to pay a toll at the Borgo Panigale box. Although in the Italian exhibition we will be able to see material from BMW, Honda, Fiat, Maserati, Mercedes, Peugeot, Scarab and Toyota related to the distribution system. We will have to organize a trip to visit the museum, even if you do not go there in July or August because it will be closed.