Modular power end

An apparatus, comprising:

• a power end assembly, comprising:
• a crank section comprising a crank frame, the crank frame bounded by opposed front and rear surfaces and housing a crankshaft;
• a crosshead section offset from the crank frame, the crosshead section bounded by opposed front and rear surfaces and comprising a plurality of crossheads;
• in which the front surface of the crank frame is positioned intermediate the rear surface of the crosshead section and the rear surface of the crank frame;
• a rear support plate abutting the rear surface of the crank frame;
• and
• a plurality of first stay rods traversing the crank frame, the crosshead section, and the rear support plate.

A kit for assembling a power end assembly, the power end assembly situated within an ambient environment, the kit comprising:

• a crank frame configured to house a crankshaft;
• in which the crank frame is of single-piece construction;
• a plurality of crosshead frames, each crosshead frame having opposed front and rear surfaces and configured to house a crosshead, the plurality of crosshead frames configured to be positioned offset from the crank frame and in a side-by-side relationship;
• a central support plate configured to be positioned between the crank frame and the plurality of crosshead frames;
• a plurality of pony rods, each pony rod configured to be attached to a crosshead in a one-to-one relationship such that each pony rod projects from the front surface of a corresponding crosshead frame;
• a plurality of first stay rods, each first stay rod configured to traverse the crank frame, and one of the plurality of crosshead frames;
• and
• a plurality of second stay rods, each second stay rod configured to attach to the central support plate and traverse one of the plurality of crosshead frames;
• in which at least a portion of the crank frame, at least a portion of each of the plurality of crosshead frames, at least a portion of the central support plate, at least a portion of the plurality of first stay rods, and at least a portion of the plurality of second stay rods are exposed to the ambient environment when the power end assembly is assembled.