Variable reciprocating plunger pump

Claim 1

A reciprocating plunger pump having readily variable pumping modes comprising; a pump housing including an enclosed pump chamber, a valved inlet to said pump chamber, a valved outlet from said pump chamber, a first plunger hole, and a second plunger hole having an enlarged recess adjacent a side of said pump chamber; a first plunger located in said first plunger hole having a piston end extending into said pump housing and an outer end extending outside of said housing which is suitably driven, said first plunger being integrally formed and driven in a reciprocal motion in said first plunger hole of said housing along a reciprocationn axis that in a first pumping mode said first plunger alone produce a reciprocating pumping action in said pump chamber whereby a fluid is pumped into said pump chamber through said inlet and out of said pump chamber through said outlet; a second plunger located in said second plunger hole having an inner end extending into said pump chamber through said recess and an outer end located outside of said pump housing, said inner end being slightly enlarged so as to be receivable in said recess and prevented from being pushed out of said second plunger hole, said second plunger being integrally formed and mounted for reciprocation along the reciprocation axis and for rotation about the reciprocation axis; and an attaching means for removably attaching said inner end of said second plunger to said piston end of said first plunger, said attaching means including (a) a screw projecting from said inner end of said second plunger along the reciprocation axis, (b) a threaded hole located in said piston end of said first plunger in which said screw is threadably received, and (c) an actuation means located exterior to said pump housing for actuating said attaching means, said actuation means including an adaptation on said outer end which is clear of said pump housing and all other pump elements such that said second plunger is easily gripped and rotated to engage and disengage said screw from said threaded hole and to locate said enlarged inner end of said second plunger in said recess when said inner end is disconnected from said piston end; whereby the attaching of said second plunger to said first plunger in a second pumping mode results in a high pressure and low volume pumping of the fluid and the detaching of said second plunger from said first plunger in the first pumping mode results in a lower pressure and higher volume pumping of the fluid as said enlarged inner end is received in said recess of said pump chamber.