Known Problems with Conventional Milking Systems

Milking systems have evolved over the years with the introduction of new technology and automation. This has provided the dairy farmer with improvements in productivity by reducing the labor involved in the milking process. Unfortunately there are some basic functional problems with the milking equipment that causes poor milking performance and reduced milk quality.

Evidence of this exists in U.S. patent documents that provide the details of why conventional milking systems in use today do not work well. These documents explain why cows do not milk out well, why their teats are irritated and what causes liner crawl and incomplete milk out.

See videos at to understand why CoPulsation is the only humane way to milk an animal with a machine.

Patent Documents

There have been many attempts in the past 30 years to improve the performance of conventional milking systems. The known performance problems include liner crawl, teat damage, teat irritation/pain and incomplete milk outs to name a few. These attempts have produced numerous inventions by the major milking equipment manufacturers. Although these products are not being marketed, the U.S. patents issued for them document how the conventional milking systems cause the many performance problems that frustrate dairy farmers and can cause mastitis.

The following is a sample of some of the text from issued U.S. patents.

Alfa-Laval Agriculture International

United States Patent: 5,090,359
Issued February 25, 1992

However, these known apparatuses do not solve the problem of preventing crawling of the teat cups on the teats during the third milking when the milk flow ceases.

However, when the milk flow diminishes during the third milking phase the teat becomes slacker and slacker and its frictional engagement with the liner weaker and weaker, whereby the teat tends to be sucked deeper into the teat cup. Thus, each teat cup crawls on the teat towards the udder and thereby causes throttling of the milk conducting interior of the teat close to the udder, so that milking becomes more difficult and finally the milk flow completely ceases in spite of the fact that some milk still remains in the udder.

DEC International, Inc. (Bou-Matic)

United States Patent 5,218,924
Issued June 15, 1993

Various attempts have been made to ameliorate the undesirable effects of vacuum on the teat by carefully shaping the teat cup and liner to support the teat as well as possible, and by periodically relieving the vacuum to the teat.

Alfa Laval Agri

United States Patent 5,769,024
Issued June 23, 1998

a conventional milking machine exposes the cow's teat tips to a relatively strong milking vacuum, usually about 40-50 kPa. (40-50 kPa is 11.8 to 14.8 in Hg) However, this strong milking vacuum gives rise to the problem that the teats are treated ungentle initially during the milking, when the milk flow is small or non-existing, which may result in discomfort and even pains to the cow. This may lead to that the hormone adrenaline is secreted and makes continued milk extraction difficult.

Alfa Laval Agri

United States Patent 5,697,323
Issued December 16, 1997

In milking machines currently marketed by Alfa Laval, the pulsation chamber of each teat cup is exposed to a pulsating vacuum having a rate of typically 60 cycles/minute and varying between atmospheric pressure and a peak vacuum level of about 42-46 kPa and 48-50 kPa for low level milking system and high level milking system, respectively, while the interior of the liner under the teat is exposed to a milking vacuum of about the same level as the peak vacuum level.

The relatively strong milking vacuum is needed primarily for ensuring a safe attachment of the teat cups to the teats and, secondary, for achieving a rapid milking and a high milk yield. However, a disadvantage of such a strong milking vacuum is that it might treat the teats roughly, especially at the beginning and at the end of the milking interval when there is no or insignificant milk flow through one or more teats. Attempts have been made to eliminate this disadvantage by milking according to different modes of operation during the milking interval, in order to provide for a gentle milking also at the beginning and at the end of the milking interval

DEC International, Inc. (Bou-Matic)

United States Patent 6,039,001
Issued March 21, 2000

The present inventor's conclusion from the various pieces of research is that a mean mouthpiece chamber vacuum greater than 20 kPa (20kPa is 5.9 in Hg) seems to be less comfortable to cows, results in more teat congestion and oedema, and has been linked to a higher rate of new mastitis infections.

Babson Bros. Co. (Surge)

United States Patent: 4,572,104
Issued February 25, 1986

Systems have been provided in which the ratio of milk period to rest period can be adjusted. Such a system is shown, for example, in U.S. Pat. No. 3,317,685. However, while these systems have allowed for the ratio of milk period to rest period to be increased from 50:50 to increase the amount per cycle of (and thus the rate of) milking, they are constrained by the risk of hurting the cow by not providing sufficient periods of rest.

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Known Milking System Design Flaws

Conventional milking system suffer from numerous design flaws. Several of the basic problems are detailed below.


Conventional pulsators fail to move the air in and out of the shell fast enough. This results in the pinching of the liner on the teat end. You can actually feel this by inserting your finger into the liner with the milking machine operating. You will note the pinching and constant sucking of the vacuum that will cause your finger to hurt and turn red. Different liner shapes have been developed by other companies in an attempt to distribute the pinching action.

Another result of poor liner action caused by a conventional pulsator is liner crawl. The constant sucking on the teat during the “rest” phase causes the liner to crawl up the teat to the udder and choke the flow of milk. The conventional pulsator is also incapable of supplying vacuum fast enough to the shell resulting in difficulty opening the liner. This causes the need for a stiffer liner so that the stiffness of the liner helps open the liner into the milk phase. This stiffness counter-acts the forces to close the liner for a proper rest phase.

These performance short-comings are admitted to in many issued U.S. patent documents issued to the companies that make the conventional pulsation in use on your farm. Some examples of these are shown above under the Patent Documents section of this page.

Splitter tees:

Some splitter tees are designed to provide a side-to-side action for the pulsation as opposed to front-to-back. The following diagrams illustrates the difference.

Side-by-side tee (A) Side-by-side tee (B) Front to back tee

The side-to-side style has a design defect relative to air flow. When the pulsator transitions between the milk and rest phases it moves air or vacuum in or out of the shell. The side-by-side (A) style of splitter tee allows the first shell (1) to get the air or vacuum first. The second shell (2) gets the air or vacuum at a slower rate due to the pressure drop caused by filling the first shell first. Side-by-side (B) has the same problem as (A) except the first shell (1) gets the air or vacuum at a slower rate causing poor liner action. The front-to-back style of splitter tees allows both shells to be filled at the same equal rate because both see the same pressure.

The problem that the side-by-side causes is poor liner action for the second shell. This results in poor milking performance for the quarter that is being milked by that shell. The end result for the cow will be greater incidents of mastitis in that quarter and ultimately reduced production for that quarter. This style of splitter tee should not be used.

Hose length, bends

Maximum hose length between pulsators and claws is critical. Parlors must be designed to maintain pulsation hose lengths less than 8.5 feet. Some parlor designs can results in long hoses with several bends. One potential example is a basement or subway style parlors which have become more popular in recent years as dairy farmers attempt to get the pulsators and milk meters in a clean and dry environment. The basement parlor has a basement underneath the floor of the parlor facility where the pulsators, milk meters, pulsator vacuum supply lines and milk lines are located. The potential design flaw associated with this facility is the necessity for long hoses and multiple bends in the hoses. Excess hose length greater than 8.5 feet and multiple bends result in pressure drops that effect both liner action and vacuum supply to the claw. A facility that does not result in hose lengths less than 8.5 feet for pulsator connections need to be discussed prior to purchase and installation. All facilities can be upgraded to provide the desired design requirements.

90 degree elbows

The use of any elbow in an air or liquid flow system represents a restriction. A 90 degree elbow is the worst and a 45 degree is preferred if an elbow is required. Many facilities have located the vacuum pumps a sizable distance from the milk lines and receiver jars. This often requires the use of multiple elbows in addition to the lengths of straights pipe sections. This all results in losses in air flow capacity.

This principle has been long recognized by other industries. A good example is a standard clothing dryer. A review of the installation manual for any clothing dryer will provide a table defining the maximum allowed number of bends in the vent pipe and maximum length of vent pipe. Unfortunately many portions of milking facilities (vacuum pipes, pulsator hoses, milk hoses, etc) fail to account for length and bends.


There are other design flaws commonly found in dairy facilities. Those discussed above and others are easily found in even the newest of facilities. These flaws will rob the dairy farmer of production and milk quality. There are other flaws in addition to these. A knowledgeable and qualified individual should be capable of evaluating your facility and identifying them and explaining how they impact the milking performance of your herd.

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Conventional Milking Systems Known Problems

LR Gehm markets several products to dairy farmers: