Abstract: A cylinder assembly is disclosed. The cylinder assembly may include a cylinder body having an internal cavity therein and a piston and rod assembly disposed for axial movement within the internal cavity of the cylinder body. The piston and rod assembly may have an axial passage extending therein. The cylinder assembly may further include a tubular element received within the axial passage of the piston and rod assembly. At least a portion of the tubular element may extend 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.

Abstract: An apparatus and method for coupling a piston member to a rod member to create a piston and rod assembly are provided. The piston and rod assembly may include a piston member having a longitudinal bore and first and second retaining passages in communication with and extending away from the bore. The piston and rod assembly may further include a rod member having a third retaining passage arranged therein, a portion of the rod member being received within the bore of the piston member so that the third retaining passage is arranged within the bore in an offset configuration relative at least one of the first and second retaining passages. The piston and rod assembly may further include a retaining member arranged within the first and second retaining passages of the piston member and the third retaining passage of the rod member.

Abstract: A method and system for operating a tree harvesting machine including a tree harvesting tool are provided. The method may include identifying a tree to be harvested, generating one or more tree position signals indicative of a position of the tree, and controlling movement of the tree harvesting tool toward the tree as a function of the one or more tree position signals. The system may include a tree position sensor operable to generate one or more tree position signals indicative of a position of a tree. The system may further include a controller operable to receive the one or more tree position signals. The controller may be further operable to generate one or more tool control signals for controlling movement of the tree harvesting tool toward the tree as a function of the one or more tree position signals.

Abstract: A method and apparatus for detecting the position of a rod member of a cylinder assembly are provided. The cylinder assembly may have a cylinder body with a cylinder chamber therein, a gland member disposed within the cylinder chamber, and a rod member movably arranged within the cylinder chamber and a rod opening of the gland member. The method may include moving the gland member within the cylinder chamber to substantially align a gland aperture of the gland member with a cylinder aperture of the cylinder body; substantially fixing the gland member relative the cylinder body; positioning a position sensor within at least one of the cylinder aperture and the gland aperture; moving the rod member within the rod opening of the gland member and the cylinder chamber of the cylinder body; and operating the position sensor to detect the position of the rod member.

Abstract: A method and apparatus for detecting the position of a rod member of a cylinder assembly are provided. The cylinder assembly may have a cylinder body with a cylinder chamber therein, a gland member disposed within the cylinder chamber, and a rod member movably arranged within the cylinder chamber and a rod opening of the gland member. The method may include moving the gland member within the cylinder chamber to substantially align a gland aperture of the gland member with a cylinder aperture of the cylinder body; substantially fixing the gland member relative the cylinder body; positioning a position sensor within at least one of the cylinder aperture and the gland aperture; moving the rod member within the rod opening of the gland member and the cylinder chamber of the cylinder body; and operating the position sensor to detect the position of the rod member.

Abstract: A method and apparatus for controlling the motor output speed of a variable displacement hydraulic motor are disclosed. The method may include determining a value indicative of a motor output speed, determining a value indicative of a desired motor output speed, determining a desired position of a control valve using a nonlinear feedback control law, and, controlling the motor output speed as a function of the control valve position, wherein the nonlinear feedback control creates a first order system response.

Abstract: In a fluid system, a source of pressurized fluid operably communicates with first and second actuators. First and second control valves control fluidly communicates with the first and second actuators. A first pressure compensating valve fluidly communicates with the first control valve and first actuator. A first signal conduit fluidly communicates with fluid flow being directed by the first control valve to the first pressure compensating valve and first actuator. A second pressure compensating valve fluidly communicates with the second control valve and second actuator. A second signal conduit fluid communicates with fluid flow being directed by the second control valve to the second pressure compensating valve and second actuator. A control signal pressure generated from a greater of a first signal pressure carried by the first signal conduit and a second signal pressure carried by the second signal conduit fluidly communicates with the first and second pressure compensating valves.

Abstract: A method and apparatus for updating a machine database. The database includes data representing the desired and actual terrain of a work site. Additional data represents portions of the work site which have been further worked. An indicator detects the machine's current work function and updates the data in the database based on the current work function.