Maintenance of the milking machine

Milking machine - static testing

Regular check ups of the basic functioning of the milking machine  should be done regularly. It is recommended that qualified technicians perform a full evaluation of the system every six months using precision instruments.

There are two types of testing:


These tests are performed when cows are not being milked. Confirmation of the following points is included.

Characteristics of the equipment, nominal vacuum, and vacuum pump flow

  • Verification of the milking equipment features: includes length and diameter of the milk and air transport pipes, height and slope of the milk transfer line, etc.
  • Verification of the nominal vacuum level: should be performed with the entire system operating and at various points (receiver vessel, regulator, etc.). A precision vacuum gauge with a graduated scale in cmHg and kPa, or a digital gauge should be used. The vacuum measurement should be compared to the one indicated by the operating vacuum gauge.
  • Verification of the vacuum pump flow: Use an airflow meter at a pressure difference of 50 kPa. Compare with the flow indicated on the vacuum pump's plate. There are formulas established for calculating pump flows.

Consumption of the pipes, pulsators, and milking points

  • Consumption of the pipes: the air flow meter is used along with a precision or digital vacuum gauge. The air pipe should be isolated from the milk using a valve near the sanitary trap. Disconnect all of the points, close the taps, remove the regulator and then take the measurement. To check the consumption of the milk transport pipe the valve must be opened again. In both cases the air flow meter is installed in a testing T in the air transport pipe or in the receiver vessel.
  • Consumption of the pulsators: this process is similar to the measurement for the transport lines, but with the pulsators connected.
  • Consumption of the milking points: the measurement has to be performed as in the previous process, but with the milking points connected.

Manual and effective reserve

  • Manual reserve: this is checked using the air flow meter and without the regulator, with all of the equipment operating, and at 2 kPa below the nominal vacuum level for milking.
  • Effective reserve: the measurement takes place as in the previous case, but with the regulator installed. Calculation of the effective reserve is predetermined for each system by the different country standards, based on the number of points and the type of milking. The difference between the manual reserve and the effective reserve will indicate leaks in the regulator. Dividing the effective reserve by the manual one will produce the efficacy of the regulation. It is common for the regulators to get dirty or blocked, allowing less air to enter the system. It is adviced to chech and/or clean them once weekly.

Condition of the pulsators

Measurement is performed using a Pulsotester device, which is coupled between the short pulsation tubes and the chamber.

The Pulsotester records the following parameters:

  • Pulsation frequency: should be 60 pulses/minute and should not vary by more than 3 cycles from the values indicated by the installer.
  • Imbalance (difference in the number of pulses between pairs of quarters): never more than 3% of the pulsation cycle.
  • Pulsation ratio: should never vary by more than 5% from the values indicated by the installer. Some manufacturers incorporate different pulse ratios in the front and rear quarters.
  • Duration of the phases: the duration of the suction phase or phase B should be above 30% of the total pulsation cycle, and the massage phase or phase D should never have a duration of less than 15% or 150 ms.

Requirements and basic characteristics of teat liner rings

The teat liner rings should form an airtight seal at both ends of the pulsation chamber. The liner's mouth and barrel must fit perfectly onto the teat in order to prevent slipping or falling off. The milking should take place as quickly and cleanly as possible (to minimise congestion and injury to the teat) and the alignment must be correct. The pressure difference reached by the liner walls when closing or touch point pressure difference (TPPD) can be used to help select teat liners with high or low vacuum. A high TPPD indicates that a higher vacuum can be used. A device known as a Coofret Optiflo can be used to take this measurement. Verifiy with your finger whether there are cracks inside the liner. When this procedure results in a black finger, it also indicates that the liners are being worn by the use of detergents.

This test is performed during milking and is influenced by the production levels of the cows that the machine is milking. The following items have to be verified, among other:

  • Working vacuum level: this is measured in the short milk tube of the rear cup or in the claw. It should be performed during the maximum flow period and in the claw farthest from the pump. The values range from 32-42 kPa, with a vacuum of 40 kPa being ideal.
  • Vacuum fluctuations in the collector: there should be an average of less than 10 kPa for high lines and less than 7 kPa for low lines. Both measurements are taken during the period of maximum milk flow.
  • Operation of the pulsators: frequency, balance, pulsation ratio, etc.
  • General vacuum fluctuations: with application and removal of the milking points.
  • Teat liner collapse force: this depends on the type of liner; in other words, whether they are made of rubber or silicone and whether they have been recently installed or have been used for several milkings. With rubber liners the collapse force is between 10-15 kPa, while in the case of silicon this value tends to be around 21 kPa or higher. These values show that there are liners that can use lower or higher vacuums. There may be differences in critical pressure values.
Previous Article Next Article