Hand Tools

This invention relates to hand tools comprising two co-operating members which are arranged to be moved relatively to one another by handles which are connected to the respective co-operating members. In particular the invention is applied to garden pruners and considerable research and development work is directed in this field to reducing manufacturing costs, and providing flexible designs which permit substantial variation of the finished product by the use of interchangeable parts.

According to one aspect the present invention provides a hand tool comprising two co-operating members, two handles each secured to a separate one of said members, means interconnecting the members in mutually overlapping relationship to permit movement of the members relatively to one another by said handles, one said member having a slot therein, the other member having a recess therein, and a catch pin movable within said slot into engagement with said recess to lock the members together, characterised in that the catch pin forms part of a catch unit comprising a mounting plate having an elongate slot therein, a catch button slidable on one side of the mounting plate, a spring plate slidable on the mounting plate in sprung engagement therewith on the opposite side to the catch button, and means extending through said elongate slot and securing the catch button to said spring plate, said catch unit being mounted on said one member, and said catch pin being in permanent engagement with said catch button.

According to another aspect, the present invention provides a hand tool comprising two cooperating members, two handles each secured to a separate one of said members, means interconnecting the members in mutually overlapping relationship to permit movement of the members relatively to one another by said handles, each member including a tang portion and each handle being in the form of a sleeve which fits removably over the associated tang portion, each handle and the associated member having apertures therein which register with each other when said tang portion of the member is correctly inserted in the handle, each member being secured within its associated handle by a pivot bolt and nut assembly of which the bolt passes through said registering apertures.

One example of a hand tool according to the invention, in the form of a garden pruner, is illustrated in the accompanying drawings in which:

FIG. 1 is a plan view of the front of the pruner;

FIG. 2 is a plan view of the back of the pruner;

FIG. 3 is an elevation of one side of the pruner;

FIG. 4 is a plan view of a male blade and integral tang of the pruner;

FIG. 5 is a plan view of a female blade and integral tang of the pruner;

FIGS. 6 and 7 are plan views of the two handles of the pruner;

FIG. 8 is a side elevation of a catch pin for locking the female and male blades in the closed position;

FIGS. 9, 10 and 11 are respectively a plan view, a sectional side elevation and sectional view on line XI--XI of FIG. 1, of a catch button assembly for operating the catch pin of FIG. 8, FIG. 11 showing the associated handle, and

FIG. 12 is a plan view of a locating spring forming part of the catch button assembly of FIGS. 9 to 11.

The pruner shown in the drawings is of know construction insofar as it comprises a male blade 10 and integral tang 11, a female blade 12 and integral tang 13, handles 14 and 15 secured respectively to the tang 11, 13, a pivot bolt and nut assembly 16, 16' pivotally interconnecting the two blades in face to face relationship, a catch pin 17 mounted in the blade and handle assembly 12, 15 for engagement with the other blade and handle assembly 10, 14 to lock the blades together in the closed position, and a spring 18 for biassing blades to an open position. The pruners illustrated in the drawing differ however from existing pruners in a number of constructional details which will be discussed below.

Considering first the catch pin 17, it will be seen from FIG. 8 that this comprises a circular head portion 17a, a circular section shank portion 17b and a circular section foot portion 17c, the diameter of the foot portion being larger than that of the shank portion but smaller than that of the head portion, and a spigot portion 17d projecting axially from the head portion 17a. The length of the shank portion 17b will be equal to the thickness of the metal forming the female blade and tang assembly, plus clearance for sliding movement. The three portions of the catch pin will normally be turned from a single length of bar.

In assembly of the catch pin in the female blade, the catch pin 17 is inserted into a keyhole slot 19 (see FIG. 5) formed in the female blade and extending substantially radially with respect to a hole 12a in the blade for receiving the pivot bolt assembly. The width of the slot is such as to receive the shank portion 17b of the catch pin 17 in a sliding fit but the slot has an enlargement 19a, at its end nearest the pivot bolt hole 12a, of a size to allow the foot portion 17 of the catch pin to pass therethrough. The foot portion 17c is first inserted through the enlarged end 19a of the slot to locate the shank portion 17b within the slot, and the catch pin is then moved away from the enlarged end portion 19a so that the shank portion 17b forms a sliding fit in the slot. The male blade is so shaped as to provide a back edge 10a which, when the male blade has been assembled on the female blade, traverses the slot 19. This edge of the male blade contains a recess 10b into which the foot portion 17c of the catch pin can engage when the blades are in their closed position, in order to lock them in this position. In the locked position of the blades however, the foot portion 17c of the catch pin is spaced from the enlarged end portion 19a of the slot 19 (see FIG. 1) so that, after assembly, the catch pin remains locked within the slot and cannot be removed therefrom without disassembling the blades of the pruner. The edge 10a of the male blade is so shaped that, over the permitted range of movement of the blades, it does not interfere with the catch pin when the catch pin has been moved to the radially outer end of the slot 19. However, the back edge 10a of blade 10, at a point thereon on the side of recess 10b remote from tang 11, acts as a stop for the catch pin defining the maximum open position of the blades. If desired the recess 10b in the edge 10a can be stepped to provide a restricted range of opening for the blades. Preferably recess 10b is slightly undercut on one side, as shown, to form a safety lock, making it necessary to slightly close the pruners before the catch can be released.

The catch pin co-operates with a catch button assembly which is mounted in a recess on the front face of the pruners, i.e. on the handle 15 of the female blade, as seen in FIG. 1. This handle 15 is extended to overlap the whole of the area of the female blade which surrounds the pivot bolt assembly.

The catch button assembly (seen in FIGS. 9-12) comprises a decorative catch mounting plate 20 moulded in plastics material and formed with two elongate slots 20a and 20b extending in side by side relationship longitudinally of the handle, and a catch button 21 which is rectangular in plan view but roof shaped in sectional view for easy operation by the thumb of the user. The catch button has a spigot 21a extending downwardly from its underside, the initial portion of the spigot being of square cross section to fit slidingly within the slot 20a of the plate 20 and the remainder of the spigot being of circular section. The spigot is located to one side of the centre line of the button with respect to the direction of movement of the button. On the opposite side of the centre line, the button has a recess 21b in its underface overlapping the slot 20b in the plate 20, both the slot 20b and the recess 21b receiving therein a spigot 17d of the catch pin, which is upstanding from the head portion 17a.

A further component of the catch assembly is a spring plate 22 (see FIG. 12) formed of plastics material and received in a recess 20c in the underside of the plate 20. The spring plate has an aperture 22a therein matching the shape of the circular end of the spigot 21a and in which the spigot will be welded in production of the assembly, and a second aperture 22b therein for receiving the end of the spigot 17d of te catch pin. At its four corners, the plate 22 is formed with spring fingers 22c.

The mounting plate 20 has dependent flanges 20d, 20e along its opposite longitudinal edges to define the recess 20c and to provide slide rails for engagement with the spring fingers 22c. Each of these fingers is formed with two pairs of indentations 20f into which the spring fingers 22c of the plate 22 can engage to locate the catch button in either the closed position or the open position of the catch pin and hence of the blades.

If the male blade is formed with a stepped recess for receiving the catch pin, three pairs of indentations for receiving the spring fingers 22c can be provided to locate the catch pin selectively in three positions corresponding to the `fully open`, `partially open`, and `closed` positions of the catch pin.

In fitting together the parts of the catch assembly, the catch button 21 is placed on top of the mounting plate 20 and the catch spring 22 fed in from the underside to engage in the recess 20c of the mounting plate. The four spring fingers 22c at the corners of the catch spring are located in one pair of indentations 20f in each of the flanges 20d, 20e, of the mounting plate. The spigot 21a on the catch button 21 passes through the mounting plate into the spring plate and is welded to it. It will thus be seen that as the catch button slides along the slot, the spring fingers ride out of one set of indentations 20f along the flanges of the mounting plate 20 to the next set of indentations. These indentations thus provide positive positional location for the catch. The provision of four location points means that despite the off centre application of the load to the catch pin, the whole assembly is stable. The spigot 21a of the catch button being welded to the spring plate 22 assists stability, preventing the catch button 21 from turning about the catch pin 17. The catch pin passes through the catch spring and into the button, the pin having close clearance through the spring and an interference fit in the button in the plane of its movement. The catch button locating recess 21b for the catch pin is slotted at right angles to the movement of the button so that the effect of tolerances on the assembly with respect to the catch are catered for in this direction.

The head of pivot bolt 16 is received in an aperture 20g in the plate 20 and overlies a D washer (not shown) which in turn overlies a web 20h of the plate 20 to assist in securing the catch unit within handle 15. The D washer provides a rubbing surface to protect the handle from movement of the bolt head. A web 20j prevents movement of the washer relative to the handle.

In the pruner illustrated in FIG. 1, it will be seen that the spring 18 for urging the blades apart is a helical spring located in a slot 12b formed in the female blade, the slot, over its length traversed by the movable end of the spring, being arcuate about the axis of the pivot bolt assembly, whereas the remainder is straight to reduce spring friction. A pin 23 fitted into an aperture 10c in the male blade extends into the arcuate portion of the slot and is located at the closed end of the arcuate portion of the slot when the blades are in the open position. As the blades are rotated from the open position towards the closed position, the pin 23 moves along the slot compressing the helical spring 18 and creating a biassing force tending to open the blades. Since the helical spring must be inserted into the slot under load, a shoulder 12c is formed at a position spaced from the closed end of the arcuate portion against which the spring can abut in its extended state to hold the spring away from the end of the slot 12b and thereby facilitate insertion of the pin into the slot during assembly of the pruner.

Considering now the blade, tang and handle assemblies with reference first to FIGS. 4 and 5, it will be seen that the tangs 11 and 13 are of similar shape and construction and therefore only one of them need be discussed. Considering tang 11 on male blade 10, it will be seen that a shoulder 11a is formed on the forward edge of the tang, i.e. on the edge which forms a continuation of the blade cutting edge, and a recess 11b is formed on the same edge adjacent its tip. On the rearward edge of the tang there is a rectangular shaped cut-out 11c located in a portion of the tang intermediate the shoulder 11a and recess 11b.

These configurations of the tang facilitate fitting of various handles to the tang. Thus the handle can be a diecasting fitted removably to the tang and secured to the tang by the bolt 16 which passes through apertures such as 12a and 15a in the member 12 and handle 15. These apertures register with one another when the tang 13 is correctly inserted in the handle 15. The flat surface 11d between shoulder 11a and recess 11b, and continuing for a short distance on the opposite side of recess 11b, provides a location surface for the handle. The recess 14a (see FIG. 6) in the handle for receiving the tang 11 will also open to the surface of the handle in the vicinity of the recess 11c of the tang to provide an opening 14b to receive a cushion stop 24 which will then seat in the recess 11c and on the edge of the diecasting. Thus the impact on the cushion stops will be carried both by the tangs and by the diecast handles.

As an alternative, the handle can be moulded onto the tang in plastics material, and in this event the plastics material will flow into the recess 11b to key the handle to the tang. The mould in which the handle is formed is such as to leave an aperture in the handle opposite the cut-out 11c (see FIG. 6) but with a portion of the handle projecting from the base of the cut-out 11c to form a spigot on which the cushion stop can be located. If desired, a single cushion stop can be provided on one handle only, the other handle being plain.