Traversing hoists – Adjustable to transport or nonuse position – Collapsible or foldable boom
Patent
1998-10-30
2000-06-27
Brahan, Thomas J.
Traversing hoists
Adjustable to transport or nonuse position
Collapsible or foldable boom
212238, 212261, B66C 2342
Patent
active
060795778
DESCRIPTION:
BRIEF SUMMARY
This application is the national phase of international application PCT/f197/00259 filed Apr. 29, 1997 which designated a U.S.
The invention relates to a loader comprising a turntable for connecting the loader to a base machine, a main arm and a secondary arm that are articulated together, the main arm being placed in connection with the turntable, and a lift cylinder and a maneuvering cylinder that control these arms.
Such a loader is used primarily in logging machines. One end of a loader is usually provided with different timber-handling devices, such as a logging head or a harvester part, or a feller head or a grapple for energy firewood. Due to its working area and movement path, such a loader enables the processing and felling of forest either in a selected manner, i.e. by thinning the forest, or in the form of final felling, which means group felling. Loaders are usually attached to a base formed by a logging machine by means of bolts via a collar plate, for example.
It is previously known to use in logging machines a timber loader comprising a separate lift arm and a secondary arm with separate movement paths and hydraulic cylinders that control them, so that the movement paths of these cylinders and arms do not intersect. The movement paths of the lift arm and the secondary arm are thus not connected to each other. When the arms of the loader are used, it is necessary to perform two separate motions simultaneously so that for example a horizontal motion would be provided with the end of the secondary arm within the working area of the arm.
It is also conventional to use telescopic extending means to increase the operating span of the loader. The simultaneous use of extending means and arms is difficult as regards the movement paths, however, and when the loader is used in the near distance such telescopic extending means must be retracted.
When the end of the loader is set to a horizontal motion, it moves jerkily up and down as a result of the separate use of the arms of the known loaders, and not directly and smoothly as would be advantageous for the load or the actuator. Such an uneven movement path increases the consumption of energy of the loader and makes the strains acting on the arms disadvantageously high.
A conventional timber loader further comprises a turntable that is mounted on a logging machine or a base machine and that is provided with a vertical pillar. This vertical pillar is conventionally provided with a lift arm that is guided by a lift cylinder and that is provided at one end with a secondary arm controlled by a rocker cylinder. In order to increase the working area of the loader, the telescopic extending means are placed inside the secondary arm far from the base machine. The centre of gravity of the loaders will thus be situated high and far from the base machine. This weakens the balance of the logging machine, wherefore the machine requires more mass in order to remain stable during the use of the loader.
The stress on the arms formed by the lift arm and the secondary arm is also increased by the point stresses caused by the lift and the rocker cylinder. In conventional loaders, the lift cylinder causes a point stress on the arms since the lift cylinder is usually attached to the arms from only one point. Also, the fastener for the lower end of the rocker cylinder is usually welded to the middle of the lift arm. The arms are generally subjected to fractures that start from the aforementioned points. To prevent the occurrence of such fractures, the manufacturing materials of the arms have usually been strengthened, as much as possible, at the expense of the total weight of the apparatus.
Since the actuating cylinder for the lift arm is usually situated below the lift arm, it is often exposed to blows. When the loader is in the vertical position, the unprotected lift cylinder is easily hit by the end of the secondary arm or a device mounted on its end or a log placed in the device. The distant position of the actuating cylinder of the secondary arm in the arm structure also
REFERENCES:
patent: 2903142 (1959-09-01), Wills
patent: 5197615 (1993-03-01), Gunnarson
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