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US 7,481,051 B2Granted
Tree feller power management
AssigneeTimberjack Inc.
InventorUlf Bergquist
Life of this patent
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AssigneeTimberjack Inc.
InventorUlf Bergquist
Estimating the term…
A tree felling machine has a main pump for operating functions of the machine such as the drive wheels or tracks, the steering, the brakes, and the lifting and extension of the boom, and a separate saw pump for driving the cutting element, for example, a circular disc saw driven by a hydraulic motor. Both pumps are driven by the same prime mover, i.e. the same internal combustion engine, and the power division between the two pumps is determined by the operator and by the hydraulic control system. In particular, a control provided in the cab is controllable by the human operator to limit the maximum power that the saw pump can draw from the prime mover. In addition, the power that the saw pump can draw from the prime mover is limited by a combination of the displacement setting of the main pump, the output pressure of the saw pump, and the pressure exerted on the load by the main pump.
In a tree felling machine having an operator cab and a hydraulic system that has at least two hydraulic pumps operated by the same prime mover, said two pumps including a pump for driving a cutting element of the machine and the other pump being a main pump for providing fluid under pressure to operate other functions of the machine, the improvement wherein the machine has a control in the operator cab that is adjustable by the operator, apart from any manually adjustable pump displacement controls operable by the operator, so as to place an upper limit on the amount of power the saw pump can draw from the prime mover while reserving any remaining power for operation of the other functions.
In a tree felling machine having a hydraulic system that has at least two hydraulic pumps operated by the same prime mover, said two pumps including a pump for driving a cutting element of the machine and the other pump being a main pump for providing fluid under pressure to operate other functions of the machine, the improvement wherein de-stroking of the saw pump is automatically effected at least in part in response to a displacement setting of the main pump.
In a tree felling machine having a hydraulic system that has at least two hydraulic pumps operated by the same prime mover, said two pumps including a pump for driving a cutting element of the machine and the other pump being a main pump for providing fluid under pressure to operate other functions of the machine, the improvement wherein the saw pump has a de-stroking valve with opposed pilot pressure ports that normally balance each other when the saw pump is not being de-stroked to result in the de-stroking valve being in a non-de-stroking position of the de-stroking valve in which the saw pump is not de-stroked by the valve, but that when imbalanced, moves the de-stroking valve into a position in which the de-stroking valve pressurizes a saw pump de-stroking cylinder to reduce the displacement of the saw pump, said ports including a non-de-stroking port which when pressurized biases the de-stroking valve into the non-de-stroking position, the non-de-stroking port being in communication with a limit valve that vents the non-de-stroking port to a lower pressure that permits the de-stroking valve to de-stroke the saw pump at least in part dependent on the displacement setting of the main pump, the pressure exerted by the saw pump, and the pressure exerted on the load by the main pump.
Dependencies are inferred from the claim text.