CHAIN SAW FOR PRUNING TREES AND SHRUBS

Abstract: A tree pruner comprising a small chain saw (35) attached to one end of an elongate tubular guide bar (12) which has a motor (10) attached to the other end thereof. A belt drive (19, 20) extends between a pulley (11) on the motor and a pulley (32) at the chain saw to drive the cutting chain (36) and the belt is enclosed within the guide bar. A flywheel (33) is included on a common shaft with the chain saw pulley (32) and has a mass sufficient at full speed to store enough energy to cause the saw to cut through smaller branches whereby the motor and the belt drive can be of reduced power capability and only sufficient to spin the flywheel to maximum speed within a short space of time under a no load condition. A turbine drive between motor and chain saw is also disclosed as is a guard member (38) for the saw blade. The guard member (38) also has guide portions (39) for guiding the cutting chain over a branch to be severed.

Description: 1 CHAIN SAW FOR PRUNING TREES AND SHRUBS -> This invention relates to portable chain sa s and more 3 particularly to chain saws, or attachments for chain saws. 4 which facilitate use of the saw for tree pruning whereby the 5 user is able to stand at ground level and cut branches hich 6 would normally be out of reach. 7 Apparatus of the general kind in question is known and 8 examples can be found in U.S. patents 4 ,341 ,017 and 9 4 ,654,971 , for example. The U.S. paten t 4 ,341 ,017 to 0 Janczak discloses a guide bar supporting a chain saw at one 1 end and being suitable for holding by the user at the other 2 end whereby it can extend up ardl to reach branches hicn 3 would normal ly only be accessible by the user being in an 4 elevated position. An internal co bustion engine and 5 hydraulic pump are strapped to the user and the chain sa is 6 driven by hydraulic fluid pumped to the saw via h draulic 7 lines hich pass along the guide bar. A major disad an age 8 of the Janczak apparatus is that the hydraulic l ines, en 9 ful l of fluid, become quite heavy and it is difficul t: for 0 the user to hold the chain sa in an up ard or raisec 1 orientation for any length of time. Furthermore, since ar. 2 oi l coo l er i s required and since the motor mu t be 2 relatively large in power to provide sufficient po er a t e - cnain sa . trie apparatus strapped to the user is neavy ar.2 5 cumbersome . 6 The U.S. patent 4.654,971 which has been assigned t . ~ Hud d Enterprises uses a hand-held electric or gasolin S driven engine to drive a remote chain saw. In this case a 9 drive shaft ex ends between the motor and saw and ne ma i t feature of the Hudd patent is to provide extension an: 1 retraction of the drive shaft and housing y a uπic je 2 telescoping arrangement. A ain, however, a drive s aft j capable of transmitting sufficient po er itnout too mu .-. - .1 exin: of ne shaf becomes somew at h a y anc ai s : req ires expensive bevel gears at t e remote cr c.nain saw D e Ώ i in orαer _ _■ con er ne rive throu 9 'J " . I wil l - e ~ aofrεc atec at t is necessarv t pre vice sufficien D «-:r i i ; t .- e ≤a w t a v : • t ■_ s t a 1 ^ iπ 2 ;■ : t n e c u t t 1 π 2 c .1a 1 n w n er. t -. -"- 1 chain catches on a knotty or particularl hard piece of timber, and thus the prior art arrangements provide 3 considerable po er at the motor as el l as dri e 4 arrangements which are capable of transmitting that power to 5 the remote chain saw. The result is apparatus which is 6 heavy or cumbersome and thus incapable of use over 7 continuous extended periods. 8 A further problem which exists with the known apparatus 9 concerns the difficulty in accurately guiding the cutting 10 chain onto a branch to be severed particularly because the 11 cutting chain is at a height ell above the user which makes 12 accurate vision and control of the cutting chain difficult. 13 It is desirable to avoid jumping of the blade from an 14 initial position or re-starting a cut in another position or. 15 a branch, particularl if the cuts caused by a false start 16 remain on the tree or shrub since this causes damage 17 thereto . IS Accordingly. it is an object of this invention to 19 provide an improved chain saw which overcomes or reduces the 20 a orementioned disadvantages of known apparatus. 21 Thus the in ention provides a chain sa for pruning trees and shrubs wherein a guide bar extends from a motor to _ > a remote chain saw and incorporates drive means whereby said 2ύ motor is able to dri e the cutting chain of sai-i nair: saw. 25 characterized i tha , a flyvneei is provided on said dri e 26 means at said remote chain sa». said flywneel having a mass 27 sufficient to provide sufficient inertia when said flywheel 2S is rotating at full speed to enable the cutting chain to cut 29 through a relatively small branch of a said tree or shrub. 30 In order that the in ention may be more readi l 31 understood, one particular exoodime t will now be described with reference to the accompanying drawings wherein: Figure 1 is a sche atic perspecti e ie sho ing a 3^ chair, saw apparatus according to the in ention, bein hel 35 in position for use in a pr ning operation. 36 Figure 2 is a Der≤ ΓJec t i v e side i n z a m 3 c r . sho scne.-a-tιc≥ 1 ~ : . o mi g : Fia'jre 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, D Figure 5 is a side view of the chain saw end of the 6 apparatus including a sectional view of the other end of the 7 guide bar and belt drive, and 8 Figure 6 is a section taken on the line 6-6 of Figure 9 5. Referring now to the dra ings, the chain saw apparatus 1 according to this particular embodiment is shown to comprise 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 o larger capacity may be used. The motor 10 is provided i a pulley 11 which is connected to the output shaft of the motor. A ounting bracket 13 formed of aluminium is connected to the side of the motor 10 adjacent the pulley 11 b means of bolts 14. The mounting bracket has spaced substantially circular boss members 15 and 16 arranged he eo for supporting one end of a t bular guide bar 11 hich extends to a chain sa arranged at the other e d c: the guide bar 12. The circular boss members 15 and 16 are each formed in t o parts with a space therebetween to forrr. cavities 17 and 18 (see Figure 4) enabling passage of drive belts 19 and 20 along the tubular guide bar 12. An oil fee.: 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 1C. The guide bar 12 has l ongi tudina l s l ots ( not s owr, diametricall opposed ana adjacent tne end of the bar 1 i ~ . enable it to cia ei o the boss embers 15 and 1 o -.- tishteπiπs of c 1 ax.~ s 21 an 22. As is vident r. . μ i 2 r t _. a na n α 1 c 2 - is c arr.0e i .:• r z t n e r v1 e at ache t: : ■ .: : • . 1 bar 12 a short distance from the motor 10. Of course -> another handle 25 is provided on the motor 10 in a manner 3 kno n per se and ould normally have a throttle control 4 lever (not shown) attached thereto. By gripping the 5 respective handles the user is able to control the device 6 despite the fact that the chain saw end is considerabl 7 remote from the user. 8 Referring now to Figures 5 and 6 the other end of the 9 guide bar 12 is shown in more detail. The other end refers 0 to the remote or chain saw end of the guide bar 12. As is I evident in Figure 6 the tubular guide bar 12 is cut away at 2 its remote end and is attached to a further mounting bracket 3 26. The further mounting bracket 26 is affixed to the guide 4 bar 12 by screws (not shown) which pass through the wall of 5 the tubular guide bar 12 and into respective semi-circular 6 boss members 27 and 28 on the bracket 26. Spaced plates 29 7 and 30 of the bracket 26 support a shaft 31 mounted in 8 bearings in the respective plates 29 and 30. A multiple 9 groove V-belt pulley 32 is mounted on the shaft 31 between 0 the plates 29 and 30 and a flywheel 33 is mounted o the 1 outer end of the shaft 31. The flywheel has a gear 34 1 attached to the inside thereof for the purpose of driving a 3 cuttmε c ain 36 which moves on a chai saw bar 35. The 5 bc-_t 37 whicn passes through a slot in the chain saw bar 35. b The si t of tne c ain sa bar is not evide in the 7 dra ings. The bolt 37 passes hrough the plate 29 and or. S the opposite side of the plate 29 to the bar 35 there is a 9 nut which clamps a guard member 38 to the plate 29. As is 0 e ident in Figure 5. the guard member 38 passes around the 1 cutting chain 36 in close proximity thereto for the purpose 2 of pre enting contact with the cutting chain along tne 3 extent of the guard member 38 when the apparatus is in use. 4 It will be seen that the guard member leaves one elongated 5 sice of tne cutting c ain e osed for the urpose of c performing a cutting operation. ~ T e ard me ber 35 πas αeoen i guice o onions 2 ^ 6 w n : n extend a w a v f r c rr. ne expose: e i o n 2 ≥ t e : si e :: ' t o - cutting chain. The guide portions 39 in combination ith the chain define a bight for accommodating a branch to be severed by the pruning apparatus. In use 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. 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. Alternatively, he guide portion 39 at the free end of the apparatus ma 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 bet een the pulley 32 at the remote end of the guide bar 12 and the pulley 11 mounted on the motor output shaft. T e pulley 11 has similar multiple grooves to the p lle 22. The belts pass inside the tubular guide bar 12 as previously mentioned. Additionally, a guard 40 is provided over t n t f ly heel 33 to protect the flywheel against inadverte t contact ith branches of the tree or shrub during a pruning operation. The guard 40 is affixed to the guard member 25 by scre s (not sho n). According to a further form of the invention, the belt drive is replaced by a turbo drive. In this instance tne output shaft of the motor 10 drives an impeller which is arranged ithin a tubular guide bar which extends to tne remote end in a similar manner to the guide bar 12. Tne f lywheel shaf t 31 incorporates a rotor hich recei es compressed air passing up the tubular guide bar tnus rotatin the flywheel and thereby rotating the cutting cnai 36. In this embodiment the need f or a trans issii el t Dassinε inside ne suiαe bar 12 is ob iated. Z ~ . ; 1 necessary however, to have a gear reduction betwee the 2 rotor and the flywheel since the turbo drive is not capable 3 of transmitting large torque at slow speed. Thus, by using 4 a reduction gearing arrangement the rotor may be spun at 5 speeds up to about 25,000 r.p.m. in order to drive the 6 flywheel at a speed of about 10,000 r.p.m. and thus there is 7 sufficient torque to accelerate the flywheel back up to 8 speed in the required short time after a cutting operation. 9 It should be evident from the description above that 10 the present invention provides a light-weight pruner 11 apparatus which is convenient to use and which overcomes 12 some or all of the aforementioned disadvantages of prior art 13 apparatus. Whilst the transmission medium between the motor 14 and chain saw is not capable of transmitting high power, the 15 unique arrangement of a flywheel at the remote chain saw end 16 of the apparatus enables use of a smaller capacit motor 17 which is capable of spinning the flywheel to a relatively 18 high speed (8000 - 10000 r.p.m.) in a short space of time, 19 say 2 - 3 seconds, under no load conditions. The energ 20 stored In the flywheel 33 is sufficient to enable the 21 cutting chain 36 to cut through small branches and limbs -i ι before the energy is dissipated. The flywheel has a mass of about 200 gm. During the time in which the operator moves the cutting chain to another branch or limb, the motor is able to accelerate the fl wheel back to full speed. Th s 26 the use of a smaller motor and a relatively lo po er drive 27 means, results in an extremely light-weight apparatus. The 28 use of aluminium in the guide bar 12 and brackets 13 and 2c 29 also contributes to the light weight. 30 hilst a t in V-beit drive has been show it is clear 31 that a single belt drive or a tripple belt drive could be 32 utilized depending on the particular power to be 33 transmitted . 34 Whilst the apparatus described utilizes a guide bar 12 ha ing a length of appro imately 1.2 metres, it ill be evident that a longer guide bar 12 may be provided. In the case of a auide bar of 1.2 metres i ie a . an ooeratcr is ~ ~~ ab_e to reach c .___- metres m nexe t eπeπαins or c rse on the height of the operator, for the purpose of lopping branch. According to another embodiment of the invention the guide bar 12 has a length of about 3.5 metres which i achieved by having 3 cascaded belt drive arrangements. I other words, because of the difficulty in obtaining longe V-belts, intermediate pulley arrangements are spaced alon the length of the guide bar 12 to extend the belt drive in stages. Of course, it may be possible to use a singl longer belt to extend the full 3.5 metres in which cas intermediate pulleys would not be required. It is envisaged that a contractor engaged in the tas of pruning a forest of trees may require two of th 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. In such an instance, the contractor would first prune trees t a height which can be reached using the shorter apparatus and ould subsequently prune the trees using the longer apparatus which ould allow pruning up to 5 - 6 metres. Alternatively, the apparatus may be constructed in a way which allo s interchanging of guide bars 12 bet een a long bar and a short bar utilizing the same motor. Whilst the embodiments described above utilize either a V-belt drive or a turbine drive, it ill be apparen that other lo power light-weight drives could be use: to transmit power between the motor 10 and the f ly heel 33. Whatever type of drive means is used it must be capable of some degree of flexing particularly in the case of a long guide bar 12 and it must be of a light weigh .

Claims: CLAIMS 1. A chain sa for pruning trees and shrubs wherein a guide bar (12) extends from a motor (10) to a remote chain saw and incorporates drive means whereby said motor is able to drive the cutting chain (36) of said chain saw, characterized in that, a flywheel (33) 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. 2. A chain saw as defined In claim 1, characterized in that, said drive means is capable of transmitting sufficient po er to rotate said flywheel to maximum speed in a short time when said saw is not engaged in a cutting operation but not sufficient po er to maintain rotational speed of said flywheel during a cutting operation. 3. A chain sa as defined in claim 1 or 2, characterized in that, said drive means comprises a belt drive arrangement (19.20) extending bet een a first pulley (11) arranged at said motor and a second pulley (32) arranged on a common shaft (31) with said flywheel, said guide bar is a tube and said belt drive passes inside said tube. 4. A chain sa as defined in claim 3. c aracterized I hat, said belt drive is a twin V-belt drive. 5. A chain saw as defined in claim 1 or 2, characterized in that, said guide bar is a tube and said drive means comprises a turbine including a rotor arranged on a common shaft ith said fly heel and driven by compressed air i said tube generated by an impeller on said motor. 6. A chain sa as defined in any one of the preceding claims wherein the saw ' is a typical endless chain having a configuration of substan ially parallel elongate side chain portions an end return chain portions, characterized in that, a guard member (38) is provided on said chain saw, said guard member extends along one said elongate side chain portion and over said end return chain portions to prevent contact i the tlaαe≤ aio a the e te t of t e auar member, whereby only one of the elongate side chain portions is exposed for a cutting operation. 7. A chain saw as defined in claim 6, characterized in that, said guard member has depending guide portions (39) hich extend away from said exposed elongate side chain portion substantially in the plane of said endless chain whereby said guide portions and said exposed side chain portion combine to define a bight for receiving a branch to be cut. 8. A chain sa as defined in claim 3 or 4, characterized in that, said flywheel has a mass of about 200 gm and said motor is capable of rotating said flywheel up to a speed of about 8000 - 10000 r.p.m. in about 2 - 3 seconds. 9. A chain saw as defined in any one of the preceding claims, characterized in that, a guard (40) is provided at least substantially over said fly heel, and said chain is driven by a sprocket (34) on said common shaft. 10. A chain saw as defined in any one of the preceding claims, characterized in that, said guide bar has a handle (24) thereon adjacent said motor, and said motor has a handle (25) thereon whereby the user is able to grasp the respective handles, one in each hand, in order to operate the apparatus for pruning a tree or shrub.

Inventors: MATEY JOHN, MATEY, JOHN
Applicants: MATEY JOHN, MATEY, JOHN
Application year: 1988
Main classification: A01G3
IPC codes: A01G3, B27B17