Hydraulic machine

A hydraulic machine comprising:

• at least one actuator, the at least one actuator comprising a first actuator and a second actuator;
• a tank;
• a directional control valve disposed between the at least one actuator and the tank;
• and
• an adjustable return check valve disposed between the directional control valve and the tank, the adjustable return check valve adjusted to provide a low back pressure when the first actuator operates and a high back pressure when the second actuator operates, wherein the adjustable return check valve comprises:
• a valve block having a path defined therein;
• a poppet opening or closing the path;
• a guide configured to apply force to the poppet via a spring in a direction of closing the path;
• and
• a piston, wherein when the piston pushes the guide toward the poppet, the guide applies a greater amount of force to the poppet, so that the adjustable return check valve provides the high back pressure.