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 fluid control system includes a pressure supply and a valve arrangement having an inlet and an outlet and being in fluid communication with the pressure supply. The valve arrangement includes a relief operator configured to provide fluid communication between the inlet and the outlet of the valve arrangement in response to a predetermined pressure condition at said inlet. The valve arrangement is configured to provide fluid communication between the inlet and the outlet of the valve arrangement in response to an outlet pressure being greater than an inlet pressure.

Abstract: A hydraulic system includes a pressurized fluid supply, a plurality of non-priority elements each including a signal port and a supply port, at least one priority implement including a signal port and a supply port and a priority valve arrangement. The priority valve arrangement is adapted to receive fluid from the pressurized fluid supply and selectively apportion fluid between the supply port of the priority implement and the supply ports of the plurality of non-priority elements. The valve arrangement includes a signal circuit operative to establish a flow priority between the priority implement and the plurality of non-priority implements and the signal circuit is in fluid communication with the priority supply. The signal circuit includes a pilot portion and a dynamic load portion and the signal port of the priority implement is in fluid communication with the priority valve arrangement through the dynamic load portion of the signal circuit.

Abstract: A joystick controller is provided in a hydraulic circuit having a pair of hydraulic actuators and oriented with respect to the operator so that movement of a control lever of the joystick controller relative to a reference axis oriented perpendicular to the operator results in control signals being generated and delivered to the first and second main control valves so that the respective cylinders are moved in a direction that is intuitive to the operator. For example, forward movement of the control lever results in both hydraulic actuators moving in the same forward or downward direction and movement of the control lever rearwardly results in both actuators moving in the rearward or upward direction. Likewise, movement of the control lever along an axis that is oriented forty five degrees from the reference axis results in control of one of the actuators independent of the other one.

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.

Abstract: A single stage, electrically controlled variable pressure relief valve assembly is provided that uses a valving element assembly slideably disposed within a housing having first and second inlet and outlet ports, the valving element assembly has a differential area defined thereon which acts in cooperation with an electrically controlled coil assembly to proportionally control the flow of fluid between the inlet port and an outlet ports of the housing. The valving element assembly has inlet and outlet ports that are oriented generally perpendicular to the flow of the fluid through the valving element assembly to effectively offset the effects of flow forces acting on the valving element.

Abstract: A fluid circuit is provided to independently control the flow of fluid into and out of each end of an actuator. This is accomplished by having two different independently controlled valves controlling the flow of fluid into and out of one end of the actuator and by having two other independently controlled valves controlling the flow of fluid into and out of the other end of the actuator. Regeneration of the fluid flow from one end of the actuator to the other end of the actuator is provided by blocking the exhaust flow of fluid to the reservoir by one of the independently controlled valves and redirecting the flow across the other of the independently controlled valves to join with the flow of the pump that is being directed to the other end of the actuator. This arrangement permits a portion or all of the fluid from one end of the actuator to be regenerated to the other end of the actuator.

Abstract: A power combining device is provide for use in a work system to combine mechanical power and hydraulic power. The power combining device includes a first rotatable input/output member connected to a power source, a second rotatable input/output member connected to a working member. A valving plate, a drive sleeve and a camplate are drivingly connected to the first rotatable input/output member. A rotating barrel having a plurality of piston disposed therein to define pressure chambers is drivingly connected to the second rotatable input/output member and operative in cooperation with the valving plate to control pressurized fluid within the pressurized chambers. The subject power combining device is compact and cost effective to produce.

Abstract: A suspension control system includes a load support member, a base member and a moveable element attached to the base member and the load support member. The load support member is moveable relative to the base member through the moveable element. An accumulator is in fluid communication with the moveable element. A locking circuit is disposed between the moveable element and the accumulator and is selectively activatable to sustain the load support member in a fixed position. The locking circuit includes a pressurized fluid supply and a flow blocking mechanism operably engaged with the pressurized fluid supply. The flow blocking mechanism is urged to block fluid communication between the moveable element and the accumulator when the locking circuit is selectively activated.

Abstract: A engine controller includes a connector having pins that provide an electrical connection between devices external to the controller and internal electrical components. The programming tool is used to program the controller to assign particular pins to transmit or receive certain signals.