Abstract: A work machine to cut timber including a control system, a felling head, a hydraulic motor configured to adjust the position of the felling head, and a spool valve operatively connected to the hydraulic motor, the spool valve being configured to move the felling head responsively through operation of the hydraulic motor. A machine controller coupled to the operator controller and the spool valve executes stored program instructions to generate a first control signal responsive to an operator control signal provided by the operator controller, generate a second control signal as a function of the generated first control signal, adjust a position of the spool of the spool valve in response to a concurrent receipt of the first control signal and the second control signal by the first proportional control valve and the second proportional control valve to move the felling head through operation of the hydraulic motor.

Abstract: A work machine to cut timber including a control system, a felling head, a hydraulic motor configured to adjust the position of the felling head, and a spool valve operatively connected to the hydraulic motor, the spool valve being configured to move the felling head responsively through operation of the hydraulic motor. A machine controller coupled to the operator controller and the spool valve executes stored program instructions to generate a first control signal responsive to an operator control signal provided by the operator controller, generate a second control signal as a function of the generated first control signal, adjust a position of the spool of the spool valve in response to a concurrent receipt of the first control signal and the second control signal by the first proportional control valve and the second proportional control valve to move the felling head through operation of the hydraulic motor.

Abstract: A holddown pin mechanism for hydraulic power units is a ball guide with a cylindrical flat base having a central opening, a plurality of spaced elongated holddown pins have one end rigidly secured to one side of said ball guide. The pins extend outwardly at right angles from the side of said washer to which they are secured. The holddown pin mechanism is placed in a hydraulic cylinder block having a center bore, with the pins extending into holes in the block. A flat washer on a shaft extending through the block engages the free ends of the pins.

Abstract: Disclosed is a closed cavity piston made from a metal injection molding process. The piston has an elongated cylindrical body with a first end that is adapted to receive a slipper. The piston also has at least one hollow compartment and a hollow stem that transports hydraulic fluid. After the metal injection molding process an end cap having a central opening is sinterbonded to the second end of the body. The central opening aligns with the hollow stem to provide a fluid outlet.