Tree harvester delimbing control

Abstract

An articulated, four-wheel drive tree harvesting machine includes a front frame section upon which a felling boom assembly, a delimber assembly, and a feed assembly are mounted. The felling boom assembly is operable for severing a tree and lowering it into a generally horizontal position. The tree is released into the opened knives of the delimber assembly which close to encircle the trunk and into the opened feed rolls of the feed assembly which close to engage the trunk. The feed rolls are then rotatably driven to draw the tree trunk through the knives while the felling boom may be operated to sever and position a second tree. Two solenoid-operated valves control the operation of hydraulic cylinders which respectively open and close the delimber knives and open and close the feed rolls. Two other solenoid operated valves respectively control the operation of a clutch and a transmission to drive the feed rolls in a forward or reverse direction of rotation. A delimbing sequence and cycle may be automatically or manually controlled. Once the sequence is chosen, the frame sections are in line, and the cycle initiated, electronic logic circuitry will energize the appropriate solenoids to either close the knives, then close the rolls, and then engage the drive or close the rolls, then engage the drive, and then close the knives. Upon completion of the delimbing cycle, the cycle may be reset so that the electric logic circuitry will open the knives and rolls. Manual control circuitry is provided to permit individual control of the solenoids by manually-actuated switches.