Tree transport machine and method of transporting felled trees

Material or article handling – Pole or tree handlers

Reexamination Certificate

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Details

C414S460000, C414S546000, C414S555000

Reexamination Certificate

active

06257818

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to timber harvesting machines. It relates particularly to a type of timber harvesting machine commonly referred to as a skidder.
BACKGROUND OF THE INVENTION
Skidder machines conventionally take the form of articulated frame, rubber-tire tractors. A front section supported by front drive wheels includes the engine and the operators' cab. A rear section supported by rear drive wheels is connected to the front section on a vertical axis pivot so as to be articulatable relative to the front section. The front and rear wheels are driven by conventional drive trains from the engine through a gear box controlled by the operator. Steering is accomplished by varying the angular relationship between the front and rear sections with a hydraulic cylinder steering system
Timber Jack, Caterpillar and John Deere & Co., as well as others, manufacture skidder machines of the aforedescribed nature. Caterpillar also manufactures track skidder machines, i.e., machines where continuous drive tracks replace the four wheels.
Regardless of whether the skidder machine is wheel or track driven, loggers have found skidders to be the most versatile and cost-effective way to bring in felled trees, terrain and other conditions permitting. A hydraulically controlled boom extending rearwardly from the rear section of the skidder machine grasps a tree or a bunch of trees at a lower end with a grapple or cable loop. The boom is actuated to raise that end of the bundled trees, for example, off the ground and hold them suspended in the air behind the rear wheels of the skidder machine while the machine drags or “skids” the trees out of the forest to waiting transport.
Conventional machines which are constructed and operate in the aforedescribed manner are versatile and cost-effective, as has been pointed out. However, because the trees are lifted by the grapple, for example, at their lower ends and carried behind the rear wheels, both the rear wheels and the tops of the bundled trees caused substantial ground disturbance. The weight of the lifted trees at their lower ends and the counter-weight effect of the machines front end cause the rear wheels to rut and shear soil as they exert traction. The tops of the trees dragged along the ground also cause substantial ground disturbance. In addition, the trees frequently suffer damage as they are skidded out of the logging area.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved tree transport machine to replace conventional skidders.
Another object is to provide a tree transport machine which can transport trees from the logging site with minimal ground disturbance.
Still another object is to provide a tree transport machine which requires less tractive effort in transporting trees from a logging site than conventional transport skidders.
A further object is to provide a tree transport machine which delivers cleaner trees to their destinations, i.e., trees which have not been damaged by skidding.
Still a further object is to provide a tree transport machine wherein the lower ends of the trees are supported significantly ahead of the center line of the rear tires and the tops of the trees are partially or completely off the ground.
Yet a further object is to provide an improved method of transporting felled trees from the area where they are felled.
The foregoing and other objects are realized with a tree transport machine wherein the rear section of the machine is supported by a pair of wheels on each side. Each pair of wheels is mounted on a bogie which, in turn, is pivotally connected to the rear machine section.
In one embodiment of the invention, the wheels on each bogie are rubber-tire wheels. In another embodiment, each bogie may have a continuous track encircling the rubber tires. In either case, the rear machine section is supported on a relatively wide (fore-to-aft) footprint.
A hydraulically actuated boom assembly is mounted on the rear machine section. It includes a main boom extending upwardly from, and pivotally mounted on, the rear machine section at the front end of its chassis. A hydraulic actuator cylinder pivotally mounted on the chassis rearwardly of the main boom has its actuator piston pivotally connected to the boom to facilitate pivoting the main boom rearwardly and forwardly under the control of the operator.
Extending rearwardly from the main boom, and pivotally connected to its upper end, is a stick boom. The rear end of the stick has a grapple or cable suspended from its free end; the cable or grapple being readily connectable to a felled tree on the ground in a generally conventional manner. A hydraulic actuator cylinder intermediate the ends of the main boom has its actuator piston pivotally connected to the stick boom at a point rearwardly of its connection to the main boom to provide the stick boom with desired lifting force at its grapple or cable end.
According to the invention, a heel boom is also pivotally connected to the main boom and extends rearwardly beneath the stick boom. The heel boom is slightly more than one-half as long as the stick boom so that its free end is forward of the free end of the stick boom; about two-fifths of the distance between the stick boom's free end and the pivot of the stick boom.
An actuator cylinder for the heel boom is pivotally connected to the stick boom intermediate its ends. This actuator cylinder has its piston pivotally connected to the free end of the heel boom. Rigidly connected to the free end of the heel boom, and depending therefrom, is a tree-heeling fork.
In operation of the transport machine according to the method of the invention, the machine is maneuvered into a position where it is longitudinally aligned with and facing forwardly from the larger lower end of a felled tree or bunch of trees. The main boom and stick boom are moved to their rearwardly most inclined positions so that the grapple or cable can grasp the tree bunch (for example) about six feet from the lower end of the bunch.
The actuator cylinders for the main boom and stick boom are then actuated in coordinated fashion by the operator to raise the lower end of the tree bunch and drag it forwardly over the bogied rear section of the machine. When the lower end of the bunch has reached a point just forward of the centerline of the bogies, the actuator cylinder for the heel boom is energized to bring the free end of the tree heeling fork down perpendicular to, and into engagement with, the tree bunch adjacent its lower end.
At this point, the actuator cylinders for the main boom and the stick boom are actuated in coordinated fashion to pivot the main boom further forward and the heel boom further downward. The effect, according to the invention, is to pull the tree bunch forward so that its lower end is well forward of the bogied wheels and its top is raised off the ground. The tree bunch can then be moved out of the logging area with the tree tops lifted off the ground and a portion of the weight of the bunch also borne by the front wheels.


REFERENCES:
patent: 2903146 (1959-09-01), Meloy
patent: 3102563 (1963-09-01), Horncastle
patent: 3630246 (1971-12-01), Hamilton
patent: 3630399 (1971-12-01), Hanitz
patent: 3709390 (1973-01-01), Tanguay
patent: 3782567 (1974-01-01), Likas et al.
patent: 3921730 (1975-11-01), Farre et al.
patent: 4486136 (1984-12-01), Howard
patent: 4645410 (1987-02-01), Royer
patent: 4775276 (1988-10-01), McMillan
patent: 5018932 (1991-05-01), Croisier
patent: 2641266 (1990-07-01), None

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