Hydraulic System Basics and Safety

Russ Quinn
By  Russ Quinn , DTN Staff Reporter
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Hydraulics are the heart of tractor systems that run implements, but they require maintenance and caution. (DTN/The Progressive Farmer photo by Dan Miller)

Learning the basics is an important part of anything you do in life. Whether it is learning how to dribble the ball in basketball or learning how to do basic math problems in grade school, getting the basics down is extremely important, at least to me.

I often use the analogy with my kids of someone building a structure like a house. The builder has to have the foundation solidly constructed or the house will not stand correctly and/or it will also not be able to stand the test of time.

While I am sure they just LOVE this analogy, my point to them is to correctly learn the basics of math, English/reading, social studies and science now because everything they learn in the future will be built off of these basic academic principles.

The same holds true with things like hydraulic systems in farm machinery. Most of us have been around hydraulics for many years, but I wonder how many of us really understand how hydraulics work in the loader, combine or any implement you hook hoses to behind the tractor.

The components of a hydraulic system consist of a reservoir, pump, valves, fluid, motor, hose, filter and cylinder.

A hydraulic system uses compressed fluid to transfer force applied at one point to another point, according to an online fact sheet titled "Hydraulics 101 for Beginners" by the Tractor Supply Company (TSC). The hydraulic reservoir stores non-pressurized hydraulic fluid and this fluid travels through a filter that collects impurities.

The hydraulic pump transfers the fluid from the reservoir to the hydraulic system. This transfer raises the energy level of the fluid by increasing its pressure. The motor provides the power source for the pump.

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The high-pressure fluid acts upon the rod and piston within a hydraulic cylinder. Each stroke of the cylinder converts the fluid power (pressure) into work (mechanical force). The reservoir oil level falls while the rod and piston are extending.

When the rod and piston retract, the fluid returns to the reservoir. The metal walls of the reservoir cool the fluid by allowing heat to escape. The reduced pressure in the reservoir allows trapped or dissolved air to escape from the fluid.

The hydraulic fluid is under tremendous pressure that can exceed 2,000 pounds per square inch (psi), according to a report on hydraulic safety at extension.org. Some larger pieces of farm machinery have hydraulic systems with pressures that exceed 3,000 psi, compared to running water from a household faucet, which typically measures around 40 psi.

Knowing this, hydraulic systems and hydraulic fluid can be hazardous to those who operate machinery with these systems. Again, I think everyone knows this, but it is good to get a gentle reminder how dangerous these systems can really be.

I went to community college years ago with an older guy who returned to continue his education later in life. He had some nasty looking scars all over his hands and arms. One of our classmates finally asked what happened, and he said a hydraulic hose burst in his hands and the pressurized oil severely burnt him.

I was suddenly more much aware of the dangers of a hydraulic system.

According to the extension.org site, proper maintenance is critical for all types of machinery and equipment, including the hydraulic system. When doing maintenance to a system, wear personal protective equipment including gloves and eye production.

Do not rely solely on the hydraulic lift if you must work on hydraulic components with the system raised. Set the working unit on blocks as a precautionary measure.

The report said unless you are bleeding the system, do not run the machine engine when you are servicing the system. Hydraulic fluid can be extremely hot and can cause burns, so let the hydraulic system cool before changing lines, connections, filters or fittings.

Operators need to examine the hydraulic lines for leaks and wear. Periodically replace filters and keep hydraulic oil away from contaminants as dirt is the biggest culprit in hydraulic system damage.

Before removing the cylinders from working units, make sure that the units are resting on the ground, safety stands or safety blocks and that the engine is shut off. Use a chain, floor jack or other type of assistive device if you need to remove heavy hydraulic pumps or control valves, the site recommended.

To see the entire TSC release, go to http://bit.ly/….

To read the entire extension.org report on hydraulic safety, visit http://bit.ly/….

Russ Quinn can be reached at russ.quinn@dtn.com

(JP/ES)

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Russ Quinn