Remote controlled chainsaw

Abstract

A remote-controlled chainsaw comprises fixing means e.g., a chain 2, attached to a triangular baseplate for fixing to a tree 1. One or more supports 3 are connected to the chain 2 and a pair of rails 4 is mounted on the supports 3 with a control platform 7 movably mounted on the rails 4. There may be a separate chain tensioner. A chainsaw holder 5a is mounted on the control platform 7 and a chainsaw 5 is connected to the holder, with a chainsaw blade 6 extending therefrom. A motor moves the control platform 7 relative to the pair of rails 4 to effect cutting the tree. Following an initial partial cut, the rails may be manually or motor tilted about a horizontal axis 10 to enable an inclined cut to form a notch or birdmouth in the tree stem. The saw may then be rotated and moved on the rails to the other side of the tree to perform a felling cut. Allows remote cutting to improve safety when felling diseased trees e.g., with chalara, ash-dieback without the need for heavy equipment.

Description

REMOTE-CONTROLLED CHAINSAW This invention relates to a remote-controlled chainsaw. The fungal disease Chalara or Hymenoscyphus fraxineus is infecting Ash trees in Europe, and the majority of ash trees, estimated at up to 20 million in the United Kingdom, are expected to be affected. Diseased trees present a danger to the public as they may drop branches or fall unpredictably. Public safety will therefore necessitate the felling of many ash trees. Tree felling is an inherently dangerous operation, and the felling of diseased trees even more so. Infected trees are weakened, and the act of felling carries with it the danger of unpredictable falling branches and / or shattering of the tree stem, which poses a danger to tree workers. It is therefore an object of the invention to improve upon the known art. According to the present invention, there is provided a remote-controlled chainsaw comprising fixing means for fixing to a tree, one or more supports connected to the fixing means, a pair of rails mounted on the supports, a control platform movably mounted on the rails, a chainsaw holder mounted on the control platform, a chainsaw connected to the chainsaw holder, with a blade of the chainsaw extending from the chainsaw holder, and a motor for moving the control platform relative to the pair of rails. Owing to the invention, it is possible to provide a remote-controlled chainsaw which can fell diseased trees without risk to the chainsaw’s operator. The apparatus described here enables a tree surgeon to control the felling of a tree remotely, from a safe position. The apparatus can comprise a regular chainsaw, preferably electric and powered by battery, that can be controlled remotely, preferably by radio control, and a jig that allows the chainsaw to perform the same cuts that an arborist would make in felling a tree. The apparatus is a lightweight alternative to a large tree felling “harvester”, a heavy forestry vehicle that can fell trees also without risk to the operator. Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is an elevation of a tree to be felled, with a schematic view of the apparatus in place that holds the remote chainsaw, Figure 2 is a plan view of the same, Figure 3 is a schematic elevation view of the remote chainsaw apparatus angled to make the angled cut of a notch or “birdmouth”, Figure 4 is a plan view of the way in which the device is fitted securely to the tree, Figure 5 is a plan view of the sequence of movements carried out by the apparatus to move from making the notch or “birdmouth” to make the “felling cut”. Figure 6 is a plan view of the chainsaw in its holding box, Figure 7 is an exploded view of the control box and the chainsaw holding box, and Figure 8 is a perspective drawing of the horizontal axis, supports, and the rails. Referring to the simplified view in Figure 1, a chain 2 can be securely but removably fitted to a tree 1, and supports 3 are connected to the chain 2, via the axis 10. Two rails 4 are mounted by the supports 3, and are provided with cogs that will engage positively with cogs on wheels 8, (shown here schematically). The rails 4 support a control platform 7, which is securely but movably fixed to a chainsaw box 5a, which contains a chainsaw 5. The control platform 7 is able to move along the rails 4, by power applied through one or more of the wheels 8. The chainsaw 5, in its box 5a, is able to rotate about a vertical axis 9. This rotation is used to manoeuvre the chainsaw 5 from one side of the tree 1 to the other and may also be used in the act of cutting. Figure 2 is a simplified view showing the apparatus in operation viewed from above. The tree 1 has been partially cut by the blade 6, as a result of the chainsaw 5 moving along the rails 4, in the direction shown by the arrow. This cut is the first of three cuts made to fell the tree, a horizontal cut in this case, and cuts into one quarter to one third of the diameter of the tree 1, as decided by the operator. Figure 3 shows the rails 4, tilted at an angle of about 45 degrees around the horizontal axis 10, which joins the support 3 to the chain 2. The chainsaw blade 6, will make an angled cut to meet a prior horizontal cut in order to remove a wedge shaped section of stem in order to form a notch or “birdmouth” in the tree stem so as to be ready for the “felling cut” which will be made from the opposite side of the tree 1. Figure 4 shows how the rails (not shown in this figure) are securely attached to the tree to be felled. The chain 2 is attached to a triangular base plate 19 that is provided with three conical pegs 23, which will provide firm contact with the tree 1. Immovably fixed to the base plate 19 is a robust rod or axis 10 that will carry the rest of the apparatus. The chain 2, passes around the trunk, over a tensioning unit 20, and back to the triangular plate 19, where the chain 2 can be removably but securely fixed in a slotted tang at the rightward extremity (in this case) in the triangular plate 19. If necessary, more plates with conical pegs may be fitted to the chain 2 in order to stabilise the apparatus. Figure 4a shows the chain tensioning unit which is provided with a tensioning base plate 19a, with three conical pegs 23a, that will provide a firm contact with the tree 1, and a hook 21, which supports the chain 2. The hook 21 engages by a screw thread 32 with the bolt 22 that is securely but rotatably attached to the tensioning base plate 23 by a collar 33. The tension in the chain 2 can be adjusted by turning the bolt head 31. Figure 5 is a plan view showing how the chainsaw 5 moves from making the preparatory notch or “birdmouth” cut, to the felling cut on the opposite side of the tree 1. Having completed the notch, the chainsaw 5 is rotated by a motor 90 degrees anticlockwise from position A so that the chainsaw 5 is aligned with the rails 4, in position B. The chainsaw 5 is then moved rightwards in the diagram, driven by the motor applied to one or more of the wheels 8 moving the chainsaw 5 to position C. The chainsaw 5 and blade 6 complete the manoeuvre by rotating 270 degrees anticlockwise (viewed from above) to position D. The chainsaw 5 is now in a position to complete the felling of the tree 1 by moving (in this diagram) in a leftwards direction. The chainsaw 5 may be rotated during the early stages of a cut in order to act more effectively, but will in the later stages be kept parallel to the angle of the notch cuts in order to make a good “hinge”, which is the narrow uncut portion of tree 1 that breaks under tension and controls the direction of fall. It will be noted that in the present embodiment the two horizontal cuts are made in the same plane whereas it is good practice in making manual cuts to run the felling cut about one inch (2.5 cm) above the plane of the horizontal cut of the notch. However, it is permissible to make the cut in the same plane. It should be noted also that in some trees it may be judged safe to make the notch by hand, and only use the remotely controlled chainsaw to make the final felling cut, which can then be made at a level higher than the notch. Figure 6 shows an embodiment a robust chainsaw box 5a, of which the purpose is to gain positive control of the position of the chainsaw 5. In the present embodiment the chainsaw 5 is securely bedded into the box 5a, by mouldings that fill the space between the chainsaw 5 and the interior of the box 5a. Mouldings may be made by enclosing the chainsaw 5 in a plastic bag and filling the space between the chainsaw body and the box 5a with expanding foam. Alternatively blocks of wood or plastic may be fixed around the chain saw body so that the chainsaw 5 is in secure but removable contact with the box 5a. Vents will be provided in the box 5a to allow air in for cooling (in the case of electric motors) and for ignition and exhaust gases (in the case of internal combustion engines), and also for the ejection of wood chips produced by the chain. In other embodiments the chainsaw 5 may be securely attached to the base of the box 5a by other means such as bolts, straps or cables. The base of the box 5a is made of steel, and is immovably attached to a substantial rod 9, which provides a vertical axis for the movement of the chainsaw 5. Secured to the chainsaw 5 is a means of turning the chainsaw 5 on and off by remote control in the case that the chainsaw 5 is electric or has an electric starter motor. In the case of a chainsaw 5 with a manually started internal combustion engine it will be possible to use the pull cord to start the motor. However, electric chainsaws are preferred in this application because they produce less vibration and therefore reduce the probability of branch fall or shattering of the stem of the tree 1. In the present embodiment this control mechanism will comprise a radio receiver 13 that operates a pump 17, that inflates a robust expandable envelope 24, that will press the trigger and safety button of a battery driven electric chainsaw 5 with sufficient force to cause the electric chainsaw to start. Other mechanical means can be assembled that have the same effect. A corded electric chainsaw 5 may be started remotely by turning on power to the chainsaw 5. The rotation of the chainsaw box 5a will occur around the vertical axis 9, which is immovably fixed to the base of the chainsaw box 5a. It will be stabilised by three or more stabilising wheels 25, located between the bottom of the chainsaw box 5a and the top of the control platform 7. Figure 7 shows a perspective exploded view of the control platform 7, which contains the apparatus that will enable remote control of the chainsaw 5. In the present embodiment, control is preferably by a radio control unit 13, with arborists standing in a position that is safe from any falling branches and also away from the area where the tree may fall in case the “hinge” formed by the two horizontal cuts does not work as predicted due to the condition of the wood. An alternative is to send control messages by wire. A radio receiver 13, transmits control information to a small computer 14, which passes specific information to the motors 15 and 16. The motor 15 rotates the chainsaw around the vertical axis 9, transmitting motion by a worm drive 26, on the spindle of the motor 15, which engages with splines on the vertical axis 9. The information given to the motor 15 is to perform a specified number of turns, which will determine the degree of rotation made by the chainsaw 5. The axis 9 is securely but rotatably bedded onto the floor of the control platform 7, with a bearing 11. The axis 9 will pass through a bearing in the roof of the control platform 7a and will be robustly and permanently fixed to the steel base of the chainsaw box 5a. At least three wheels 25, will provide stability between the chainsaw holding box 5a, and the roof of the control platform 7a. The motor 16 applies power to the wheels 8, preferably by worm drive. The information given to motor 16 will be the number of turns necessary to get the chainsaw assembly (the control platform 7, chainsaw holder 5a and chainsaw 5) to travel a specified distance along the rails 4. In both cases worm drive is preferred because the driven part will then remain in place when the drive is terminated. The wheels 8, and rails 4 engage positively with each other by means of cogs. Figure 7a is an elevation of a section of the junction of the rails 4 with the horizontal axis 10. It shows one pair of cogged wheels 8, sited on the cogged rails 4. The wheels 8 are provided with flanges 27 to keep them on the rails and with preventer plates 28, which stop the control platform 7 and chainsaw holding box 5a from jumping upwards off the rails 4. Holding the rails 4 in place are the supports 3 and support box sides 29. The support box sides 29 comprise two flat plates 29 that are connected to the supports 3 (see Figure 8). The supports 3 engage rotatably with the horizontal axle 10 which is fastened to the base plate 19. Figure 8 shows the way in which the rails 4, may be tilted to create the notch cut. There are two options. First, the rails 4 may be tilted by hand, and a rod may be passed through the series of holes H1 or H2 to lock the rails 4 at the desired angle. The rod will be provided with spring loaded pip pins to keep them from moving out of position. The second alternative is to set an electric motor M3, in place to act on splines 34, on the horizontal axis 10, by means of a worm drive. The motor M3, will tilt the rails 4, into the desired position by remote control mediated by the receiver, chip and battery 35, placed on the support strap 29 which connect the supports 3. The base plate 19 is joined to the axis 10, which passes through holes in the supports 3 which are joined by the support strap 29. Fixed to the support strap 29 is the motor M3, which is connected to a battery, chip, and receiver 35. The motor M3 engages with the horizontal axle 10, by means of worm 5 drive 36. The rails 4 are provided with cogs for the full length of their upper surface, of which a sample of cogs 37, are shown here.

Claims

1. A remote-controlled chainsaw comprising:• fixing means (2, 19) for fixing to a tree (1),• one or more supports (3) connected to the fixing means (2),• a pair of rails (4) mounted on the supports (3),• a control platform (7) movably mounted on the rails (4),• a chainsaw holder (5a) mounted on the control platform (7),• a chainsaw (5) connected to the chainsaw holder (5a), with a blade (6) of the chainsaw (5) extending from the chainsaw holder (5a), and• a motor (16) for moving the control platform (7) relative to the pair of rails (4).

2. A remote-controlled chainsaw according to claim 1, wherein the fixing means (2, 19) comprises a chain (2) for wrapping around the tree (1) and a base plate (19) for fixing to the tree (1) and connected to the chain (2).

3. A remote-controlled chainsaw according to claim 2, and further comprising a tensioning unit (20) for fixing to the tree (1) and connected to the chain (2) and arranged to increase or decrease the tension of the chain (2) around the tree (1).

4. A remote-controlled chainsaw according to claim 1, 2 or 3, wherein the chainsaw holder (5a) is rotatably mounted on the control platform (7).

5. A remote-controlled chainsaw according to any preceding claim, wherein the one or more supports (3) connected to the fixing means (2) are arranged to be tilted relative to fixing means (2).

6. A remote-controlled chainsaw according to any preceding claim, and further comprising a processor (14) arranged to control the operation of the chainsaw (5).5 7. A remote-controlled chainsaw according to any preceding claim,and further comprising a radio receiver (13) connected to the processor (14) and arranged to receive control communications and to transmit the control communications to the processor (14).io10

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