Air spring
An air spring is a carefully designed rubber/fabric bellows which
contains a column of compressed air. The rubber bellows itself does not
provide force or support load. This is done by the column of air.
Firestone air springs are highly engineered elastomeric bellows with
specially designed metal end closures. The standard two ply bellows is
actually made up of four layers:
a. An inner liner of calendered rubber.
b. One ply of fabric reinforced rubber.
c. A second ply of fabric-reinforced rubber (with the cords at a specific bias angle to the first ply).
d. An outer cover of calendered rubber.
Many are also available in high strength construction for higher
pressures. In this case, there are four plies of fabric-reinforced
rubber, with an inner liner and outer cover.