GB2143717A - Stunning gun - Google Patents

Abstract

A knocker head (6) is integrally carried by the shank of a bolt (5) which is held captive in a barrel assembly (1) by a pair of semi-circular collar elements (13a, 13b). The collar elements (13a, 13b) are externally stepped to engage with a face (17) of an annular flange (9) in the muzzle portion (3) of the barrel assembly. <IMAGE>

Description

SPECIFICATION Devices for use in the humane slaughtering of animals This invention relates to devices for use in the humane slaughtering of animals and of the kind in which a captive bolt is housed substantially within a barrel and is adapted to be driven lengthwise of the barrel by an explosive or pneumatic force applied thereto. Such a device will hereinafter be referred to as a 'device of the kind defined'.

Devices of the kind defined either employ a penetrating bolt, that is a one-piece bolt having a shaft of continuous cross-section the end portion of which penetrates the animals skull, or a bolt having what is termed a "knocker head" secured to the end of the bolt which does not penetrate the animals skull. Knocker heads have hitherto comprised a knob-like attachment of a generally mushroom shape and of considerably larger diameter than the bolt shaft, which was secured to the end of the bolt.

One known method of securing the knocker head to the end of the shaft is to provide the head with a threaded bore and screw it to a threaded end portion of the bolt, as shown in British patent specification 1 444 547. In another known method the head is located by means of grub screw which extends through a transverse bore in the head and engages a recessed portion of the shaft, as shown in British patent specification 854 061. Failures of the bolt shaft in these known types of knocker head have occurred causing the head to fly off and it was discovered that such failures usually developed from a fatigue nucleus at the base of the threads for retaining the head, or from sharp changes in section such as at the recess for receiving the end of the grub screw retaining the head.

For safety reasons it is considered advisable to provide an improved type of knocker head and the present invention has this object in view.

According to the present invention a device of the kind defined for use in the humane slaughtering of animals comprises a barrel assembly in which the captive bolt is in one piece and formed with an integral knocker head on one end thereof and integral abutment means on the shaft of the bolt spaced from the head.

The bolt is preferably a steel forging and the head of a generally mushroom shape smoothly tapered from the largest diameter to the shaft diameter.

The abutment means is preferably an annular flange formed at or near the rear end of the shaft and of such diameter as to permit the bolt to be assembled to the barrel by inserting the rear end of the shaft into the bore of the barrel from the muzzle end thereof.

The bolt is preferably held captive to the barrel by a thrust collar adapted to encircle the shaft between the head and the abutment means, retaining means being provided for securing the collar in the barrel.

The thrust collar preferably comprises at least two discrete elements adapted to encircle the shaft of the bolt and to locate against a fixed abutment within the barrel of the device.

Each element of the thrust collar preferably com prises an arcuate flanged portion adapted to abut an annular flange within the barrel, and an arcuate recess which in use combines with the recess of the other portion to provide a bore supporting the bolt for sliding movement. The internal diameter of the flange permits passage of the bolt flange on assembly of the bolt to the barrel.

Preferably, dowel means are provided for locat ing adjacent collar elements one to the other on assembly.

The dowel means may be in the form of a helical spring, the ends of which extend into opposed bores in adjacent end faces of the elements.

The barrel of the device may be in two parts and preferably comprises a separate muzzle portion adapted to be secured to the barrel and arranged to facilitate assembly of the bolt and collar means.

Spacing and/or locking washers may be mounted behind the collar means to secure the assembly.

A preferred embodiment of the invention will now be described by way of example only with reference to the accompanying drawings wherein: Figure 1 shows a device of the kind defined incorporating a captive bolt in accordance with the invention, the barrel assembly being shown in longitudinal cross-section, Figure 2 is a longitudinal cross-section through a muzzle portion of the barrel, Figure 3 is an elevation, partly in section, showing the bolt, Figure 4 is a rear view of a detail of the assembly and, Figure 5 is a vertical section on the centre line of Figure 4.

Figure 1 shows the barrel assembly 1 and breech block 2 of a stunning device of the captive bolt type. The breech block and trigger mechanism form no part of this invention and will not be described in detail.

The barrel assembly 1 comprises a muzzle 3 and a barrel 4 which together house and slidably locate a one piece captive bolt 5. The bolt 5 is of forged steel and formed with an integral head 6 and integral annular abutment 7 adjacent to the rear end of the bolt shaft.

The head 6 is generally mushroom shaped and tapers inwardly, as indicated by the reference 28, from the greatest diameter to the shaft diameter in order to avoid sharp changes in section. Similarly, the annular abutment 7, tapers inwardly, as indicated by the reference 30 in Figure 3, from the greatest diameter to the shaft diameter for the same reason. The bolt 5 is slidably located in the barrel assembly by means of annular abutments extending inwardly from the walls of the muzzle 3 and barrel 4 which limit the forward and rearward movement of the bolt. The head 6 is slidable in the bore 8 of the muzzle 3 and in the rearmost position of the bolt it abuts the angled forward face of an annular flange 9. The annular abutment 7 is slidable in a bore 10 of the barrel 4 and in the rearmost position of the bolt 5 abuts an angled flange 11 at the end of the barrel.In this position a cylindrical end portion 12 of the bolt extends into the expansion chamber of the breech block 2.

As the bolts is made in one piece, in order to assemble and locate the bolt 5 within the barrel assembly the outside diameter of the annular abutment 7 is made slightly less than the diameter of the bore 31 of the annular flange 9. This permits the abutment 7 to be passed through the bore 31 in the flange 9. In order to hold captive the bolt 5 within the barrel 4 on assembly a thrust collar 13 is provided comprising a pair of arcuate collar elements 13a, 13b. Each element 13a, 13b has an arcuate flange portion 14 and a semi-circular recess 15 (Figs 4 and 5).When assembled to the shaft of the bolt the flange portions 14 of the elements 13a, 13b, combine to provide a right angled continous annular flange which abuts the right angled rear face 17 of the annular flange 9 and the semi-circular recesses 15 combine to provide a bore for slidably receiving and supporting the shank of the bolt 5. The mouth portions 15a of each recess 15 are counter-sunk to receive the taper 28 of the bolt head 6. The radial abutment faces 18 of each element 13a, 13b, are bored tangentially to the recess 15 to receive opposite ends of helical springs 19.

These springs assist in the assembly of the collar elements 13a, 13b and take up any end play between the elements once assembled in the device.

The one-piece bolt does not permit the mounting of conventional resilient shock absorbing sleeves on the shaft of the bolt 5, but instead the assembly 1 includes one or more resilient sleeves 20 having a longitudinally extending split 21 enabling the sleeves to be mounted on the shaft between the head 6 and abutment 7. Alternatively, the sleeves may be in two parts as in the case of the thrust collar 13.

The muzzle 3 is secured to the barrel 4 by means of screw threads 22. A spacer ring 23 and locking washer 24 are inserted into the bore of the muzzle behind the thrust collar 13 on assembly so that the thrust collar 13 is clamped tightly between the abutment face 17 and the end face of the barrel 4.

In use of the device it is necessary to prevent the bolt 5 dropping forwards away from the flange 9 once the device has been cocked for firing and known bolt retention means are provided for this purpose. The retention means comprises an external channel 25 having a plurality of holes 29 in its base which open into the bore 8 of the muzzle 3 and these holes locate balls 26 which are trapped in piace by a resilient band 27. In the rearmost position of the bolt 5 the balls 26 engage the lip of the bolt head 6.

It is to be understood that the barrel assembly 1 as hereinbefore described may be provided separately and assembled to any suitable breech block employing any suitable firing mechanism.

It will be appreciated that on firing of the device the bolt is arrested by the impact between the knocker head 6 and the animals head, and by collision of the abutment 7 with the resilient sleeves 10, the force on sleeves 10 being taken substantially by the elements 13a, 13b.

Claims (7)

1. A device of the kind defined in which the captive bolt is in one piece and comprises a shaft with an integral non-penetrating knocker head on one end thereof and an integral radial abutment spaced from the head, a thrust collar is secured in the barrel between the head and the radial abutment to hold captive the bolt and comprises at least two discrete substantially arcuate elements which are assembled together around the shaft so as substantially to encircle the shaft.

2. A device as claimed in claim 1 in which there are only two such elements, each of semi-circular shape.

3. A device as claimed in claim 1 or claim 2 comprising dowel means extending into opposed bores in adjacent faces of the elements.

4. A device as claimed in claim 3 in which each dowel means is a helical spring.

5. A device as claimed in any of the preceding claims in which the elements are stepped on their radially outer surface, the step on the elements engaging with a corresponding step in the barrel.

6. A device as claimed in claim 5 in which the step in the barrel is defined by a radially inwardly directed flange in a muzzle portion of the barrel, the internal diameter of the flange being sufficient to enable the radial abutment to pass through the muzzle portion on assembly of the device.

7. A device of the kind defined and substantially as described with reference to the accompanying drawings.