GB2160139A - Lawn shears - Google Patents

Abstract

A lawn shear comprises a U-shaped first bearing support 15 formed as a one-piece casting and having a first arm 15c to which a first blade 13 is rigidly secured, a cast second bearing support 16 to which a second blade 14 is rigidly secured and located within the space between the first blade 13 and a second arm 15b of the first bearing support 15, a pivot bolt 17 extending through the blades and through the first and second bearing supports and carrying a nut 19 at its free end, the two bearing supports being formed integrally with spigots 18 to which tubular handles are rigidly secured. <IMAGE>

Description

SPECIFICATION Lawn shears This invention relates to lawn shears, and in particular to so-called long-handled lawn shears.

In the operation of long-handled lawn shears, the pivot bolt carries a substantial amount of stress, and in order to bear this stress it is normal to make the pivot bolt relatively long. Where, however, one handle drives the associated blade through the pivot bolt, this only increases the stress. In any event, the construction of traditional long-handled garden shears involved in a large amount of welding of parts and accordingly is very expensive.

According to the present invention there is provided a lawn shear comprising first and second shear blades, first and second handles, a first Ushaped bearing support secured to said first handle and having a body portion and first and second arms integral with and extending substantially parallel to one another from opposite ends of the body portion, the first shear blade rigidly secured to the internal face of the first said arm; a second bearing support secured to said second handle, said second shear blade rigidly secured to the second bearing support, the second bearing support and the part of the second blade secured thereto being disposed within the space between the first blade and the second arm of the U-shaped bearing support with the blades lying in face-to-face contact with each other, and a pivot bolt which extends from said first arm, through said blades and said second bearing support into said second arm, one end of the bolt being secured to one of said arms and the other end of the bolt having a screwthread on which is a nut in engagement with the other of said arms, the bolt supporting the second bearing support and the second blade for rotation, by operation of the handles, about the axis of the bolt relative to the first bearing support, and means resiliently urging said blades against one another.

Preferably the means resiliently urging said blades against one another comprises a helical spring surrounding the bolt and acting between the nut and said second bearing support.

In a preferred embodiment, the first and second bearing supports are metal castings cast on to the first and second blades respectively and rigidly secured thereto in the casting operation by metal flowing into apertures in the blade formed for that purpose. These bearing supports are also cast with integral spigots on to which tubular handles can be forced and secured by friction only. Such a construction can thus be free from welding.

One embodiment of lawn shear in accordance with the invention will now be particularly described with reference to the accompanying drawings in which: Figure 1 is a side elevation of the shears; Figure 2 is a plan view of the shears; Figure 3 is a section on the line Ill-Ill of Figure 2; Figure 4 is a section through the bush illustrated in Figure 3; Figure 5 is a plan view of the bush of Figure 4, and Figure 6 is a rear view of the shears.

The lawn shears as illustrated in the drawings comprise first and second handles 11,12, first and second shear blades 13,14 and first and second bearing supports 15,16 through which a pivot bolt 17 extends. The first handle 11 is secured to the first bearing support 15 which in turn is secured to the first blade 13, and the second handle 12 is secured to the second bearing support 16 which in turn is secured to the second blade 14. Thus by moving the handles 11,12 towards and away from each other, the two blades 13,14 are caused to move relative to one another about the axis of the pivot bolt 17.

Considering the construction in greater detail, it will be seen from Figures 1 and 3 that the first bearing support 15 is substantially U-shaped and preferably made as a die casting, for example in aluminium or magnesium alloy, and is formed integrally with a spigot 18 to which the tubular handle 11 is secured.

The first bearing support 15 is cast onto the first blade 13 which has apertures 13a,13b therein into which the metal of the casting extends. These openings, which are disposed on opposite sides of a pivot bolt opening 13c, have an area substantially larger than that of the pivot bolt opening, and are preferably slightly flared so that the metal of the casting is lockingly engaged with the blade.

The second bearing support 16 is cast on to the second blade 14 in a similar manner.

The first bearing support 15 comprises a body 15a from opposite ends of which two arms 15b,15c extend parallel to one another. The upper arm 15 of the first bearing support 11 has an opening 15d therethrough on the axis of the pivot bolt, and at the base of this opening the arm is formed with a frusto-conical seating surface 15e for a frusto-concical nut 19 which engages a screwthread 17a on the bolt.

The second bearing support 16 has a central opening 16a of substantially frusto-conical shape which tapers towards the bolt in a direction towards the blades, and a frusto-conical bush 20 is seated within the frusto-conical opening 16a.

This bush (as seen in Figure 4) comprises a generally circular upper portion 20a, a generally circular lower portion 20b of smaller diameter and a pair of webs 20c interconnecting the upper and lower portions. The upper portion is formed with two lubricating apertures 20d through which lubricant placed on the upper surface of portion 20a can run downwardly and on to the upper surface of lower portion 20b and thence on to the pivot bolt to lubricate the bearing surface of the bolt and the contacting surfaces of the blades.

In order to maintain the desired pressure between the blades, a helical spring 21 acts through washers 22,23 at its upper end on the under surface of the nut 19 and at its lower end on the upper surface of the bush 20. Thus the pressure applied downwardly by the spring acts through the bush 20 on the second bearing support 16 to press the second blade 14 downwardly against the first blade 13.

In assembly of the shears, the second bearing support 16 to which the second blade 14 is rigidly attached is fitted between the first blade 13 and the upper arm 15b of the first bearing support 15. the axial length of the second bearing support is such as to leave a small clearance between its upper end and the inside face of the upper arm 15b of the first bearing support 15. The bolt 17 is then passed upwardly through the lower arm 15c of bearing support 15, through the bolt apertures of the two blades, through the central aperture of the bush 20, through the washer 23, spring 21 and washer 22 into the upper arm 15a of the bearing support 15. The nut 19 is then applied to the end of the bolt to make contact between the downwardly facing frusto-conical surface of the nut and the upwardly facing frusto-conical surface 15e in the upper arm 15a of the bearing support 15. The co-action between these two frusto-conical surfaces serves to centre the bolt and provide an accurate bearing surface for the second bearing support 16, thereby accurately locating the blades relative to one another.

Claims (10)

1. A lawn shear comprising first and second blades, first and second handles, a first U-shaped bearing support secured to said first handle and having a body portion and first and second arms integral with and extending substantially parallel to one another from opposite ends of the body portion, the first shear blade rigidly secured to the internal face of the first said arm; a second bearing support secured to said second handle, said second shear blade rigidly secured to the second bearing support, the second bearing support and the part of the second blade secured thereto being disposed with in the space between the first blade and the second arm of the U-shaped bearing support with the blades lying in face-to-face contact with each other, and a pivot bolt which extends from said first arm, through said blades and said second bearing support into said second arm, one end of the bolt being secured to one of said arms and the other end of the bolt having a screwthread on which is a nut in engagement with the other of said arms, the bolt supporting the second bearing support and the second blade for rotation, by operation of the handles, about the axis of the bolt relative to the first bearing support, and means resiliently urging said blades against one another.

2. A lawn shear according to claim 1 wherein said means resiliently urging said blades against one another comprises a helical spring surrounding the bolt and acting between the nut and said second bearing support.

3. A lawn shear according to claim 2 having a bush which is housed within a central opening in the second bearing support and fits closely around the bolt, the spring force acting on the blades through the bush.

4. A lawn shear according to claim 3 wherein the bush is made of plastics materials impregnated with lubricant, the said central opening being of substantially frusto-conical shape, the larger end of which supports said spring.

5. A lawn shear according to claim 4 wherein the bush has at least one lubricating opening therein to enable liquid lubricant applied to the upper end of the bush to pass downwardly through the bush and on to the bolt close to the lower end of the bush.

6. A lawn shear according to any preceding claim wherein said U-shaped bearing support is formed in one piece in metal.

7. A lawn shear according to any preceding claim wherein said bearing supports have been die cast on to said blades.

8. A lawn shear according to any preceding claim wherein first and second spigots are formed integrally with the first and second bearing supports, each handle being mounted on a separate one of said spigots.

9. A lawn shear according to claim 8 wherein said handles have been force-fitted on to the spigots.

10. A lawn shear substantially as herein described with reference to the accompanying drawings.