GB2028624A - Power driven plant-cutting machine - Google Patents

Abstract

A portable plant-cutting machine comprises a rigid tube 1 having a conventional reciprocating blade cutting head 2 mounted on one end thereof and an internal combustion engine 3, which drives the head, mounted on the other end thereof, the tube further having bicycle type handlebars 19 mounted thereon and anchorage points 20, 21 for a harness 22, the harness and its mounting being such that the machine can be slung from both shoulders of the user with the tube passing between the thighs of the user and with the load being evenly taken by the user's shoulders. The machine can thus be readily manoeuvred by use of the handlebars as the user walks about with the machine. <IMAGE>

Description

SPECIFICATION Power driven plant-cutting machine The present invention relates to a portable, power driven, plant-cutting machine.

A need arises in creating a plantation, to protect the young trees against weeds such as bracken and nettle, which for convenience hereinafter will be referred to as tall weeds. Uniess the tall weeds are cut down they are likely to grow and proliferate to the extent of starving the young trees. Because of the difficult terrain, it is not feasible to use a wheeled power driven cutting machine, which might otherwise be suitable; and the presently available shoulder slung power driven machines, while being portable, are not capable of sufficient rate of working to make it feasible to use them in a large acreage such as is usually encountered in a plantation.

It is an object of the present invention to provide a power driven, plant-cutting machine which, although providing a rate of cutting such as to make its use feasible in a large acreage, is nevertheless portable and easily manoeuvrable manually by the user.

The present invention seeks to achieve this object by providing a power driven plant-cutting machine comprising a frame member having mounted thereon a reciprocating blade cutting head and an internal combustion engine spaced apart from one another in the length of the frame member and connected by a transmission mounted within or along the frame member to provide a drive from the engine to the cutting head; the frame member comprising a handle bar, located between the engine and the cutting head, and attachment points for a harness such that the frame may be slung from both shoulders of the user with the frame member passing between the thighs of the user, and with the engine disposed to the rear of the user and the cutting head disposed forwardly of the user; the handle bar being located so that when the frame member is so slung from the users shoulders, the handle bar is disposed in front of and adjacent the user's body.

The use of a reciprocating blade cutting head makes it possible to provide a cutting rate that is needed if it is to be feasible to cut down large areas of tall weeds; and the slinging of the machine with the frame member passing between the thighs, not only makes possible an even loading of the weight of the machine on the users body, which makes the machine easy to carry, but also enables the machine to be readily manoeuvred so that the cutting head can be trained with little effort to follow rough terrain and to avoid obstacles.

Thus, the present invention provides a machine of the requisite capacity which is readily portable and manoeuvrable and can be carried without undue strain and can be used with a minimum of effort.

The frame member is preferably a straight rigid tube with the cutting head mounted on one end thereof and the engine on the other end thereof.

Preferably, the harness used is such as to permit the tube to be slung at a height of some 27" (68 cm) from the ground at the point where the tube passes between the thighs. Fixing this height determines the length of tube forwardly of the user for any chosen angle of inclination of the tube in use of the machine; and the length of tube rearwardly of the user is chosen in practice so that the engine counterweights the weight of the cutting head.

Conveniently, the transmission from the motor to the cutting head is mounted within the tube so that no moving part is exposed adjacent the position in which the user uses the machine.

It is also preferred that a harness be used having some resiliency in it, for instance, by incorporating one or more springs, so that the harness itself aborbs vibration from the machine arising in use thereof. Alternatively or additionally, the handlebar mounting may comprise a shock absorber such as a "Silentbloc" device.

The present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a side elevational diagrammatic sketch of a cutting machine according to the present invention; Figure 2 is a diagrammatic plan view of the machine of Figure 1 with a harness shown in Figure 1 omitted; and Figure 3 is a detail of the machine of Figures 1 and 2.

Referring now to the drawings, the illustrated machine comprises a frame member 1 in the form of a straight rigid tube having mounted thereon at one end a reciprocating cutting blade mechanism 2, and at the other end, an internal combustion engine 3.

The cutting blade mechanism is itself conventional and consists of two blades 4,5 (see Figure 3 in particular) housed between two rigid strips 6,7 so as each to be reciprocable in the housing in the longitudinal direction of the blade. The blades may be as long as 60" (approximately 152 cm) although preferably they are not less than 24" (approximately 61 cm) long. They are driven from a two-throw crank shaft 8 via connecting rods 9, 10 respectively; the crank shaft being driven from the engine by a transmission described hereinafter.

The housing formed by strips 6,7 bears two rearwardly trailing, downwardly inclined, stiff flaps 12, 13 one adjacent each end of the housing to prevent the blades from bottoming on the ground in use of the machine; and one of the connecting rods carries a shield 11 to prevent cut piants from fouling the crank shaft.

The transmission comprises a "prop" i.e. propeller, shaft (not shown) housed internally of the frame member. The prop shaft drives a fly wheel 14 (see Figure 3) to which the crank shaft 8 is connected, and is itself driven via a centrifugul clutch (not shown) from the output shaft of the engine. The centrifugul clutch is housed in a boss (Figure 1) secured on the respective end of the frame member; and the engine provides a boss 16 surrounding the output shaft, which is bolted to the boss 15 to secure the engine to the frame member.

Adjacent the engine, the frame member is provided on the underside thereof with a stand 17 formed of wire struts secured to the frame member, to avoid bringing the air intake 18 of the engine in touch with the ground when the machine is laid down.

At a point intermediate the ends thereof, the frame member has secured thereto a handle bar 19 of the bicycie type, and anchorage points 20, 21 for a harness 22.

The anchorage points may each simply be a lug bored to receive a hook connection 23, 24 of the harness. The harness provides two straps 25, 26 one to pass over each shoulder of the user.

The straps are connected to the hook member 23 for the more forward 20 of the anchorage points via a quick release buckie 27 and to the hook member for the other anchorage point 24 via a spring 28, the spring acting to take up vibration produced when the engine is set going.

In a specific construction of the illustrated machine, the engine used was a Tecumseh 670-71A petroil-fuelled, two stroke engine of something over a 100 cc capacity, which, including a full fuel tank, weighed some 15 Ibs (approximately 6.8 Kilogrammes); and the cutter blades were 3'-10V2" long (approximately 118 cm) with the cutter blade assembly weighing some 6 Ibs (approximately 3 Kilogrammes).

Sinc M in use of the device, the cutting head needs to be brought close to the ground, the frame member needs to be inclined and a convenient angle is about 30 .

The machine was intended to be slung from the user's shoulders to leave the frame member passing between the thighs of the user and at this point to provide a clearance between the frame and the ground of some 27" (68 cm).

Accordingly, in the specific construction, the reach of the frame member forwardly of the handlebar position (as indicated by dimension A in Figure 1) was some 29" (approximately 73.6 cm), and the extension of the frame member rearwardly of that position (as indicated by dimension B in Figure 1) was some 35" (approximately 98 cm) giving a total length for the frame member of some 64" (approxi n?:ely 162.6 cm). The engine occupied an axial 'goth of some 8" (approximately 20.3 cm) and the cutter blade assembly extended forwardly of the respective end of the frame member some 3" (approximately 7.6 cm) giving an overall length of some 75" (approximately 190.5 cm). The total weight of the machine was some 38 Ibs (approximately 17.2 Kilogrammes).

The more forward of the anchorage points for the harness can be regarded as being at the handle bar position and the other anchorage point as indicated by dimension C in Figure 3, was set some 23" (approximately 59.4 cm) rearwardly thereof. The height of the handle bar above the frame member 1 (as indicated by dimension D) was 111/2" (approxi- mately 29 cm).

With these dimensions, the machine proved to be well balanced when slung from the user's shoulders in the intended manner, to impose an even loading on the user's shoulders and thus avoid unnecessary strain on the user's body, to be readily manoeuvrable and not to obstruct the user's legs in walking about with the machine.

That these requirement should be met is of considerable practical importance since a machine of the invention is intended to be used in circumstances entailing a continous use of the macing for several hours in a day and possibly for many days in succession.

Further, the engine was arranged to run at a constant speed at substantially less than its maximum speed, to provide for reliability of operation and minimum wear of moving parts.

In the interests of safety, an engine cut out control 29 was mounted on the handle bar to permit the user to stop the engine at any time.

In addition to use in plantations on difficult terrain, the machine can conveniently be used for rapid cutting of tall weeds, such as thistles, nettles, and brambles, in fields, orchards, and gardens.

It is especially suitable for weed cutting on road sides, because it does not throw stones, it will operate on embankments of any slope, and it can move over verges which are interrupted by drainage channels or posts or trees. Further, the machine can be used for weeding or harvesting on wet, muddy, or even water-covered ground, where an operator can walk but where wheeled machines cannot go - for example in rice growing fields. It may in some cases be suitable for actually cutting under the water surface.

Claims (16)

1. A power driven plant-cutting machine comprising a frame member having mounted thereon a reciprocating blade cutting head and an internal combustion engine spaced apart from one another in the length of the frame member and connected by a transmission mounted within or along the frame member to provide a drive from the engine to the cutting head; the frame member comprising a handle bar, located between the engine and the cutting head, and attachment points for a harness such that the frame may be slung from both shoulders of the user with the frame member passing between the thighs of the user, and with the engine disposed to the rear of the user and the cutting head disposed forwardly of the user; the handle bar being located so that when the frame member is so slung from the users shoulders, the handle bar is disposed in front of and adjacent to the user's body.

2. A machine according to claim 1, wherein the frame member is a straight rigid tube.

3. A machine according to claim 2, wherein the cutting head is mounted on one end of the tube, and the engine is-mounted on the other end thereof.

4. A machine according to any of the preceding claims, wherein the harness is one having resiliency in it to absorb vibration arising from the engine in use of the machine.

5. A machine according to claim 4, wherein the resiliency is provided by one or more springs.

6. A machine according to claim 4 or 5, wherein the resiliency is provided by a shock absorber.

7. A machine according to any of the preceding claims, wherein the harness is such as to permit the frame member to be slung at a height of some 68 cm from the ground at the point where the frame member passes between the user's thighs.

8. A machine according to claim 7, wherein the cutting head comprises supporting feet.

9. A machine according to claim 8, wherein the supporting feet are in the form of trailing; downwardly inclined, stiff-flaps one adjacent each end of the cutting head.

10. A machine according to any of the preceding claims, wherein the blades of the cutting head are of a length of from substantially 61 cm to substantially 152cm.

11. A machine according to claim 10, wherein the blades of the cutting head are substantially 118cm long.

12. A machine according to any of the preceding claims, wherein the cutting head weights substantially 3 kilogrammes.

13. A machine according to any of the preceding claims, wherein the reach of the frame member forwardly of handlebars is substantially 73.6 cm and the extension of the frame member rearwardly thereof is substantially 89 cm.

14. A machine according to claim 13, wherein one of said attachment points is substantially at the handlebar position and a second one thereof is substantially 59 cm rearwardly thereof.

15. A machine according to any of the proceding claims, wherein the height of the handlebar above the frame member is substantially 29 cm.

16. Aportable, power driven, plant cutting machine substantially as hereinbefore described with reference to the accompanying drawings.