- - AGRICULTURE CORE CURRICULUM - - (CLF2000) Advanced Core Cluster: AGRICULTURE MECHANICS (CLF2900) Unit Title: WORK AND POWER ____________________________________________________________________________ (CLF2914) Topic: SAFETY Time Year(s) 3 Hours 1 / 2 / 3 / 4 ____________________________________________________________________________ Topic Objectives: Upon completion of this lesson the student will be able to: Learning Outcome #: (S-4) - Demonstrate an awareness of the importance of safety in relation to the application of energy, force, pressure, friction, work, and power. (T-4) - Develop awareness of the importance of safety in the transmission of power. Special Materials and Equipment: None References: Smith, H. P., & Lambert, H. W. (1976). FARM MACHINERY AND EQUIPMENT (6th ed.). New York: McGraw-Hill. Deere & Company. (1974). AGRICULTURAL MACHINERY SAFETY (Fundamentals of Machine Operation (FMO) Series). Out-of-print. Resources: Deere & Company. (1987). AGRICULTURAL SAFETY (3rd ed.) (Fundamentals of Machine Operation (FMO) Series). Available from: John Deere Technical Services, Dept. F, John Deere Road, Moline, IL 61265 (Available in Spanish) Deere & Company. (1981). TRACTORS (2nd ed.) (Fundamentals of Machine Operation (FMO) Series). Available from: John Deere Technical Services, Dept. F, John Deere Road, Moline, IL 61265 (Available in Spanish & French) Evaluation: Quiz by instructor. TOPIC PRESENTATION: SAFETY A. Power systems on the farm and throughout the agricultural occupations are a primary source of this industry's high injury and accident rate, which is the highest of any occupational group in the United States. Understanding power equipment and utilizing safe power application techniques can help reduce accidents. Modern farm machinery is extremely powerful and safe operation requires both knowledge of safety principles and care in actually using these principles. 1. Safety shields and guards on machinery are specifically designed to protect the operator from being injured by the machine's moving parts. These shields and guards should not be modified. 2. Shields and guards should not be removed from machinery except just long enough to service or repair the machine. They should then be immediately replaced. 3. Repairs, adjustments, and service to machinery should always be made with the engine and power system turned OFF. Many accidents occur because an engine or drive system is left running while some service operation is being performed. The engine and drive system should also ALWAYS be turned OFF when unclogging or unjamming the machine. 4. Before operating any piece of machinery, the operator's manual should be read and any particular safety problems associated with that machine should be noted. It is especially important to check the operator's manual with new machines or those which are used infrequently. 5. Farm tractors are involved in one-fourth of all farm machinery accidents. Over half of the tractor-related deaths result from overturns; most go over sideways, some go backwards. Chances of survival are much better if the tractor is equipped with rollover bars. B. Machines and Hazards 1. Because machines use power, motion, and energy to do work, they present many different kinds of potential hazards that are difficult to completely eliminate. 2. However, knowledge of common machine hazards can help a person avoid them or minimize their danger if they cannot be avoided. (For example, feeder rollers on silage choppers are not shielded because they have to be open in order to perform their intended function. Similarly, the blades on a rotary mower must rotate at high speeds in order to cut grass, cornstalks, etc.) 3. The following are the most common machine hazards that a machine operator should keep in mind at all times: a. Pinch Points (Mesh Points, Run-on Points, Entry Points) - Pinch points are formed when two objects move together and at least one of them moves in a circle, for example, the point where a belt runs onto a pulley. Pinch points are frequently found in power transmission devices such as belt drives, chain drives, and gear drives. 1) Serious injury can occur when hands, feet, clothing, or hair are caught directly or drawn into pinch points. 2) Anyone who takes a chance and deliberately reaches into moving rotating machine parts risks becoming entangled. Also, removal of a shield makes slipping or falling or even a mere brush against a pinch point a deadly danger. 3) Machines operate too fast for a person to withdraw from a pinch point once either the person or his clothing is caught in it. 4) Know the locations of the pinch points on machinery, avoid being near them when the machine is operating, and, above all, NEVER attempt to service or unclog a machine until all power parts are disengaged, the engine is shut off, and all moving parts have stopped moving. b. Wrap Points - Any exposed machine component that rotates is a potential wrap point, but rotating shafts are most frequently involved in wrap-point accidents. 1) Smooth shafts and slowly rotating shafts may appear harmless but they can nevertheless wrap and wind clothing. Rust, nicks, dried mud, or dried manure make them rough enough to catch clothing. 2) Splined, square, and hexagon-shaped shafts are even more aggressive than smooth shafts. 3) Rotating shafts that stick out beyond bearings can also wrap clothing; also, people sometimes inadvertently lean against them. 4) Couplers, universal joints, keys, keyways, pins, and other fastening devices on rotating components are even more aggressive than some shafts. 5) Beater-type or feeder-type mechanisms which must be exposed so they can handle or tear apart agricultural products are almost certain to entangle and wrap clothing if contact is made with them. 6) Wrapping often begins with just a thread or frayed piece of cloth (such as on a cuff or sleeve) catching on the rotating part. The part continues to rotate and, because of the power involved, can entangle and cause serious injury or death. If the clothing would tear away, injury would be minimized but work clothes are usually too rugged to tear easily. Long hair as well as clothing can be caught and wrapped. c. Shear Points and Cutting Points - Shear points are created when the edges of two objects are moved toward or next to one another closely enough to cut a relatively soft material. Hedge trimming shears are an example. Cutting points are created when a single object moves rapidly or forcefully enough to cut a relatively soft object. Knives and rotary lawn mower blades are examples of cutting points. 1) Farm machinery used to shear or cut crop materials for livestock feed are sickle bar mowers, rotary shredders and cutters and cutter heads of forage harvesters; the shearing and cutting parts may rotate or they may move in sliding or reciprocating motions. 2) These machines must cut crop materials at rates of several tons per hour; consequently, they are very powerful and very aggressive. They cannot be shielded or guarded or they could not perform their function. Their moving parts must therefore be scrupulously avoided; assistants, bystanders, and children must be kept away from them. 3) Grain augers, paddle-flight conveyors, or hinged implement frame members that move when an implement is raised or lowered create cutting or shear points even though they are not specifically designed to cut or shear. Care must be taken not to place either objects or body parts near the functioning parts of these machines. d. Crush Points - Crush points are created when two objects move toward each other or one object moves toward a non-moving object. This may occur in either a reciprocating or a sliding motion. Examples of crush point hazards are hitching tractors to implements or working under heavy objects that haven't been securely blocked. 1) Crushing can be avoided if the potential for crushing is first of all recognized, and second, simply avoided. This seems obvious, but many people are killed and injured because they disregard this simple rule. e. Pull-in Points - These exist on rotating parts of many farm machines, for example, feed rolls, grinders, forage harvesters, corn pickers. 1) Pull-in accidents can be avoided by turning off the machine BEFORE any attempt is made to remove plugged material, stalks, vines, twine, or any other obstruction from moving rollers or rotating shafts. 2) Machines are faster than people and they are also stronger than people. A person attempting to remove a corn stalk from corn picker rolls should consider that the rolls rotate at about 12 feet per second. It takes a person 0.3 seconds just to tell himself to release the corn stalk. In that split second the corn stalk travels 3.6 feet between the stalk rolls. His hand will be taken into the rolls because the machine is faster than he is. 3) Clean, lubricate, unplug, or handfeed a machine only when it is shut down. Always disengage power, shut off the engine, and wait for all parts to stop moving before performing any of these operations unless the operator's manual instructs otherwise. f. Free-wheeling Parts (Inertia) - Inertia is the tendency of a body in motion to remain in motion and a body at rest to remain at rest. The heavier a part is and the faster it moves, the longer it will continue to move after the power is shut off. Many farm machines--for example, cutter heads of forage harvesters, hammer mills of feed grinders, rotary mower blades, fans and blades on ensilage blowers, and flywheels on balers--have components that continue to rotate for up to 2 to 2 1/2 minutes after power is shut off because of their own inertia or the inertia of other moving parts connected to them. How can injuries from free- wheeling parts be avoided? 1) Listen! Almost any free-wheeling, rotating part makes a sound--often a whirring or humming sound--especially at higher speeds. Clutch devices often make fairly loud and distinctive clicking or clanking noises until free-wheeling parts stop. 2) Look! A person can see the motion of flywheels, pulleys, PTO shafts, and the ends of shafts. Even though they are moving very slowly as they are finally coasting to a stop, these free-wheeling parts can cause serious injury because of their weight. g. Thrown Object Hazards - Farm machines that have rapidly rotating parts designed to cut or chop crops in open fields can hurl objects great distances with tremendous force. Similarly, machines that chop or grind crop or feed material may throw particles of the material being processed from the machine. How can injuries from thrown object hazards be avoided or minimized? 1) Recognize the type of machines that may throw objects and keep them properly shielded. Know how far and in what direction the objects can be thrown, even when shielding is in place. 2) When operating a machine that may throw crop materials or "foreign objects" such as rocks, make sure that people and animals are not in the path of any thrown objects. h. Stored Energy Hazards - Stored energy is energy that is confined but waiting to be released. A coiled spring is a common example of stored energy that is found on many farm machines; other examples of stored energy are hydraulic systems, compressed air, and electricity. 1) Springs store energy in the form of either tension or compression. A spring under tension is usually connected to one or more linkages. Before removing any of the linkages, know in what direction and how far all the parts will move, that you or no one else will be in the path of any part connected to a spring under tension or compression, and that proper tools are used in removing or replacing any spring-loaded device. Even small springs can store a lot of potentially dangerous energy. 2) Hydraulic systems on farm machinery also store energy and this energy is stored under high pressure--often 2,000 pounds per square inch, or more. Fluid under pressure attempts to escape or move to a point of lower pressure. Careless servicing, adjustment, or replacement of hydraulic parts can result in serious injury. Before attempting to service any hydraulic system, shut off the engine that powers the hydraulic pump, lower the implement to the ground, move the hydraulic control lever back and forth several times to relieve pressure, and follow precisely the instructions in the operator's manual regarding specific procedures. 3) Compressed air is stored energy and should be recognized as a potential hazard. Air (or any other gaseous substance) under pressure tries to escape from its container because when it is compressed its volume is reduced and energy is stored. Keep air pressure at a proper level according to the capacity of the compressor equipment. Stand to one side when inflating tires. 4) Electricity is one of the most common forms of stored energy. The electrical systems on farm machinery can cause fires if not properly maintained. Inspect electrical systems periodically to make sure wires are properly insulated and to prevent dust, chaff, leaves, or oil from collecting near electrical wires. Short-circuit starting is another electrical hazard associated with farm machinery. If insulation on the electrical wires becomes cracked or worn in operation, a short circuit or contact between that wire and some other part of the machine can start the engine when no one is around. The energy in an electrical system is waiting to do something. Replace any worn or defective wiring, contacts, or switches to prevent fires or accidental starting. i. Slips and Falls - Accidents happen when getting on and off farm machines and also from slipping and falling when working near them. Steps, handholds, ladders, platforms, and other devices that aid in getting on and off farm machinery should be kept clear of mud, snow, ice, or grease. Otherwise a slip could cause the operator to fall into a moving part of the machine or bump one of the controls and cause the machine to lurch into unexpected action. Simple good housekeeping can prevent many slips and falls. Wearing shoes and boots that have slip- resistant soles also reduces the hazard of slipping and falling. j. Slow-moving Vehicles - There are thousands of slow-moving vehicle accidents each year; many of these accidents are fatal. Why? Because a motorist traveling 55 mph topping a hill and coming up behind a tractor traveling 15 mph that is 400 feet ahead of him has only 7 seconds to recognize the speed of the tractor, react, and slow down. That is only about 1/4 of the time he would have to slow down for a car the same distance ahead that is traveling 45 mph. How can slow-moving vehicle accidents be minimized? 1) Always attach a Slow-moving Vehicle (SMV) emblem to any farm machine that is taken on a public road. 2) Keep the emblem surface clean and in good repair. Replace the emblem when the reflective red border or fluourescent orange center lose their brilliance. Mount the emblem securely and always with the point upward. 3) Keep all lights and reflectors in good working order for farm machines traveling on public roads. k. Second Party Hazards - These are situations involving more than one person. There are two categories: necessary second parties are other persons who are needed to help with a machinery operation; unnecessary second parties are persons who are not needed or should not be around a machinery operation. Both of these types of accident situations can be avoided. 1) Necessary second party activities can be made more safe if each person knows what the other plans to do and if each person anticipates the possible action and errors of the other person. 2) Unnecessary second party accident victims are primarily children and youths under 15 years of age. For their own protection, anyone not needed for the operation of farm machinery should be kept away from it. Machinery has much too much power to be used as either a toy or as entertainment. __________________________________________________________ ACTIVITY: 1. Check all the machinery at the school shop to see if all guards and shields are in place and each machine has an operator's manual. 2. Have students check machinery on home farms to see if all guards and shields are in place and each machine has an operator's manual. Have them make a report to the class on their findings. 3. Analyze accidents and near-accidents that have happened to students and/or their family members and determine if and how they could have been avoided or minimized. __________________________________________________________ 7/15/91 CH/YNJ/tf #%&C