Drive system for a positive displacement pump

A displacement pump comprising:

• a first housing at least partially defining an internal pressure chamber configured to be filled with a working fluid charged to a charge pressure, the working fluid being one of a compressed gas and a non-compressible hydraulic fluid under pressure;
• a reciprocator disposed within the first housing and configured to be driven along a first axis;
• a first diaphragm disposed at a first end of the first housing, the first diaphragm at least partially defining the internal pressure chamber;
• wherein the reciprocator is connected to the first diaphragm to mechanically displace the first diaphragm through a first suction stroke;
• and
• wherein the internal pressure chamber is configured such that the working fluid exerts the charge pressure on the first diaphragm during both the first suction stroke and during a first pressure stroke of the first diaphragm, wherein the first diaphragm is configured to shift in a first direction along the first axis to increase a volume of a first process fluid chamber through which the process fluid is pumped by the first diaphragm during the first suction stroke, and wherein the first diaphragm is configured to shift in a second direction along the first axis to decrease a volume of the first process fluid chamber during the first pressure stroke.