Meat + Poultry - May 2005 - 73

Dr. Temple Grandin's From the Corral

Stunning details can make a difference
Equipment can't be expected to
work well, to maintenance issues
are ignored. In many plants, I have
observed that line speed can be increased without reducing quality, but
the line between optimal operation
and poor quality narrows.
Performance does not gradually
worsen. It often crashes after a critical speed is reached. Often, an employee no longer has enough time to
complete a task, becomes overloaded
and fails to focus on the details of doing his job correctly.
Changing a few small details in
equipment design will often make
the task easy again. For example, in
one plant, a single stunner operator
can only stun 270 cattle per hour, but
in another, he can do many more and
maintain a good stunning score of 97
percent or better.
The plant with the higher
speed made three small
changes in its equipment. The changes
involved adjusting the angle
of a handle
on the pneumatic stunner,
improving the
balancer
and
providing shorter operators with
a platform that was
raised three inches.
In some facilities, I have
observed that the equipment manufacturer's maintenance and operating specifications are not followed.
Computer-controlled electronic hog
stunners can greatly reduce blood
splash if they are maintained correctly. Because this stunner is a
computer, it must be housed in a
climate-controlled room, and it must
not be put in a box at the restrainer.

MEAT&POULTRY

May 2005

Plants where the stunner does not
work correctly, it is often housed in
a damp location. I asked one plant
manager, "Would you keep your new
laptop computer in the restrainer
room?" In plants where this stunner
really performs well, it is stored in a
climate-controlled room, and switches,
cords and plugs in the stunning wand
are replaced frequently because wear
and moisture affect the current.
It is also essential to keep the stunning wand handle, where the switch
is located, dry. Wet wires and switches will interfere with precise control
of the current.
In another plant, a pneumatic stunner was breaking down frequently. I
noticed that it sounded extra loud. I
later discovered that the plant was using a slightly undersized compressor,
and to maintain the minimum pressure required to stun the cattle the
operator had turned the compressor
up 20 pounds per square inch over
the manufacturer's recommended
setting. By doing this, the undersized
compressor was able to maintain the
minimum required pressure.
The problem was that the compressor could not provide enough air volume to maintain a continuous amount
of air at the correct pressure. The
higher setting enabled the undersized
compressor to catch up during breaks
and lunch. Therefore, the setting was
too high about half the time.
Hydraulic pressure adjustment
Another detail often overlooked in
hydraulic systems is the need to set
different parts of a restraining device
at different pressures. For example, a
head-holding device requires much
less pressure than a heavy door on
a stun box. If the door and the head
holder work off the same pressurerelief valve, too much pressure can

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A head-holding device
requires much less
pressure than a heavy
door on a stun box.
be applied to the cow's head. The
head holder should have a separate
pressure-relief valve set at a lower
pressure. Running the door and the
head holder off the same relief valve
will result in too much pressure being
applied to the cow's head unless the
operator is very careful.
A separate relief valve should be
set so the pressure applied to the
cow's head will automatically stop
at the right pressure. The cow should
not vocalize when the control lever is
held all the way down, and the pressure-relief valve opens and bypasses
hydraulic fluid back to the reservoir.
Dr. Temple Grandin operates Grandin
Livestock Systems, Inc., Fort Collins,
Colo., and is a faculty member in
the animal science department at
Colorado State Univ.
We would like to hear from you- your comments
and questions about this article are welcome.
E-mail the author at: meat&poultry@sosland.com

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Meat + Poultry - May 2005

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