Paul D. Ayers
Colorado State University Cooperative Extension
- Popular
hydraulic systems must store fluid under high pressure.
- Three
kinds of hazards exist: burns from the hot, high
pressure spray of fluid; bruises, cuts or abrasions
from flailing hydraulic lines and hydraulic injection
of fluid into the skin.
- Safe
hydraulic system performance requires general maintenance.
- Proper
coupling of high and low pressure hydraulic components
and pressure relief valves are important safety
measures.
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Hydraulic
systems are popular on many types of agricultural equipment
because they reduce the need for complex mechanical linkages
and allow remote control of numerous operations. Hydraulic
systems are used to lift implements, such as plows; to change
the position of implement components, such as a combine header
or bulldozer blade; to operate remote hydraulic motors, and
to assist steering and braking.
To do
their work, hydraulic systems must store fluid under high
pressure, typically 2,000 pounds or more per square inch.
One hazard comes from removing or adjusting components without
releasing the pressure. The fluid, under tremendous pressure,
is also hot. The worker then is exposed to three kinds of
hazards: burns from hot, high-pressure fluid; bruises, cuts
or abrasions from flailing hydraulic lines and hydraulic injection
of fluid into the skin.
Many
systems store hydraulic energy in accumulators. These accumulators
are designed to store oil under pressure when the hydraulic
pump cannot keep up with demand, when the engine is shut down,
or when the hydraulic pump malfunctions. Even though the pump
may be stopped or an implement disconnected, the system is
still under pressure. To work on the system safely, relieve
the pressure before the work begins.
Probably the most common injury associated with hydraulic
systems is the result of pinhole leaks in hoses. These leaks
are difficult to locate. A person may notice a damp, oily,
dirty place near a hydraulic line. Not seeing the leak, the
person runs a hand or finger along the line to find it. When
the pinhole is reached, the fluid easily can be injected into
the skin as if from a hypodermic syringe.
Immediately
after the injection, the person experiences only a slight
stinging sensation and may not think much about it. Several
hours later, however, the wound begins to throb and severe
pain begins. By the time a doctor is seen, it is often too
late, and the individual loses a finger or entire arm.
Unfortunately,
this kind of accident is not uncommon. To reduce the chances
of this type of injury, run a piece of wood or cardboard along
the hose (rather than fingers) to detect the leak (see Figure
1).
Another
hazard is improper coupling of low-and high-pressure hydraulic
components. Do not connect a high-pressure pump to a low-pressure
system. A low-pressure component, hose or fitting should not
be incorporated into a high-pressure system. Component, hose
or fitting ruptures are likely to occur.
Pressure
relief valves incorporated into the hydraulic system will
avoid pressure buildups during use. Keep these valves clean
and test them periodically to ensure correct operation.
An
improperly maintained hydraulic system can lead to component
failures. Safe hydraulic system performance requires general
maintenance.
- Periodically
check for oil leaks and worn hoses.
- Keep
contaminants from hydraulic oil and replace filters periodically.
- Coat
cylinder rods with protective lubricants to avoid rusting.
Follow
these rules for safe hydraulics operation.
- Always
lower the hydraulic working units to the ground before leaving
the machine.
- Park
the machinery where children cannot reach it.
- Block
up the working units when you must work on the system while
raised; do not rely on the hydraulic lift.
- Never
service the hydraulic system while the machine engine is
running unless absolutely necessary (bleeding the system).
- Do
not remove cylinders until the working units are resting
on the ground or securely on safety stands or blocks; shut
off the engine.
When
transporting the machine, lock the cylinder stops to hold
the working units solidly in place.
- Before
disconnecting oil lines, relieve all hydraulic pressure
and discharge the accumulator (if used).
- Be
sure all line connections are tight and lines are not damaged;
escaping oil under pressure is a fire hazard and can cause
personal injury.
- Some
hydraulic pumps and control valves are heavy. Before removing
them, provide a means of support such as a chain hoist,
floor jack or blocks.
- When
washing parts, use a nonvolatile cleaning solvent.
- To
insure control of the unit, keep the hydraulics in proper
adjustment.
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
Service
in Action
5.017
,
Cooperative Extension, Colorado State University. Published
July 1985. Reviewed October 1992. Copyright 1992. For more
information, contact your county Cooperative Extension office.
Colorado
State University Cooperative Extension agricultural engineer
and associate professor, agricultural and chemical engineering.
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