Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
  • B27B17/00—Chain saws; Equipment therefor
  • B27B17/08—Drives or gearings; Devices for swivelling or tilting the chain saw
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
  • A01G3/00—Cutting implements specially adapted for horticultural purposes; Delimbing standing trees
  • A01G3/08—Other tools for pruning, branching or delimbing standing trees
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
  • B27B17/00—Chain saws; Equipment therefor
  • B27B17/0008—Means for carrying the chain saw, e.g. handles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
  • B27B17/00—Chain saws; Equipment therefor
  • B27B17/0083—Attachments for guiding or supporting chain saws during operation

Definitions

• This invention relates to portable chain saws and more particularly to chain saws, or attachments for chain saws. which facilitate use of the saw for tree pruning whereby the user is able to stand at ground level and cut branches which would normally be out of reach.
• Apparatus of the general kind in question is known and examples can be found in U.S. patents 4,341,017 and 4,654,971 , for example.
• the U.S. patent 4,341 ,017 to Janczak discloses a guide bar supporting a chain saw at one end and being suitable for holding by the user at the other end whereby it can extend upwardly to reach branches which would normally only be accessible by the user being in an elevated position.
• a drive shaft extends between the motor and saw and the main feature of the Hudd patent is to provide extension and retraction of the drive shaft and housing by a unique telescoping arrangement.
• a drive shaft capable of transmitting sufficient power witnout too much flexing of the shaft becomes somewhat heavy and also requires expensive bevel gears at the remote or chain saw end in order t o convert the drive through
• a further problem which exists with the known apparatus concerns the difficulty in accurately guiding the cutting chain onto a branch to be severed particularly because the cutting chain is at a height well above the user which makes accurate vision and control of the cutting chain difficult. It is desirable to avoid jumping of the blade from an initial position or re-starting a cut in another position on a branch, particularly if the cuts caused by a false start remain on the tree or shrub since this causes damage thereto.
• the invention provides a chain saw for pruning trees and shrubs wherein a guide bar extends from a motor to a remote chain saw and incorporates drive means whereby said motor is able to drive the cutting chain of said chain saw, characterized in that, a flywheel is provided on said drive means at said remote chain saw. said flywheel having a mass sufficient to provide sufficient inertia when said flywheel is rotating at full speed to enable the cutting chain to cut through a relatively small branch of a said tree or shrub.
• Figure 1 is a schematic perspective view showing a chain saw apparatus according to the invention, being held in position for use in a pruning operation.
• Figure 2 is a perspective side view o f a motor. shown schematical i y , forming p art of the apparatus.
• Figure 3 is a side view of part of the motor if Figure 2 and showing a sectional view of one end of a guide bar and belt drive connected to the motor,
• Figure 4 is a section taken on the line 4-4 of Figure 3,
• Figure 5 is a side view of the chain saw end of the apparatus including a sectional view of the other end of the guide bar and belt drive, and
• Figure 6 is a section taken on the line 6-6 of Figure 5.
• the chain saw apparatus is shown to c omp r i s e a motor 10 represented schematically and being in the form of a conventional small internal combustion engine of the kind used to drive a conventional small chain saw or brush cutter, for example.
• the motor may have a capacity of about 15cc - 18cc maximum in order to provide a very light-weight apparatus but of course in some circumstances a motor of larger capacity may be used.
• the motor 10 is provided with a pulley 11 which is connected to the output shaft of the motor.
• a mounting bracket 13 formed of aluminium is connected to the side of the motor 10 adjacent the pulley 11 by means of bolts 14.
• the mounting bracket has spaced substantially circular boss members 15 and 16 arranged thereon for supporting one end of a tubular guide bar 11 which extends to a chain saw arranged at the other end of the guide bar 12.
• the circular boss members 15 and 16 are each formed in two parts with a space therebetween to form cavities 17 and 18 (see Figure 4) enabling passage of drive belts 19 and 20 along the tubular guide bar 12.
• An oil feed line 21 also enters the tubular guide bar 12 and passes via one of the cavities.
• the tubular guide bar 12 fits snuggly over the boss members 15 and 16 and terminates adjacent the motor 10.
• the guide bar 12 has l ongitudinal slots (not shown diametrically opposed and adjacent the end of the bar 12 t o enable it to clamped on to the boss members 15 and 16 by tightening of clamps 22 and 23.
• a handle 21 is clam ped o r otherwise attached to the out of bar 12 a short distance from the motor 10.
• another handle 25 is provided on the motor 10 in a manner known per se and would normally have a throttle control lever (not shown) attached thereto. By gripping the respective handles the user is able to control the device despite the fact that the chain saw end is considerably remote from the user.
• the other end of the guide bar 12 is shown in more detail.
• the other end refers to the remote or chain saw end of the guide bar 12.
• the tubular guide bar 12 is cut away at its remote end and is attached to a further mounting bracket 26.
• the further mounting bracket 26 is affixed to the guide bar 12 by screws (not shown) which pass through the wall of the tubular guide bar 12 and into respective semi-circular boss members 27 and 28 on the bracket 26.
• Spaced plates 29 and 30 of the bracket 26 support a shaft 31 mounted in bearings in the respective plates 29 and 30.
• a multiple groove V-belt pulley 32 is mounted on the shaft 31 between the plates 29 and 30 and a flywheel 33 is mounted on the outer end of the shaft 31.
• the flywheel has a gear 34 attached to the inside thereof for the purpose of driving a cutt ing chain 36 which moves on a chain saw bar 35.
• the chain saw bar 35 is affixed to the mounting bracket 26 by a bal t 37 which passes through a slot in the chain saw bar 35.
• the sl ot of the chain saw bar is not evident in the drawings.
• the bolt 37 passes through the plate 29 and on the opposite side of the plate 29 to the bar 35 there is a nut which clamps a guard member 38 to the plate 29.
• the guard member 38 passes around the cutting chain 36 in close proximity thereto for the purpose of preventing contact with the cutting chain along the extent of the guard member 38 when the apparatus is in use.
• the guard member leaves one elongated side of the cutting chain exposed for the purpose of performing a cutting operation.
• the guard member 35 has depending guide portions 39 wnizn extend away from the exposed elongated side of the cutting chain.
• the guide portions 39 in combination with the chain define a bight for accommodating a branch to be severed by the pruning apparatus.
• the cutting head that is, the cutting chain 36 and guard member 38 may be located above a branch to be severed with the points of the guide portions 39 against the trunk of the tree or shrub.
• the guide portions 39 By sliding the guide portions 39 down the trunk until the cutting chain contacts the branch to be severed, it is ensured that the cutting chain does not jump to several different starting points when it contacts the branch and thus damaged caused by false starts to the cutting operation is avoided.
• the guide portion 39 at the free end of the apparatus may be hooked over a branch to be severed whereby the inclined surface 41 is used to guide the branch onto the cutting chain 36.
• the oil line 21 which extends from the motor inside the tubular guide bar 12 provides oil to the cutting chain 36 in a manner known per se.
• a pair of like poly V-belts of type section J extend between the pulley 32 at the remote end of the guide bar 12 and the pulley 11 mounted on the motor output shaft.
• the pulley 11 has similar multiple grooves to the pulley 32.
• the belts pass inside the tubular guide bar 12 as previously mentioned.
• a guard 40 is provided over the f lywheel 33 to protect the flywheel against inadvertent contact with branches of the tree or shrub during a pruning operation.
• the guard 40 is affixed to the guard member 38 by screws (not shown).
• the belt drive is replaced by a turbo drive.
• the output shaft of the motor 10 drives an impeller which is arranged within a tubular guide bar which extends to the remote end in a similar manner to the guide bar 12.
• the f lywheel shaf t 31 incorporates a rotor which receives compressed air passing up the tubular guide bar thus rotating the flywheel and thereby rotating the cutting chain 36.
• the need f or a transmissing bel t passing inside the guide bar 12 is obviated. I t is necessary however, to have a gear reduction between the rotor and the flywheel since the turbo drive is not capable of transmitting large torque at slow speed.
• the rotor may be spun at speeds up to about 25,000 r.p.m. in order to drive the flywheel at a speed of about 10,000 r.p.m. and thus there is sufficient torque to accelerate the flywheel back up to speed in the required short time after a cutting operation.
• the present invention provides a light-weight pruner apparatus which is convenient to use and which overcomes some or all of the aforementioned disadvantages of prior art apparatus.
• the transmission medium between the motor and chain saw is not capable of transmitting high power
• the unique arrangement of a flywheel at the remote chain saw end of the apparatus enables use of a smaller capacity motor which is capable of spinning the flywheel to a relatively high speed (8000 - 10000 r.p.m.) in a short space of time, say 2 - 3 seconds, under no load conditions.
• the energy stored In the flywheel 33 is sufficient to enable the cutting chain 36 to cut through small branches and limbs before the energy is dissipated.
• the flywheel has a mass of about 200 gm.
• the motor is able to accelerate the flywheel back to full speed.
• the use of a smaller motor and a relatively low power drive means results in an extremely light-weight apparatus.
• the use of aluminium in the guide bar 12 and brackets 13 and 26 also contributes to the light weight.
• the apparatus described utilizes a guide bar 12 having a length of approximately 1.2 metres, it will be evident that a longer guide bar 12 may be provided.
• a guide bar of 1.2 metres in length an operator is able to reach 3 to 3.5 metres in height depending of course on the height of the operator, for the purpose of lopping a branch.
• the guide bar 12 has a length of about 3.5 metres which is achieved by having 3 cascaded belt drive arrangements.
• intermediate pulley arrangements are spaced along the length of the guide bar 12 to extend the belt drive in 3 stages.
• a contractor engaged in the task of pruning a forest of trees may require two of the apparatus according to the invention, namely, a first apparatus using a shorter guide bar 12 and a second apparatus using the aforementioned longer guide bar 12.
• the contractor would first prune trees to a height which can be reached using the shorter apparatus and would subsequently prune the trees using the longer apparatus which would allow pruning up to 5 - 6 metres.
• the apparatus may be constructed in a way which allows interchanging of guide bars 12 between a long bar and a short bar utilizing the same motor.

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• Life Sciences & Earth Sciences (AREA)
• Forests & Forestry (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Wood Science & Technology (AREA)
• Biodiversity & Conservation Biology (AREA)
• Ecology (AREA)
• Environmental Sciences (AREA)
• Sawing (AREA)

Applications Claiming Priority (2)

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ID=3772353

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Citations (5)

Family Cites Families (3)

• 1988
  • 1988-07-29 JP JP50666488A patent/JPH02500246A/ja active Pending
  • 1988-07-29 EP EP19880907167 patent/EP0330689A4/de not_active Withdrawn
  • 1988-07-29 WO PCT/AU1988/000278 patent/WO1989000806A1/en not_active Application Discontinuation

Patent Citations (5)

Non-Patent Citations (1)

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