Progressive cavity pump (PCP) drive head stuffing box with split seal

A stuffing box having a mechanical seal assembly for a pump, comprising:

• an outer housing having a longitudinal bore therethrough;
• a seal housing having a longitudinal bore therethrough, wherein the seal housing is disposed in the outer housing bore;
• first and second semi-annular mechanical seals, each at least partially disposed in the seal housing bore, and each having two radial faces, each radial face of each seal abutting a radial face of the other seal;
• a seal sleeve having a longitudinal bore therethrough and rotatable relative to the seal housing;
• third and fourth semi-annular mechanical seals, each at least partially disposed in the seal sleeve bore, each having two radial faces, each radial face of each seal abutting a radial face of the other seal, at least one of the third and fourth seals rotationally coupled to the seal sleeve but axially movable relative to the seal sleeve;
• one or more biasing members biasing longitudinal faces of the third and fourth seals into engagement with longitudinal faces of the first and second seals;
• and
• an internal sleeve that extends through the seal sleeve bore.