Control valves for waterjet systems and related devices, systems, and methods

A waterjet system, comprising:

• a fluid container;
• a control valve positioned to receive fluid from the fluid container, wherein the control valve includes a seat, a pin, and an actuator including a piston movable to change a spacing between the seat and the pin;
• a cutting head including a waterjet outlet downstream from the control valve;
• a load cell configured to detect a hydraulic force from the fluid within the control valve acting against the piston in a first direction, wherein force acting against the piston in the first direction tends to increase the spacing, and force acting against the piston in a second direction opposite to the first direction tends to decrease the spacing;
• and
• a controller operably connected to the load cell and the actuator, wherein the controller is programmed with instructions that, when executed, cause a change in a pneumatic input to the actuator based at least in part on the detected hydraulic force, wherein the change in the pneumatic input changes a pneumatic force acting against the piston in the second direction.