.~.~ Including plural controlled inlet or outlet flow paths {2}
495
.~.~.~ Pumping member comprises valved piston
DEFINITION
Classification: 417/495
(under subclass 493) Apparatus including a piston type pumping member provided with a fluid passage extending from the end face thereof through the opposite end of the piston or through a side wall portion thereof, said passage being provided with a relatively movable valve means to control the flow of fluid through said passage.