DESMODROMIC VALVE PDF

Desmodromic valve drive was often justified by claims that springs could not close valves reliably. There was once a time when Desmodromic valve technology was cutting edge and a necessary competitive advantage for Ducati in racing. Ducatisti around the world know that the red bikes have desmo valves. Not all of them can tell you what that means, exactly. The Greek words.

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Technical reviews and explanations of some in-car gadgets. In mechanical terms, the word desmodromic is used to refer desomdromic mechanisms that have different controls for their actuation in different directions.

A desmodromic valve is a reciprocating engine poppet valve that is positively closed by a cam and leverage system, rather than by a more conventional spring. Ultimately, Ducati uses desmo because it knows desmo and also because it is known for desmo.

You should have enough rep to comment now: Archived copy as title Webarchive template wayback links All articles with unsourced statements Articles with unsourced statements from January Accuracy disputes from Desmodromuc All accuracy disputes Articles with unsourced statements from March All articles with vague or ambiguous time Vague or ambiguous time desmodromicc November I think it’s possible that things could shift so that desmo valves once again have a performance edge.

A second, complementary cam lobe on the same camshaft operates an L-shaped closing lever whose clevis-shaped other end pulls the valve closed, acting against the underside vlve a collar fixed to the valve stem.

Desmodromic valve system

Ducati Meccanica, the motorcycle division, was questioning its very existence. It should be noted that Taglioni also was the driving force behind the wildly successful L-twin. This was somewhat acceptable, because engineers and customers alike prized the simplicity and large service intervals valve springs offered.

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Given the metallurgy of the day it required a lot of spring pressure to ensure that the spring was push the valve closed. Part of the Automobile series. It’s called the desmodromic valve train. As such, valve springs would often break. The main physical aspect of desmodromic systems that make mitigates this problem is that the engine no longer has to overcome the static force from the spring mechanism.

This denotes the major characteristic of the valves being continuously “bound” to the camshaft. It must work against the momentum of the valve opening and closing, and that force still depends on the effective mass of the moving parts.

Why things are the way they are: Desmodromic valves

He worked for Ducati, and inhe developed a desmodromic system for Ducati motorcycles. Today, most cams have mirror image symmetric profiles with identical positive and negative acceleration while opening and closing valves.

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This is great when a car is going fast, but engines with stiffer valvr have to work harder at lower RPMs, resulting in worse fuel economy and greater wear on the engine and valvetrain. Enter the Land of Joy. As in a valve-spring engine, a cam lobe operates a pivoted finger follower that presses against the end of the valve stem to open the valve.

The disadvantage of the Desmodromic valve system is its complexity and cost. The highest peak of technology and Ducati design to reach the maximum perfomances. The SuperSport perfectly balances sport and comfort to guarantee excitement and riding pleasure. News from all around the word.

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Desmodromic valve drive

Since those days, lift, velocity, acceleration, and jerk curves for cams have been modelled by computer [6] to reveal that cam dynamics are not what they seemed. The common cam and spring mechanism is perfect for engines that keep rev counts low and are meant to be low maintenance. Not all of them can tell you what that means, exactly.

Yes, sometimes it acts on a rocker arm or a shim bucket, but the protrusion that is the lobe is handling the opening duties. Desmodromic valve actuation has been applied to top-of-the-range production Ducati motorcycles sincewith the introduction of the “widecase” Mark 3 single cylinders. If you want to know more or refuse the use of some or all cookies click here.

That is, as the valve lifts, the pressure under the gas piston rises steeply, allowing valve return force to be very much greater at full lift than when the valve is on its seat. And while the overall efficiency possible in a Desmodromic design can not be achieved in current applications it’s main advantage, greater power output, can be achieved at less expense by using four or more valves per cylinder.

Why did Ducati decide to use the desmodromic valve train rather than a more tradition valve train?

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