Woodworking – Special-work machine – Combined
Patent
1988-10-28
1989-11-21
Bray, W. Donald
Woodworking
Special-work machine
Combined
144 27, 144 34R, A01G 2308
Patent
active
048815829
DESCRIPTION:
BRIEF SUMMARY
The object of the invention is a suspension device to be installed at the upper end of the jib of a timber harvester by means of the upper joint, to suspend a harvester, the suspension device consisting of a turning motor to turn the frame of the suspension device and with it the harvester, an operating device, e.g. a hydraulic cylinder, to turn the harvester to the desired vertical or horizontal position, and in which the suspension of the harvester from the frame of the suspension device is carried out by means of a transverse joint and the aforementioned operating device is connected between the frame of the suspension device and the frame of the harvester.
Timber harvesters, which carry out all stages of the work except felling, are called timber processors. Nowadays most of them can be equipped with a so-called felling head. The purpose of this felling head is to bring the processor to a vertical position. The vertical position is required in order to take hold of the tree. In practice it is sufficient if the processor is even roughly in a vertical position so that the tree can be taken hold of. Felling and sawing is carried out by the cutting saw of the processor.
When the harvester is hanging freely it naturally tends to take a horizontal position, i.e. the center of gravity in the middle of the machine tends downwards. By means of the cylinder in the suspension device the harvester is turned in the direction of the suspension device by pushing the frame of the suspension device towards the stripping blades and the harvester now moves into a nearly vertical position, for the center of gravity tries to move under the upper joint.
After the felling stage the stripping and cutting of the tree take place with the tree in a horizontal position. The harvester hangs freely from its felling head and in addition a so-called grab turner is located on the felling head. The harvester is directed round its vertical shaft by this turner. Really this felling head is a suspension device, by which the harvester is made to rise to a vertical position advantageously by means of a hydraulic cylinder.
The problem with these felling heads or suspension devices is their great weight, great length, and also price. These problems are due to the fact that ordinary grab turners are used in these suspension devices. Because the diameter of the grab turners is large the turner must be located at the extreme top of the suspension device and further the turner should be in the felling position above the harvester. This is so that the harvester is able to turn sufficiently vertically. But now the length of the suspension device becomes great because the turner must be entirely situated in front of the stripping blades of the harvester.
In the suspension device in accordance with the invention an attempt is made to achieve a short length for the suspension device and nevertheless achieve a sufficient vertical rise. In addition the invention attempts to achieve as light and easily used construction as possible. The characteristics of the invention appear in the accompanying patent claims.
Even in the stage where the harvester is taking hold of the tree the jib of the crane can push the harvester against the trunk without the harvester in the vertical position trying to much to move away from the lower part of the tree as happened with earlier suspension devices. In a suspension device in accordance with the invention the upper joint is located during the felling stage close to the upper stripping blade. Thus a turning moment creating a horizontal pushing movement away in the lower part of the harvester is nonexistent. Further, by placing the cylinder that tilts the suspension device in the center of the device it is possible to minimize the length of the stroke of the cylinder. By selecting suitable securing points for the cylinder when the suspension device at one stage tilts towards the cutting saw the piston rod of the cylinder begins once again to push out of the cylinder. This kind of situation appears for example when the tree
REFERENCES:
patent: 3738401 (1973-06-01), Wiklund et al.
patent: 3817303 (1974-06-01), Kantola et al.
patent: 4083463 (1978-04-01), Ericsson
patent: 4412777 (1983-11-01), Foreslund
patent: 4537236 (1985-08-01), Kulju
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