Reciprocating pump, system or reciprocating pumps, and method of driving reciprocating pumps

A method of driving a reciprocating pump, comprising:

• providing a housing having a first pressure chamber and a second pressure chamber disposed therein, wherein the first pressure chamber is at least partially defined by a first flexible member and the second pressure chamber is at least partially defined by a second flexible member;
• filling the first pressure chamber with a control fluid and increasing a volume of the first pressure chamber;
• filling a first piston chamber with the control fluid and pressing a first shift piston at least partially housed within the first piston chamber against the first flexible member;
• displacing the first shift piston to create a shift conduit between an outside surface of the first shift piston and an inside surface of the first piston chamber;
• filling a first shift line in communication with the shift conduit and the first piston chamber with the control fluid;
• and
• displacing the first shift piston and eliminating communication between the first piston chamber and the first shift line.

A reciprocating pump, comprising:

• a body defining a first fluid chamber and a first pressure chamber separated with a first flexible member and a second fluid chamber and a second pressure chamber separated with a second flexible member;
• a shaft connecting the first flexible member and the second flexible member;
• a switching mechanism for alternately supplying control fluid to the first pressure chamber and the second pressure chamber, the first flexible member and the second flexible member being displaceable with the supplied control fluid;
• a first shift piston configured for displacement with the first flexible member and driveable by the supplied control fluid, wherein the first shift piston comprises an elongated member including a first end portion having a first cross-sectional area and a central portion having a second cross-sectional area greater than the first cross-sectional area;
• a second shift piston configured for displacement with the second flexible member and driveable by the supplied control fluid, wherein the second shift piston comprises an elongated member including a first end portion having a first cross-sectional area and a central portion having a second cross-sectional area greater than the first cross-sectional area;
• a first shift line in communication with the supplied control fluid when the first end portion of the first shift piston is adjacent thereto and isolated from the supplied control fluid when the central portion of the first shift piston is adjacent thereto;
• and
• a second shift line in communication with the supplied control fluid when the first end portion of the second shift piston is adjacent thereto and isolated from the supplied control fluid when the central portion of the second shift piston is adjacent thereto.

A system of reciprocating pumps, comprising:

• a control pump having a reciprocating shift piston with at least three bands of contrasting colors;
• an optical sensor configured to detect at least a first position, a second position, and a third position of the reciprocating shift piston;
• a shifting system in communication with the optical sensor, the shifting system configured to shift the supply of a control fluid from a first side of the control pump to a second side of the control pump;
• and
• a second pump controllable by the shifting system, the control fluid being alternately supplied to a first side of the second pump and a second side of the second pump from the shifting system.