The milking machine is a nearly automatic machine installation for milking cows. It is not a single unit, but rather an assembly of components designed to handle as many as 200 cows an hour. The system consists of the cluster (the assembly that is manually attached to the cow), a milk tube, a pulse tube and pulsator, a vacuum pump or blower, and perhaps a recorder jar or milk meter that measures yield. Together, the system allows milk to flow into a pipeline in preparation for shipping to a processing plant.
The cluster consists of teatcups, a shell and liner device that actually performs the milking action, and a claw or manifold that spaces the teatcups and connects them to the milk and pulse tubes. The milk tube carries the milk and air mixture away from the cow's udder to receiving tanks. The pulse tube, or airline, carries the varying air pressure from the pulsator device to the tanks, drawing the milk and fluids out of the cows as well.
In operation, milk is drawn from the cow's teats because a vacuum is created within the cup device, forcing the milk through the teat canal. The pulsator alternates the pressure, first creating a vacuum (milk phase), and then applying air, which causes the flexible liner in the cup to collapse and massage the teat (rest phase). The alternating process of milk-and-rest is continued in a rhythmic pattern for the cows' health and good milk productivity.
Early attempts at milking cows involved a variety of methods. Around 380 B.C. , Egyptians, along with traditional milking-by-hand, inserted wheat straws into cows' teats. Suction was first used as a basis for the mechanized harvesting of milk in 1851, although the attempts were not altogether successful, drawing too much blood and body fluid congestion within the teat. To encourage further innovations, the Royal Agricultural Society of England offered money for a safe, working milking machine. Around the 1890s Alexander Shiels of Glasgow, Scotland, developed a pulsator that alternated suction levels to successfully massage the blood and fluids out of the teat for proper blood circulation. That device, along with the development of a double-chambered teatcup in 1892, led to milking machines replacing hand milking. After the 1920s machine milking became firmly established in the dairy industry. Today, the majority of all milking is processed by machine.
The milking machine components are created and assembled in several major manufacturing plants throughout the world using traditional processes and procedures. Stainless steel and plastic are used for containers and liners and cast iron and steel for vacuum pumps, controls, and metering devices.
Workers at assembly will also make initial line connections from valves to pumps to meters, checking for tolerances and poor fits. Vacuum pumps or blowers, the heart of the milking system, are tested so that both milk and accompanying air can be efficiently removed. The pumps will be tested under simulated loads.
Vacuum controllers, which admit the necessary air to maintain the proper vacuum level, are selected. The air lines and milk lines are selected to size and connection hardware grouped. Controls, also purchased, are prepared for installation.
Milking machine manufacturers are subject to a variety of standards, some self-imposed. In addition to inspections throughout the manufacturing process, all installations are set up by trained dealers and electrical contractors. Equipment designers follow Association of Agricultural Engineer standards and sanitary guidelines established by a dairy industry council.
Advances in technology have introduced several new innovations to milking machines. Automatic detacher units that connect loosely to the milking claw allow cows to move and shift freely during milking. Based on the rate of milk flow, the detacher can also detect the end of milking, shutting the vacuum and actually removing the claw from the cow.
Automatic backflushing units are also gaining popularity. These units and systems send chemical and rinse solutions through pipelines and clusters to reduce the risk of infection and mastitis (udder inflammation).
The use of automatic identification systems, such as electronic transponder cow neck-tags, have enabled dairy farmers to keep track of milk production by individual cows.
Robotics are at the forefront of milking technology, especially in Europe. Automatic attachment devices have been created but not quite perfected. This new innovation will require little manual labor, and the machines will oversee much of the milking process from the time a cow enters a milking center until it leaves to graze.
Machine Milking and Lactation. Insight Books, 1991.
Maximizing the Milk Harvest. Milking Machine Manufacturers Council, 1993.
Blankesteijn, Herbert and Daniel Clery. "Milking Automation for All It's Worth." New Scientist, February 1, 1992, p. 27.
Spahr, Sid. "Coming: New Dairy Ideas from Europe and Israel." Successful Farming, October 1987.
Wittenberg, Gunter. "A Robot to Milk Cows." The Industrial Robot, 1993, pp. 22-25.
— Peter Toeg