Charles
V. Schwab, Shawn Shouse and Laura
Miller
Iowa State University Extension
Farm
equipment operators want powerful machinery to be able to
handle the demands of modern agriculture. They recognize the
dangers, yet many people become entangled in equipment every
year. Here's a common scenario:
The
field was wet and a little weedy and the header was clogging
too often. The operator was annoyed at having to stop the
combine, turn off the engine, climb out of the cab, and pull
stalks out of the cornhead. When it happened for the fourth
time in 30 minutes, he decided to save time by not turning
off the engine. He knew he'd be able to let go of the stalk
before the cornhead engaged again.
The
situation was ripe for an accident, which took the operator's
arm. Before he could even release his grip, the spinning stalk
rolls pulled his entire arm into the machine.
Misconceptions
about the hazards of specific farm equipment can result in
a mangling injury or even death. One of the most common misconceptions
is that a human being can react fast enough to avoid potential
injury. Relying on your reaction to a situation is never the
route to safety.
An average
person can respond to a stimulus within three-fourths to one
second. This reaction speed is only an estimate, and is affected
by many factors. Gender, age, physical condition, and the
use of alcohol or medications alter reaction time. However,
fast reaction time is not the key issue. No matter how
fast the reaction time, it will never be enough to avoid injury
from farm equipment.
Table
1 is a chart that compares the average human reaction time
to speeds of various farm machinery. It shows that reaction
time alone cannot help you avoid injury on farm machinery.
You also must use proper safety precautions so that you
do not get into dangerous situations.
Figure
1. Common entanglement hazards |
Equipment
|
|
Average
speed (feet/second)
| What
happens before you can react?* (feet)
|
PTO |
7.0 |
5.25 |
Auger |
10.0 |
7.5 |
Cornhead |
12.0 |
9.0 |
Belt/Pulley |
66.0 |
49.5 |
Rotary
Lawnmower |
52.0** |
39.0** |
Falling
equipment |
32.0*** |
9.0*** |
*
This is the number of feet that can be entangled in the
equipment during the average reaction time of .75 second.
** A lawnmower blade makes 52 rotations every second.
By the time you can react, a single blade will have gone
around 39 times.
*** Gravity moves falling objects at 32 feet/second/second.
For example, equipment 9 feet in the air hits the ground
in .75 second.
NOTE: This chart is based on estimated values. Conditions
vary that can increase or decrease the values shown
in chart.
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One of the
slowest entanglement hazards - and most common, making it the
most deadly - is the power take-off (PTO) unit. PTO shafts make
either 540 or 1,000 revolutions a minute. At this speed, even
slower units can pull in approximately 7 feet every second.
Within three-fourths second (the average time it takes someone
to react), more than one complete person will have been wrapped
around the shaft before he or she could jump out of the way.
What
if that person was very quick and could react within 0.1 second?
Could he or she avoid injury? No, because even in that short
time the PTO would have pulled in .7 feet (about 8 inches,
a hand or shirt sleeve). Once entangled, a person has few
choices.
PTO
entanglement can be avoided by always following these
precautions:
- Keep
all safety shields and guards in place, especially after
repairs are made.
- Stay
clear of moving parts at all times.
- Disengage
equipment and shut off engine before working near PTO.
- Wear
close-fitting clothes that do not have loose sleeves or
cuffs, and frayed edges. Never wear things that dangle,
such as jewelry, jackets with drawstrings, long shoelaces,
or scarves. Long hair and braids also pose hazards around
PTOs.
A
six-inch auger entangles at a rate of 10 feet per second. Augers
can cause serious injuries because the sharp edge of the auger
shears off items caught against the housing.
To prevent
auger entanglement always:
- Keep
safety guards on the auger intake and drive mechanisms.
A proper guard will not let fingers touch the hazard when
pushed against the guard. Makeshift guards may not adequately
protect bystanders.
- Stay
clear of moving parts at all times.
- Disengage
equipment and shut off engine before working near auger.
Belts
and pulleys on some combines and other machinery travel faster
than some PTO units, which can be deceptive. Belts running on
pulleys travel at various rates, but a common speed is 66 feet
per second, about nine times faster than a PTO shaft.
To prevent
entanglement always:
- Make
sure guards are securely fastened and in good repair.
- Stay
clear of moving parts at all times.
- Disengage
equipment and shut off engine before working near belts
or pulleys.
A
cornhead pulls in crops at a rate of 12 feet per second, faster
than PTOs or augers. To prevent entanglement always shut off
the engine before removing stalks or working near the cornhead.
A
rotary lawnmower blade makes 52 rotations every second. To avoid
rotary blade hazards, always:
- Shut
off the engine before unclogging the discharge chute.
- Wear
close-fitting clothes and leather shoes with good traction.
- Keep
rear shields and bags in place while operating the mower.
- Disconnect
spark plug while working on the mower to prevent accidental
engine ignition caused by manually moving the blade.
Equipment
that is propped up or on jacks also can be a hazard. The time
it takes for falling equipment to hit the ground is usually
not enough time to react and get out of the way. To avoid
these hazards always mechanically lock and block equipment
to make repairs. Do not rely on hydraulic systems to suspend
equipment for servicing.
Reaction
time is important. When driving a tractor, the operator must
respond to situations as they are presented. Operator reaction
time is critical in avoiding injury in these situations, but
never forget that machines are always faster than humans possibly
can react.
How
much do you know?
- If
your reaction time is very fast, you can avoid being entangled
in farm equipment. True or false?
- It
takes three-fourths of a second for most people to respond
to something. True or false?
- At
what rate does an arm get wrapped around a power take-off
(PTO) shaft?
- 1
foot per second
- 7
feet per second
- 7
feet per minute
- At
what rate does a glove get caught in spinning stalk rolls?
- 1
foot per second
- 12
feet per second
- 12
feet per minute
- At
what rate does a loose bootlace get pulled into a moving
belt and pulley?
- 1
foot per second
- 66
feet per second
- 66
feet per minute
- Reacting
quickly is the best way to avoid entanglement in farm machinery.
True or false?
See
answers at the end of the next section.
What
can you do?
No matter
how fast you react to farm equipment hazards, it will never
be enough to avoid injury. You must use proper safety precautions
to avoid potentially dangerous situations.
- Read
the equipment operator's manual to determine potential hazards
for each implement.
- Examine
equipment for potential hazards.
- Always
follow recommended procedure to adjust equipment.
- Read
safety decals that explain the dangers of equipment.
Answers
to quiz:
1-False;
2-True; 3-b; 4-b; 5-b; 6-False.
- Other
publications in the Safe Farm series include: Evaluate equipment
for dangers, Pm-1265c; Harvest safety yields big dividends,
Pm-1265h; Reduce risks around big round bales, Pm-1518g,
and Practice lawnmower safety on farms, Pm-1563d.
- For
group presentations, contact any extension office to use
the Wheel of Misfortune display. This display measures reaction
time and compares it with the speed at which equipment injuries
occur.
- For
plans to construct your own reaction display, contact the
ISU Extension Safety Specialist at 207 Davidson Hall, Iowa
State University, Ames, IA 50011-3080.
Disclaimer
and Reproduction Information: Information in NASD does not represent
NIOSH policy. Information included in NASD appears by permission
of the author and/or copyright holder. More
NASD Review: 04/2002
This document
is Fact Sheet
Pm-1563j
,
a series of the Safe Farm Program, Iowa State University Extension,
Ames, Iowa. Safe Farm promotes health and safety in agriculture.
It is funded by the National Institute for Occupational Safety
and Health (NIOSH #U05/CCU706051-03), Iowa State University,
and a network of groups that serve Iowa farm workers and their
families. Publication date: December 1994.
Prepared
by Charles V. Schwab, extension farm safety specialist; Shawn
Shouse, extension agricultural engineer; and Laura Miller,
extension communications, Iowa State University Extension,
Ames, Iowa.
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