As Robbie stated, with most lock and cancel arrangements the cancel
is overridden by the lock command.  A convenient way to convert a lock
and cancel system to using "steady on" coding is to hold the cancel
port "on" permanently.  The valve will then turn on only in response
to the presence of the lock signal.

Of course, it is possible to make a pneumatic flip flop which will act
as a lock and cancel but will not work in this manner and this may be
used in systems other than the Ampico.

Best regards,
Spencer Chase
Garberville, Calif.
http://www.spencerserolls.com/