Abstract: A piston assembly for a piston pump includes an actuator rod, a piston coupled to the actuator rod and configured to contact a radially-inner wall of a cylinder, and a piston support structure coupled to the actuator rod and configured to contact the radially-inner wall of the cylinder. A fluid channel extends through the actuator rod and the piston support structure, and the fluid channel is configured to deliver a lubricating fluid to an annular space positioned between the piston and the piston support structure along an axial axis of the piston assembly.

Abstract: A piston assembly for a piston pump includes an actuator rod, a piston coupled to the actuator rod and configured to contact a radially-inner wall of a cylinder, and an piston support structure coupled to the actuator rod and configured to contact the radially-inner wall of the cylinder. A fluid channel extends through the actuator rod and the piston support structure, and the fluid channel is configured to deliver a lubricating fluid to an annular space positioned between the piston and the piston support structure along an axial axis of the piston assembly.

Abstract: A drilling fluid pump system includes a plurality of modular pump units that are each driven by a linear electric motor. A control system that can include positional feedback information which is used to control all of the linear motors in the pump system and reduce pressure pulsation. The linear motors can be controlled to reduce fluid pressure pulsation by controlling velocity and relative timing between pistons. To accommodate removal and addition of individual pump units the pump modules can be isolated electrically and hydraulically. This can improve scalability, reliability, and serviceability of the pump system.