Milking Machine(redirected from milking machine vacuum pressure)
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an apparatus for milking cows mechanically.
The first attempts to mechanize milking were made at the beginning of the 19th century. In 1836 (Great Britain) milking tubes appeared (invented by Blarton); strippers appeared somewhat later, and in 1851, a milking machine that operated on the principle of suction was used for the first time. The modern milking machine is based on the creation of a vacuum under the teat. The milking machine consists of four teat cups, a collector, a pulsator, and a milk pail (sometimes a milk line) connected by rubber tubing. Some of the tubes transmit pneumatic pulses to the teat cups; through others, the milk is fed from the teat cups to the pail. In terms of design, milking machines are divided into those with single-chamber and those with double-chamber teat cups; in terms of the milking action, into two-stroke (found both abroad and in the USSR) and three-stroke (in the USSR).
The single-chamber teat cup, which is placed on the teat of the cow, is made from a hard material, such as metal or transparent plastic. The milking is carried out in two strokes: suction (a vacuum is formed below the teat and the milk flows out) and relaxation (air flows into the cup, the teat contracts, and the discharge of milk is interrupted). Two-chamber teat cups consist of an inner tube of rubber and an outer one of metal, between which there is an airtight pulsation chamber that connects to the pulsator through the collector; beneath the teat there is an inner suction chamber in a rubber tube. In two-stroke milking a constant vacuum is maintained in the inner chamber. When a vacuum is created in the pulsation chamber, the rubber tube will not squeeze the teat and the milk flows out; this is the suction stroke. When air is released into the pulsation chamber, the rubber is compressed, squeezing the tip of the teat, and the milk stops flowing; this is the compression stroke. The percentage ratio of the suction stroke to the compression stroke in time ranges from 50:50 to 85:15. In three-stroke milking the compression stroke is reduced to a minimum, and a third stroke, relaxation, is introduced. This makes it possible to milk the cows more completely and to minimize dangerous irritation of the udder. The optimal percentage ratio between the suction, compression, and relaxation strokes in time is 60:10:30.
The pulsator transforms a continuous vacuum into a variable one. The collector distributes the vacuum and collects the milk from all four teat cups; in three-stroke milking machines there is also a mechanism that creates a relaxation stroke. The vacuum necessary for milking is 25-65 cm mercury (optimally, 35-40). The number of pulsations is between 35 and 200 (most often 40-60) per minute.