GB2195222A - Branch cutting - Google Patents

Abstract

In a branch cutting device, using a chain saw 27, which climbs and rotates around a standing tree, resistance to cutting is sensed by clockwise rotation of a frame 46, the movement of which is communicated to a brake band 64 which tightens around a motor driven wheel 61, thereby slowing down rotation of the device around the tree. <IMAGE>

Description

SPECIFICATION Pruning machine This invention relates to a pruning machine and, more particularly, to a pruning machine adapted to move along a portion of a tree whilst moving around it to perform cutting operations.

A previously-proposed tree pruning machine employs a cutting unit for cutting off branches of a standing tree while the machine dlimbs up the tree using wheels driven by a motor.

However, the cutting force of the cutting unit of such a tree pruning machine is relatively small and it can therefore be difficult to cut branches offering a relatively large resistance to cutting, such as particularly thick or hard branches. A motor of greater horsepower has been considered as a means of increasing the cutting force of the cutting unit so as to cut thick or hard branches. However, if an engine (motor) of greater horsepower is employed, the weight of the engine itself increases and it is further necessary to provide a more rigid frame for the pruning machine, thereby increasing the weight of the machine and hence wasting the output of the engine on the increased force needed to raise the machine up the tree.Therefore, although the horsepower of the engine has been increased, there is lit tle or no extra power available to increase the cutting force of the cutting unit.

Accordingly, it is desirable to provide a tree pruning machine which is better adapted to cut branches of a standing tree having large cutting resistance, such as thick or hard branches.

Preferably, the horsepower of an engine powering such a tree pruning machine is not significantly greater than'that of any conventional tree pruning machine.

According to an embodiment of the present invention there is provided a tree pruning machine comprising a body for vertically elevating on a standing tree through a wheel driven by an engine, a rotary device for turning on the periphery of the body, a cutting unit provided in the rotary device and having a detector for detecting the cutting resistance effected from the cutting branch, and a rotating speed reduction unit of the rotary device, wherein the rotating speed reduction unit is controlled by the detector of the cutting resistance. More particularly, if a branch having a large cutting resistance such as a thick or hard branch makes contact with the cutting unit, a detector detects the contact of the cutting unit with such a branch and the rotating speed of the rotary device is decreased, thereby enabling the branch to be cut more slowly.

Reference will now be made, by way of example, to the accompanying drawings, in which': Fig. 1 shows a perspective view of compo nents -of a tree pruning machine embodying the present invention; Fig. 2 shows a perspective view of a transport device of the machine shown in Fig. 1; Fig. 3 shows a schematic diagram of transmission coupling arrangements of the machine when climbing up a standing tree; Fig. 4 shows a schematic diagram of transmission coupling arrangements of the machine when descending a standing tree; and Fig. 5 shows a perspective view of parts of a cutting unit and a speed control device of the machine.

In Fig. 1 a tree pruning machine A comprises a transport device B, adapted to embrace a standing tree, and a rotary drive and cutting unit C adapted to be detachably attached to the transport device B. The transport device B is provided with a plurality of wheels w. Rotation of the wheels w by an engine 1, carried in the rotary drive and cutting unit C, can cause the transport device B to climb up the trunk of a standing tree embraced thereby, or to move along a portion of such a tree. The unit C is provided with a cutting unit 2 having a chain saw 27 for cutting a branch of the tree from the trunk as the unit C moves around the periphery of the transport device B while the transport device B moves up the trunk of the tree. The tree pruning machine is provided with a cover plate 3.

Fig. 2 shows a view of the transport device B when it is being mounted on a standing tree T or dismounted from the tree T. The transport device B has circular frames F1, F2 and F3 as main frames, and various components to be described later are mounted on the respective frames F1 to F3. A large movable ring gear G1 is disposed at the uppermost part of the transport device B and is formed with teeth on the outer and inner peripheral surfaces thereof. When the tree pruning machine A climbs on the standing tree T, the ring gear G1 is driven by the engine 1 to turn around the trunk of the standing tree T, with the tree at its center, in a direction as designated by an arrow X in Fig. 2, thereby causing the wheels w to rotate in a sense such as to move the tree pruning machine upward.

When the tree pruning machine A moves (under its own weight) down the standing tree T, the wheels w rotate in the opposite sense and drive the ring gear G1 to turn in the reverse direction as designated by an arrow Y in Fig. 2. A large stationary ring gear G2 is disposed directly under the movable ring gear G1 and is formed with teeth on the outer peripheral surface thereof. The ring gear G2 is not rotated in the X-Y direction of the ring gear G1, but is fixed. When the transport device B climbs up the standing tree T, the cutting unit 2 of the unit C cuts a branch t as the unit C turns in the direction of the arrow X along the ring gear G2. In other words, the ring gear G2 acts as a guide rail for moving the unit C around the standing tree T.

A large arcuate interlocking ring gear G3 surrounds the standing tree T and is disposed directly above the frame F3. The ring gear G3 is driven by the engine 1 to control the positioning of three interlocked wheel units W in which the elevating wheels w are mounted, so as to equalize any movements thereof towards or away from the axis of the tree T and thereby keep the transport device B coaxial with the tree T.

The frame F1 has a main frame Fla and a sub-frame F1b. In order to mount or dismount the transport device B on or from the tree T, the sub-frame F1b is opened as shown in Fig.

2. An openable plate 4 is attached to the frames F2 and F3. When the transport device B is mounted on the standing tree T or dismounted from the tree T, the openable plate 4 is opened as shown in Fig. 2.

The ring gears G1 and G2 also respectively have main gears Gla, G2a and sub-gears G1b, G2b. When the transport device B is mounted on the standing tree T or dismounted from the tree T, the sub-frame Flub, the openable plate 4 and the sub-gears Glob, G2b are all opened as shown in Fig. 2 to provide an opening through which the standing tree T may pass. Thus, after positioning the transport device B about the standing tree T, with the tree T at the center of the transport device B, the sub-frame F1b, the openable plate 4 and the sub-gears Glob, G2b are closed as shown in Fig. 1. Stoppers 5,6,7,8, and 9 are attached to sub-frame Flub, plate 4, sub-gear G2b, main gear Gla and sub-gear Glb respectively.Fig. 1 also shows a climbing height setter 10 for setting the climbing height of the tree pruning machine A, a cover plate 20, a gasoline tank 21, a timing belt 25 for transmitting the rotation of the engine 1 to the chain saw 27 of the cutting unit 2, and a box 30 for containing gears to be described later.

Also illustrated in Figs 1 and 2 are a small gear gl engaged in mesh with the inside of the ring gear G1,,a bevel gear 93, and a chain 14. The rotation of the engine 1 is transmitted through'the gears gl, 93 and the chain 14 to the wheels w. A cam 17 is provided for pushing the wheel units W toward the axis of the standing tree T. A coil spring S1 is mounted on the rotational shaft of the cam 17, and a handle 19 is provided for forcibly opening the cams 1 7.

Figs. 3 and 4 show schematic developed views of the transmission of the tree pruning machine. The transmission of the machine will be described with reference to Figs. 3 and 4.

A gear 92 is disposed between the gears gi and 93, and the rotation of the engine 1 is transmitted through the gears gl to 93 and the chain 14 to the respective wheels w.

Transmission belts 31 and 33.driven by the engine 1, a reduction gear 32, a frictional clutch 34, and a speed control device comprising a rotating speed reduction unit D of the unit C, are also provided.

A gear g7 is coupled with the speed reduction unit D, and gears g9 and gil are disposed on either side of the gear g7. A gear g10, engaged in mesh with the ring gear G2, is coupled with the gear g9. A movable gear g8 is provided which supports a rotary lever 36.

When the tree pruning machine A climbs on the standing tree T, the gears g7 and g8 are engaged as shown in Fig. 3. In this state, the rotation of the engine 1 transmitted to the gear g7 is transmitted through the gears g8 and g,9 to the gear g10, which rolls along the ring gear G2. Thus, the unit C rotates in the direction designated by the arrow X around the transport device B to cut the branch t by applying the cutting unit 2 thereto. In this case, a stopper 42 is engaged with a gear g12 to prevent it from rotating. Therefore, when the unit C rotates in the direction of the arrow X, the ring gear G1 is caused to rotate in the same direction as the arrow X. This rotation is transmitted through the gears g1 to g3 and the chain 14 to the respective wheels w.The wheels w thus rotate, thereby causing the tree pruning machine A to climb up the standing tree T.

When the tree pruning machine A is to descend the standing tree T, the gear g8 is engaged with the gears g7 and gll as shown in Fig. 4. The rotation of the engine 1 is not transmitted to the gear g9 in this state, the stopper 42 is separated from the gear g12 in a free state, and the tree pruning machine A moves down the standing tree T under its own weight. In this case, the ring gear G1 is turned in the direction of the arrow Y by the rotation of the wheels w. A lever 36a is provided for manually operating the rotary lever 36. The lever 36a projects from the box 30 as shown in Fig. 1. When the transport device B is intended to climb up the tree T, the lever 36a is operated to engage the gear g8 with the gear g9 as shown in Fig. 3.

With reference to Fig. 5, the cutting unit 2 has as its main body a frame 40 of substantially inverted L shape. Rollers 43 are journaled to the top of the frame 40, and the chain saw 27 is engaged with the rollers 43 and a sprocket 44 (Fig. 1). The sprocket 44 is driven by a belt 25 (Fig 1) and a spline shaft 45 by the engine 1. Numeral 46 denotes a supporting frame pivotally mounted on a frame 47, by means of a pin 59, so as to be rotatable in the directions of arrows d and e, and a box 48 is mounted on the frame 46. A spring 52 is connected between the frames 46 and 47.When the cutting unit 2 is pressed backward in the direction designated by an arrow f, owing to the large cutting resistance offered by a thick or hard branch t which is contacted by the saw chain 27, the frame 46 is rotated about the pin 59 in the direction of arrow d against the tension of the spring 52, as shown by a dotted chain line in Fig. 5. In other words, the frame 46 and the spring 52 form a detector E responsive to the cutting resistance afforded by the branch during cutting by the cutting unit 2. The spline shaft 45 and levers 49, 50 of the frame 40, which are parallel to the shaft 45, are mounted telescopically in the box 48 in the direction R, i.e.

radially of the standing tree T. The cutting unit 2 is pressed toward the axis of the standing tree by the tension of a spring, not shown, so as to be held resiliently in contact with the surface of the standing tree. A mounting plate 51 is provided for the rear ends of the shaft 45 and the levers 49, 50.

It is difficult to cut a branch t contacted at the top of the cutting unit 2. Therefore the tree pruning machine A comprises a branch sensing member 41 which is elastically supported by a spring 76, as shown in Fig. 1, attached telescopically to the top of the frame 40. When the sensing member 41 makes contact with a branch t so that the sensing member 41 is moved backward, the stopper 42 is pulled by a wire, not shown, contained in a pipe 81 (Fig. 1) so as to be separated from the gear g12 as shown in Fig. 4. The tree pruning machine A then moves down the standing tree T under its own weight so as to avoid the branch concerned. The sensing member 41 is then projected forward immediately by the spring 76, so that the stopper 42 becomes again engaged in mesh with the gear g12 as shown in Fig. 3.In this condition the tree pruning machine A will again climb the standing tree to attempt to cut the branch avoided previously as described above.

The rotating speed reduction unit D of the unit C is composed of a brake unit which has a driven wheel 61, a drive wheel 62, a belt 63, and a brake band 64 engaged with the lower portion of the driven wheel 61. The wheels 61 and 62 have rotational shafts 61a and 62a respectively. At the rear end of the brake band 64 is a stopper 65. The end of the brake band 64 is fixed to a pin 67 carried by a rotary plate 66. At the rear of the rotary plate 66 is a rotational shaft 68. The end of the rotary plate 66 is elastically supported by a spring 69. The spring 69 has a stopper 70.

A lever 71 is engaged with the end of the rotary plate 66 and is coupled with a lever 73 engaged with a stopper 72 projecting from the frame 46. The lever 71 is supported by a support 74.

When the tree pruning machine A climbs up the standing tree, the drive wheel 62 is driven by the engine 1 to transmit the rotation of the engine to the driven wheel 61. The gear g7 is rotated by the rotation of the driven wheel 61. Thus the unit C is moved in the direction of the arrow X around the transport device B as described above, and the branch t is cut by the chain saw 27. If a branch t having a large cutting resistance, such as a thick or hard branch, is in contact with the chain saw 27, the cutting unit 2 is pressed backwards by the branch in the direction of the arrow f.

Thus, the frame 46 and the box 48 are rotated in the direction of the arrow d about the pin 59, as designated by a dotted chain line in Fig. 5. Then, the lever 71 is pulled in the direction of an arrow p,the driven wheel 61 is clamped by the brake band 64, and the rotating speed of the driven wheel 61 is decreased. Thus, the rotating speed of the gears g7 to g10 is decreased, the rotating speed of the rotary device C in the direction of the arrow X is thereby decreased, and the cutting unit 2 is advanced more slowly with respect to the branch t.When the branch t is cut, the frame 46 and the box 48 are rotated by the tension of spring 52 in the direction of the arrow e to be returned to their original positions (designated by a solid line in Fig. 5), the brake band 64 is loosened, the driven wheel 61 is returned to its normai constant speed, and the unit C moves around the transport device B at its normal predetermined speed.

This invention is not limited to the particular embodiments described. For example, in the embodiment described above, the rotating speed reduction unit has been described with the example of a brake unit using a brake band. However, a frictional clutch unit may be used instead of such a brake unit, and when the cutting unit is pressed backwards by a branch the frictional clutch unit may be operated so as decrease the rotating speed of the cutting unit in the branch cutting direction.

Various other changes and modifications may be made within the spirit and scope of this invention.

According to an embodiment of the present invention, when a branch offering a large cutting resistance, such as a thick or hard branch, is in contact with the cutting unit 2, the contact is detected by the detector E which controls the rotating speed reduction unit D so as decrease the rotating speed of the unit C and thereby cut the branch more slowly.

Claims (6)

1. A pruning machine comprising a cutting unit carried by a transport device, for embracing a portion of a tree, and motor means coupled with the cutting unit and transport device for actuating the cutting unit and causing the transport device to move along the said portion and driving the said cutting unit to move therearound so as to bring a saw thereof into cutting engagement with members projecting laterally from that portion, wherein there is provided cutting-resistance detection means which are responsive to changes in the resistance to movement of the said saw around the said portion and are coupled to a speed control device of the said motor means sothat an increase in the said resistance can cause a decrease in the rate at which the cutting unit is driven to move around the said portion.

2. A machine- as claimed in claim 1, wherein the said cutting unit is mounted so as to be pivotally movable, about an axis extending in the direction of movement of the transport device along the said tree portion, such pivotal movement being resisted by a resilient connection between the cutting unit and a support member, on which movement around the said portion is imposed when the machine is in use, and serving to operate the speed control device.

3. A machine as claimed in claim 2, wherein the said cutting unit is pivotally mounted on a pin carried by the said support member.

4. A machine as claimed in claim 1, 2 or 3, wherein the said speed control device comprises a controllable braking unit.

5. A machine as claimed in any preceding claim, wherein the said transport device includes a motor-driven wheel for engaging the said tree portion to bring about the movement therealong.

6. A pruning machine substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings.