NZ202763A - Tree felling head:circular saw blade housing exposes segments of blade,felling head moved in scything action - Google Patents

Description

2 02763 Priority Datc(s): J. .. f./ Complete Specification Filed: C!^s: fl.O / fA .. Z?.-2.?£f/. P.l. ..

Publication Date: ...(■? ?! .^PX! P.O. Journal. No: Patents Form No.5.

Patents Act 1953 COMPLETE SPECIFICATION "Improvements in Disc Felling Heads" WE, AMCA INTERNATIONAL LIMITED, a company organised and existing under the laws of Canada, of 1155 Dorchester Boulevard West, Montreal, P.Q. Canada, H3B 4C7, hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularl described in and by the following statement:- .// f 202763 4* IMPROVEMENTS IN DISC FELLING HEADS .This invention relates generally to the tree-harvesting industry, and has particularly to do with the design of a boom-mounted felling head for a tree harvestor, capable of permitting harvesting rates at relatively low vehicle lA speeds. t I -j BACKGROUND OF THIS INVENTION t3*"T P rv A ° • s . "Parcr\1 *T i I , 11>*1 l- In copending application 383> 217 f iled on August pen\M.iM- -5-?—there is disclosed a boom-mounted felling head which incorporates a horizontally oriented circular saw blade in the lower portion, and tree grappling means in the upper portion, in a construction which is such as to allow the saw blade to cut through the trunk of a tree before the tree grappling means is activated to 15 clasp the tree. This results in the considerable advantage of leaving the tree trunk completely unstressed and without bending moments of any kind during the cutting phase. It will be appreciated that, if the design had been such that the tree grappling means were in engagement with 20 the tree during the cutting procedure by the circular saw blade, any misalignment between the tree grappling means and the tree itself would place a localized bending moment on the tree trunk, so that as the saw blade were nearing the completion of its cut, it is likely that the 25 tree, both above and below the location of the cut or kerf, would splinter. Any splintering results in an 3 202763 unusable end portion for the cut tree, and reduces the usable production capability of the machine.

A. The main embodiment disclosed in the said earlier u.S \/r\> 1 I 4-1 4-^1 ,erKG{/jJ patent ajipi imfinn spriai Nn.—3&3-t-2±-7 is one in which ^7 ^>5/-**' the felling head is adapted for "straight-ahead" operation, in which the motion of the felling head during the cutting phase is intended to be along a line parallel with the boom.

There are two operations which can accomplish such 10 straight-ahead cutting for a felling head of the kind just mentioned. In the first procedure, the boom is held stationary in front of the vehicle, and the vehicle is driven forwardly to carry the felling head toward a tree in the path of the vehicle. This is a somewhat uncertain 15 maneuver because of the possibility of uneven terrain beneath the vehicle. In the case of uneven.terrain, the boom and the felling head can be caused to oscillate or gyrate in such a way that it is difficult to arrive at a clean cut. The second operation is to keep the vehicle 20 stationary and to extend the boom. In the case of a telescoping boom, the felling head would normally be controllable and capable of producing a clean cut. However, in the case of a knuckle boom, in which two boom portions are articulated together with the felling head being articulated 25 to the end of the remote portion, a complex arrangement of hydraulic controls and compensating maneuvers must be used in order to allow the felling head to move forwardly without gradually tilting, i.e. without a shift in the orientation of the plane in which the circular cutting •30 saw is rotating.

GENERAL DESCRIPTION OF THIS INVENTION Essentially, the present invention seeks to solve the foregoing difficulties by so arranging the felling head on the end of the boom that it is possible to harvest 3 5 a tree by swinging the boom sideways. Specifically, since it is convenient to keep the circular saw blade largely enclosed in a housing for safety and other reasons, the 202763 aim of this invention is attained by arranging to expose a portion of the periphery of the circular cutting saw over an arc which is offset with respect to a line through the cutting saw axis parallel with the boom. Moreover, by using an arc sufficiently large and appropriately located, the felling head will be capable of harvesting a tree whether operating in the straight-ahead mode, or in the side-swing or scything mode. With these two modes as extremes, it will be appreciated that angles between the straight-ahead mode and the side swathing can also be utilized. A preferred embodiment of this invention meets the latter criteria.

Accordingly, this invention provides a felling head for attachment to a boom, the felling head comprising: an upper part and a lower part, the upper part including a brace portion for contacting a tree being felled, along with tree grappling means for clasping a tree trunk against said brace portion, the lower part having a circular saw blade mounted thereon in a plane perpendicular to the longitudinal extent of a tree clasped between the brace portion and the grappling means, and housing means for said circular saw blade, the housing means being shaped to expose the circular saw blade over an arc thereof, said arc being offset to one side with respect to a line and a first hypothetical plane xvhich passes through the rotational axis of the saw blade and is parallel to said boom, whereby the felling head can cut trees in a scything action with the boom swinging sideways, the felling head including means for mounting the felling head to the boom for pivotal motion in a vertical plane substantially parallel with the boom.

In another embodiment, this invention provides a felling head for attachment to a boom, ^ 202763 which again includes an upper part and a lower part. The upper part includes a brace portion for contacting a tree being felled, along with tree grappling i'or claspinp, a tree trunk against said brace portion. The 5 lower part has a circular saw blade mounted thereon in a plane perpendicular to the longitudinal extent of the tree clasped between the brace portion and the grappling means. A housing is provided to enclose the saw blade except for two exposed portions thereof on either side of a 10 line parallel to the boom and passing through the rotational axis of the saw blade. In this manner, the felling head can fell, trees when the boom swings horizontally without extension in either direction. One of the exposed portions is aligned with the tree grappling means.

Finally, this invention provides a method of felling a tree, which includes providing a felling head on a horizontally swingable boom, the felling head including tree grasping means and a circular saw blade, the blade being in a housing shaped to expose the blade over an arc thereof 20 which is offset with respect to a line through the saw blade axis parallel with the boom. A tree is cut through with the exposed saw blade arc by swinging the boom horizontally. In a preferred form of the method, the tree is grasped in the tree grasping means immediately after the 25 tree has been cut through.

GENERAL DESCRIPTION OF THE DRAWINGS One embodiment of this invention is illustrated in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which: 30 Figure 1 is a somewhat schematic elevational view of a boom-supported felling head mounted on a vehicle; Figure 2 is a plan view of the apparatus shown in Figure 1; Figure 3 is a horizontal sectional view taken at 35 the line 3-3 in Figure 1; and 2 0 7 & Figure 4 is a vertical sectional view taken at •' the line 4-4 in Figure 3.

DETAILED DESCRIPTION. OF THE DRAWINGS Attention is first directed to Figure 1, which 5 shows a somewhat schematic elevational view of the'front portion 10 of a wheeled vehicle of conventional nature, adapted to move through wooded or forested terrain for the purpose of harvesting trees. The vehicle includes wheels 12, a frame structure 14, a turntable 16, a cab 10 18 and cab base 19 mounted for rotation about the axis 20 of the turntable 16, and a boom generally shown by the numeral 22. The boom includes an inner portion 23 mounted to rotate about a horizontal axis in a vertical plane which is fixed with respect to the cab 18 and thus 15 rotates therewith. The horizontal pivot location for the inner portion 23 is not visible in Figure lt but is seen in Figure 2 at the line 25. A hydraulic cylinder 26 is secured between a bracket 28 on the inner portion 23 of the boom 22, and at a further location fixed with 20 respect to the cab base 19 (not seen in the figures), so that extension and retraction of the hydraulic cylinder 26 will cause the inner portion 23 of the boom 22 to rotate clockwise or counter-clockwise about its pivot line 25, respectively, thus raising and lowering, respectively, 25 a junction axis 29 between the inner portion 23 of the boom 22 and an outer portion 31. The outer portion 31 C of the boom 22 is pivotally mounted about a horizontal axis identified by the numeral 29, and thus the outer portion 31 remains always in the same vertical plane with 30 the inner portion 23, swivelling along with the inner portion 23 as the cab base 19 rotates about the axis 20. A further hydraulic cylinder 3 3 is-pivoted between a bracket 34 on the inner portion 23 of the boom 22 and a bracket 36 on the outer portion 31. Extension and contraction 35 of the hydraulic cylinder 33 causes the outer portion - 2 027 6 m ' 31 to rotate clockwise and counter-clockwise, respectively, about the horizontal pivot 29.

At the distal end of the outer portion 31 is a horizontal pivot axis 38 about which a felling head generally 5 shown by the numeral 40 is pivotally mounted. In order to positively control the attitude of the felling head 40, a third hydraulic cylinder 42 is pivotally mounted between a bracket 44 on the outer portion 31 of the boom 22 and a lever arm 45 which is pivotally mounted about 10 the horizontal axis 46. At a location intermediate of the lever arm 45 is an axis 48 to which a link 50 is connected. The other end of the link 50 is pivotally connected to a bracket 51 on the felling head 40. It.will be seen that extension and retraction of the third hydraulic cylinder 15 42 will cause counter-clockwise and clockwise movement, respectively, of the head 40 about the pivot axis 38, as pictured in Figure 1.

The felling head 40 includes an upper portion generally shown by the numeral-53, and a lower portion generally 20 indicated by the numeral 55. The upper portion of the felling head 40.includes two pairs of grappling arms identified by the numerals 57 and 58 respectively for the upper and lower pairs in Figure 1. The top pair 57 of arms is illustrated in Figure 2, and is seen to include two 25 individual arms 60 and 61, which are pivotally mounted for swinging motion in a horizontal plane about axes 63 and 64, respectively. The arms 60 and 61 are mounted to brackets 6 5 and 66, respectively, which extend outwardly from a central column 6 9 which is pictured in both Figures 30 1 and 3. Hydraulic means are provided for closing and opening the individual pairs 57 and 58 of arms, some of the hydraulic mechanism being shown at the numeral 70 in Figure L. Because this particular hydraulic structure plays no part in the present invention, further detailed 35 description thereof is not essential. A description of % 2 0 o equivalent hydraulic control for arms of this kind may be found in copending application Serial No. 383,217 filed on August 5, 1981.

Shown in broken line 72 in Figure 2 is the outline 5 of a brace portion located between the arms 60 and 61 of the top pair 57, the brace portion 72 being horizontally aligned with the arms, so that the grappling arms are enabled to clasp a tree trunk against the brace portion 72.

The lower part 55 of the felling head 40 includes a circular saw blade 74 mounted in a plane perpendicular to the 'general longitudinal extent of the tree clasped between the brace portion 72 and the grappling arms 57 and 58. In the actual construction, with the column 69 15 oriented vertically, the circular saw blade 74 is in a horizontal plane. This attitude is shown in Figure 1, and it is in this orientation that the felling head 40 would be used to fell a vertical tree whose centre line lay along the broken line 76 in Figure 1. 20 The felling arm 40 includes an extension brace portion 77 which projects above the location of the tree grappling arms 57 and 58 as can be seen in Figure 1, and has mounted thereon a boomerang-shaped flange 78 (see in both Figures 1 and 2) which defines a recess 80 adapted 25 to receive a tree being felled, for example the tree shown at 81 in Figure 2). A similar recess is provided just above the saw blade 74, and for a description thereof attention is directed to Figures 2 and 3.

The circular saw blade 74 is located within a housing 30 83 which covers most of the blade but which is shaped and constructed so as to expose the circular saw blade 74 over an arc A which is offset with respect to a line 85 which passes through the saw blade axis 86 parallel to the boom. The line 8 5 is drawn as a broken line in 35 both Figures 2 and 3. In this disclosure and in the » 2 027 € appended claims, the word "offset" does not necessarily imply that the arc is wholly to one side of the line 85, since it is conceivable that the.arc A could pass across the line 85. What is deemed important is that the arc 5 A be located sufficiently around the circumference in one direction from the line 85 to allow the felling head to cut trees in a scything action with the boom moving sideways. In Figure 2, it can be clearly seen that the tree 81 could be cut with the boom 22 simply swinging 10 sideways, without undergoing extension, and without requiring the vehicle 10 to move forwardly.

Looking at Figure 3, it can be seen that the housing 83 is cutaway or recessed by virtue of an upstanding plate 87 which is bent generally in an L-shape so that it includes 15 a first arm 88 extending from the periphery of the housing 83 inwardly to a location about even with the pivot axis 86 of the saw blade 74, but offset leftwardly therefrom. The arm 88 is substantially parallel with the line 85 which extends parallel with the boom. The plate 87 then 20 undergoes a 135° angulation at 89, and then a further 135° angulation to define a second arm 90 extending again to the periphery of the housing 83. The plate 87 is reinforced by an additional plate 92 as seen in Figure 3, over its inner portion, i.e. the location which will receive 25 the most contact from tree trunks.

As can be seen in Figure 3, the internal 135° angulation 89 of the plate 87 is welded directly to the column 69, and is braced therefrom by virtue of angulated brace plates 94 and 95 of known construction.

The recess defined by the reinforced bent plate 8 7 just above the saw blade 74 is in alignment with the recess 80 defined by the boomerang-shaped plate 78 shown in Figure 2. Hence, a tree trunk can be securely grasped and supported by the pairs 57 and 58 of arms, with two 35 locations or pressure points being applied to the tree at distances spaced in opposite directions from the arms 57 and 58, to steady the same.

J 20276 It will be noted that, in the particular structure shown in Figure 3, a line or vertical plane through the rotational axis 86 of the saw blade which is also at right angles to the plane or line represented by the line 85 5 also passes through the exposed arc A of the saw blade. The location of the further plane just mentioned is shown by the broken line 96 in Figure 3.

As can be seen in Figure 3, the housing 83 is shaped to expose a further arc B of the circular saw blade 74 10 which is offset to the side of the line 85 that is opposite the offset of the first-mentioned exposed arc A. To this end, tEe housing 83 is cut away as shown in Figure 3, and two plates 98 and 99 are disposed substantially radially with respect to the pivot axis 86 of the saw blade 74, 15 suitably welded to the outer portion "of the housing 83. A cross-wall 100 is provided to span between the walls 98 and 99 and is welded thereto just above the plane of the saw blade 74. In the preferred embodiment shown in Figure 3, the further arc B is wholly to the righthand 20 side of the line 85 in Figure 3, just as the arc A is wholly to the left of the line 85. Also as seen in Figure 3, the line 96, which lies at right angles to the line 85, also passes through the arc B. ■ The arc A shown in Figure 3 is approximately • - -1 although it is considered that arcs of different angles would also be useful. In a general way, an exposed arc of between about 90° and about 110° of the blade's periphery would be useful for the arc A.

For the arc B, shown in Figure 3 as approximately ^5°, 3 0 the approximate range would be between about 40° and about 60° of the blade's periphery. These angulations, however, are not considered to be limiting in any sense.

It will be noted in Figure 2 that the arms 60 and 61 are substantially symmetrically disposed about an imaginary 35 line at 135° with respect to the line 85 which is parallel -\\3 - / 2 0?7 with the boom 22. This allows trees to be cut when the felling head is being moved in a direction forming an angle of 135° with respect to the boom. Hence, it will be appreciated, particularly by looking at Figure 2, that 5 trees can be felled when (a) the boom is simply swinging sideways without extension and without vehicle movement, (b) the vehicle is stationary and the boom is merely being extended foxrwardly so that the felling head moves parallel with the boom with no swinging motion, (c) the boom is 10 held fixed with respect to the vehicle and the vehicle is driven forwardly, and (d) a combination of swinging and forward movement (either of the boom or the vehicle) causes the felling head 40 to move with respect to the terrain at an angle between 90° and 180° with respect 15 to the instantaneous elongation direction of the boom 22.

Attention is now directed to Figure 4, which shows a section through the section line 4-4 in Figure 3.

Essentially, the novel aspect shown in Figure 4 20 is that of allowing tapered cutting teeth to fit within correspondingly tapered passageways, so that the centrifugal force exerted on the teeth by the rotation of the saw blade 74 will simply lodge them more securely in their passageways, rather than work to dislodge the teeth. 25 More specifically, Figure 4 shows the peripheral portion of the saw blade 74, with the arrow C designating the direction of centrifugal force. As can be seen in Figure 4, the disc of the saw blade includes a thinner central portion 105, and a thickened peripheral portion 30 106, through which alternately angulated passageways 108 are provided. More specifically, every other one of the tooth passageways 108 angles upwardly and outwardly from the bottom surface 110 of the portion 106, and the intervening passageways are angled downwardly and outwardly, 35 opening through the top of the portion 106. In Figure -u- 2 0?7 3, an opening through the top of; the portion 106 i£ designated by the numeral 112.' As can be seen in Figure 4, the individual teeth 114 are tapered in the outward direction, as is the corresponding passageway 108. In the embodiment shown 5 in Figures 3 and 4, the passageway 108 also tapers outwardly as seen in plan view, thus there is a double taper for the essentially rectangular cross-section passageway 108. It will be understood that it is not essential to have both tapers present in order to achieve the benefits of 10 this construction.

It will therefore be apparent that the construction shown particularly in Figure 4 achieves several advantages. Firstly, as already mentioned, the individual teeth 114 simply become more securely lodged with respect to the 15 second portion 106 of' the circular saw blade 74, as a result of the centrifugal force acting in the direction of the arrow C. Secondly, however, the relatively simple tooth construction allows the individual teeth to be displaced upwardly and downwardly with respect to the central plane 20 of the disc, which is identified in Figure 4 by the line 116. This is of importance for the structure under consideration, because it is desirable to make the kerf (saw cut) through the tree trunk as wide as conveniently possible, since this will allow-a certain scope for mis-alignment 25 or out-of-horizontality for the felling head 40 as it approaches and cuts through a tree.

As seen in Figures 3 and 4, a cover plate 119 is provided directly above but not in contact with the circular saw blade 74. The plate 119 is stationary, and its purpose 30 is to support the weight of a tree after it has been cut through, and during the clasping of the tree by the pairs of arms 57 and 58. If the tree were to fall down against the saw blade 74, not only would its weight seek to bend or distort the saw blade 74, but considerable burning 35 and heat generation would take place.

-YX I X <*>> 2027,63 In the use of the felling head 40 shown in the drawings and described above, it will be appreciated that a tree can be felled during a boom swinging motion, whether or not the boom also imparts a component of motion to 5 the felling head which is parallel with the boom. In the normal performance of the method disclosed here, the pairs of arms 57 and 58 are open wide, and the felling head 40 is brought up against a tree with the saw blade 74 spinning. The saw blade is caused to cut through the 10 tree, and just as the cut terminates, the pairs 57 and 58 of grappling arms are activated to clasp the tree trunk into the V-shaped recess defined above and below the arms 57 and 58 by virtue of the plate 78 and the plate 87. By consructing the arms of the pairs 57 and 58 such that 15 they include an intermediate articulation between two O portions but such that the outer portion cannot pivot outwardly beyond a certain location in which it is roughly parallel to the inner portion, it is possible to clasp a first tree with one of the pairs of arms, then clasp 20 a second tree with the second pair of arms such that the second tree lies outside of the first pair of arms, and then to withdraw the first pair of arms from between the two trees so that a third tree can be clasped by them. T-hirg-particular-prooe4ure - is-mentiened in copending- app!4o< p L B & A x/i~2S '-t-ion Serial No.—303,219,—filed on August 5, a-^so a oatur-c of -i-csued -Canadian- Patent 3Io-. -issued on 02^ <SJ2cjL ■r>~*? j -\1

Claims (9)

202763 l-JHAT l'7E CLAIM IS

1. A felling head for attachment to a boom, the felling head comprising: an upper part and a lower parjt, the upper part including a brace portion for contacting a tree being felled, along with tree grappling means for clasping a tree truck against said brace nortion, the lower nart having a circular saw blade mounted thereon in a plane perpendicular to the longitudinal extent of a tree clasped between the brace portion and the grappling means, and housing means for said circular saw blade, the housing means being shaped to expose the circular saw blade over an arc thereof, said arc being offset to one side with respect to a line and a first hypothetical plane which passes through the rotational axis of the saw blade and is parallel to said boom, whereby the felling head can cut trees in a scything action with the boom swinging sideways, the felling head including means for mounting the felling head to the boom for pivotal motion in a vertical plane substantially parallel with the boom.

2. The felling head claimed in claim 1 which further includes an extension brace portion projecting above the location of the tree grappling means and providing a first recess for receiving a tree being felled, the housing providing, above the exposed saw blade arc, a second recess for receiving a tree being felled, whereby the tree can be securely held by said tree grappling means.

3. The felling head claimed in claim 1, in which the housing means is shaped to expose a further arc of the circular saw blade which is opposite the offset of the first-mentioned exposed arc. 202763

4. The felling head claiWtfT.n claim 3, in which said further arc covers between 40° and 60° of the blade's periphery.

5. The felling head claimed in claim 1 in which said exposed arc of the saw blade is positioned such that a second hypothetical plane which contains the rotational axis of the saw blade and which is at right angles to the first hypothetical plane through the axis passes through said exposed arc.

6. The felling head claimed in claim 5, in which the housing means is shaped to expose a further arc of the circular saw blade lying wholly to the second side of the said first hypothetical plane, the said second hypothetical plane also passing through the further exposed arc, whereby the felling head can be used to cut trees on the backswing.

7. A felling head for attachment to a boom, the felling head comprising: an upper part and a lower part, the upper part including a brace portion for contacting a tree being felled, along with tree grappling means for clasping a tree truak against said brace portion, the lower part having a circular saw blade mounted thereon in a plane perpendicular to the longitudinal extent of a tree clasped between the brace portion and the grappling means, and a housing enclosing the saw blade except for two exposed portions thereof on either side of a line parallel to the boom and passing through the rotational axis of the saw blade, whereby the felling head can fell trees when the boom swings horizontally without extension in either direction, one of said exposed portions being aligned with said tree grappling means.

8. The felling head claimed in Claim 7, in which said one of 15 202763 m . said exposed portions is large enough to allow the head to cut and collect trees when the felling head is being moved in a direction forming an angle of 135° with respect to the boom, the grappling arms being substantially symmetrically disposed about a line at 135° with respect to the boom.

9. A felling head for attachment to a boom, substantially as hereinbefore described with reference to and as shown in the accompanying drawings. AMCA INTERNATIONAL LIMITED by their authorised agents P.L. BERRY & ASSOCIATES Per: k'- Ox