(under subclass 510) Apparatus in which the pumping member comprises a piston, said piston or an element rigid therewith (e.g., piston rod) having a pump fluid connecting passage formed therein, the mechanically actuated valve element being located within or carried by the piston and positioned in flow controlling relationship with said piston passage for performing the valving function.
SEE OR SEARCH THIS CLASS, SUBCLASS:
511, for a distributor carried by a piston in which either the distributor or piston frictionally engages a chamber wall and the pump drive rod is rigid with the other.
