Agricultural Engineering Safety Lesson Plan: Combine Operator Safety


To identify precautions and safety recommendations that should be observed by operators of combines.


The combine operator is responsible not only for his safety but also for the safety of others who may be working on or just be near the machine. The operator must be aware of hazards and remain alert to situations that are potentially dangerous. This includes pre-operational checks, starting, transporting, towing, operating, field repair and maintenance and stopping the combine.


  1. Hand Signals. A set of hand signals have been endorsed by several safety institutions (Fig. 1). Since spoken instructions are very difficult to hear over the sounds of a combine, a knowledge of hand signals can be extremely helpful to the operator when maneuvering a combine, especially in tight places.
  2. Safety Before Starting.
    1. Before attempting to operate a combine, study the operator's manual. It has information on general safety rules, plus specific safety recommendations for the particular machine. the more you know about the combine, the better prepared you will be to safely operator it.
    2. The exhaust fumes from a gasoline or diesel engine are very poisonous. If the combine is run inside a building, be sure to open the doors to provide good ventilation.
    3. Always clean the combine before starting. Trash around the exhaust system can cause fires. Oil, grease or mud on ladders or the platform can cause serious falls. If the combine is equipped with a cab, clean the glass to provide maximum visibility.
    4. Check the tire pressure each day. Under-inflation can cause buckling of the sidewall, which can cause dangerous tire failure. Over-inflated tire have a great deal of "bounce" and cause upsets more readily that tires with correct pressure.
    5. Check the brakes once a week. With hydraulic brakes, make sure that the master cylinder is full of fluid and that no air is present in the lines. Adjust the pedal free travel, if necessary, so that the brakes are engaged with the pedals an equal distance from the floor of the platform. Check the operator's manual for specific instructions.
    6. Check the threshing cylinder rocking bar to see it is clear of the cylinder.
    7. Make sure that all shields and covers are in place and fastened securely.
    8. Remove or stow all service equipment.
    9. Always use the handrails and ladders provided on the combine for safe mounting and dismounting.

  3. Starting the Combine.
    1. Before mounting the combine, make sure that everyone is clear of the machine. Do not allow anyone it ride with you, unless combine is equipped with a passenger seat.
    2. Before starting the combine:
      • Disengage header drive.
      • Disengage separator drive
      • Place gearshift in neutral
      • Depress clutch pedal

    3. Be careful when using diesel starting fluid. It is extremely flammable.
    4. If it is necessary to use jumper cables to start the combine, be careful to avoid sparks around the battery. Hydrogen gas escaping from the battery can explode. Follow the operator's manual instructions for using jumper cables.

  4. Transporting the Combine.
    1. Always keep your mind on the dangers of driving the combine on public roads. Beside maintaining control of the machine, you must watch for obstacles on the road, pedestrians and traffic.
    2. High speed is the leading cause of accidents. Never drive faster that the road conditions allow for safe operation. Anticipate dangers and slow down to avoid accidents.
    3. Make sure you are familiar with local traffic laws. Check the safety flashers and SMV emblems to be sure they are clean and visible.
    4. Always lock the brake pedals together. If the combine is not equipped with locking mechanism, be sure to depress both pedals at the same time evenly. Applying only one brake, or applying one harder than the other can cause the combine to swerve and perhaps tip over.
    5. Be careful when applying brakes when a header is attached to the combine. The added weight up front can cause the combine to tip forward if the brakes are applied abruptly. Always drive slow enough to allow controlled application of brakes at all times.
    6. Always check headlights and safety flashers to make sure they are properly adjusted and in working order.
    7. Put the unloading auger in the transport position. Be certain it is not blocking a safety flasher or SMV emblem.
    8. On self-propelled combines, never use the header safety support when transporting the machine. Raise the header enough for safe ground clearance, but not high enough to reduce visibility.
    9. On pull-type combines, always use header support when transporting. Towing at transport speeds can be hazardous because of side forces on the tractor when stopping too quickly. Side forces from slowing a combine too quickly may cause a tractor to skid, especially on loose gravel. Slowing down while turning can cause jack-knifing. Slow down before the corner so the towed combine doesn't get out of control.
    10. Watch for low power or telephone lines, bridges, buildings and any other obstacles, to make sure you can pass under them safely. Always keep as far to the right of the roadway as possible. Keep a careful watch to see that you have safe clearance on both sides.
    11. Always sit down when traveling at high speeds or going over rough terrain.
    12. Be careful when making turns. Make sure that the rear of the combine will clear obstacles when it swings around. Avoid sharp turns. Turning too sharply at high speed can cause the machine to turn over.
    13. Because the wheels for steering are in the back, self-propelled machines often fishtail when turned too quickly at transport speeds. Steering to the right will whip the rear to the left, and vice versa. Steering suddenly to the right when meeting oncoming traffic causes the back of the combine to swing out into the path of on coming traffic.
    14. Slowing or braking too rapidly could cause loss of some steering control (weight on rear wheels). This is most noticeable when driving with a corn head or some other heavy header raised high. In this case, most of the weight will be on the drive wheels. Install rear wheel weights. Keep header as low as possible. Use the variable speed drive or engine throttle to slow the machine. Reduce speed before you need to apply brakes and always lock brake pedals together.
    15. Never depress the clutch pedal or take the combine out of gear to coast down hill. When the combine is moving it is impossible to shift the transmission back in gear. Always maintain complete control of the combine. The same applies to tractors that are towing pull-type combines.

  5. Towing the combine.
    1. If the combine must be transported over long distances, it is safer to haul it on a large truck or a special low trailer.
    2. Never tow the combine at speeds higher than 20 mph.
    3. Always keep the transmission in neutral or in the "tow" position, if the combine is so equipped.
    4. Never tow a combine equipped with hydrostatic drive. Towing can cause damage to the drive unit. Instead, haul the combine.

  6. Operating the combine.
    1. Never operate the combine if you are ill or sleepy. Operating safety depends on alert, efficient handling of the combine.
    2. Wear safety glasses at all times.
    3. Wear clothing that fits snugly to avoid catching clothing in moving parts.
    4. Never let anyone ride on the combine unless it is equipped with a passenger seat. A rider's clothing may become entangled in moving parts, or he may be thrown off the machine.
    5. Before starting to harvest a field, check it carefully for ditches, fences or other obstacles. Be aware of weather conditions which present safety hazards.
    6. Be especially careful when operating on hillsides. Avoid sharp turns that could tip the combine over. Beware of ditches or obstacles--they are doubly dangerous on slopes.
    7. If grain tank extensions are used, remember that the added weight may make the combine top heavy and more subject to upsets.
    8. Never travel over 10 mph (16 km/h) with a full grain tank. The added weight makes the combine more difficult to maneuver and easier to upset.
    9. Always sit down when traveling over rough terrain. A sharp jolt can throw you from the platform or away from he controls.
    10. Hillside combines are equipped with automatic or manual leveling devices. Hydraulic cylinders act to level these combines on steep slopes. These machines are equipped with a warning signal that indicates when the leveling system has reached its limit. Be especially careful after the device activates.
    11. When using the steering brakes, always turn the steering wheel before applying the steering brakes. Failure to do so can cause the combine to swerve and turn dangerously.

  7. Field repair and maintenance safety.
    1. Always keep the machine clean. Field trash around the exhaust system can cause fires. Mud, grease or oil on the operator's platform or ladders can cause falls.
    2. Before lubricating or adjusting the combine, disengage all drives and stop the engine. Never leave the operator's platform with the engine running.
    3. Make sure that the header drive and separator drive are disengaged before attempting to clean the combine. Never try to unclog the machine with a stick or pole with the machine is running. The stalk rolls on a corn head can pull a 12 foot (3.6 cm) stick through in one second--shorter sticks or stalks even faster--before you can let go.
    4. On a pull-type combines, always disengage the PTO and turn off the tractor before attempting to unclog, adjust or lubricate the machine.
    5. Always stop the machine before opening the inspection doors.
    6. Keep all shields in place. After working on the combine, make sure the shields are fastened securely.
    7. When operating in very dusty or noisy locations, wear goggles and ear plugs to insure safe visibility and prevent hearing loss. Never wear loose clothing that can become entangled in moving parts.
    8. Stay clear of moving parts at all times.
    9. Keep belts and chains properly adjust and aligned.
    10. Don't rely on the hydraulic system for support when working under the machine header. Always use the stops or supports provided on the machine. If no safety device is provided, block the header securely.
    11. When adjusting the wheel spacing, make certain the machine is blocked. Never rely on jacks alone for support.
    12. Always support the reel arm securely when adjustments are being made.
    13. Be careful when removing heavy parts. Make certain they are held firmly to avoid dropping them. Have someone help you with heavy jobs.
    14. When operating in dry fields. Install a spark arresting muffler to prevent fire.
    15. Avoid sparks or open flames when working the battery. Hydrogen gas escaping from the battery may explode.
    16. When possible always refuel the combine outside the field. Let the engine cool before attempting to refuel and never smoke around fuels.
    17. Allow the system to cool and remove the radiator cap slowly, turning it until pressure escapes through the overflow pipe. Make sure all pressure is relieved before removing the cap.
    18. Stay clear of the exhaust system until it cools.
    19. High-pressure fluid leaks in the hydraulic or diesel fuel system are very dangerous. The leaks can be invisible and still have enough pressure to penetrate the skin. When checking for leaks, use a piece of cardboard. If an injury does occur, seek medical aid immediately.
    20. Always carry a first aid kit and fire extinguisher on the combine.

  8. Stopping the combine safely.
  9. To make sure drive units do not cause injury when the machine is started again, do the following when stopping the combine.

    1. Disengage header drive
    2. Disengage separator drive
    3. Place gearshift lever in neutral
    4. Lower header
    5. Apply parking brake
    6. Remove ignition key to prevent tampering or accidental starting.

REMEMBER: The hydraulic drive unit is not an effective parking brake.

Source: Fundamentals of Machine Operation - Combines, Deere & Co.

Kansas State University Cooperative Extension Service, Manhattan, Kansas.

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