IE42123B1 - Spraying devices and positioning means for use therewith - Google Patents

Description

The present invention relates to spraying devices which are adapted for operation by livestock, in particular by cattle.

In order to control mastitis in dairy herds, it is recommended to disinfect the cows' teats after each milking !, with a suitable disinfectant such as an iodophor. Heretofore this has been done in practice by dipping the teats in a container of the disinfectant or by spraying the teats by means of a hand pump. However, this requires that the herdsman treats each cow individually, which is time-consuming and interrupts the smooth running of the milking operation.

It has been proposed to use a spray unit incorporating a pressurised vessel from which the teat dip is delivered by air pressure, but this again would involve the herdsman directing the spray nozzle at the udders of each cow and it could be very wasteful of disinfectant.

Various automatic sprayers are known in the patent literature in which a spraying device is activated by an animal so as to cause a spray of fluid to be directed at itself. Such sprayers, as shown in U.S. Patent Specifications Nos. 3,884,192; 3,699,928 and 2,542,280 for example, typically comprise a chute through which the cattle may be driven, the floor of the chute incorporating a platform or treadle depressible by the weight of the cattle to actuate the spraying device which sprays a treatment fluid at the animal in the chute. 42133 These prior proposals have generally been concerned with spraying fluids such as insecticides all over the animal's body and have not dealt with the difficult problem of directing a spray specifically at the udder of a cow.

British Patent Specification No. 1,135,874 discloses a stall for washing the udders of cows which comprises a frame having entry and exit doors, a movable member carrying a manifold with nozzles for supplying cleaning solution, and a holding arm arranged to press on the hind quarters of the animal so as to locate the nozzles in the correct position to spray the udder. However, each animal in turn must be isolated in the stall and held between the two doors, which is likely to disturb dairy cows. Also the equipment in the stall, with a movable spray manifold and automatically operated doors, is complicated and difficult for the ordinary farmer to maintain. Furthermore, the hind legs of the animal in the stall are likely to interfere with the spray of fluid and prevent it from reaching at least part of the udder.

U.S. Patent No. 3,554,166 discloses a floor-mounted spraying unit having a convex dome exterior surface through which treatment fluids are sprayed upwardly at the udder. This unit can be used for, inter alia, applying a disinfectant to dairy cows after milking. However, the Patent also discloses that in order to take account of the various sizes of cows that might be in any one milking herd, it is necessary to provide means for sliding the spraying unit along the floor of the stall and an operator has to move the unit until it is properly positioned beneath the udder of the cow.

It is an object of the present invention to provide a spraying device in which the spray is activated when the udder of the cow is in the correct location with respect to the spray nozzle or nozzles.

It is a more general object of the invention to provide an animal spraying unit in which a spray is activated when the animal is at a defined location so that the spray can be directed at a selected portion of the animal. This is useful not only for udder spraying but also for spraying other parts of the body which are liable to disease or irritation. For example the infection known as pink eye can attack the eyes of cattle and sheep and is desirable to spray the eyes regularly, particularly if an epidemic of the infection is threathened. However, it is difficult to arrange for all the cattle in a herd to be sprayed in the face, particulary in view of the reluctance of cattle to approach a spray which is in continuous operation.

The present invention provides a spraying unit for spraying a selected portion of an animal as it passes the unit, said unit comprising a spraying device, means operated by the feet of the animal to activate the spraying device, and positioning means comprising a series of spaced-apart obstacles and footplaces between said obstacles the arrangement being such that the animal steps over the obstacles and puts its feet into the foot places, the spacing of the obstacles in relation to the spraying device and the activating means being such that the selected portion of the animal is positioned to receive the spray when the feet of the animal operate the activating means located in one or more of the foot-places. In general the separation of the foot places (and likewise of the obstacles) is approximately equivalent to the average length of the stride of the type of animal to be sprayed. The foot places are long enough to receive one foot but not long enough for the animal to make a stride inside one foot place.

In its preferred embodiment, the invention provides a cow spraying unit having positioning means arranged so that when the spraying device is activated the cow's udder is positioned to receive the spray. The udder spraying unit normally has one or more spray nozzles located in or beside one of the obstacles which separate the foot-places.

According to another aspect, the invention provides a spraying unit for spraying a selected portion of a cow comprising a frame having two longitudinal side members which define a chute having an entry and an exit; a series of obstacles each extending across the chute between the side members, the obstacles being such that cows can step over them; foot-places between the obstacles; a foot-operated spray-activating device located in one or more of the footplaces; a spray nozzle mounted in such a position relative to the activating device so as to direct a spray of liquid at the selected portion of the cow when the cow's feet operate the activating device; and means operated by the activating device to pump liquid to the spray nozzle.

In a unit for spraying cows' udders which is a preferred embodiment of the invention the spray nozzle is mounted in one of the obstacles upstream of the foot places containing the activating device. In this specification the word “upstream is used to mean ''nearerto the entry while the word downstream is used to Mean nearer to the exit. In an alternative unit for spraying cows' eyes, the spray nozzle is mounted oh the frame side members, at least some of the foot places containing the activating device being upstream of the spray nozzle.

In a particular form of the udder spraying unit, the activating device comprises two treadles, both of which must be operated by the cow's feet to activate the spray, the two treadles occupying foot places separated by a single obstacle, the spray nozzle being mounted in another obstacle immediately upstream of the said two treadles and so as to direct a spray of liquid upwardly at the cow's udder.

Preferably the unit also includes a re-setting device for the spraying means, the re-setting device being located in a foot place downstream of theactivating treadles and separated therefrom by two obstacles and one foot place.

Preferably the spraying device comprises a pump operable by means of the activating device. The pump may itself directly pump the fluid to the spray nozzle or it may suitably be adaoted to pump air into a pressure vessel, in which case the fluid is directed to the nozzle by air pressure. <3133 Preferably the activating device operates a valve through which the fluid passes to the nozzle. The activating device may suitably operate both a valve and a pump. Alternatively if a source of hydraulic and/or pneumatic pressure is available to drive the fluid, the pump may be omitted and the activating device may operate a valve only.

In a transportable spraying unit, a compressor may be provided in order to supply compressed air. The compressor may be driven by an engine, for example a petrol engine, which suitably comes into operation when the pressure in a pressurised vessel falls below a certain level.

According to one aspect of the present invention, the spray nozzle is located behind a shield or cover, and means are provided to move the nozzle from behind the shield or cover, or to move the shield or cover from in front of the nozzle, said means being operated when the spraying device is activated by an animal.

The spraying device may conveniently be located at the exit or entrance of a farm building or in a passage or race leading, for example, to a water trough or feeding trough. Alternatively, a transportable unit may be used at any location around the farm, The obstacles preferably are arranged at regular intervals along the unit. For cows, the pitch (or the distance measured between the upstream edges of adjacent obstacles may suitably be from 2 ft (60 cm) to 2 ft. 6 in. (75 cm), while the separation (or the length of the foot places) may suitably be from 6 inches (15 cm) to 10 inches (25 cm) and each obstacle may suitably have a height (measured from the level of the foot places) of from 3 inches (7.5 cm) to 8J inches (21 cm).

Each obstacle normally is longer at the base than at the top.

The chute for cattle may suitably be from 2ft. 1 in. (63.5 cm) to 2 ft. 8 in. (81.5 cm) wide, the obstacles normally being about 2 ft (61 cm) wide.

The invention is illustrated in the accompanying drawings.

The symbols used in Figures 5, 6 and 7 are standard symbols for fluid power transmission.

Figure 1 is a view of a cow stepping across a series of obstacles in a unit according to the invention; Figure 2 is a perspective view of a unit according to the invention, with the near side cut away; Figure 3 is an enlarged side view of a platform in the 15 unit of Figure 2; Figure 4 is an elevation of the spray nozzles and means for moving them in a unit according to the invention; Figure 5 is a diagram of a pneumatic control circuit for the spraying unit according to the invention; Figure 6 is a diagram similar to Figure 5 and showing two additional features; Figure 7 is another diagram similar to Figure 5 showing an extra feature; Figure 8 is an elevation of a detail of the end mounting ?5 of the obstacles in the unit of Figure 2; and Figure 9 is a cross-section on the line B-B of Figure 88 42133 Figure 1 shows a series of obstacles 1, 2, 3 4, 5, 6 Separated hy foot places 31, 32, 33, 34, 35. Spray nozzles are contained within obstacle 2, the spray be->’ng emitted through apertures 7,8 (only one of which is visible in Figure 1). Activating devices for the spray are contained in foot places 32 and 33, while a resetting device for the spray is contained ih foot place 35.

The cow steps over the obstacle, putting one of her front feet and one of her hind feet into each of the foot places as she strides along through the unit. When the right front foot 9 is put into place 33 while the left front foot 10 is in foot place 32, the spray device is activated. The cow's udder is then located just behind obstacle 2 containing the spray nozzles. As the cow continues forward, carrying her right rear leg 11 over obstacle 2, the udder passes above obstacle ? and receives the spray from the spray nozzles.

The cow walks on in the downstream direction and puts her right front foot 9 into foot place 35 which contains the re-setting device. By this time, her left feet 10 and 12 are in foot places 34 and 33 and her right rear foot has moved from foot place 32. Since the spray is only activated when a cow has feet in both foot places 33 and 32 simultaneously, the left rear foot 12 does not cause t.he spray to fire again after re-setting. The device is now re-set for the next cow entering the unit., if the re-setting device were more than 2 steps away from foot place 33, it is possible that the next cow, following immediately on the tail of its predecessor, could reach step 32 and 33 before the device had been re-set. 4Ζ1Ζ3 On the other hand, if the re-setting device were only 1 step away from foot place 33 (i.e. in foot place 34) then the device would be re-set too early and the rear feet 11 and 12 would cause the spray to.fire.

It will be apparent that if the cow places its left front foot into foot place 31 first, the references to right and “left feet in the foregoing description will be reversed.

Figure 2 shows the construction of one form of unit according to the invention. The unit comprises two longitud10 inal side members, of which only one side member 13 is shown in full, each side member consisting of a base housing 14 and a fence of rails 15. The side members define a chute or race having an entry 16 and an exit 17. Mounted between the two base housings is a series of obstacles 1, 2, 3, 4, 5, 6. Each obstacle consisits of a ridge of sheet metal having a vertical upstream edge 18, an inclined ramp portion 19 leading up to a flat summit portion 20, and an inclined downstream edge 21.

The obstacles are so spaced that the separation of their leading edges (i.e. the pitch of the series) is about 2 ft 3 inches (66 cm) while the foot places between them are about 8 inches (20 cm) long. Each obstacle is about 7 inches (17.5 cm) high.

The five foot places between the obstacles are occupied by treadles which for convenience are given the same reference numerals 31, 32, 33, 34, 35 as the foot places in Figure 1.

The treadles are metal grids through which the treatment liquid and urine can drain. Each treadle is mounted near to its upstream edge on a pair of pivot pins 22 which engage in holes 43123 in the two base housings 14. Treadles 31 and 34 are rigidly supported at their downstream edges while treadles 32, 33 and 35 are mounted in springs 23 at their downstream edges. Treadles 32, 33 and 35 each carries an inverted L-shaped trigger 24, the arm 25 of which extends through an aperture in the base housing 14 to engage a pneumatic valve (not shown in Figure 2) which is operable by downward pressure against spring bias. A standard pneumatic valve such as one sold under the Trade Mark MARTONAIR is suitable.

The pneumatic valves associated with treadles 32 and 33 activate the spray device and the pneumatic valve associated with treadle 35 re-sets the spray device.

The spray nozzles and means for moving them are contained in obstacle 2, the spray being emitted through apertures 7, 8.

Figure 3 shows treadle 32 to a larger scale, the treadle being mounted on pivot pin 22 at its upstream edge and being supported by compression spring 23 at its downstream edge.

A bayonet fitting 26 is provided at the end of the treadle so that it can be removed from the pivot pin for cleaning.

The trigger 24 has a horizontal arm 25 which carries an adjustable screw 27.

The pneumatic valve 28 is shown in Figure 3 although in practice it would be separated from the treadle by the walls of base housing 14. Screw 27 acts on pivoted lever 29 which operates the valve.

Figure 3 also shows in dotted outline an addition to the unit, this addition being a pump for compressing air. The pumo 30 is operated by a lateral extension 41 from horizontal arm 25 of the trigger 24. Each depression of the treadle 32 operates the pump. If desired, similar pumps may be provided in association with each of the treadles 3T, 32, 33, 34 and 35 which may all be mounted on springs so as to be depressible.

Figure 4 shows the spray nozzles and the means for moving them, all contained within obstacle 2. The spray nozzles 43, 44 are carried between respective pairs of pivoted swing arms 45, 46, of which the nearer one of each pair is omitted from the drawing. The swing arms 45, 46 are pivoted on bearings 47 attached to a base 48 which conveniently incorporates a compressed air reservoir 60. The arc of swing of the arms 45, 46 is determined by a stop which comprises a rod 50 extending between the two swing arms of a pair and contained within a box 51 of square cross-section. The two end positions of swing arm 46 are shown in the drawing, the retracted position being shown in full line while the extended position is shown in dotted outline. It will be seen that the movement of swing arm 46 swings the nozzle 44 from an inactive position in which it is shielded below the summit portion 20 of obstacle 2 to an active position in which it is in line to emit a spray of liquid through aperture 8. Swing arm 45 swings in a similar fashion to bring nozzle 43 in line behind aperture 7. 42133 The swing arms 45, 46 are moved by an air cylinder 52 and a liquid cylinder 53 which are slung between the two swing arms in opposed relationship with their pistons rigidly joined together at the ends of their respective piston rods 54, 55. The housing of cylinder 52 is connected by bars 56 to a pivotal mounting between the pair of swing arms 45 while the housing of cylinder 53 is mounted on pivotable bearings between the pair of swing arms 46. The cross-sectional area of the air cylinder 52 is about 3 times the cross-sectional area of the fluid cylinder 53.

The control circuit is shown in Figure 5. Compressed air is supplied to a reservoir 60 provided with an adjustable pressure regulating valve 61. The air reservoir 60 is connected to the inlet port of a first control valve 62 which is operated by the trigger on treadle 32. The outlet port of valve 62 is connected to the inlet port of a second control valve 63 operated by the trigger on treadle 33. Control valve 63 has an auxiliary port connected to a resetting control valve 59 operated by the trigger on treadle 35.

The outlet port of valve 63 is connected to the chamber of floating air cylinder 52. Both the cylinder housing and the piston within it are free to move. The piston 64 of air cylinder 52 is rigidly connected to the piston 65 of fluid cylinder 53. Here again both the cylinder housing and the piston are free to move. The cylinder housings are pivotally connected to swing arms 45, 46 carrying nozzles 43, 44.

T3 The fluid cylinder 53 pumps treatment liquid (e.g. disinfectant) supplied to the cylinder from a fluid tank 66 via a non-return valve. The liquid is pumped by cylinder 53 via a non-return valve to the nozzles 43, 44 in a metered amount determined by the capacity of cylinder 53 and the stroke of the piston 65.

When a cow enters the unit, her front foot treading on the treadle 32 causes valve 62 to open but no air passes because valve 63 remains shut. When the cow then puts her other front foot on treadle 33, valve 63 is opened and air passes to the air cylinder 52. Entry of air into the cylinder causes the cylinder housing to move (to the right in Figure 5) and causes the piston to move in the opposite direction. The movement of the piston is transmitted via the rigid piston rods 54, 55 to the fluid cylinder 53. Initially the treatment liquid in the cylinder resists movement of the piston and the result is that the cylinder housing moves (to the left in Figure 5). These movements by the cylinder housings cause the swing arms 45 and 46 to swing in opposite senses to' move the nozzles 43, outwardly so that they are in line with apertures 7, 8 (as shown in Figure 4). When movomunu of the housings stop, the piston in fluid cylinder 53 moves relative to the housinq and pumps treatment liquid via a non-return valve to the nozzles 43 and 44. The liquid is expelled from the two nozzles on convergent paths arranged to meet at the location of the cow's udder. 43123 When the cow then puts her foot on to treadle 35, resetting control valve 59 opens and this allows air to bleed out of air cylinder 52 via the auxiliary port of valve 53, thus resetting the positions of cylinder 52, 53 and the pistons therein. The nozzles 43, 44 are then swung hack behind the summit portion 20 of obstacle 2.

The location of each cow relative to the spray nozzles is arranged so that the udder will normally be moving directly over the nozzles when the fluid is expelled from the nozzles.

The udder moves about 16 inches (40 cm) during the period of emission of the spray. The device is only activated when a cow puts one of her front feet on to treadle 33. She normally then has one front foot on treadle 32, while one hind foot remains on the inactive entry control treadle 31. At this moment the udder is moving directly over obstacle 2 between treadles 31 and 32, which is the location of the spray nozzles. Further forward movement by the cow will not activate the device again because it is not reset until the cow puts a foot on treadle 35 by which time her hind feet have left treadle 32.

Figure 6 shows the control circuit of Figure 5 with two additions which may be incorporated separately or together.

Treadles 32 and 33 operate air pumps 70, 71 which draw in air via non-return valves, compress the air and pass it via non-return valves to a common air line passing to the air reservoir 60. These air pumps, if desired in conjunction with other air pumps operated by the remaining treadles, may supply the compressed air for the unit, thus making it independent of any power-operated compressor. This may be very useful if the unit is to be used in a pasture which is some distance away from the farm buildings.

The outlet from valve 63 is connected to the inlet port of an additional valve 90 which is operated by a lever engaging a cam on the piston rod 55 connecting air cylinder 52 to fluid cylinder 53. The outlet port of valve 90 is connected to a second air cylinder 72, the housing of which is fixed. The piston rod 73 is rigidly connected to the piston of a liquid cylinder 74, the housing of which is also fixed. Treatment liquid is supplied to the fluid cylinder 74 from a tank 75 via a non-return valve. Liquid from the fluid cylinder is supplied via a non-return valve to a spray nozzle 76. This nozzle (which may be duplicated if required) can be mounted on the higher one of the side rails 15 of the unit adjacent to obstacle 5 so as to spray the cow's eyes. Alternatively the extra nozzle 76 can be located elsewhere on the unit to spray a chosen part of the body, or an array of nozzles 76 can be provided in order to spray the cow over the whole body, for example with a fly repellent, in the manner known from the prior art. When the udder spray is activated, movement of the piston rod 55 (to pump liquid from the fluid cylinder 53) causes the cam to open valve 90 which allows air to pass to air cylinder 72.

Liquid is then expelled from fluid cylinder 74 in a metered amount (determined by the capacity of cylinder 74 and the stroke of the piston 73). After operation of the udder spray, the 43123 return movement of piston 55 causes the cam to close valve 90 and exhaust the air from cylinder 72 via an auxiliary valve port connected to atmosphere. The spray from nozzle(s) 76 is emitted a brief interval after the udder spray, which is advantageous particularly if nozzles 76 are providing an overall body spray.

Figure 7 shows an alternative addition to the circuit of Figure 5. Compressed air from reservoir 60 is supplied to the air chamber 77 of a pressurised liquid reservoir 78.

The flow of liquid to a spray nozzle 79 is controlled by a control valve 80 transiently operated by air passing from valve 63 to air cylinder 52. A treatment liquid can thus be sprayed from nozzle 79 at the same time as the udder spray is operating.

Figures 8 and 9 show a convenient means for detachably mounting the obstacles on the base housing 14, An L-shaped plate 80 is attached to the end of the obstacle in such a position that the flange 81 rests on the top of the base housing. Two inverted L-shaped brackets 82, 83 are fixed to the exterior of the base housing so as to overlap the flange 81 close to the ends thereof. A portion 84 slightly larger than one of the brackets 83 has been removed from the flange adjacent to the part overlapped by that bracket. A stop 85 is provided on the base housing beyond the other bracket 82.

A pin (not shown) is dropped down through the top of the base housing beyond bracket 83. When that pin is removed, the obstacle can be slid (to the right in Figure 8) and then lifted up from the base housing. This is convenient for cleaning purposes.

The obstacles as described above and as illustrated in the drawings are particularly suitable for use in the unit of the present invention. However, the invention is not limited to the use of the obstacles of this particular shape and form. The obstacles may, for example, be semi-cylindrical, or they may be formed with a smaller or greater number of flat surfaces than the obstacles as described above. For example, the summit portion 20 may be omitted and the inclined surfaces may meet at an apex ridge. Alternatively each obstacle may be made up from several components, for example bars or tubes, arranged to extend across the unit, preferably in parallel relationship. The important characteristics of the obstacles are: that they should not be so high as to trip the animals or to cause the animals to refuse to step over them; that they should not be so low as to induce the animals to step on to the obstacles instead of putting their feet into foot places, that they should be shaped so that if an animal does put a foot on to one of the obstacles the foot is not trapped but tends to slide down into one of the adjacent foot places; and that the upstream face of each obstacle is inclined, bevelled or rounded to reduce the chances of an animal tripping as it lifts its foot.

In order to get cattle moving forward in line at the entry to the unit of the present invention, it is normally necessary to arrange a preliminary chute or race upstream of the unit. This preliminary chute may consist of a simple frame with two longitudinal side members. A downstream chute may be provided on the exit end of the unit of the invention, in order to ensure that the cattle continue to move away from the unit after treatment. A non-return gate may be mounted at the exit end of the unit or on the downstream chute in order to ensure that cattle do not enter the unit at the exit end. The non-return gate swings open in the downstream direction but closes the chute and resists movement in the upstream direction.

Although the preferred embodiment of the invention comprises a self-contained unit with longitudinal side members, it is possible to achieve the objects of the present invention by arranging a series of obstacles across a passageway and locating foot-operated spray-activating devices between the obstacles. The passageway may be a permanent structure, for example, between two walls of a farm building complex, or it may be formed by use of conventional fencing or penning rails.

If desired, the foot places which do not contain activating devices (i.e. foot places 31, and 34 in Figure 1) may be left open so that the animal steps on the ground below the unit.

The foot-operated spray-activating devices may, if desired, be electrical switches which are wired into an electrical control circuit for the spraying device. However, in general it is desirable to avoid the use of electrical equipment in farms, because of potential danger to both animals and farm workers. It is therefore an advantage of the present invention that the spray unit can work without electricity.

The unit of the present invention, more particularly as shown in Figures 4 and 5, generates a short burst of spray which directs treatment liquid at the selected part of the animal's body. The quantity of liquid emitted is determined by the capacity of the fluid cylinder 53. There is little waste of the liquid and the animal is not aware of the spray until it is in position to be sprayed. Disinfectants, particularly iodophors, can be harmful if they are too widely distributed and it is desirable to restrict the amount of such liquids sprayed on to animals or into the environment of a milking parlour.

As shown in Figure 4, the air cylinder 52 has a crosssection area about 3 times that of the fluid cylinder 53. This means that a moderate air pressure can be used to generate a high fluid pressure. For example, an air pressure in the range 25-40 pounds per sq. in. can produce a spray of liquid at a pressure in the range 60 - 100 pounds per sq. in. The amount of liquid emitted can be metered by providing an adjustable stop on the piston rod 55 and/or by adjusting the air pressure in the control circuit by means of the regulating valve 61. It is important from the economic point of view that the amount of treatment liquid consumed can be regulated.

In the unit as shown in Figure 2, the air lines and valves can all be mounted in the base housing 14 and a cover plate may be provided on the outside of the base housing in order to protect the air lines and valves. The cover plate may be hinged to the base housing at the top or bottom.

Although means are described above for moving the nozzles to hring them into line behind the apertures, it is also possible to fix the nozzles and to provide movable covers which open and close the apertures. For example, the covers may be plates which slide to and fro across the apertures or they may be hinged caps which swing on pivots alongside the apertures. The covers may be moved by a pneumatic cylinder or cylinders operated by control valves incorporated into the control circuit or by control valves transiently controlled by the movement of the treatment liquid to the spray nozzles.

The obstacles in the unit of the present invention are substantial obstacles which determine the position in which the animal puts down its feet. The treadles are individually mounted in the foot places between the obstacles so that the unit is responsive to the movement of each animal as it passes through the unit. No adjustment by an operator is needed to take account of varying sizes of animal in a herd.

Claims (23)

1. A spraying unit for spraying a selected portion of an animal as it passes the unit, said unit comprising a spraying device, means operated by the feet of the animal to activate the spraying device, and positioning means comprising a series of spaced-apart obstacles and foot-places between said obstacles, the arrangement being such that the animal steps over the obstacles and puts its feet into the foot-places, the spacing of the obstacles in relation to the spraying device and the activating means being such that the selected portion of the animal is positioned to receive the spray when the feet of the animal operate the activating means located in one or more of the foot-places.

2. A spraying unit according to claim 1 having a spray nozzle or nozzles located in or beside one of the obstacles.

3. A spraying unit according to either of claims 1 and 2 having a foot-operated resetting device for the spraying device, the resetting device being located in a foot-place downstream of the foot-place(s) containing the spray-activating device.

4. A spraying unit according to any of the preceding claims for-spraying cows wherein the positioning means are arranged so that when the spraying device is activated by a cow the cow's udder is positioned to receive the spray.

5. A spraying unit according to claim 4 having spray nozzle(s) located in one of the obstacles upstream of the footplace(s) containing the activating device.

6. A spraying unit according to claim 5, wherein the activating device comprises a pair of activating treadles occupying adjacent foot-places and the spray nozzle(s) are mounted in an obstacle immediately upstream of the said nair Of activating treadles,

7. A spraying unit according to claim 6 having a resetting device for the spraying device, the resetting device comprising a treadle occupying a foot-place downstream of the activating treadles and separated therefrom by two obstacles and one foot place.

8. A spraying unit according to any of claims 2-7 having a spray nozzle located behind a shield or cover, and means to move the nozzle from behind the shield or cover, or to move the shield or cover from in front of the nozzle, said means being operated when the spraying device is activated by an animal.

9. A spraying unit according to any of the preceding claims, wherein the obstacles are ridges formed of sheet metal.

10. A spraying unit according to claim 9, wherein the ridge has a summit portion and upstream and downstream faces downwardly inclined from said summit portion.

11. A spraying unit according to either claim 9 or 10, wherein one of the ridges houses a pair of spray nozzles and apertures are provided in the said ridge to permit the emission of liquid from the nozzles.

12. A spraying unit according to claim 11, wherein means are provided to move the nozzles from an inactive position in which each nozzle is shielded behind a portion of the ridge to an active position in which each nozzle is in line with an aperture.

13. A spraying unit according to claim 12, wherein the means for moving the nozzles comprises a pair of pivoted swing arms on which the nozzles are mounted and two opposed cylinders the housings of which are pivotally attached to the swing arms and the piston rods of which are rigidly connected together.

14. A spraying unit according to claim 13, wherein one of the cylinders is an air cylinder to which air is supplied by the spray-activating device and the other cylinder is a fluid cylinder from which liquid is pumped to the spray nozzles. 15. A spraying unit according to any of claims 1 - 14, wherein the spray activating device comprises pneumatic directional control valves and a source of compressed air.

15. A spraying unit according to claim 15, wherein the source of compressed air is a plurality of pumps operated by treadles in the foot-places of the unit.

16. 17. A spraying unit according to any of the preceding claims which includes an auxiliary spray nozzle or nozzles for spraying a different selected portion of the animal or for spraying the whole body of the animal.

17. 18. A spraying unit according to any of the preceding claims which comprises a frame having two longitudinal side members which define a chute having an entry and an exit, and a series of obstacles each extending across the frame between the side members. 43123

18. 19. A spraying unit according to claim 18, wherein a non-return gate is provided at the exit end of the frame.

19. 20. A spraying unit according to either claim 18 or 19, wherein the obstacles are detachably mounted on the side members of the frame.

20. 21. A spraying unit according to any of claims 18 to 20, wherein individual treadles are detachably mounted between the obstacles on pivot pins engaged in apertures in the side members. ZO

21. 22. A spraying unit according to any o£ claims 18-21 wherein one of the side members incorporates a base housing in which air lines and control valves for the spray-activating device are located.

22. 23. A spraying unit having a spraying device adapted to be activated by the feet of an animal as it passes through the unit, said unit having positioning means comprising a series of spaced-apart foot-places into which the animal will put its feet, the foot-places being so spaced that when the animal's feet activate the spraying device a selected portion of the animal to be sprayed is positioned so as to receive the spray.

23. 25. A spraying unit according to claim 1 substantially as described herein with reference to the accompanying drawings.