Hydraulic circuits for tree-harvesting knuckle booms

A knuckle boom apparatus, comprising:

• a machine base;
• a hoist boom having a proximal end pivoted to the machine base, and a distal end remote therefrom;
• a stick boom having a proximal end pivoted to the distal end of the hoist boom, and a distal end specifically configured to carry a tree-working tool;
• at least one hydraulic hoist cylinder mounted between said machine base and said hoist boom;
• at least one hydraulic stick cylinder mounted between said hoist boom and said stick boom;
• at least one hydraulic reach cylinder mounted between said machine base and said hoist boom;
• and
• a hydraulic circuit for operatively supplying hydraulic oil to said cylinders, wherein said hydraulic circuit comprises at least one hydraulic conduit line connecting respective base end ports of said hoist and stick cylinders so as to allow hydraulic oil to shunt between base ends of said hoist and stick cylinders.

A knuckle boom apparatus, comprising:

• a machine base;
• a hoist boom having a proximal end pivoted to the machine base, and a distal end remote therefrom;
• a stick boom having a proximal end pivoted to the distal end of the hoist boom, and a distal end;
• a tree-working tool mounted on said distal end of said stick boom;
• a first hoist-located hydraulic cylinder mounted beneath said hoist boom and pinned to stroke between said machine base and said hoist boom;
• a second hoist-located hydraulic cylinder mounted beneath said hoist boom and pinned to operate the angle between said machine base and said hoist boom;
• a hydraulic stick cylinder located beneath said hoist and stick booms to stroke between said hoist and stick booms;
• and
• a hydraulic circuit with at least first and second directional control valves for operatively supplying hydraulic oil to said cylinders;
• wherein a base end hydraulic port of said first hoist-located hydraulic cylinder is connected via hydraulic conduit to a base end hydraulic port of said stick cylinder;
• a hydraulic conduit connects said so-connected base end ports to a first work port of said first directional valve;
• and the second of said hoist-located cylinders is connected via hydraulic conduit to said second directional valve to operate as a reach cylinder whereby a manual operation of only said second directional valve causes all said cylinders to stroke simultaneously and said stick boom distal end to move in a desired path.

A knuckle boom apparatus, comprising:

• a machine base;
• a hoist boom having a proximal end pivoted to the machine base, and a distal end remote therefrom;
• a stick boom having a proximal end pivoted to the distal end of the hoist boom, and a distal end;
• a tree-working tool mounted on said distal end of said stick boom;
• a hydraulic hoist cylinder mounted beneath said hoist boom and pinned between said machine base and said hoist boom to stroke between said hoist boom and said machine base;
• a first stick-located hydraulic cylinder mounted beneath said hoist boom and said stick boom and pinned between said hoist boom and said stick boom to stroke between said hoist boom and said stick boom;
• a second stick-located hydraulic cylinder mounted between said hoist boom and said stick boom and pinned between said hoist boom and said stick boom to operate the angle between said hoist boom and said stick boom;
• and
• a hydraulic circuit with at least first and second directional control valves for operatively supplying hydraulic oil to said cylinders;
• wherein a base end hydraulic port of said first stick-located hydraulic cylinder is connected via hydraulic conduit to the base end hydraulic port of said hoist cylinder;
• said so-connected base end ports are connected via hydraulic conduit to a work port of said first directional valve;
• and the second of said stick-located cylinders is connected via hydraulic conduit to said second directional valve to operate as a reach cylinder, whereby a manual operation of only said second directional valve causes all said cylinders to stroke simultaneously and said stick boom distal end to move in a desired near-horizontal path.