Fluid pump

Claim 1

A fluid pump comprising: a. a main body; b. a pair of housings each disposed at an opposite side of said body; c. a pair of pumping diaphragms one in each of said housings and dividing the interior of each housing into primary and secondary pressure chambers; d. inlet and discharge manifolds disposed to communicate with said secondary pressure chambers and havIng one-way check valves therein and secondary inlet and outlet ports respectively; e. means connecting said diaphragms together for common reciprocatory movement in their respective housings; f. said main body defining primary inlet and outlet ports and passage means connecting said primary inlet and outlet ports to said primary chambers, said passage means including pilot and reversing valve chambers, said primary inlet port being adapted for connection to a source of fluid under pressure; g. and a pilot valve and a reversing valve movably mounted in respective ones of said pilot and reversing valve chambers; h. said pilot valve being movable alternately in opposite directions responsive to movement of said diaphragms to control flow of fluid to said reversing valve chamber; said pilot valve comprising a spool axially movable in said pilot valve chamber and having a diametrically reduced portion within said pilot valve chamber, a tubular member encompassing said reduced portion and axially movable relative to said main body and spool, and stop means in said pilot valve chamber limiting movements of said tubular member axially of said spool; i. said reversing valve being fluid pressure operated and operative responsive to movement of said pilot valve in opposite directions to direct flow of fluid from said primary inlet and alternately to said primary pressure chambers and from alternating primary pressure chambers to said outlet port.