GB1561821A

GB1561821A - Automatic release of milk

Info

Publication number: GB1561821A
Application number: GB5054676A
Authority: GB
Original assignee: Gascoigne Gush & Dent Ltd
Current assignee: Gascoigne Gush & Dent Ltd
Priority date: 1976-12-03
Filing date: 1976-12-03
Publication date: 1980-03-05
Also published as: FR2372591A1; NL7702113A

Description

(54) AUTOMATIC RELEASE OF MILK (71) We, GASCOIGNE GUSH & DENT (AGRICULTURAL) LIMITED, a British com- pany, of Gascoigne House, Jacklyn's Lane, Alresford, Hants, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to an automatic milking system.

The system is particularly but not exclusively useful for parlour milking with an installation having milking units which have a recording jar. A typical installatioin suitable for this system is shown in the drawing entitled "pipeline milking installation with recorder vessel" from British Standard code of practice CP3007:1968. This drawing is reproduced as Figure 1 of the accompanying drawings. The milking units are connected to three pipelines: a vacuum line to the pulsators, a vacuumlwashline and a milk line. In automatic milking systems, the milkunit is attached to a cow and, once milkflow has commenced following initiation, the system can take control and leave the operator free until the next cow at that milking unit is ready for milking.When the milkflow has fallen below a predetermined level (for example 0.25 litres per minute) the automatic system will remove the teat cup cluster from the cow and allow the milk that has collected in the recording jar during milking to be released and to flow to the dairy via the milkline.

The invention provides an automatic milking system comprising a teat cup cluster, a milk receiving jar, a milkline from the teat cup cluster to the milk receiving jar, a milk outlet from the milk receiving jar, a vacuum line to the milk receiving jar, an initiator in the said milkline adapted to stop milkflow when it falls below a predetermined level, and a control valve in the said vacuum line which can be actuated by the initiator when milk-flow stops and which is adapted to vent the vacuum line when actuated so that milk can be released from the milk receiving jar.

The control valve is preferably actuated by vacuum. A vacuum line passes from the initiator to the control valve. When the milk-flow falls below the predetermined level, the initiator causes vacuum to be present in this vacuum line and the control valve is consequently actuated, thereby venting the vacuum line to the receiving jar. An initiator valve is positioned in the vacuum line from the initiator to the control valve. At the start of milking, this initiator valve is closed so that the vacuum line to the control valve is vented and the control valve is not actuated.

The teat cup cluster is preferably raised and lowered by means of a pneumatically operated ram. Vacuum supply for raising the ram is obtained from a branch of the vacuum line from the initiator to the control valve.

The milk outlet from the milk receiving jar preferably comprises a pneumatically operated valve stop assembly. A pneumatic cylinder of the valve stop asssembly is connected by a pipeline to the control valve.

Normally the pneumatic cylinder is vented via the control valve and this maintains the valve in the milk outlet in the open position. When milk-flow stops, vacuum is diverted by the control valve from the milk receiving jar to the pneumatic cylinder of the valve stop assembly. This allows the valve in the milk outlet to close when the milk has been released from the milk receiving jar.

In a preferred embodiment, the control valve for use with the automatic milking system comprises first and second internal chambers. A first piston can slide in the first chamber and a second piston in the second chamber. The first chamber com- municates with first and second inlet/outlet ports. The second chamber communicates with third, fourth and fifth inlet/outlet ports.

There is a communicating line between the two chambers. Each piston has a rest position and an operational position and the arrangement is such that different combinations of ports can communicate with each other according to the positions of the pistons. When both pistons are in their rest positions, the first port communicates with the third port via the connecting line between the two chambers, and the fourth port communicates with the fifth port via the second chamber. When the first piston is in the rest position and the second piston is in the operational position, the first port communicates with the fifth port, and the third port communicates with the fourth port.When the first piston is in the operational position and the second piston is in the rest position, the third port communicates with both the first and second ports together, and the fourth port communicates with the fifth port. The first piston is preferably actuated manually, and the second piston is preferably actuated by vacuum.

Reference is now made to the accompanying drawings.

Figure 1 shows a pipeline milking installation with recorder vessel which is suitable for use with an automatic milking system according to the invention.

Figures 2A and B show in combination an initiator, ram and teat cup cluster which can be used in an automatic milking system according to the invention.

Figure 3 shows in diagrammatic form an embodiment of automatic milking system according to the invention.

Figures 4A, B, C and D show the automatic milking system of Figure 3 at different stages in the milking process.

Figures 5A, B and C show an embodiment of control valve which can be used in the automatic milking system.

Figures 6A and B show an initiator valve.

Figure 7 shows a non-return valve.

Figures 8A and B show a butterfly valve.

Figure 1 shows the following items in a conventional pipeline milking installation: a teat cup cluster 11, recorder jar 12, milk line 13, vacuum/wash line 14, vacuum line to pulsators 15, receiver vessel 16, milk pump 17, line to bulk tank 18, pulsator or relay 19, wash jetter 20, vacuum controller 21 and vacuum pump 22.

The combination shown in Figures 2A and B is a known system manufactured by AHI Plastic Products Moulding Company, Hamilton, New Zealand. This system causes the teat cup cluster 31 to be removed from the cow automatically when the milk output falls below a predetermined rate. The teat cup cluster 31 is attached by a connecting cord 32 to the piston 33 of a pneumatically operated ram 34. When vacuum is present in the ram (Figure 2A) the piston raises the teat cup cluster. When the ram is vented (Figure 2B) the teat cup cluster is lowered, i.e. placed in the position for milking. The initiator comprises a body portion 35 and an upper cap portion 36 which are separated by a flexible diaphragm 37. A milk inlet 38 from the teat cup cluster leads into the upper part of the body portion and a milk outlet 39 leads from the bottom of the body portion.The milk outlet can be closed by a float-operated valve (not shown). When milk is present in the body portion the float 40 is raised and the float valve is open. The dimensions of the float valve are chosen so that, when the milk output falls below 0.25 litres per minute, the float falls to such a level that the float valve is closed.

The cap portion of the initiator has a vacuum inlet 41, an outlet 42 for the vacuum line to the ram, and a vent 43. A valve 44 in the cap portion is actuated by the diaphragm. When the diaphragm is raised (Figure 2A) vacuum passes from the vacuum inlet through the cap and into the ram, and the air vent is cut off. When the diaphragm is lowered (Figure 2B) the diaphragm valve closes the vacuum inlet and air can pass from the vent through the cap and into the ram.

The initiator is provided with an external lever 45 for manual raising of the float.

The milking operation using this known system is carried out as follows. Vacuum is initially present in the milkline leading from the initiator. The lever is turned to the ieft-hand side or "manual" position. This raises the float and allows vacuum to pass into the milkline to the teat cup cluster.

The vacuum in the body portion of the initiator lowers the diaphragm. This shuts off the vacuum supply to the cap and air is vented into the ram. This causes the teat cup cluster to be lowered so that it can be placed on the cow with the vacuum supplied.

As soon as milk starts to flow from the cow, the float will stay in the raised position on the milk in the initiator. The lever is then turned to the right-hand side or "automatic/off" position. When the milk output falls below 0.25 litres per minute, the float valve closes and the vacuum supply to the milkline and teat cup cluster is shut off.

The teat cup cluster accordingly falls off the cow automatically. A small vent (not shown) in the teat cup cluster allows the remaining milk in the milkline to be drawn into the initiator and the initiator body is then at atmospheric pressure. This raises the diaphragm with consequent openings of the diaphragm valve. The air vent in the cap is then shut off and vacuum passes from the vacuum inlet through the cap portion and into the ram. The piston in the ram is accordingly raised and the teat cup cluster is therefore also raised away from the cow.

The cow can then be released from the stall and the system is ready for the next cow.

Reference is now made to Figure 3 which shows a preferred arrangement of automatic milking system according to the invention. The teat cup cluster 1, initiator 2 and ram 3 are as described above. The vacuum supply line to the initiator cap is known as the ACR (automatic cluster removal) vacuum line 51. The milk outlet line 52 from the initiator 2 passes into a recording jar 4. The vacuum line 53 from the initiator cap to the ram branches and passes through an initiator valve 5. The line then passes to a pneumatic cylinder 54 of a control valve 10. The control valve 10 governs a vacuum-wash line 55 which passes from a vacuum supply or washing fluid supply, through the control valve 10 and into the top of the recording jar 4. The control valve 10 also controls the supply of wash fluid to wash jetters 6.Furthermore, the control valve 10 controls the supply of vacuum or atmospheric air to the pneumatic cylinder of a valve stop assembly 9 in the outlet of the recording jar 4. A non-return valve 7 and a butterfly valve 8 are positioned in the milk line 56 leading from the outlet of the recording jar 4.

The construction and operation of the control valve 10 are shown in Figures 5A, B and C. This is a double slide valve having first and second internal chambers. The first chamber 61 has first 62 and second 63 inletloutlet ports which at various stages in the milking cycle are used for vacuum, atmospheric air or wash fluid. The second chamber 64 has third 65 and fourth 66 inlet/ outlet ports which again are used for vacuum, atmospheric air or wash fluid. The second chamber also has a fifth inlet port 67 (indicated as a vent 67 in Figure 3) through which atmospheric air enters the valve.

A manually operated piston 68 slides in the first chamber between a rest position and an operational position (when the plunger 69 of the piston is pushed in). A second piston 70 slides in the second chamber. This second piston is actuated by vacuum in a pneumatic piston assembly 54.

When no vacuum is present, the second piston extends into the second chamber and is said to be in the rest position. When vacuum is present, the second piston is partly withdrawn from the second chamber and is said to be in the operational position.

Finally, there is a communicating channel 71 between the first and second chambers in line with the first and third inlet/outlet ports.

Transverse channels are present in the first and second pistons so that different combinations of the five inlet/outlet ports are interconnected according to whether the first and second pistons are in the rest position or the operational position.

In Figure 5A, the first (manual) piston is in the rest position and the second (vacuum-operated) piston is also in the rest position. A direct channel then exists from the first port, through the valve and out of the third port. At the same time, the fifth port (air vent) is connected to the fourth port.

In Figure SB, the manual piston is still in the rest position, but the vacuum-operated piston is in the operational position. The air vent is then connected to the first port, and the fourth port is connected to the third port.

In Figure 5C:, the manual piston is in the operational position, and the vacuumoperated piston is in the rest position. The third port is then connected to both the first and second ports, and the air vent is connected to the fourth port.

When used in the automatic milking system, the pneumatic piston 54 which operrates the vacuum-operated piston of the control valve 10 is connected to the vacuum line 57 from the initiator cap via the initiator valve S. The vacuum wash line 55 is connected to the third port and the vacuum line 5 & to the recording jar 4 is connected to the first port. The line 59 to the pneumatic cylinder of the valve stop assembly 9 is connected to the fourth port and the line to the wash jetters 6 is connected to the second port.

Figures 5A, B and C accordingly show the three possible arrangements of the control valve 10 which are used in the milking cycle. Figure SA shows the valve in the normal milking position. Vacuum 72 from the vacuum wash-line passes through the valve and into the jar. Atmospheric air passes from the air vent 67 through the valve and into the valve stop assembly 9 so as to maintain the outlet valve at the bottom of the recording jar in the open position.

When milk flow from the cow has stopped, the control valve 10 is in the milk release (transfer) position shown in Figure SB. Atmospheric air 73 from the air vent then passes through the valve and into the recording jar 4, permitting milk to be released from the recording jar. At the same time, vacuum 74 passes from the vacuum wash line through the valve and to the valve stop assembly 9. This allows the valve in the outlet of the recording jar to close when the milk level has fallen to a sufficiently low level.

Figure SC shows the control valve 10 in the wash position. For washing, the manual plunger 69 is pushed in sò as to place the first piston in the operational position. Wash fluid 75 then passes from the vacuum wash line through the valve and into both the line to the recording jar and the line to the wash jetters. At the same time, atmospheric air passes from the vent and into the line to the valve stop assembly, so that the valve in the outlet of the recording jar is maintained in the open position.

Reference is now made to Figure 6 which shows the initiator valve 5. This valve has a connection 81 to the initiator cap and another connection 82 to the pneumatic cylinder 54 of the control valve 10. The initiator valve is manually adjusted between an open position A and a closed position B. When the initiator valve is closed, air passes from a vent 83 in the valve into the line to the pneumatic cylinder of the control valve 10. The connection in the initiator valve to the initiator cap is simul tanedusly closed. When the initiator valve is open, the connection to the initiator cap communicates with the connection to the pneumatic cylinder of the control valve 10.

The air vent is closed. The initiator valve is operated by a hand wheel 74 on the valve spindle. This spindle is also connected to the operating lever 45 on the initiator 2.

Accordingly, when the initiator valve is turned to the closed position, the initiator lever is turned to the manual (left-hand) position, thereby manually raising the float 40. When the initiator valve is turned to the open position, the initiator lever is also turned to the automatic/off (right-hand position.

The valve arrangement in the outlet of the recording jar 4 is shown in Figure 3. The valve comprises a floating ball 85 restricted within a cage 86. When the milk level in the jar is sufficiently low, the ball rests on a valve seating 87 and the valve is then said to be closed. The valve can be maintained in the open position by the valve stop assembly 9. A rod 88 is actuated by a pneumatic cylinder which is supplied with air or vacuum from the control valve 10.

When air is present in the cylinder, the rod is in the raised position and prevents the ball from reaching the valve seating. The valve is thereby kept in the open position.

When vacuum is present in the pneumatic cylinder, the rod is lowered and the ball valve can close when the milk level is sufficiently low. A small vent (not shown) is present in the milk outlet below the valve seating to assist in final draining of the milk from the recording jar without significant loss of vacuum.

The milk line 56 from the outlet of the recording jar includes a non-return valve 7 which is shown in Figure 7. The valve com prises a ball 89 which is constrained against the outlet side of a valve seat by a spring 90 fixed to a pin 91 in the milk line. Milk flow presses the ball away from the valve seat and allows the milk to pass. When there is no milk flow, the valve is maintained in the closed position by the spring and prevents vacuum passing into the system from other parts of the milking installation.

The butterfly valve shown in Figures 8A and B is also in the milk line 56 from the outlet of the recording jar 4. The butterfly valve can be manually varied between a closed position B and an open position A.

When the butterfly valve is closed, milk is retained in the recording jar and its volume can be measured, the milk subsequently being released by opening the butterfly valve.

The butterfly valve can also be closed to retain milk which may subsequently have to be discarded instead of being passed to the dairy.

The operating cycle of the automatic milking system is shown in Figures 4A, B, C and D which correspond to Figure 3. The start of milking is shown in Figure 4A.

The line V represents vacuum and the line A represents air. The initiator valve 5 is closed and the floating in the initiator is manually raised so that the float valve is open. The line to the pneumatic piston of the control valve 10 is vented at the initiator valve 5 and the vacuum-operated piston is accordingly in the rest position. The manual ally operated piston in the control valve 10 is maintained in the rest position (with the plunger kept out) except for washing.

Vacuum from the vacuum-wash line 55 accordingly passes through the control valve 10 and into the recording jar 4. Vacuum also passes from the recording jar into the initiator body through the open float valve, and into the teat cup cluster. The diaphragm in the initiator is lowered so that the diagraphm valve is closed. Air is accordingly vented from the diaphragm cap into the ram.

The ram piston is therefore lowered, so that the teat cup cluster is also lowered and can be put on the cow with vacuum supplied. In the meanwhile, air is vented at the control valve 10 into the pneumatic cylinder of the valve stop assembly 9, so that the valve in the outlet of the recording jar is maintained in the open position. The non-return valve 7 is closed and the butterfly valve 8 is open.

Once milk has begun to flow from the cow, the arrangement is as shown in Figure 4B. The line V represents vacuum, the line A represents air. and the line M represents milk. The initiator valve 5 is manually opened. Although the initiator lever is consequently turned to the automatic/off position, the float remains raised on the level of milk in the initiator 2. The float valve is therefore open. Milk therefore passes from the teat cup cluster 1, through the open float valve in the initiator 2 and through the milk tube 52 into the recording jar 4.

The milk is held in the recording jar by the non-return valve 7 being closed, or may be retained in the jar after milk flow has ceased by closing the butterfly valve 8. The diaphragm in the initiator remains in the lowered position, with the diaphragm valve closed. Air is vented from the initiator cap into both the ram and, via the open mitiator valve, to the pneumatic cylinder of the control valve 10. Vacuum therefore continues to be passed from the vacuum wash line 55, through the control valve 10 and into the recording jar 4, so as to maintain the flow of milk from the initiator 2. Air is also vented from the control valve 10 into the pneumatic cylinder of the valve stop assembly 9, so that the valve in the outlet of the recording jar is kept open.

Figure 4C shows the arrangement at the end of milk flow from the cow, e.g. when the milk flow falls below 0.25 litres per minute. At this predetermined rate of flow, the float valve in the initiator 2 closes. Air is vented from the teat cup cluster 1 so that the remaining milk is drained into the initiator body causes the diaphragm to rise, so that the diaphragm valve is opened. This allows vacuum to pass from the ACR vacuum line 51, through the initiator cap and into the vacuum line 53 to the ram.

The loss of vacuum to the teat cup cluster causes the cluster to fall off the cow and the simultaneous vacuum supply to the ram causes the teat cup cluster to be raised by means of the connecting cord to the piston in the ram. The ACR vacuum supply also passes through the open initiator valve 5 to the pneumatic cylinder of the control valve 10. This actuates the vacuum-operated second piston in the control valve. As a result, air is vented from the control valve 10 into the recording jar 4. This will allow the milk to be released from the recording jar by opening the non-return valve 7. Also, vacuum from the vacuum wash line 55 is passed through the control valve 10 and into the pneumatic cylinder of the valve stop assembly 9.The rod in the valve stop assembly is accordingly lowered, and the valve ball will close the valve in the outlet of the recording jar when the milk level in the jar has fallen to a sufficiently low level.

Naturally, if the butterfly valve 8 has been closed during milking, this valve can now be opened to release the milk from the recording jar.

It will be appreciated that the above described operations at the end of milk flow take place automatically. The operator only has to close the initiator valve 5 and place the teat cup cluster on the cow at the start of milking. Once milk flow has begun, the operator turns the initiator valve to the open position. He is then free until the next cow is reading for milking.

The arrangement during washing is shown in Figure 41). The line A represents air and the line W represents wash fluid. The initiator valve 5 is closed and the manual plunger 69 in the control valve 10 is pushed in.

Wash fluid is supplied to the vacuum-wash line 55. The wash jetters 6 are connected to the teat cup cluster 1. Wash fluid passes from the vacuum-wash line 55 to the control valve 10 and is there distributed both to the wash jetters 6 and directly through the line 58 to the top of the recording jar 4.

The wash fluid passes from the wash jetters in the teat cup cluster and into the initiator 2. The float valve is maintained in the open position since the initiator valve is closed.

Accordingly, the wash fluid passes from the initiator into the recording jar 4. The A.C.R.

vacuum line 51 is shut off from the vacuum supply and therefore the diaphragm valve is closed and the ram 3 is in the lowered position. Air is vented at the initiator valve 5 into the pneumatic cylinder of the control valve 10. Air is also vented at the control valve 10 into the pneumatic cylinder of the valve stop assembly 9. The valve in the outlet of the recording jar is therefore kept open. The wash fluid therefore flows out of the recording jar into the milk line 56. The non-return valve 7 and the butterfly valve 8 are kept open. The washing can be carried out either by a circulation wash or by ABW (acidified boiling water) cleaning.

WHAT WE, CLAIM IS: 1. An automatic milking system comprising a teat cup cluster, a milk receiving jar, a milk line from the teat cup cluster to the milk receiving jar, a milk outlet from the milk receiving jar, a vacuum line to the milk receiving jar, an initiator in the said milk line adapted to stop milk flow when it falls below a predetermined level, and a control valve in the said vacuum line which is actuatable by the initiator when milk stops and which is adapted to vent the vacuum line when actuated so that milk can be released from the milk receiving jar.

2. An automatic milking system according to claim 1, wherein the control valve is actuatable by vacuum via a second vacuum line between the initiator and the control valve.

3. An automatic milking system according to claim 2, wherein the initator is adapted to vent the second vacuum line during milking so that the control valve is not actuated and vacuum passes through the first vacuum line to the milk receiving jar, and wherein the initiator is adapted to allow vacuum to pass into the seeded vacuum line in response to stopped milk flow, thereby actuating the control valve and venting

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the teat cup cluster 1, through the open float valve in the initiator 2 and through the milk tube 52 into the recording jar 4. The milk is held in the recording jar by the non-return valve 7 being closed, or may be retained in the jar after milk flow has ceased by closing the butterfly valve 8. The diaphragm in the initiator remains in the lowered position, with the diaphragm valve closed. Air is vented from the initiator cap into both the ram and, via the open mitiator valve, to the pneumatic cylinder of the control valve 10. Vacuum therefore continues to be passed from the vacuum wash line 55, through the control valve 10 and into the recording jar 4, so as to maintain the flow of milk from the initiator 2. Air is also vented from the control valve 10 into the pneumatic cylinder of the valve stop assembly 9, so that the valve in the outlet of the recording jar is kept open. Figure 4C shows the arrangement at the end of milk flow from the cow, e.g. when the milk flow falls below 0.25 litres per minute. At this predetermined rate of flow, the float valve in the initiator 2 closes. Air is vented from the teat cup cluster 1 so that the remaining milk is drained into the initiator body causes the diaphragm to rise, so that the diaphragm valve is opened. This allows vacuum to pass from the ACR vacuum line 51, through the initiator cap and into the vacuum line 53 to the ram. The loss of vacuum to the teat cup cluster causes the cluster to fall off the cow and the simultaneous vacuum supply to the ram causes the teat cup cluster to be raised by means of the connecting cord to the piston in the ram. The ACR vacuum supply also passes through the open initiator valve 5 to the pneumatic cylinder of the control valve 10. This actuates the vacuum-operated second piston in the control valve. As a result, air is vented from the control valve 10 into the recording jar 4. This will allow the milk to be released from the recording jar by opening the non-return valve 7. Also, vacuum from the vacuum wash line 55 is passed through the control valve 10 and into the pneumatic cylinder of the valve stop assembly 9.The rod in the valve stop assembly is accordingly lowered, and the valve ball will close the valve in the outlet of the recording jar when the milk level in the jar has fallen to a sufficiently low level. Naturally, if the butterfly valve 8 has been closed during milking, this valve can now be opened to release the milk from the recording jar. It will be appreciated that the above described operations at the end of milk flow take place automatically. The operator only has to close the initiator valve 5 and place the teat cup cluster on the cow at the start of milking. Once milk flow has begun, the operator turns the initiator valve to the open position. He is then free until the next cow is reading for milking. The arrangement during washing is shown in Figure 41). The line A represents air and the line W represents wash fluid. The initiator valve 5 is closed and the manual plunger 69 in the control valve 10 is pushed in. Wash fluid is supplied to the vacuum-wash line 55. The wash jetters 6 are connected to the teat cup cluster 1. Wash fluid passes from the vacuum-wash line 55 to the control valve 10 and is there distributed both to the wash jetters 6 and directly through the line 58 to the top of the recording jar 4. The wash fluid passes from the wash jetters in the teat cup cluster and into the initiator 2. The float valve is maintained in the open position since the initiator valve is closed. Accordingly, the wash fluid passes from the initiator into the recording jar 4. The A.C.R. vacuum line 51 is shut off from the vacuum supply and therefore the diaphragm valve is closed and the ram 3 is in the lowered position. Air is vented at the initiator valve 5 into the pneumatic cylinder of the control valve 10. Air is also vented at the control valve 10 into the pneumatic cylinder of the valve stop assembly 9. The valve in the outlet of the recording jar is therefore kept open. The wash fluid therefore flows out of the recording jar into the milk line 56. The non-return valve 7 and the butterfly valve 8 are kept open. The washing can be carried out either by a circulation wash or by ABW (acidified boiling water) cleaning. WHAT WE, CLAIM IS:

1. An automatic milking system comprising a teat cup cluster, a milk receiving jar, a milk line from the teat cup cluster to the milk receiving jar, a milk outlet from the milk receiving jar, a vacuum line to the milk receiving jar, an initiator in the said milk line adapted to stop milk flow when it falls below a predetermined level, and a control valve in the said vacuum line which is actuatable by the initiator when milk stops and which is adapted to vent the vacuum line when actuated so that milk can be released from the milk receiving jar.

the first vacuum line.

4. An automatic milking sysem according to claim 2 or 3 also comprising an initiator valve in the second vacuum line from the initiator to the control valve, wherein the initiator valve in the closed position vents the second vacuum line to the control valve to commence milking.

5. An automatic milking system as claimed in any one of Claims 1 to 4, wherein the control valve comprises first and second internal chambers, a first piston slidable in the first chamber and a second piston slidable in the second chamber, a plurality of inletloutlet ports communicating with the first or second chamber, and at least one communicating line between the first and second chamber, whereby different combinations of ports can communicate with each other according to the position of each piston in its respective chamber.

6. An automatic milking system according to claim 1, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.