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.
Pinhole Leak Injuries
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.
When transporting the machine, lock the cylinder stops to hold the working units solidly in place.
Publication #: 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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