Valve Springs
In
the 1980's, Renault introduced pneumatic valve springs in 1500cc Formula
One engine technology. The springs consist of bellows (made of metal)
which consume an area roughly the same space as metal springs such as
those used to close the valves in high performance combustion engines.
A good engineering practive is to minimise the quantity of moving parts, this reduces the failure rate. The restriction in sped in which metal springs could close often reduced in failure in high performance engines such as those used in forumal one racing vehicles. This led to engine failure when the pistons smashed into the unclosed valves.
The idea to replace the steel springs with low density compressed air bellows (making response times shorter) was introduced by Renault. This reduced the possiblity of valve crashes.
To keep a sprung coil valve under pressure requires a certain amount of seat tension which results in a drastically higher peak lift. By replacing the springs regularly the incidence of bellow failures is much reduced.
The advantage was entirely Renault's using the pneumatic valves within it turbo charged performance engines.
A valve spring holding is the installed altitude variable. This is too recognize as assembled altitude and measures the length between the margin (outer) of the valve retainer and the bottom outer spring. The new proportion is the pouch in the chief of the cylinder.