In a Internal Combustion Engine, camshaft is responsible for opening and closing of the intake and exhaust valves. The input of the camshaft is taken from the crank and generally it is driven by the chain & sprocket mechanism. In a bevel mechanism, a shaft with splined or spiral bevel gears will be linking the crank and camshaft. Still now, we can able to see this mechanism in the Kawasaki W800 motorcycle.
Though the bevel drive takes less amount of space than a chain or belt drive, its still complicated. Motorcycle manufacturer Ducati implemented this mechanism combining it with their Desmo system which resulted in its own advantages of precise valve control without the problem of re-adjusting the tension.
The ratio of 2:1 must be achieved as the camshaft's speed must be haft the speed of the crankshaft. This is achieved by varying the number of teeth in the bevel where in the case of belt and chain drive, the diameter of the pulley and sprocket will be adjusted.
Bevel driven camshafts doesn't require any auto adjustment system like tensioners thereby resulting in ultimate weight reduction. But, the linear expansion between the crankshaft and the head must be taken in account seriously in the bevel implemented cam system.
Comparing this system with the traditional pushrod engines, extra reciprocating masses are totally neglected. Bevel mechanism doesn't change its timing whereas other driving mechanisms may vary in dimensions with respect to wear and heat. It have low rotating mass and the friction produced is very less compared to that of the other mechanisms.
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Though the bevel drive takes less amount of space than a chain or belt drive, its still complicated. Motorcycle manufacturer Ducati implemented this mechanism combining it with their Desmo system which resulted in its own advantages of precise valve control without the problem of re-adjusting the tension.
The ratio of 2:1 must be achieved as the camshaft's speed must be haft the speed of the crankshaft. This is achieved by varying the number of teeth in the bevel where in the case of belt and chain drive, the diameter of the pulley and sprocket will be adjusted.
Bevel driven camshafts doesn't require any auto adjustment system like tensioners thereby resulting in ultimate weight reduction. But, the linear expansion between the crankshaft and the head must be taken in account seriously in the bevel implemented cam system.
Comparing this system with the traditional pushrod engines, extra reciprocating masses are totally neglected. Bevel mechanism doesn't change its timing whereas other driving mechanisms may vary in dimensions with respect to wear and heat. It have low rotating mass and the friction produced is very less compared to that of the other mechanisms.
Related articles
SOHC vs DOHC - Simplified
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