Woodworking – Special-work machine – Combined
Patent
1990-12-17
1992-01-21
Bray, W. Donald
Woodworking
Special-work machine
Combined
144 2Z, 144 34R, 144336, 144338, 144246R, 144246F, A01G 2308
Patent
active
050820362
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention concerns a forest harvester suspended pivotally at the end of a crane jib and rotatable around its shaft of suspension for felling of a tree trunk and for trimming and possible cutting-off of the tree trunk in the horizontal position. The harvester comprises a suspension arm shaped substantially as an inverted L and a processor unit mounted pivotally at the lower end of the arm, the side of the processor unit placed facing away from the suspension arm being provided with a crosscutting member, with two groups of trimming members placed at a distance from one another, and with at least two drive rolls jointly operative with each other, with variable mutual spacing, and mounted between said groups of trimming members.
BACKGROUND OF THE INVENTION
It is a feature common of all prior-art harvesters of the type described above that, during the felling movement, they are arranged to pivot forwards in the direction towards the trimming knives so that, in the horizontal position, the processor unit is placed above the tree trunk and holds its grasp on the trunk only by means of the trimming members or knives. In order that the tree trunk could be kept in its place, it is required that the trimming members in each group are pressed against each other and, thus, against the tree trunk with a very intensive force, because in this position the drive rolls have vertically directed shafts of rotation and press the tree trunk each of them from its side, as a result of which they cannot contribute to supporting of the tree trunk to a significant extent. This has the consequence that the force of friction that has to be overcome by the drive rolls when feeding the tree trunk during the trimming stage becomes enormously high and results therein that the trimming knives cut unduly deep into the wood in the tree trunk, at the same time as the spikes or equivalent friction-increasing members on the drive rolls also tear deep wounds into the wood in the trunk. Thus, a considerable portion of the topmost layer of wood is lost. Since, as a rule, the trimming members cannot keep a tree trunk in a fully stable position during a trimming process, this also results therein that the cutting of the tree trunks in predetermined lengths does not take place precisely, but major variations occur as a result of the fact that the operation of the measuring means that are used for this purpose is disturbed greatly.
SUMMARY AND OBJECTS OF THE INVENTION
The object of the present invention is to eliminate all of the above problems, which is achieved by means of a forest harvester which is characterized in that the felling movement of the processor unit is arranged to take place towards the side in a vertical plane so that the shafts of the drive rolls maintain their substantially horizontal positions all the time.
A suspension arm is pivotally connected to the processor unit and allows the processor unit to pivot from a starting position where the processor unit grasps the tree trunk to a trimming position where the tree has been cut off from the ground and the tree is movable through the processor unit in order for trimming members to remove the branches. In both positions the drive rolls or rollers are horizontal. The weight of the tree is now mainly supported by one of the drive rolls. The two drive rolls are arranged to rest against the tree trunk from opposite sides. The rolls are driven in order to move the tree trunk. One of the drive rolls, preferably the lower drive roll in the trimming position is stationarily mounted on the processor unit and the upper drive roll is adjustably mounted on the processor unit in order to accommodate tree trunks of varying size. It is also possible to have two stationary rollers mounted on the processor unit for contacting one side of the tree trunk and having one side of the adjustable drive roller contacting another side of the tree trunk. These two stationary rollers would be on the lower side of the tree trunk in the trimming position. Having these tw
REFERENCES:
patent: 4552191 (1985-11-01), Kuusilinna
patent: 4881582 (1989-11-01), Ketonen
Bray W. Donald
Oy Erco-Mek AB
LandOfFree
Forest harvester does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Forest harvester, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Forest harvester will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-110687