Milking machines: design, types and operating principle

A milking machine is a special installation for facilitating and speeding up the milking process, which is needed on every farm where cattle are kept.

Such units allow not only to effectively milk several cows at once, but also protect their mammary glands from damage and infection. What models of the device exist and what is the principle of their operation, we will find out further.

A bit of history

Early attempts at milking cows involved using a variety of methods. Around 380 B.C., the Egyptians attached a straw of wheat to the teat of a cow, in addition to traditional hand milking. The first milking machine was used in 1851, although the attempt was not entirely successful.

To encourage further inventions, the Royal Agricultural Society of England offered a reward for the invention of a safe milking machine.

At the end of the 19th century, a machine with a vacuum pump powered by a steam engine was developed in Scotland. This unit, along with the introduction of the double milking cup, led to automated milking of animals. Since the beginning of the 20th century, the principle of machine milking has taken root in the dairy industry.

The device structure

The classic milking machine has a simple structure, which includes the following parts:

• the frame is on wheels, which makes the device mobile (there are large units without wheels, but they are rare);
• a pump from which vacuum hoses for supplying milk and air run (the pressure in them can be measured using a vacuum gauge);
• a pulsator or manifold where the vacuum line ends (in some models the pulsator is absent, and its role is performed by a piston pump and valves that open and close in the direction of the piston movement);
• 4 milking cups (according to the number of teats on a cow), the outer wall of which is metal (made of food grade steel or aluminum), and the inner wall is covered with rubber cuffs, one of which is connected to the sub-teat (inner) chamber for sucking out milk, and the other to the chamber between the walls to create a vacuum pulsation;
• receiver for stabilizing the vacuum in the line (not present in all models);
• milk and vacuum tubes coming out of the glasses and entering the manifold, on which there is a valve for supplying vacuum to the glasses;
• milk main line, coming from the collector and leading to the common tank;
• a can with a capacity of 20 liters, which can be made of stainless steel, aluminum or plastic.

An aluminum tank is light and soft, so it can be damaged if accidentally knocked over, but a steel bucket is very heavy and inconvenient to use. Therefore, the best option is a plastic can with a transparent lid, so that it is easier to control the milk level in it.

Principle of operation

The milking machine operates on the basis of a vacuum pump. A cup is attached to each teat of the cow.

When the device is connected to an electric current, milk is sucked out and flows through glasses via hoses into a container for collecting it – a bucket or can.

The technology of milk extraction is as follows:

1. A vacuum is created in the sub-teat chamber, which is always at low pressure.
2. The pulsator, mounted on the lid of the can, throws vacuum pulses into the cups. The presence of the pulsator allows you to control the vacuum supply, making milking more comfortable for the cow.
3. Under the pressure of the vacuum pulsation, the nipple is compressed in the inter-wall chamber.
4. When low pressure is created in these two chambers, milk flows first into the collector and then into the storage tank.
5. The pressure in the inter-wall chamber rises to atmospheric pressure, at the same time the rubber tube contracts and squeezes the nipple, and the milk stops flowing.

A similar operating principle is typical for two-stroke milking machines, which perform two main functions: they squeeze the teat and pump out milk.

There are also three-stroke machines, the difference of which is that they suck milk from each nipple in turn, squeezing them in order.

Between the suction cycles, short breaks are observed to restore the blood supply to the mammary glands, thanks to which the cow gets used to the device more quickly.

In a three-stroke engine there are 50 pulsations per minute, and in a two-stroke engine there are 90.

The operating principle of two- and three-stroke devices is shown in the diagram:

Types

Milking machines may differ both in technical characteristics and in the way they operate. Let’s take a closer look at the popular criteria for their classification.

By type of engine and pump

The cow milking machine can be equipped with the following engine:

Buttery

Its advantage is its quiet operation, which significantly increases the cow’s comfort level during milking.

The disadvantages of an oil engine include:

• sensitivity to low temperatures (possible starting problems);
• the need for constant maintenance (you will have to regularly top up the fluid and monitor the oil level to avoid leaks).

In winter, the oil may freeze, making it difficult to start the machine.

Dry action

More unpretentious engines, but they have a significant drawback – they make a lot of noise when working. To cope with it, you will have to install mufflers.

Dry running engines are also sensitive to air humidity, which causes them to quickly overheat.

When operating and storing dry-type devices, do not allow any liquid to enter the structure.

The pump in the milking machine also comes in three types:

• Membrane. The cheapest option and is designed for minimal loads – milking up to 3 heads at a time. Suitable only for small farms.
• Piston. Compared to the membrane one, it is more productive, but during operation it makes a lot of noise and quickly overheats. Units with a piston pump have larger dimensions.
• Rotary. A reliable dry or oil type pump that takes up little space and does not make any loud noises during operation.

By milking type

Depending on the method of milking and connecting the cups to the nipples, the device can be of two types:

• Simultaneous (normal)The cups are attached to 4 milkers, so the machine simultaneously sucks milk from all nipples.
• Pairwise (asynchronous). In such models, the cups are installed in pairs. Milking is carried out using 2 cups. They are put on the nipples in turns. This is the most gentle mode for the animal.

Machines with a paired milking method allow you to quickly accustom the cow to machine milking, and also completely eliminate problems with the udder.

By purpose of application

Machines for milking cows are conventionally divided into two more types:

• Household. They are chosen mainly for small households. Such devices have a simple design and are equipped with removable parts that can be replaced with new ones after wear.
• Industrial. Such units are produced for industry and are designed for milking a large number of cows. They are powerful and assume several automatic systems of operation, the choice of which is carried out depending on what cattle needs to be milked.

Browse popular models

Milking machines are presented on the market in a wide variety, but among them the following models are especially popular:

AID-1

The device is based on a two-stroke principle of operation and without a pulsator. It is convenient for small farms, since it can serve no more than 1 cows in 10 hour.

It has an oil pump that does not overheat and does not make much noise when operating. The pressure is 47 kPa, that is, close to the optimal 50 kPa.

AID DA-3M “Volga”

A three-stroke universal machine that has two-chamber milking cups made of stainless steel, and is also equipped with a pulsator, vacuum valve and main hose.

Doyushka 1P

Compact in size, automated and reliable. Suitable for small farms – can milk about 1 cows per hour. The farmer does not need to adjust the number of strokes. Pulsation depends on the operation of the piston pump, which creates 10-64 strokes per minute.

Maiga

A two-stroke and easy-to-maintain unit. A bucket with a handle is attached to the device, so it is very convenient to drain the milk. It is highly mobile.

My Milka

Dry rotary type units. Equipped with a powerful engine capable of 1450 revolutions. The kit includes 4 cups for paired milking. The models are designed to service 8 cows per hour.

Birch-1, Birch-2

Mobile dry type units. Can milk up to 30 cows in 24 minutes. Equipped with a powerful engine that makes loud noises. Power – 1500 rpm.

Compact (1 STD, 2 STD) from Milkline

Popular dry type machines from a leading European manufacturer. One mobile unit can process up to 1 cows in 14 hour. Milk is collected in a transparent bucket with a measuring ruler.

DeLaval

Dry-type electric motor units from a Swedish manufacturer. They do not make noise during operation. They are considered to be among the best, but have a high cost.

Burenka

The lightest unit in weight, which differs from other models by the separate location of the milking bucket. Farmers recommend choosing the Burenka Tandem equipment for simultaneous double milking.

The units are also produced in the following modifications: “Standard”, “Euro”, “Stainless Steel”, “Maxi”. They can service up to 1 heads per hour. Power – from 20 to 1500 revolutions.

Tips for choosing a device

When purchasing a milking machine, you should consider a number of recommendations:

• If there are a large number of cows, it is better to choose a three-stroke milking unit. If there are 2 cows on the farm, a two-stroke machine is enough.
• For milking cows on the grazing site, choose a more mobile and lighter unit. It is desirable that the bucket or can for collecting milk be installed directly on the unit, otherwise there will be difficulties with its movement.
• If the cows are kept in stalls, it is better to purchase a stationary device with which you can milk several animals at once.

When purchasing a device in a store, you need to check its operation, adjustments and the fastening of all parts.

How to milk a cow with a machine?

The technology of machine milking of a cow is simple, but requires adherence to the correct order of actions and a number of rules:

• Before milking, check the equipment for proper operation., in particular the operation of the pulsator, collector and vacuum unit.
• Examine the cow. If there is mastitis on the udder and teats, milk her by hand. Transfer the cow to machine milking only after complete recovery.
• An hour before milking, clean the stalls and wash the udder with warm water or a special solution. Do not use cold or hot liquid, as this will slow down milk flow. Behave calmly near the cow, without raising your voice.
• After treatment, wipe the nipples dry. using individual napkins and massage them with circular movements, lightly pushing up individual parts of the udder, repeating the actions of a calf when feeding.
• Milk a small amount of milk manually and check that there are no blood clots, lymph inclusions, etc. During this time, the animal’s milk-let-down reflex is activated.
• Open the machine’s vacuum valve first. and immediately after preparing the udder, put on the milking cups. To do this, take the collector from below with one hand and move it to the udder, and with the other hand, put the cups on the teats one by one, starting with the back ones.
• Only after milking has begun should you move on to the next cow. If milk flow slows down or stops, massage the cow’s udder until the process resumes. There is no need to remove the equipment.
• If the milking cups fall off, turn off the machine., rinse the cups with clean water, massage the udder and start milking again. The machine itself should be positioned closer to the cow’s front hooves to make it harder to tip over.
• After milking, remove the cups. To do this, take the manifold or milk tubes with one hand and squeeze them, and close the valve on the manifold or the clamp on the hose with the other. Then squeeze the rubber suction cup of the glass to release the air, and at the same time smoothly remove all the glasses. Connect the manifold to the vacuum and suck out the remaining milk in the glasses.
• Finally, wipe the nipples with a dry towel. and lubricate with Vaseline or an emulsion with an antiseptic effect.
• Clean the milking machine using a vacuum. First, run warm water (32-35°C) through it, and then a disinfectant. From time to time, it is advisable to disassemble the device into parts and wash off the resulting plaque. Store the machine in a specially designated place.

If there is milk left in the udder after milking with a machine, milk the cow manually to prevent her from developing mastitis.

The scheme of using the milking machine looks like this:

How to do it yourself at home?

If you have ready-made units and some materials at hand, you can assemble the unit yourself. We will consider the sequence of actions below.

Preparation of components

To assemble a milking machine, you need to prepare the following components:

• an electric motor to operate the pump;
• pump – oil, dry or vacuum;
• a belt that provides rotation from the pump to the engine;
• vacuum hoses for pumping out air;
• a vacuum cylinder that smooths out fluctuations caused by air pressure (in factory designs, this function is performed by a receiver);
• exhaust pipe for removing air outside;
• a dielectric insert that prevents the spread of voltage throughout the device;
• vacuum gauge (to control the pressure created, milking is carried out only when the indicator is at 50 kPa);
• glasses, collector and pulsator are the components of the hanging part of the device, which must be purchased in a specialized store;
• silicone milk hoses;
• container for collecting milk (can or bucket);
• vacuum regulator for pressure correction;
• Air valve for introducing air into the can.

Assembly

Assembly of the suspension unit is of great importance. It is carried out in the following order:

1. Connect the milk pipe ring to the lower end of the rubber intended for the nipples. The distance between them is at least 5 mm.
2. Insert the thin end of the milk tube into the rubber, pull it through it and place it in the milking cup.
3. Put the rubber head on top of the cup. It is imperative to monitor the evenness of the tension, because all this affects the speed of milking.
4. Place the vacuum hose on the side pipe located on the body.

After assembly, rinse the system, which will also allow you to check the tightness of the connections. To do this, pour hot water into a bucket, immerse the milking cups in it and plug the machine into the network. Rinse for 5 minutes. After this, the cups can be put on the teats and milk the cow for about 6 minutes.

Once a month, it is recommended to disassemble the device into parts so that each of them can be thoroughly washed in hot water.

Troubleshoot problems

After self-assembly of the milking machine, some malfunctions occur that require timely elimination:

• Insufficient vacuum pressure due to extraneous air suction. Most likely, the reason lies in the poor tightness of the suspension unit. This problem can also be encountered when the cups are not attached to the milkers correctly.
• Extraneous sounds are being madeIf the device makes extraneous sounds during operation, this indicates poor fastening of the connecting elements.
• The engine is slippingThe malfunction may be caused by a loose belt or oil getting on it.

Advantages and disadvantages