Camshaft and valvetrain technology is a topic we've written much about over the years. The basic technology that's been used to actuate the valves hasn't changed in decades, whether we're talking pushrod engines or overhead cam engines. A rotating eccentric lobe on a camshaft still opens the valves. In the case of an overhead valve engine, the cam lobe pushes a follower or bucket tappet to open the valve. With a pushrod engine, the cam lobe pushes a lifter, pushrod and rocker arm to open the valve. In the 1980s, Renault introduced its exotic "pneumatic valve springs" as an alternative to ordinary mechanical coil wire valve springs for Formula One racing. With this setup, the valve springs are replaced with small bucket style cylinders that are pressurized internally with nitrogen gas. The air springs can handle engine speeds up to 16,000 rpm or higher, which is beyond the capacity of traditional metal coil springs. Pneumatic springs are now the norm for Formula One racing, but it's unlikely many of our readers will ever see this exotic technology on a drag strip, circle track or street engine any time soon.
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