Re "Enigmatic Pneumatics On Some Ampico A Actions"

The strange little 1" square pneumatics which D.L. Bullock refers
to on a few of his Ampico spring pneumatic mechanisms is a loud pedal
compensator.  They try to oppose the spring pneumatic, equivalent to a
bellows that measured about 1/2" square.  That's why they are attached
about in the middle of the spring pneumatic.  They are paralleled and
teed into the pedal valve output.

Craig Brougher