Cylinder with internal pushrod

A fluid system comprising:

• a cylinder body including an internal cavity therein;
• a piston and rod assembly disposed for axial movement within the internal cavity of the cylinder body, the piston and rod assembly having an axial passage extending therein, the piston and rod assembly including a piston having a rod side and a head side;
• a tubular element received within the axial passage of the piston and rod assembly, at least a portion of the tubular element extending out of the axial passage and into the internal cavity of the cylinder body between the axial passage and a wall of the cylinder body, the tubular element having a fluid passage therein;
• a source of fluid in fluid communication with the head side of the piston;
• a source of fluid in fluid communication with the axial passage of the piston and rod assembly through the fluid passage of the tubular element, and
• a control valve, wherein the axial passage of the piston and rod assembly is also fluidly connected through the control valve with the source of fluid in fluid communication with the head side of the piston.

A method for actuating a fluid actuator including a cylinder body with an internal cavity therein, and a piston and rod assembly having an axial passage extending therein, the piston and rod assembly being disposed for axial movement within the internal cavity of the cylinder body, the method comprising:

• creating a first urging force on the piston and rod assembly in an axial direction by directing pressurized fluid from a fluid source into the cylinder body and upon a first side of a piston of the piston and rod assembly;
• creating a second urging force on the piston and rod assembly in the axial direction by directing pressurized fluid from a source of fluid into the axial passage of the piston and rod assembly as the piston and rod assembly moves in the axial direction;
• preventing the pressurized fluid that is creating the first urging force on the piston and rod assembly from substantially communicating within the cylinder body with the fluid within the axial passage of the piston and rod assembly;
• preventing the pressurized fluid that creates the first urging force from contributing to the second urging force when the pressure of the pressurized fluid that creates the first urging force is below a threshold pressure;
• and
• allowing the pressurized fluid that creates the first urging force to contribute to the second urging force when the pressure of the pressurized fluid that creates the first urging force exceeds a threshold pressure.