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The power of precision inside the Ducati 1199
Controlling such large valves with the precise Desmodromic system also led engineers to replace the original belt-drive concept with a combined chain and gear-drive arrangement.
The conventional bush-type chain runs from the crankshaft to the cylinder head where a single sprocket positioned between inlet and exhaust camshafts, is attached back-to-back to a gear wheel mounted on its own short, dedicated shaft. The attached gear meshes directly with gears on the ends of both the inlet and exhaust camshafts, which are also designed with +/- position adjustment for ultra-precise cam-timing. The cam chain, therefore, provides highly efficient point-to-point drive route and, tensioned automatically, provides continuous reliability and further reducing the cost of routine maintenance.
On the end of each exhaust cam drive gear is a centrifugal flyweight which retracts at speeds below tick-over to rotate a "protrusion" from the concentric section of the cam, thus creating just enough inlet valve lift to act as a de-compressor. This ingenious device enables the Superquadro engine to be started easily without using a larger battery and starter motor, which has reduced overall vehicle weight by approximately 3.3kg (7.3lb). When the engine starts and the camshafts begin to rotate at tick-over speed, the centrifugal flyweight flicks out, retracting the "protrusion" back into the cam and allowing complete valve closure for full compression. This innovative feature further underlines the lengths to which designers and engineers have worked together in the single-minded pursuit of weight-saving.
Source: Ducati
Controlling such large valves with the precise Desmodromic system also led engineers to replace the original belt-drive concept with a combined chain and gear-drive arrangement.
The conventional bush-type chain runs from the crankshaft to the cylinder head where a single sprocket positioned between inlet and exhaust camshafts, is attached back-to-back to a gear wheel mounted on its own short, dedicated shaft. The attached gear meshes directly with gears on the ends of both the inlet and exhaust camshafts, which are also designed with +/- position adjustment for ultra-precise cam-timing. The cam chain, therefore, provides highly efficient point-to-point drive route and, tensioned automatically, provides continuous reliability and further reducing the cost of routine maintenance.
On the end of each exhaust cam drive gear is a centrifugal flyweight which retracts at speeds below tick-over to rotate a "protrusion" from the concentric section of the cam, thus creating just enough inlet valve lift to act as a de-compressor. This ingenious device enables the Superquadro engine to be started easily without using a larger battery and starter motor, which has reduced overall vehicle weight by approximately 3.3kg (7.3lb). When the engine starts and the camshafts begin to rotate at tick-over speed, the centrifugal flyweight flicks out, retracting the "protrusion" back into the cam and allowing complete valve closure for full compression. This innovative feature further underlines the lengths to which designers and engineers have worked together in the single-minded pursuit of weight-saving.
Source: Ducati
