Safety Engineering of Machinery

Agricultural machines cut, pick, lift, load, move, carry, unload, strip, thresh, grind, mix, chop, spread, spray, discharge, and otherwise process many types of agricultural materials, including crops, soils, chemicals, and wastes. They also include tractors and other units that provide the power necessary to pull and actuate the machines that actually process the materials. This processing requires machine components of two types:

1. Functional components that perform the desired function on the materials

2. Power transmission components that transmit the power from the engine or motor to the functional components

Operation of machines can result in acute or chronic injury if they are not designed with ergonomics and human factors in mind.

Machine Components Presenting Hazards Types of functional components include:

1. Rotating, oscillating, swinging, or stationary knives

2. Rolls and rollers, including pairs that press tightly together

3. Plungers

4. Rotating bars or cylinders carrying rasps

5. Teeth or blades

6. Augers

7. Swinging hammers

8. Fans

9. Chains and conveyors

10. Large spikes

11. Pinch and crush points

Types of power transmission components that present hazards include:

1. Rotating shafts

2. Gears, chains, and sprockets

3. Belts and pulleys

If an engine is present, there are additional hazards of related chemicals (e.g., fuel, battery acid), and heat, which can lead to contact burns, fires, or heat exhaustion.

Hydraulics (high-pressure oil that flows from power unit to machine to perform tasks) is commonly found on agricultural machines. Components include:

1. Cylinders that extend under pressure to lift or move loads or other machine components

2. Motors that turn the energy of flowing oil into rotary motion

3. Hoses and tubing that carry the oil

Leaks, ruptures, or failures in the system can expose the operator to hot oil of 2500 psi or more, resulting in injection injury or burns, or resulting in cylinders retracting suddenly and dropping loads on unsuspecting people below.

Machines that are transported on public roads risk collisions with other vehicles. Any machine can be involved in a "runover," where the machine runs over a victim. These two hazards, plus the hazard of overturns with the operator beneath are particularly applicable to operators of tractors and self-propelled machines.

There are additional hazards specific to certain types of machines. For example, a gravity-unloading grain wagon, which has a slanted floor and can unload grain by gravity flow, has the hazard of entrapping a person who is standing on top of the grain when the unloading door is opened.

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