GB2289610A - Hand held motorised garden cutting tool - Google Patents

Abstract

A hand held motorised garden cutting tool which comprises a cutting head 10, a handle on an elongate handle shaft 1; motor mounted to the handle shaft at or near the handle; and a swivel coupling 5 on the handle shaft between the said motor and the said cutting head to enable the cutting head to swivel relative to the motor. <IMAGE>

Description

IMPROVEMENTS TO HAND HELD MOTORISED GARDEN CUTTING TOOLS Field of the Invention The present invention relates to hand held motorised garden cutting tools and more particularly, but not necessarily exclusively, to hand held motorised saws or hedge cutters.

Background to the Invention Garden maintenance is a pass time indulged in by a substantial proportion of the population of the United Kingdom including both amateurs and professionals. The level of equipment available for use by amateur and professional alike has become increasingly more sophisticated over recent years and the likes of the motorised hedge trimmer and motorised lawn edge trimmer are now sold across the market spectrum.

Devices such as the aforementioned trimmers are designed to facilitate garden maintenance by reducing the effort and inconvenience to the user of the device as far as practically possible. By the provision of electric or petrol motors to drive the cutters of such trimmers the mechanical effort that must be exerted by the user is minimised. However, little effective development has been made to improve the handling of such tools particularly where there is a problem of poor accessibility to certain regions of a bush, tree, hedge or lawn, for example.

This problem is particularly apparent in the context of hedge trimmers which generally have a motor directly linked to a reciprocating blade with handles being mounted to the casing of the motor requiring the user to wield the device in close proximity to the face of the bush, hedge or tree to be trimmed.

In the inevitable circumstance where it is desired to trim the top of the hedge it is generally necessary to make use of a ladder to bring the user up to the same level as the said top to enable him to hold the device in substantially that same plane.

It will be appreciated that the need for the user to elevate or otherwise bring himself close to the height or location of the part of the hedge to be trimmed is at least a significant inconvenience and at worst can be a severe handicap that wholly prevents access to that part of the hedge.

In the field of hedge cutters, the closest prior art of which the applicant is currently aware is disclosed in US patent No 4974325, which describes a portable power-driven cutting tool having a pair of handles on the housing to enable it to be wielded by both hands of the user with one of the handles having a swivel mounting to enable the position of holding of the tool to be adjusted. This gives the user a somewhat greater degree of flexibility in wielding of the tool but does not significantly assist in overcoming the aforementioned problem.

In the field of lawn trimmers, it is known to provide a rotary nylon cord garden trimmer having a pivotable handle tube as disclosed in US patent No 4603478. This provides easy adjustment of the cord cutting angle with respect to the handle but has the significant disadvantage that the motor remains at the end of the handle tube making the device unwieldy in circumstances where it is desired to use the trimmer head in an otherwise than substantially vertically downwards orientation with respect to the handle.

It is a general objective of the present invention to overcome these problems of the prior art to provide a hand held motorised garden cutting tool for improved access of the cutting head of the tool to otherwise relatively inaccessible areas of the garden.

Summarv of the Invention According to the present invention there is provided a hand held motorised garden cutting tool which comprises a cutting head; a handle on an elongate handle shaft; a motor mounted to the handle shaft at or near the handle; and a swivel coupling on the handle shaft between the said motor and the said cutting head to enable the cutting head to swivel relative to the motor.

Preferably the handle shaft is hollow and accommodates therewithin a drive shaft extending from the motor towards the cutting head.

Preferably the swivel coupling comprises a plurality of co-operatively interengaging gears, at least one pair of which roll or disengage when the cutting head is swivelled about said coupling.

Preferably an adjustable locking bolt is provided to enable the cutting head to be locked in a range of orientations relative to the handle stem.

Advantageously the swivel coupling is integrally formed or assembled with the actuating mechanism of the cutting head. In the case of a reciprocating action (saw blade) trimmer the actuating mechanism of the cutting head comprises a crank shaft or rack and pinion arrangement or other mechanism to convert the rotary motion induced by the drive shaft into the linear reciprocating movement of the moveable blade or blades of the cutting head.

Brief Description of the Drawings A preferred embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a longitudinal sectional view of a reciprocating action (saw blade) hedge trimmer; Figure 2 is an alternative longitudinal sectional view taken along the line ii-ii in figure 1; and Figure 3 is a transverse sectional view taken along the line iii-iii in figure 1.

Description of the Preferred Embodiment Referring to figures 1 and 2, the reciprocating action hand held motorised hedge trimmer thereshown comprises a hollow rigid and robust handle shaft 1, a free extremity of which (not shown) serves as a handle by means of which the tool may be wielded. The handle shaft is most suitably formed of a plastics coated metal or metal alloy for sufficient rigidity and robustness but other suitable materials will be self evident to those skilled in material selection.

A motor (not shown) is mounted to the handle shaft 1 at or near the handle.

The handle itself may simply comprise a portion of handle shaft 1 or may be specially shaped to provide easy grips.

The manner and exact position of mounting of the motor to the handle or handle shaft 1 may be selected without exercise of inventive thought by the man skilled in the art and does not require further elucidation. Following the broadly conventional design the handle may arise from the casing of the motor to give effective control of the heaviest and bulkiest part of the tool.

A drive shaft 2 operatively coupled to the motor extends axially through the handle shaft 1 and the end of the drive shaft 2 remote from the motor terminates in a bevel gear 3. This drive shaft bevel gear 3 co-operatively engages with a complementary bevel gear 4.

The complementary bevel gear 4 is housed, together with other transmission gears, within a combined transmission and swivel coupling assembly 5.

A first part 6 of the assembly 5 is fixed over the end of the drive shaft 2 remote from the motor and is operatively coupled with a second part 7 of the assembly 5 in such a manner as to allow the second part 7 to swivel relative to the first part 6 to be secured together in a desired one of a range of different relative orientations.

A pair of reciprocating saw blades 8,9 extend from the second part 7 of the housing and are held in longitudinal sliding relation thereto by a sheath 10.

Within the assembly 5 the bevel gear 4 which co-operates with the drive shaft bevel gear 3 is mounted upon an axle 11, one end of which axle 11 is mounted to the second part 7 of the assembly 5 while the other end of the axle 11 has a further bevel gear 20 thereon. This third bevel gear 20 co-operatively engages with a fourth bevel gear 21 which, in turn, transmits the motive force to a pair of crank shafts 13, 14 which move the blades 8,9 back and forth, respectively.

The two parts 6,7 of the combined transmission and swivel coupling assembly 5 are suitably of rigid robust construction and have low friction co-operative bearing surfaces.

A locking arm 15, illustrated in figures 1 and 3, is suitably provided to releasably lock the first and second parts 6,7 in the desired relative orientation. The locking arm 15 has a bolt portion 16 which extends through a shortened annular channel 17 in the second part 7 of the assembly 5 into cooperative engagement with a threaded socket 18 in the first part 6 of the assembly 5.

In use the cutting head, comprising the reciprocating blades, 8,9 and sheath 10, is angled relative to the handle shaft 1 to the desired orientation by swivelling the second part 7 of the assembly 5 relative to the first part 6 of the assembly 5 with the bolt 16 of the locking arm 15 in the released state. The locking arm 15 may then be turned to tighten together the two parts 6,7 of the assembly 5 to thereby lock the two in the desired orientation. For trimming the top of a tree, hedge or bush the desired orientation would suitably be with the cutting head 8,9,10 substantially perpendicular to the handle shaft 1. For other applications lesser or greater angles may be appropriate.

By the provision of this swivel facility between the motor and the cutting head a high degree of versatility in use of the tool is achieved. Furthermore, by providing an extensive length of handle shaft the device may be used to easily reach distant areas without the need to resort to a ladder or the like. To this end the handle shaft may be constructed to provide adjustable extensions.

The handle shaft 1 may be telescopic. This is most easily achieved where the motor lies between the handle and the swivel coupling but it is feasible to construct an extensible drive shaft.

Although the present invention has been described herein above with respect to one preferred embodiment, in relation to a reciprocating action hedge trimmer, numerous alternative embodiments and alterations may be made to the invention without departing from the inventive scope thereof. The device may, for example, be adapted for use as a lawn edge trimmer or the like having a rotary cutting action.

In the single illustrated embodiment the transmission of power from the motor to the cutting head comprises a geared transmission mechanism. Such mechanism may, however, be substituted with a hydraulic, pneumatic, belt drive or other means for transmission of power from the motor to the cutting head.

Claims (7)

1. A hand held motorised garden cutting tool which comprises a cutting head; a handle on an elongate handle shaft; a motor mounted to the handle shaft at or near the handle; and a swivel coupling on the handle shaft between the said motor and the said cutting head to enable the cutting head to swivel relative to the motor.

2. A garden cutting tool as Claimed in Claim 1, wherein the handle shaft is hollow and accommodates therewithin a drive shaft extending from the motor towards the cutting head to drive the cutting head.

3. A garden cutting tool as claimed in Claim 1 or Claim 2, wherein the swivel coupling comprises a plurality of co-operatively inter-engaging gears, at least one pair of which roll or disengage when the cutting head is swivelled about said coupling.

4. A garden cutting tool as claimed in any of Claims 1-3, wherein the tool further comprises an adjustable locking means to enable the cutting head to be locked in a range of orientations relative to the handle stem.

5. A garden cutting tool as claimed in any preceding Claim, wherein the swivel coupling is integrally formed or assembled with the actuating mechanism of the cutting head.

6. A garden cutting tool as claimed in any preceding Claim, wherein, the tool is a reciprocating action (saw blade) trimmer and the actuating mechanism of the cutting head comprises a crank shaft or rack and pinion arrangement or other mechanism to convert the rotary motion induced by the drive shaft into the linear reciprocating movement of the moveable blade or blades of the cutting head.

7. A garden cutting tool substantially as hereinbefore described with reference to the accompanying drawings.