Maintenance of Milking
and Milk Handling Equipment
Table of Contents
- Milk Cooler
- Refrigeration Unit
- Vacuum Pump
- Vacuum Control Valves or Regulators
- Vacuum Pipeline
- Vacuum Reserve Tank
- Milk Claw
- Milk Pipeline
- Milk Receiver Jar
- Milk Pump
- Testing Equipment
Following a program of preventive maintenance can bring great benefits
to the dairyman by eliminating unnecessary service calls and down
time, and by minimizing the chance of a major breakdown or permanent
damage to a vital piece of equipment. The operator should know not
only how his milking system works, but also what regular inspection
and servicing it needs to keep it performing at near new efficiency.
A checklist and maintenance suggestions are given below to help
the dairyman to keep his milking system in top working condition.
- Check the agitator motor for grease leaks or noisy operation,
also worn shaft shields and bearings.
Check the timer to be sure that it will start the agitator motor
and advance to the "off' position.
- Replace leaking agitator motor seals. Tighten bolts holding
motor mounting brackets. Replace worn shaft shields and bearings.
Check the thermometer for accuracy - should read 0° C (32°
F) when submerged in ice water. Be sure it is not sticking.
- Replace timer if not functioning properly
Check milk tank outlet valve for 4. leaks. Plug type valve will
have to be refinished.
- Replace thermometer if faulty.
Check the running time of the cooler. It should cool to 10°
C (50° F) within one hour of first milking and cool to 4°
C (40° F) and hold that temperature after the second hour.
The blend temperature of the second, third and fourth milking
should remain under 10°C (50° F).
- Replace valve "O" ring, if leaking.
Check for foam, churned milk, and frozen milk on the milk surface.
- If running time is too long check and clean condenser coil.
- The presence of foam indicates air indicates air leaks
in the milking system or excessive agitation of the milk;
- churned milk (clumps of fat floating on the surface) usually
is caused by excessive agitation and slow cooling of the milk.
Check refrigerant; and
- frozen milk on the surface or as layers of ice on the bottom
of the tank. The freezing of milk can be avoided by turning
on the refrigeration when the milk level reaches the level
of the agitator blades and setting the tank thermostat so
that the milk is cooled to 4° C (38 to 40° F).
- Check condenser coil for dirt or dust - air must flow freely
through the coil and exit into the atmosphere.
Check refrigeration unit and tubing for signs of leaks (grease
- If condensor coil is dirty turn disconnect switch to "off"
position, brush wash with milk detergent solution, rinse with
tap water from the fan side out and allow to drain for three
hours before restarting.
Check refrigerant sight glass after unit has been operating
15 minutes refrigerant should be clear without any indication
- Call to the attention of refrigeration service man, any air
or refrigeration leaks.
Check condensor fan motor(s).
- If refrigerant is foaming, have refrigerant added by serviceman.
- Call to the attention of refrigeration service man any malfunction
of the condensor fan motor.
- Check oil level weekly.
Check type and tension of belts. Spin pump by hand to see if
vanes fall freely, or to detect unusual drag loose pulleys or
rough bearings. Check that pulleys are in line.
- Fill with correct type of oil recommended by manufacturer.
Some oils contain additives which form a sludge when mixed with
water and detergent. Do not overfill - excess oil will blow
Check cleanliness of vacuum pump.
- With v-belts care must be taken that the belt section used
matches the the correct section pulley, for example, B section
belting should not be use on A section pulleys. Tighten drive
belts so there is a slight sag on the slack side while running.
Repair or replace worn vanes, bearings and drive belts.
Check exhaust pipes.
- Once every six months, or when the pump becomes fouled by
milk, it should be cleaned using diesel fuel or a 4:1 kerosene-oil
mixture. Approximately two pints of mixture are fed into the
suction port while the pump is running. If extensive cleaning
is required, the pump can be filled with this mixture and allowed
to soak. After the pump is cleaned half a pint of oil should
be added through the suction port to ensure thorough lubrication.
Check capacity of pump with a flow meter.
- The exhaust pipe must never be smaller than the outlet from
the pump, otherwise pressure will seriously limit the performance
of the pump. Elbow bends should not be used as they are too
restrictive. Bends with large radii are better. A non-return
valve should prevent reverse rotation when pump is switched
- Every six months have vacuum pump capacity checked by service
man to help detect wear, leaks or stoppage in the system.
Vacuum Control Valves or Regulators
- Check the location of regulator.
Check the capacity of the regulator.
- In bucket systems the regulator should be placed in a clean
spot on the vacuum line between the reserve tanks and the first
stall cock. In milk pipeline systems the regulator should be
- between the vacuum reserve tank and the sanitary-trap
near the milk receiver, or
- on the vacuum reserve tank.
Check valve, screen and filters.
- The regulator must be capable of admitting air at least equal
to the capacity of the vacuum pump. All milking systems should
be equipped with a vacuum relief valve set 2 or 3 inches higher
than normal line vacuum, for safety in event of regulator failure.
- Regulator valves, valve seats, screens and filters should
be dismantled and thoroughly cleaned at least twice a year
unless regulators are unavoidable in a dusty location then
they should be cleaned more often. Do not oil valves or moving
parts since this will only collect dust and dirt and make
the valve stick.
- Check the pulsation ratio. The pulsation ratio refers to the
length of time the inflaction or liner is in the "milking"
phase compared to the "rest" phase. This can only be
checked by special test instruments.
Check pulsation rate. The pulsation rate refers to the number
of cycles ("milking" phase + "rest" phase
= 1 cycle) the pulsator makes in one minute. You can check this
with a watch by inserting your thumb inside an inflation when
system is operating and counting the number of squeezes per minute.
- Example pulsation ratios are 50:50 and 60:40. Know what is
recommended for your equipment and report any malfunctions to
the service man.
Check cleanliness of pulsators. Check pulsator filters and diaphragms.
- The recommended rate is in the range of 50 to 60 pulsations
per minute. This depends on such things as pulsation ratio,
vacuum level and type of inflation. Know and follow manufacturer's
recommendations to keep these factors in balance. Do
not experiment on your own.
Check voltage, look for loose connections and electric shorts
on electric pulsators.
- Older type pulsators need frequent cleaning of air inlets
and occasional replacement of valve rubber seals. Some can be
wahed out regularly, but check manufacturer's recommendations
before bringing in contact with water.
- Report problems to a service man.
- Check stall cocks for leaks.
Check drain cocks for leaks.
Check line for buildup of residue.
- Tighten or replace faulty stall cocks.
Check gasket on sanitary traps for leaks.
- Flush vacuum pipeline with hot water and a non-foaming detergent.
Vacuum Reserve Tank
- Check capacity of tank.
Check inside tank for rust.
- Tanks should at least have 5 gallon capacity for each milker
Check cleanliness and self-drain.
- Replace tank if necessary.
- Check short air tubes on milker units.
Check inflation or liners.
- Never milk with holes in pulsator air tubes.
Check storage of rubberware.
- Discard any inflation of liner with holes or cracks. Discard
any liner than has passed the number of cow milkings recommended
by the manufacturer: for example 1000 cow milkings.
- It is recommended that two sets of liners be kept on hand.
One set stored in a lye solution and used on alternate weeks.
- Check air admission hole ("air vent").
Check valve, float, claw gaskets and air manifold.
- Clean air vents thoroughly. Slow milking and/or flooding of
claw could be caused by blocked air vents. Do not increase vent
Check for vacuum stability during milking with all units in
- Clean and replace any defective claw parts.
- This test will determine if a constant, steady vacuum exists
at the teat cup at all times during milking.
- Check for proper slope.
Check milk inlets for location and leaks.
- Maintain slope of 40 mm per 3 m (1 1/2 in. per 10 ft) downward,
towards the milk receiver jar from the high point in the line.
Check for leaky couplings.
- Maintain inlets in the top third of the pipeline to prevent
vacuum fluctuations. Make sure valves close properly to prevent
- To prevent vacuum losses tighten couplings; clean and/or
Milk Receiver Jar
- Check gaskets, fittings and non-return valve for leaks.
Check electrical probes for corrosion and wear.
- Clean and/or replace gaskets. Tighten couplings.
- Report "unexplained" buildups to service man.
- Check bushings, seals and diaphragms.
- To assure proper performance and sanitation make necessary
adjustments or replacements.
Dairy farmers may do much to maintain the performance of their
milking and milk handling equipment but to locate many faults, regular
checks by a person skilled in the use of the necessary scientific
testing equipment are necessary.
Milking machine efficiency often deteriorates gradually, unnoticed
by the farmer. It is for this reason that it is advisable to have
the system tested at least twice a year. These tests are designed
to locate faults in the operation of the vacuum pump, vacuum regulator,
vacuum gauge, pulsators and inflations. The air reserve is measured
and if inadequate the reason for the low reserve is determined.
In many cases, small repairs or adjustments to the equipment on
the spot will restore its efficiency.
For more information:
Toll Free: 1-877-424-1300