CA1044749A

CA1044749A - Stunning tongs

Info

Publication number: CA1044749A
Application number: CA211,568A
Authority: CA
Inventors: John J. Collins
Original assignee: Haverhill Meat Products Ltd
Current assignee: Haverhill Meat Products Ltd
Priority date: 1973-10-23
Filing date: 1974-10-16
Publication date: 1978-12-19
Also published as: DE2450277C3; GB1477310A; IE40063B1; FR2247978A1; DE2450277B2; NL177793C; IE40063L; NL7413698A; LU71118A1; IT1024652B; BE821271A; NL177793B; FR2247978B1; DE2450277A1; DK550374A

Abstract

ABSTRACT OF THE DISCLOSURE

A stunning tongs for stunning animals prior to slaughter comprising a frame having a handle portion and a pair of stunning arms mounted thereon to permit relative movement between the arms, stunning electrode heads on the arms, a prime mover operable to effect rapid relative movement between the arms to impart a stunning blow on opposite sides of the animal's head, and an electronic stunning circuit operable in timed relation to the prime mover to pass an impulse of predetermined waveform, frequency and voltage/current for a predetermined time period between the electrode heads through the animal's head coterminous with the stunning blow.
A manually actuable control switch is provided to supply actuating energy from an energy source simultanously to the prime mover and to the stunning circuit.

Description

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This invention relates to stunning tongs for use in abattoirs for stunning animals such as pigs, sheep and cattle prior to slaughtering them by any conventional methods such as bleeding as by,cutting the throat or humane killer slaughter.
Stunning tongs are known comprising a pair of stunning ~`
arms carrying stunning heads and pivoted together to enable the arms to be spread apart to embrace any part of the head -area of the animal and apply pressure thereto, the arms having handles for manual manipulation enabling the stunning heads to be engaged on either side of the animal's head. When the stunning heads are engaged on the animal's head, an electric impulse is passed between them to stun the animal.
Such known stunning tongs are difficult to operate as well as being time consuming in use and the electric impulse ~ ;
is selected at random so that the tongs are not as efficacious :
as is desirable for satisfactory humane slaughter of animals.
Moreover slaughter is effected by suspending the animal up by its hind legs and severing blood vessels in its throat to release the blood. It is desirable that the heart be beating at that time so that it pumps blood quickly out ~ :
of the body. During this bleeding operation it is desirable for the body to be completely relaxed and without nervous ;
tension. Otherwise the body would be stiffened by the muscles `
being in tension and might kick violently even though lifeless.
This would cause blood clots and would also cause splashing of , ` the blood from the body, and hence there would not be a steady -, quick drain of the blood from the body which is important if -~he meat is to be of high quality.
, ., It would additionally be desirable that the body not bleed from any other point than the throat, especially not from -the head, because too slow a bleeding flow would be established and blood splashing would result.

' It has been found that to achieve a satisfactory body state after stunning and before slaughter there is an optimum relationship between the firm contact of the stunning arms on the animal's head and the waveform/frequency and voltage current of the electric inpulse at the moment of impact as well as the time period of the application of the tongs - on the head and the impulse in order effectively to stun the animal.
In modern abattoirs pigs are placed in a restrainer which consists of a downwardly tapering trough which lifts the animal off its feet and then feeds it forward so that its -head projects. The stunning is then carried out and the stunned animal is moved onto a table from which it is immediately picked up by its rear leg(s) and the animal's throat blood vessels severed over drip pans which collect the escaping blood. In this method there is a time delay of sufficient duration for ; -the animal to react into tension before it is stunned.
~` The main object of the present invention is to provide improved stunning tongs in which the aforesaid disadvantages -20 are reduced to an acceptable level whilst maintaining humane ~
slaughter. ~ `
According to the present invention a stunning tongs ~, for stunning animals prior to slaughter comprises a frame and .
, handle assembly, a pair of stunning arms mounted on the assembly, :: ~ - .
with at least one of the stunning arms be;ng pivoted to the frame. A prime mover is operable to effect relative movement : :.
between the arms to cause them to ma]ce rapid firm contact wi~h '. :
,~ opposite sides of an animal's head disposed between them. Stun-ning electrode heads on the arms and in an electroni~c circuit are operable to apply between the heads an impulse of predetermined waveform/frequency and voltage, and an electronic Means is operable to apply the impulse to the heads and to cause operation of ti~e

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prime mover to engage the energized electrode heads on -the animal's head and simultaneously to pass the impulse through the animal's head to stun the animal for sufficient time to enable the animal to be slaughtered.

The invention also contemplates a method for stunning animals prior to slaughter which utilizes stunning tongs which comprise a frame, a handle portion mounted on the frame, a pair of stunning arms mounted on the frame for relative movement of at least one of the arms with respect -to the frame, and a st~nning head on each of the arms. Each of the stunning heads comprise a stunning electrode and present an area configured for pressure engagement of the head of an animal without pene- ` ;
tration, and a prime mover connected to the at least one arm.
Electronic stunning circuit means are connected to the elect-rodes, an energizing means is connected to the prime mover and : ;: :
the electronic stunning circuit means, and manually actuable control means are connected to the energizing means. The method steps are, positioning the arms on opposite sides of ,....
an animal's head, actuating the control means to supply energy `~
from the energizing means simultaneously to the electronic stunning circuit means and the prime mover. The control means effects rapid relative closing movement between the ;
arms to make rapid firm contact on opposite sides oE the ., , ~ .
animal's head, and prior to such contact, it energizes the ~-electrodes so that instantaneously with the contact of the electrodes on the animal's head an impulse of predetermined - ;
waveform/frequency and voltage/current passes between -the electrodes through the animal's head for a predetermined .1 period, sufficient to ensure complete stunning, until the animal is slaughtered immediately afterwards.

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Preferably one or both stunning arms is or are pivoted to the frame and the prime mover comprises a pressure fluid piston-cylinder connected between the frame and the stunning arm or arms.
The prime mover may comprise a compressed air cylinder mounted on the frame with a piston therein having a piston rod articulated to at least one stunning arm, the compressed air supply to the cylinder being controlled by a trigger and preferably incorporating means to adjust the pressure value.
The stunning heads preferably comprise electrodes electrically insulated from the arms and in circuit with said electronic means which is controlled by an electronic timlng device operatively associated with the prime mover actuating means, the electronic means including means to apply the impulse between the electrodes in timed relation with the actuation of the stunning arms and to maintain a current flow through the animal's head for a predetermined period.
In order that the invention may be more fully under-; stood an embodiment in accordance therewith will now be described by way of example with reference to the accompanying i drawings, in which:-Fig. 1 is an elevation of a stunning tongs;
Fig. 2 is a side elevation looking from the right of ;~
Fig. l;
Fig. 3 is a line diagram of the pressure fluid circuit of the prime mover of the tongs; and Fig. 4 is a circuit diagram of the timing and impulse ' generating means which energizes the electrodes of the tongs.
,1 30 Referring to Figs. 1 and 2, the tongs comprise a U-~ shaped frame 1 to the arms 2, 3 on which stunning arms 6, 5 ','; ''~': ':
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are mounted. Any shape of frame may however be used. As shown the arm 6 is pivoted at 5a to the arm 2 but both arms 5, 6 may be pivoted to the arms 3, 2, respectively, the essential requirement being,that the outer ends of the arms 5, 6 can be spread apart to permlt an animal's head to be located freely between them and then moved rapidly to make firm contact on each side of the animal's head and instantaneously therewith to stun the animal so that the animal is wholly unaware of what occurs. The stun does not kill the animal and hence the heart continues to beat so that when the throat blood vessels are cut the blood is pumped out of the carcass while the nervous system remains relaxed.
The frame 1 is mounted on a handle 7 shown in Fig. 2 in the form of a pistol grip handle with a trigger 8 pivo-ted thereto for operating the tongs as will be described.
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Mounted on the frame-handle assembly is a prime mover shown as a pneumatic cylinder 10, the piston rod lOa of which is articulated at 11 to the arm 6 on the opposite side of the arm pivot 5a from the stunning head of the arm. The outer ends ;
of the arms 5, 6 carry stunning heads 13, 12, respectively, each formed of a number of rigid plates 14 of electrically conducting material separated by resilient oam pads 15,e.g. of rubber or plastics, with the pads and plates being mounted on a base 16 of electrically insulating material, e.g. nylon or polytetra-fluoroethylene, and fixed to the arms 5, 6. These heads form the electrodes of the tongs and are connected by leads 17 to a cable 18 from a source of an electric signal connected to the handle-frame assembly and electrically insulated therefrom.
The cylinder 10 is connected through pressure ~luid lines 18a to a valve I9 in the handle and actuated by the trigger 8. This valve is connected to a pressure fluid supply line 20.
-' The pressure fluid may be a gas, e.g. air, or a liquid, e.g.

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hydraulic oil.
Alternatively the prime mover may be a solenoid device or a servomotor.
The trigger 8 may actuate both the ~alve 19 and a switch in the leads 17 and may perform a double function, i.e.
to cause the stunning arms to be rapidly and firmly engaged on the animal's head and to actuate a switch to provide the impulse through the animal's head.
Referring to Fig. 3 this shows the pressure fluid cir- -cuit for the prime mover cylinder 10, in which an air supply 21 of conventional form is connected by a pipe 22 through a filter `
23, a pressure regulator 24 of conventional form and a trigger operated valve 25 (i.e. the valve 19 in Fig. 2) to the cylinder 10 oE ~he tongs. A pressure gauge 27 is provided in -the circui-t.
By adjustment of the regulator 24 the air supply to the cylinder 10 and hence the actuating of the cylinder 10 can be controlled to provide the requisite snap action of the movement of the electrodes ayainst the animal's head, so that as soon as the animal's head projects from the restrainer the tongs immediately snap into position for the impulse to pass. The air pressure from the valve 25 is also applied to a pressure switch 26 which operates the electronic timer which in turn ener~izes a stunning impulse unit described with reference to Fig. 4.
Referring to Fig. 4 the top portion shows the timing circuit and the bottom portion an impulse generating circuit.
In the timing circuit an AC voltage is applied from the input ;;
30 across the isolating switch 31 and fuse 32 to a transformer Tl, the lamp 33 indicating that the circuit is live. The voltage is transformed down to 24 volts AC and then rectified by a diode bridge rectifier 34 having the four diodes Dl, D~, D3, D~. The output voltage from the diode bridge is smoothed by a capacitor ~ Cl. ;~
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When the pressure switch 26 of Fig. 3 is no-t energized, :;
the circuit is dead and a capacitor C2 charges up and holds its charge, and when the pressure switch 26 is operated, the charge on the capacitor ~2 is transferred through a contact a and a resistor Rl to the base ~f a transistor T2 which acts as a bias on T2, i.e. triggers it. This voltage charge is sufficient to turn the transistor T2 ON and to energize a relay RL. T2 transistor is held ON via a relay contact RL/2 and the resistor Rl. At this instant T2 is still ON, a capacitor C3 starts to charge via a variable resistor R4, the resistor R2 and the transistor T2 and the transformer Tl to give a supply voltage.
When the capacitor C3 charges up to sufEicient voltage it -turns ON the transistor T3; when the transistor T3 conducts heavily, the capacitor C3 discharges very quickly through -the transistor T3, which in turn cuts the transistor T2 OFF; because the bias at junction Rl and base of T2 is grounded or taken down to negative potential in that part of the circuit. The relay RL then de-energi~es and the circuit is set into its original state before the pressure switch 26 is operated. When the relay RL is energized, contacts RL/l of a relay in the AC
circuit containing the tongs and electrodes and energized by a variablé frequency/voltage generator 35 (V.F.G.), are made and this allows a voltage to be applied to the stunning tongs.
The period during which the contacts RL~l are closed is adjust-~ able from 0 to 60 seconds by adjusting the resistor R4. A lamp :! 36 indicates that the electrodes circuit is live.
The timer circuit of Fig. 4 can be held on by an oper-ating switch 37. Voltage is applied through the switch 37 and the resistor Rl to the base of the transistor T2 which is turned ON, thus energizing the relay RL and closing the contacts RL/l It will be understood however, that any suitable timing circuit can be used providing it does actuate the contact RL/l.

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By means oft~is-timing; circuit closing the relay contacts RL/l in timed relation to the operation of the pressure --circuit of Fig. 3, the electrode heads are energized through RL/l before they strike the animal's head so that immediately on firm contact of the electrode heads on the animal's head ;~
an impulse passes'throwgh the animal's head due to the impedance of the latter. This impulse is initially at its highest amplitude and rapidly falls and then continues as a steady current. Thus the initial impulse e~fects an electric stunning blow followed by a steady stunning current so long as RL/l is held closed by the timing circuit of Fig. 4. This flow ensures that after the tongs are removed from the animal's head the animal will remain stunned for sufficient time for the animal .:
to be slaughtered. The impedance of the animal's head varies j Erom one animal to another due for example to the individual make up o the animal's skin or the degree of moisture in the skin. The impedance can be varied if desired by spraying the animal with water before it enters the restrainer or while ' it is in the restrainer: this does not shock the animal into nervous tension since it is known that spraying animals such ' as pigs with water calms the animals. ~
A suitable stunning voltage is in the order of 150 ~ -volts AC but the device will operate in a frequency range of ;
20 cycles/sec. to 2 megacycles/second and voltage 0-350 volts AC. The waveform of the voltage may be of any suitable form such as square or sinusoidal.
By means of the stunning tongs of the invention a crisp stun is achieved and the impulse which is followed by the steady voltage/current for an adequate time ensures the maintenance ! ' ,. ' - ' of a complete stun of sufficient duration while the animal is slaughtered~immediately in any conventional manner, for example i~j in the case of a pig by bleeding, so that the animal is slaughter- ~ ;

ed without suffering any pain and without being aware of being slaughtered.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A stunning tongs for stunning animals prior to slaughter comprising a frame and handle assembly, a pair of stunning arms mounted on said assembly, at least one of said stunning arms being pivoted to said frame, a prime mover operable to effect relative movement between said arms to cause them to make rapid firm contact with opposite sides of an animal's head disposed between them, stunning electrode heads on said arms and in an electronic circuit operable to apply between said heads an impulse of predetermined waveform/fre-quency and voltage, and electronic means operable to apply said impulse to said heads and to cause operation of said prime mover to engage said energized electrode heads on said animal's head and simultaneously to pass said impulse through the animal's head to stun the animal for sufficient time to enable the animal to be slaughtered.

2. A stunning tongs according to Claim 1 wherein said prime mover comprises a pressure fluid piston-cylinder connected between said frame and said at least one pivoted stunning arm.

3. A stunning tongs according to Claim 2 wherein said prime mover comprises a compressed air cylinder mounted on said frame with a piston therein having a piston rod arti-culated to at least one stunning arm, the pressure fluid supply to the cylinder being controlled by a trigger and preferably incorporating means to adjust the pressure.

4. A stunning tongs according to Claim 1 wherein said heads comprise electrodes electrically insulated from said arms and in circuit with said electronic means which is controlled by an electronic timing device operatively associated with said prime mover actuating means, the electronic means including means to apply said impulse between said electrodes in timed relation with actuation of said stunning arms, and to maintain a current flow through the animal's head for a predetermined period.

5. A stunning tongs according to Claim 2 wherein said heads comprise electrodes electrically insulated from said arms and in circuit with said electronic means which is con-trolled by an electronic timing device operatively associated with said prime mover actuating means, the electronic means including means to apply said impulse between said electrodes in timed relation with actuation of said stunning arms, and to maintain a current flow through the animal's head for a pre-determined period.

6. A stunning tongs according to Claim 3 wherein said heads comprise electrodes electrically insulated from said arms and in circuit with said electronic means which is con-trolled by an electronic timing device operatively associated with said prime mover actuating means, the electronic means including means to apply said impulse between said electrodes in timed relation with actuation of said stunning arms, and to maintain a current flow through the animal's head for a predetermined period.

7. A stunning tongs according to Claim 1, Claim 2 or Claim 3 wherein said frame is U-shaped, said handle and said prime mover are secured to the base of said U-shaped frame, and said arms carrying the stunning heads are pivoted to the arms of said U-shaped frame.

8. A stunning tongs according to Claim 4, Claim 5 or Claim 6 wherein said frame is U-shaped, said handle and said prime mover are secured to the base of said U-shaped frame, and said arms carrying the stunning heads are pivoted to the arms of said U-shaped frame.

9. A stunning tongs according to Claim 1, Claim 2 or Claim 3 wherein said handle is a pistol grip with a trigger pivoted thereto and operatively connected to means controlling the energy supply to said prime mover.

10. A stunning tongs according to Claim 4, Claim 5 or Claim 6 wherein said handle is a pistol grip with a trigger pivoted thereto and operatively connected to means controlling the energy supply to said prime mover.

11. A stunning tongs according to Claim 4, Claim 5 or Claim 6 wherein said handle has a switch device operable to energize the electronic timing device.

12. A stunning tongs according to Claim 1 wherein said handle is a pistol grip with a trigger pivoted thereto, an energy supply line is mounted on said handle and connected to said prime mover and to a source of energy and an electronic circuit including said electrode heads is provided including a connection to an electric power supply, said electrode heads and a switch device mounted on said handle and actuated by said trigger, said trigger actuation being operable to energize the electronic circuit of the electrode heads to initiate the impulse and to maintain a subsequent steady current to the animal's head.

13. A stunning tongs according to Claim 12 wherein said prime mover is a pressure fluid-actuated piston-cylinder, a fluid supply line is provided from a source of pressure fluid to said piston-cylinder device, a valve is provided on said handle in said supply line, and said trigger is movably mounted on said handle and is operatively connected to said said valve and to said switch device, said trigger having a double movement the first movement actuating said valve and the second movement actuating said switch device.

14. A stunning tongs according to Claim 1 wherein said stunning heads are formed of a number of rigid plates of electrically conducting material separated by resilient elements of non-electrically conducting material, the heads being mounted on bases of electrically insulating material, while plates are connected to the electronic means.

15. A stunning tongs according to Claim 12 wherein said stunning heads are formed of a number of rigid plates of electrically conducting material separated by resilient elements of non-electrically conducting material, the heads being mounted on bases of electrically insulating material, while plates are connected to the electronic means.

16. A stunning tongs according to Claim 13 wherein said stunning heads are formed of a number of rigid plates of electrically conducting material separated by resilient elements of non-electrically conducting material, the heads being mounted on bases of electrically insulating material, while plates are connected to the electronic means.

17. A stunning tongs according to Claim 1, Claim 3 or Claim 12 wherein said prime mover is selected from the group of a hydraulic cylinder, a pneumatic cylinder, a solenoid, and a servomotor.

18. A stunning tongs according to Claim 4, Claim 5 or Claim 6 wherein said prime mover is selected from the group of a hydraulic cylinder, a pneumatic cylinder, a solenoid, and a servomotor.

19. A stunning tongs according to Claim 13, Claim 14 or Claim 15 wherein said prime mover is selected from the group of a hydraulic cylinder, a pneumatic cylinder, a solenoid, and a servomotor.

20. A stunning tongs according to Claim 16, wherein said prime mover is selected from the group of a hydraulic cylinder, a pneumatic cylinder, a solenoid, and a servomotor.

21. A stunning tongs according to Claim 12, Claim 13 or Claim 14 wherein said electronic circuit includes a transformer to transform the voltage of said electric power supply to a low voltage, the circuit including, a diode rectifier to rectify the electronic signal, and a capacitor to smooth said electronic signal.

22. A stunning tongs according to Claim 15 or Claim 16 wherein said electronic circuit includes a transformer to transform the voltage of said electric power supply to a low voltage, the circuit including, a diode rectifier to rectify the electronic signal, and a capacitor to smooth said electronic signal.

23. A stunning tongs according to Claim 12, Claim 13 or Claim 14 wherein said frame is U-shaped, said handle and said prime mover are secured to the base of said U-shaped frame, and said arms carrying the stunning heads are pivoted to the arms of said U-shaped frame.

24. A stunning tongs according to Claim 15 or Claim 16 wherein said frame is U-shaped, said handle and said prime mover are secured to the base of said U-shaped frame, and said arms carrying the stunning heads are pivoted to the arms of said U-shaped frame.

25. A method for stunning animals prior to slaughter, said method utilizing stunning tongs comprising a frame, a handle portion mounted on said frame, a pair of stunning arms mounted on said frame for relative movement of at least one of said arms with respect to said frame, a stunning head on each of said arms, each of said stunning heads comprising a stunning electrode and presenting an area configured for pres-sure engagement of the head of an animal without penetration, a prime mover connected to said at least one arm; electronic stunning circuit means connected to the electrodes; energizing means connected to said prime mover and said electronic stunning circuit means; and manually actuable control means connected to said energizing means; said method comprising the steps of:
positioning said arms on opposite sides of an animal's head;
actuating said control means to supply energy from said energizing means simultaneously to said electronic stunning circuit means and said prime mover to:
effect rapid relative closing movement between said arms to make rapid firm contact on opposite sides of the animal's head, and prior to such contact, energize said electrodes so that instantaneously with the contact of the electrodes on the animal's head an impulse of predetermined waveform/frequency and voltage/
current passes between said electrodes through said animal's head for a predetermined period, sufficient to ensure complete stunning, until the animal is slaughtered immediately afterwards.

26. A stunning tongs for stunning animals prior to slaughter comprising a frame, a handle portion mounted on said frame, a pair of stunning arms mounted on said frame for relative movement of at least one of said arms with respect to said frame, a stunning head on each of said arms, each of said stunning heads comprising a stunning electrode and present-ing an area configured for pressure engagement of the head of an animal without penetration, a prime mover operably connected to said at least one arm to effect rapid relative closing move-ment between said arms to make rapid firm contact on opposite sides of said animal's head disposed between said arms, elec-tronic stunning circuit means including timing means and connected to said electrodes for generating an impulse of pre-determined waveform/frequency and voltage/current; an energizing means operably connected to both said prime mover and said stunning circuit means for energizing said prime mover and said stunning circuit means; manually actuable control means for actuating said energizing means to supply energy simultaneously to said prime mover and said electronic circuit means; said electronic stunning circuit means being operable in timed relation to said prime mover to energize the electrodes sub-sequent to activation of said control means but prior to engage-ment of the electrodes with the animal's head so that instant-aneously with the contact of the electrode heads on the animal's head said impulse of predetermined waveform/frequency and voltage/current passes between said stunning heads through said animal's head, for a predetermined period, sufficient to ensure complete stunning until the animal is slaughtered immediately afterwards.

27. A stunning tongs for stunning animals prior to slaughter comprising a frame, a handle portion mounted on said frame, a pair of stunning arms mounted on said frame for relative movement of at least one of said arms with respect to said frame, a stunning head comprising a stunning electrode on each of said arms, a prime mover operative to effect rapid relative movement between said arms to make rapid firm contact on opposite sides of an animal's head disposed between said arms, an electronic stunning device operable in timed relation to said prime mover so that instantaneously with the contact of the electrode heads with the animal's head, an impulse of pre-determined waveform/frequency and voltage/current is passed between said stunning heads through the animal's head for a predetermined period sufficient to ensure complete stunning until the animal is slaughtered immediately afterwards, said stunning heads being formed of a number of plates of electrically conducting material separated by resilient elements of non-electrically conducting material, said plates and resilient elements being mounted on bases of electrically insulating material, and said plates being electrically connected to a source of electric power supply.

28. A stunning tongs for stunning animals prior to slaughter comprising a frame, a handle portion mounted on said frame, a pair of stunning arms mounted on said frame for relative movement of at least one of said arms with respect to said frame, a stunning head comprising a stunning electrode on each of said arms, a prime mover operative to effect rapid relative movement between said arms to make rapid firm contact on opposite sides of an animal's head disposed between said arms, and an electronic stunning device operable in timed relation to said prime mover so that instantaneously with the contact of the electronic heads with the animal's head an impulse of predetermined waveform/

frequency and voltage/current is passed between the stunning heads through the animal's head for a predetermined period sufficient to ensure complete stunning until the animal is slaughtered immediately afterwards during stun, a trigger pivoted to said handle, a pressure supply line actuated by said trigger and connected to said prime mover and to a source of pressure, a switch mounted on said arms adjacent to said trigger and situated in an electronic circuit including a connection to an electric power supply and including a transformer to transform the voltage of said electric power supply to a low voltage, a diode rectifier to rectify the electronic signal in said circuit, a capacitor to smooth said electronic signal, and a second capacitor capable of being charged by said smoothed signal to influence a relay in timed relation with said prime mover.