GB2281840A

GB2281840A - Converting strimmers to lawnmowers

Info

Publication number: GB2281840A
Application number: GB9418205A
Authority: GB
Inventors: Raymond Richmond
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-09-18
Filing date: 1994-09-09
Publication date: 1995-03-22
Also published as: GB9418205D0

Abstract

An attachment for a strimmer to convert it to a lawn mower comprises a single unit which has a shell 36 of a shape matching the rear of the strimmer head casing. From the shell depends a rear, hollow open sided base box 46 which has a rear ground engaging roller and side skids. When the shell is fitted snugly to the rear of the head casing the strimmer head rear guard 32 fits into the base box and the unit is attached by stretching an elasticated strap between lugs 40, 42 on the shell and over the head casing. The result is that the strimmer becomes an effective lawn mower as the roller and skids keep the cutting plane of the strimmer cable parallel to the ground. The front of the striker head is not covered so the assembly can continue to be used in normal strimmer functions. <IMAGE>

Description

Improvements Relating to Strimmers This invention relates to trimmers.

A strimmer is a device which is adapted to cut what is referred to herein as "vegetation". Vegetation comprises mainly grass, wheat and other growing material of a relatively soft and flexible nature, and the strimmer has a cutting cable which is usually wound onto a spool fo the device, and the trailing end of the cable is left free so as to extend substantially radially from the spool. As the spool is rotated so the free length spins at high speed in a plane which lies at right angles to the axis of the spool, and the device is constructed so that that plane can be presented by the user substantially parallel to the ground whereby the rapidly rotating length of cable severs the vegetation adjacent the ground. If the cable length strikes a relatively rigid object such as a tree or a stone, it will yield and then when it has passed such obstruction it will again take up its radial position to continue the cutting of the vegetation. The cable is usually of a plastics nature, and will wear with use. As it wears so a further length of the cable is fed out from the spool to enable the strimmer to continue operating.

The spool for the cable is located in what is referred to as a strimmer head, and the head is manipulated by the user whilst standing upright so that there is in fact a long handle extending from the head to a hand grip which the user holds in manipulating the device. Strimmers may be electrically driven in which case they must be connected to an electrical umbilical cable, or they may be petrol driven in which case a small 2-stroke engine is usually mounted at the use end of the handle, and the engine is connected to the spool by means of a flexible drive cable extending through the handle. Generally speaking, petrol driven strimmers are deployed where they are to perform heavy duty cutting of relatively dense vegetation over a large area such as on golf courses and in large gardens, whilst the electrically operated strimmers are used for relatively small domestic garden plots. Strimmers are used mainly for tidying up overgrown areas, but they can be used for more delicate and decorative cutting such as grass cutting or grass edging, in which latter case the said cutting plane is arranged to be located at 900 relative to the ground surface.

A strimmer head typically comprises a casing supporting at least a bearing for the spool, and the front side of the casing is usually open to allow the strimmer cable to perform its function, whilst to the rear side, the side at which the user stands realtive to the head, there is usually a guard in the nature of a flange with a downwardly depending rim which overlies the rear part of the plane in which the length of strimmer rotates, and which also prevents small solid objects such as stones and pieces of grit from being thrown rearwardly towards the user. It should be mentioned that it is recommended when a strimmer is used that the operator wear a pair of protective goggles, as there is a tendency for small pieces of grit and small stones to be thrown upwardly towards the user's face.

As mentioned above, strimmers can be used in some instances for cutting lawns, but because essentially they are held by the user slightly above the ground surface and can be tipped and tilted, they are not particularly suitable for cutting lawns as they tend to cut irregular and uneven swathes, and can result in the making in the lawn of large overcut circular regions, which can ruin the decorative effect of the lawn. Consequently, most householders who own a strimmer also own a separate and conventional lawn mower.

The present invention in one aspect seeks to provide a means for converting a strimmer into an adequate lawn mower whereby a householder who is the owner of a strimmer need not necessarily purchase a separate lawn mower for lawn cutting.

This concept of converting a strimmer to make it function as a lawn mower has already been addressed in certain prior patent specifications, namely US Patent Nos. 4,343,139 and 4,411,126, but in these patents the conversion is effected by providing what amounts to a wheeled trolley having wheels at four corners of a rectangular frame, and the strimmer is adapted to be fitted into the centre of the frame with appropriate coupling plates connecting the frame and the strimmer head. A relatively large assembly results, and the connecting of the trolley and the strimmer is a process which requires a degree of mechanical engineering, and hardly is suitable for, for example, rather elderly users.

Additionally, because a strimmer has only a single handle, manipulating and operating the combined strimmer and frame for lawn cutting is awkward, especially when it is a matter of reversing the direction of cutting at the ends of the lawn being cut.

Use of a frame of the type illustrated in the said US patents furthermore increases the weight of the strimmer considerably and, depending upon the materials used, could more than double the weight of a strimmer.

The present invention in one aspect addresses the problem of converting a conventional strimmer for use as an effective lawn mower, but seeks to provide a means whereby the conversion can be effected easily and quickly by unskilled personnel without requiring any particular strength or engineering ability, and which will not substantially increase the overall weight of the strimmer so that it will continue to be as manoeuvrable as without the conversion means, and furthermore at least in the preferred cases will allow the strimmer to function either as a lawn mower or in its conventional strimming function.

In accordance with a first aspect of the present invention, there is provided an attachment for a strimmer to convert it to a lawn mower comprising a shell shaped to fit the trimmer head casing and providing a means for connecting the attachment to the strimmer and a base suspended from the shell and having ground engaging means serving to keep the strimmer cutting plane substantially parallel to the ground for grass cutting.

Preferably the base is generally flat and is adapted to lie co-planer with the cutting plane of the strimmer and the shell may be generaally semi-circular in section and defines an axis which lies at the strimmer angle relative to the base.

The base may suitably be a flat hollow box open at one side to receive the strimmer guard and the said ground engaging means in one embodiment comprises a roller on the base which in use lies at the rear of the strimmer head, and this is preferably coupled with a pair of side wheels on the base which in use lie to opposite sides of the strimmer head.

The support is therefore of a 3-point support to the side and rear of the strimmer head, enabling the strimmer to perform its normal functions if required.

For the purposes of connecting the attachment to the strimmer head, the shell may be provided with integral lugs between which an elasticated member such as an elastic strap or band may be stretched so as to extend over the front of the strimmer casing whereby connection and disconnection can be effected particularly simply.

The attachment is preferably of plastics material so that it will be lightweight and is a single unitary structure which can be readily applied to and disconnected from the strimmer head.

For providing or assisting the connection of the shell to the strimmer head, there may be a slidable sleeve which slides over the shell after it has been positioned to the strimmer head casing.

In a particularly suitable construction, the unit is made up of a number of vacuum formed mouldings which are connected together by suitable means such as welding, adhesive, screwing or the like.

Although the main aspect of the present invention is the provision of an attachment, it is recognised that a strimmer could be produced where the casing of the head is constructed so as to include a structure somewhat similar to the attachment but where the structure is integral with the head, which provides that the strimmer can be used as a lawn mower on the one hand, the ground engaging means keeping the cutting plane parallel to the ground, and on the other hand it can continue to be used in its normal strimming functions.

The invention is therefore to be considered as extended to a strimmer wherein the strimmer head is provided with ground engaging means for keeping the strimmer head disposed so that the strimmer cutting plane remains parallel to the ground enabling the strimmer to be used as a lawn mower whilst the front of the strimmer head remains open enabling the strimmer also to be used in its normal functions.

In this arrangement,m it is preferred that the handle be pivotally connected to the head so that the handle can pivot relative the head (in much the same manner as a vacuum cleaner handle pivots relative to its head) when the strimmer is used as a lawn mower.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein Fig. 1 is a diagrammatic view illustrating in outline a conventional strimmer and the use thereof; Fig. 2 is a perspective view showing the attachment according to the embodiment of the invention in solid outline whilst illustrating the strimmer head in dotted outline; Fig. 3 is a sectional view of the arrangement shown in Fig.

2; and Fig. 4 is an exploded sectional view of the attachment shown in Fig. 2 and Fig. 3.

Referring to the drawings, and firstly to Fig. 1, a conventional strimmer is indicated generally by reference numeral 10, and a person using the device is illustrated by reference numeral 12. It will be seen that the user 12 stands on the ground 14 having vegetation to be cut, in a generally upright position. He holds the device by a pair of grips 16 and 18 on a long handle 20 of the strimmer and at the lower end of the handle 20 is the strimmer head 22 whilst at the other end of the handle is in this example a petrol drive engine 24. A flexible cable from the engine 24 extends through the handle 20 to the head 22, and drives a spool 26 (best shown in Figs. 2 and 3) which lies with its axis of rotation vertical, and the spool carries a cutting cable or wire of which an end 28 thereof extends horizontally and in fact performs the cutting of the vegetation.

Because of the manner in which the strimmer is used, the handle 20 is arranged at an angle A to the horizontal, and this angle referred to herein and in the claims as the strimmer angle is designed for comfort and ease of use but what it means is that when the strimmer is in use, and the cutting length 28 of the cable spins in its cutting plane and that plane is held horizontal, the handle 20 will be at an angle A to the horizontal.

The use of the strimmer involves in fact keeping the head 22 suspended above the ground, and therefore in normal use the head will be tilted and inclined depending upon the vegetation being cut. Indeed, in some cases a strimmer is used for cutting the edges of lawns, and in such cases it will be held so that the cutting plane is vertical. Some strimmer designs construct the head 22 so that it can be switched between horizontal and vertical cutting positions.

Because the strimmer head is held suspended above the ground during cutting, it is not suitable for cutting lawns where an even cut is required for aesthetic reasons.

Another point which should be made about strimmers is that they are considered to be dangerous as concerns injury to the eyes, because the fast spinning cord 28 tends to throw up small solid particles of rock, stone and the like and the user is recommended to wear goggles. To this end, to the rear of the head 22 is a guard 30 which comprises a protective plate of a generally semi-circular configuration and provided with a downwardly extending rim. The guard is shown in Figs. 2 and 3 and the plate is indicated by reference 31 and the rim by reference 32.

The attachment according to the embodiment of the invention is illustrated in Figs. 2, 3 and 4, and it is to be pointed out that it is a one-piece unit insofar as connection of the attachment is simply by bringing the unit to the strimmer head 22 by push-fitting thereto, followed by completion of the connecting device, whereby the strimmer is quickly and easily converted to an adequate lawn mower. The attachment comprises a semi-circular sectioned shell 36 which is configured to match the rear of the casing 38 of the strimmer head 22 so as to be a snug fit thereon as shown in Fig. 3.

Once the shell has been thus fitted, the unit can be connected to the head 22 simply by stretching an elasticated strap between a pair of lugs 40 and 42 formed on the shell 56 at the top end thereof so that the band stretches over the front of the casing 38 as shown by reference 44 in Fig. 3.

The unit is now attached to the head of the strimmer, and it will be appreciated that the connecting operation is simplicity in itself.

Depending from the lower edge of the shell 36 is a hollow box casing 46 which is of generally flat configuration as shown in Fig. 2 and has a plane which lies basically in the plane of cutting of the strimmer as defined by the cable length 28.

The box base comprises a front section 48 which is of curved configuration to accommodate the guard 30, and a rear rectangular section 50, the main purpose of which is to accommodate the ground engaging roller 52 in a manner to be explained.

To the underside of the section 48 of the base are a pair of side skids 54, 56 and to the outer sides of section 48 are castor wheels 55,47, so that when the strimmer is in use as shown in Fig. 3, the wheels 55 and 57 rest on the ground at opposite sides of the spool 26, and the roller 52 also rests on the ground as shown, whereby the strimmer can be used as a lawn mower and the cable length 28 will spin in a plane which remains parallel to the ground surface.

When the strimmer is moved to the edge of the lawn and either one or both wheels 55,57 passes or pass over the lawn edge, one or both skids 54,56 will continue to support the strimmer on the lawn ensuring effective cutting of the lawn edge.

For the purposes of providing an attachment which is light in weight, and is relatively inexpensive to produce, the attachment preferably is constructed of plastics material mouldings as best illustrated in Fig. 4 which shows that there are three mouldings to make up the attachment.

Referring to Fig. 4, a first moulding 60 provides a bottom 62 and the sides 64, 66 of the base 46, whilst the second moulding 68 provides the top of the base 46. Moulding 68 is provided with an upwardly directed connecting protrusion 70 which enables the anchoring of the third moulding 72 which forms the shell 36 to be anchored to moulding 68 insofar as the shell 36 has a rearward protruberance 74 which seats on protruberance 70 when the mouldings are assembled. A screw can be passed through the abutting faces of the protruberances 70 and 74 in order to anchor the mouldings 68 and 72 together.

The shell 36 as shown comprises a first portion 76 of a first cone angle followed by a second portion 78 of a greater cone angle, and finally a skirt portion 80 which has an inwardly turned flange 82 lying in a plane disposed at an angle to the angle of the axis of the shell 36. The rim 82 defines and generally registers with a similar cut-out 86 in moulding 68 and the bottom 62 provided by moulding 60 is also cut away semi-circularly as shown at 88 in Fig. 2.

The bottom 62 of the moulding 60 is upwardly directed at 90 as shown in Fig. 4 so as to provide an underside cavity 92 which receives the roller 52. To this end the moulding 60 will be provided with suitable drillings in order to receive the roller axis 93. The sides 64,66 are bored to receive axles of wheels 55,57.

The skids 54 and 56 are provided simply by performing depressions in the bottom 62 of moulding 60.

The respective mouldings are glued together in regions 94 and 96 to complete the attachment.

The attachment provides an extremly attractive design which can be produced to suit the particular strimmer. In this connection it will be understood that the shell 36 and indeed the base will change shape depending upon the strimmer to which the attachment is to be fixed. Alternative fixing means may also be adopted. For example the shell may be fixed to the strimmer casing by fitting the shell snugly as described followed by sliding a clamping sleeve over the shell and the strimmer casing.

Should it be that it is desired that the cable length 28 should be disposed at a lower level than its normal level as set by guide eye 98, an annular guide can be fitted over the spool 26 so as to re-position cable 28 for example in position 28X as shown in dotted lines in Fig. 2, which will bring the cable length 28 to a position nearer the ground surface to enable the grass to be cut to a lower level.

Fig. 3 shows the cable 28 as cutting the grass to a height H.

As explained herein, although best utility of the invention is provided when it is an attachment for an existing strimmer, in an extension of the invention the attachment may be formed integrally with the strimmer head casing.

In such arrangment, the strimmer head casing may be provided with a cover adapted to extend over the front of the strimmer to cover the cable 28 when the strimmer is being used as a lawn mower but said cover would be removable or position adjustable to expose the cable 28 when the strimmer is being used in normal function. Also, in such arrangement the handle preferably is pivoted to the strimmer head, in much the same manner as the handle of a vacuum cleaner is pivoted to its head, when the strimmer is used as a lawn mower, but such first being lockable when the strimmer is used in its normal strimming function.

Claims

1. An attachment for a strimmer to convert it to a lawn mower comprising a shell shaped to fit the strimmer head casing and providing a means for connecting the attachment to the strimmer and a base suspended from the shell and having ground engaging means serving to keep the strimmer cutting plane parallel to the ground for grass cutting.

2. An attachment according to Claim 1, wherein the base is generally flat and is adapted to lie co-planar with the cutting plane of the strimmer.

3. An attachment according to Claim 2, wherein the shell is generally semi-circular in section and defines an axis which lies at the strimmer angle relative to the base.

4. An attachment according to Claim 2 or 3, wherein the base is a flat hollow box open at one side to receive the strimmer guard.

5. An attachment according to any preceding claim wherein the ground engaging means comprises a roller on the base which in use lies at the rear of the strimmer head.

6. An attachment according to any preceding claim wherein the ground engaging means comprises castor wheels on the sides of the base which in use lie to opposite sides of the strimmer head.

7. An attachment according to any preceding claim wherein the shell has integral lugs enabling the attachment of the shell to the strimmer head by stretching an elasticated member between the lugs and over the strimmer head covering.

8. An attachment according to any preceding claim, including a wedging sleeve which is slidable on the strimmer head casing and by which the shell can be attached to the casing by sliding the sleeve over the shell after it has been fitted to the casing.

9. An attachment according to any preceding claim wherein the attachment is a one piece unit.

10. An attachment according to any preceding claim wherein the attachment comprises plastics material mouldings connected together.

11. An attachment according to Claim 10, wherein the mouldings are vacuum formed and are glued, welded, screwed or otherwise connected.

12. An attachment for a strimmer according to any preceding claim wherein the attachment is for connection to the rear of the strimmer head leaving the front of the strimmer head free to enable the strimmer to perform its normal strimming function.

13. An attachment for a strimmer substantially as hereinbefore described with reference to the accompanying drawings.

14. A strimmer wherein the strimmer head is provided with ground engaging means for keeping the strimmer head disposed so that the strimmer cutting plane remains parallel to the ground enabling the strimmer to be used as a lawn mower whilst the front of the strimmer head remains open enabling the strimmer also to be used in its normal functions.

15. A strimmer according to claim 14, wherein the strimmer handle is pivotally connected to the strimmer head.

16. A strimmer according to claim 14 or 15, wherein the strimmer has a cover which extends over the cable at the front of the head and is removable or displaceable when the strimmer is used in its normal functions.