Preventing Tractor Overturn Incidents


Use the following format to cite this article:

Preventing tractor overturn incidents. (2013). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/68324/preventing-tractor-overturn-incidents.

 

Tractor overturn incidents can result in major injuries (crushing injuries, broken bones, and so on) and even death. The first step in preventing an injury or death is to make sure that your tractor is equipped with a rollover protective structure (ROPS) that, if used in conjunction with a seat belt, keeps the operator in a protective zone in the event of a rollover incident. Most rollover incidents can be prevented by understanding the causes of overturns and following safe operating practices. 

There are two types of tractor rollover incidents: side and rear overturns.

Side Overturns

Ag Rescue Demo at APD

(Source: Pennsylvania State University, Ag Safety & Health)

Side overturns are the most common type of tractor overturn incident. In a side overturn incident, a tractor rolls onto its side. Preventing this type of incident is possible if the operator understands specific hazards and knows the appropriate time to apply safety precautions.

The two major factors at play in side overturn incidents are center of gravity and centrifugal force. The center of gravity (sometimes referred to as CG) is the location where all of the tractor’s weight is equally balanced. This point can change due to attachments and weight from a load, as when material is carried in a front-end loader. The center of gravity must remain within the tractor’s stability baseline for the tractor to remain in an upright position. A tractor’s stability baseline is found by drawing lines between the tractor’s four tires where the tires touch the ground. Centrifugal force is the force that pushes out on a tractor as the tractor makes a turn. (Click here to link to an eXtension article on tractor stability.)

Ways of preventing a side rollover incident include, but are not limited to, the following:

  • Braking properly
  • Avoiding shear line hazards
  • Keeping buckets low during transport
  • Driving at appropriate speeds
  • Using caution on sloped areas

Braking Properly

Before driving at transport speeds, lock the brake pedals together to provide even brake pressure. If you do not lock the brake pedals together and use only one brake pedal, the tractor could swerve and potentially roll over. When traveling with a load down a steep hill, shift your tractor to a lower speed before you begin your descent so that the engine does the majority of the braking. 

Avoiding Shear Line Hazards

The soil on a bank or the shoulder of a ditch can be weak due to patterns of freezing and thawing or prolonged wet weather. Weak soil can collapse under pressure. The point at which soil is vulnerable to collapse is called a shear line. A shear line hazard exists when large vehicles such as combines operate close to a bank, putting pressure on soil inside the shear line and putting the vehicle at risk should the soil collapse. To avoid this overturn risk, drive your tractor as far back from the edge of the ditch or bank as the ditch is deep (see below). Maintain more distance for tractors pulling wide tillage or planting equipment (should a collapse occur under such equipment, the equipment could pull over the tractor or combine). When operating your tractor near a ditch or bank, always keep your tractor behind the shear line.

Shear Line

(Image Source:Safety Management for Landscapers, Grounds-care Business, and Golf Courses, John Deere Publishing, 2001. Illustration reproduced by permission. All rights reserved)

Keeping Buckets Low during Transport

Always keep the bucket of a front-end loader as low as possible during transport. A loader’s center of gravity in relation to the stability baseline changes drastically when the bucket is too high, especially on sloped areas, placing the loader at risk for an overturn.

Driving at Appropriate Speeds

Drive at a speed that is appropriate for a the given road or environmental conditions because increased speed reduces the stability of the tractor. By going at a slower speed, you will have greater time to spot obstructions in the path of the tractor and maintain better traction with the road (see below). It is also important to decrease your speed when you are pulling rear-mounted equipment to maintain stability.

Tipping Hazard

(Source: Pennsylvania State University, Ag Safety & Health)

Using Caution on Sloped Areas

Do not drive your tractor across steep slopes because the risk of a tractor overturn increases as the angle of the slope increases. If a task must be completed on a steep slope, use a tractor that has a wide front end and rear tires that are spaced as far apart as possible. When possible, back the tractor up a steep slope rather than driving uphill. When going down a steep hill, never travel at a speed faster than the speed you used going up. Centrifugal force is a significant factor when turning on slopes. When you need to make a turn while traveling on a steep slope, reduce your speed and turn downhill rather than uphill.

Pay close attention to any bumps or depressions when driving on a sloped surface, and keep your speed low when traveling on a sloped area. If you are using a side-mounted attachment on your tractor, make sure that the piece of equipment is on the uphill side of the tractor.

Rear Overturns

Rear Tractor Overturn Demo

Rear Tractor Overturn Demo

(Source: Pennsylvania State University, Ag Safety & Health)

Rear overturns occur when the front end of a tractor flips backward, landing the top of the tractor on the ground. The incidents are dangerous because they happen very quickly. A tractor typically reaches the “point of no return” in less than a second, and the entire rear rollover incident can occur in one and a half seconds. This gives the operator little to no time to react to the situation.

A critical factor involved in rear rollover incidents is rear-axle torque. When the clutch is engaged on a two-wheel tractor, a twisting force (torque) to the rear axle results. This force is transferred to the tractor tires. Normally the rear axle and tires rotate and the tractor moves. However, if the rear axle is unable to move in response to the torque, the tractor chassis rotates about the axle. This energy transfer between the engine and the rear axle can result in the front-end of the tractor lifting off the ground until the tractor’s center of gravity passes the rear stability line. Once the center of gravity passes this point, the tractor continues rearward until it comes in contact with the ground.

Tractors with four-wheel drive are less susceptible to rear overturns because torque is applied to both the front and rear axles, and the center of gravity is moved forward because more weight is carried on the front axle. However, there is little difference between a two- and four-wheel drive tractor once the front end of the tractor begins to lift.

Operators face an increased risk of rear overturn in the following situations:

  • Freeing a stuck tractor
  • Raising rear-mounted equipment
  • Using a front-end loader
  • Hitching above the drawbar
  • Operating on an incline

Note that this list is not comprehensive.

Freeing a Stuck Tractor

On occasion, tractors become stuck in mud or in frozen ground. When this happens, first try to free the tractor by backing out. To aid in this process, you may need to dig dirt or mud from behind the rear wheels and unhitch equipment. If you are unable to back out, enlist the help of another tractor to pull the stuck tractor out from behind. If this is not possible, use the other tractor to pull the stuck tractor out from the front. When trying to free a stuck tractor, never place boards or blocks in front of the rear wheels because the wheels could suddenly catch and stop turning, possibly causing the tractor to rear up and tip backwards. 

Raising Rear-Mounted Equipment

Add front-end weight to counteract the weight from raising heavy rear-mounted equipment.

Using a Front-End Loader

If you are installing a front-end loader, always use a loader designed specifically for your tractor. When moving materials in a front-end loader, the tractor becomes heavy toward the front, placing it at risk for an overturn incident. Due to the added weight from the loader and materials, you may need to add rear counterweights to the tractor or liquid ballast in the rear tires. Rear overturn incidents can be reduced by keeping the loader bucket as low as possible when transporting materials, especially when operating on a sloped area.

Hitching above the Drawbar

The risk of a rear overturn incident increases when you hitch above the tractor drawbar, which is specifically designed and located to pull loads. When you hitch to a location other than the drawbar (see below), you raise the angle at which the load pulls down and back, reducing the safety design of the tractor and increasing your risk of an overturn. 

Drawbar hitching

(Image Source:Safety Management for Landscapers, Grounds-care Business, and Golf Courses, John Deere Publishing, 2001. Illustration reproduced by permission. All rights reserved)

Operating on an Incline

When pulling something up a hill with a tractor, both the slope and the pull on the drawbar make the tractor less stable. During operation, it is important to smoothly operate the clutch and throttle. Avoid stopping or shifting gears while on the hill because extra power is needed to restart the tractor and the tractor could drift backwards.

Resources

Click HERE to be directed to the Canadian Agricultural Safety Association website, where you can review actual tractor incidents and identify causes and safe operating procedures.

For more information about safe tractor operation and hazards, click on a title below to be directed to the article:

Power Take-Off Safety

Preventing Tractor Runover Incidents

Rollover Protective Structures

 

Use the following format to cite this article:

 

Preventing tractor overturn incidents. (2013). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/68324/preventing-tractor-overturn-incidents.

 

Sources

Agricultural tractor safety. (2011) Safe Workplace Promotion Services Ontario. Retrieved from http://www.wsps.ca/WSPS/media/Site/Resources/Downloads/Agri-_Trctr_-Sfty….

Baker, D. (2002) Safe tractor operation. University of Missouri Extension. Retrieved from http://extension.missouri.edu/p/g1960.

Murphy, D. (2014) Tractor stability and instability. Penn State College of Agricultural Sciences. Cooperative Extension. Retrieved from https://extension.psu.edu/tractor-stability-and-instability.

Smith, D. (2010) Safe tractor operation: Rollover prevention. Texas A & M System AgriLIFE Extension. Retrieved from http://agsafety.tamu.edu/files/2011/06/SAFE-TRACTOR-OPERATION-ROLLOVER1.pdf.

Tractors: Roll-over prevention. (2002) Canadian Centre for Occupational Health and Safety. Retrieved from http://www.ccohs.ca/oshanswers/safety_haz/tractors/rollover.html.

 
Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
Tom Karsky, University of Idaho (Has since retired)
Dennis J. Murphy, Pennsylvania State University (Has since retired)
Robert A. Schultheis, University of Missouri schultheisr@missouri.edu
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu

Preventing Tractor Runover Incidents


Use the following format to cite this article:

Preventing tractor runover incidents. (2013). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/67752/preventing-tractor-runover-incidents.

 

The main types of tractor incidents include rollovers, power-take off entanglements, and runovers. Runover incidents that occur can involve either the operator or a bystander. Tractor manufacturers have made changes (e.g., safety start system) to reduce the risk of certain types of runover incidents. However, all types of runover incidents can be prevented by understanding the hazard and following specific safety recommendations.

Runover of Extra Rider

A runover incident can occur when an extra person on the tractor falls off the tractor and is run over by the tractor or an attachment. There should never be an extra rider on a tractor. The only exception is that a few newer, larger tractor models with an enclosed rollover protective structure (ROPS) cab have a factory-installed extra seat for temporary instructional purposes only. Most tractors used on farms and ranches only have one seat and that is for the operator only. Runover incidents can occur to a person who rides on the tractor drawbar, axle housing, side links of the three-point hitch, rear-wheel fender, or other area around the operator’s seat. When standing or sitting on one of these areas, a person can lose his or her grip, be thrown from the tractor, and be run over by the tractor or an implement.

Prevention Step:

  • Never allow an extra rider on a tractor.

Runover of Operator

A tractor runover incident can occur to the operator if he or she falls from the moving tractor and is run over by the tractor tire or an attachment. This type of incident can occur if the operator does not buckle the seat belt on a tractor with a ROPS or if an older tractor does not have a ROPS. An operator can be knocked out of the tractor seat by a tree branch or another obstacle. The operator can also lose balance if the tractor hits a tree stump or encounters rough terrain. An operator can be run over if he or she tries to mount or dismount a moving tractor.

Prevention Steps:  

  • Never dismount or mount a tractor or machine while it is in motion.
  • Use tractors with a ROPS with seat belt, and fasten the seat belt every time you operate the tractor.  
  • Slow down when driving on rough terrain or where hidden obstacles may exist.
  • Before leaving the tractor seat, always shut off the tractor and set the brake or place the tractor in PARK.
  • Make sure that the tractor’s brakes and clutch are in properly working condition.
  • Replace old pan-type seats with seats that have back and arm rests.

Runover of Person Located on the Ground due to Bypass Starting

A person located on the ground near the tractor can be involved in a tractor runover incident. This type of runover can happen to the operator or a bystander if someone attempts to start the tractor from the ground (e.g., bypass starting) and the tractor is in gear.

Prevention Steps:

  • Always start the engine from the operator’s seat.
  • Add or leave the bypass shield on the starter terminals.
  • Keep the tractor’s electrical system in good working condition.
  • Do not disable or wire around the safety interlocks installed by the manufacturer.
  • Always visually check in all directions for people around the tractor before moving the tractor.
  • Reduce your speed when operating the tractor in an area where people are located.
  • Instruct everyone how to get the attention of a tractor operator before approaching the tractor.
  • Provide a safe play area for children to keep them away from farm or ranch work areas.
  • Make sure that all children at your farm or ranch are properly supervised at all times.

Runover of Person Located on the Ground near the Tractor

Bystanders and children are at risk of a tractor runover incident if the operator does not see them. This is especially a concern if they approach a moving vehicle while it is hauling a load in a bucket or using a bale spear attached to the front or rear of the tractor and are knocked down in its path. Bystanders do not always realize they cannot be seen by the operator. They can slip and fall under a wheel of the tractor or equipment.

Prevention Steps:

  • Always visually check in all directions for people around the tractor before moving the tractor.
  • Reduce your speed when operating your tractor in an area where people are located.
  • Instruct everyone how to get the attention of a tractor operator before approaching the tractor.
  • Bystanders should not approach a moving tractor until recognized and acknowledged by the operator.
  • Provide a safe play area for children to keep them away from farm or ranch work areas.
  • Make sure that all children at your farm or ranch are properly supervised at all times.
 

 

 

Use the following format to cite this article:

Preventing tractor runover incidents. (2013). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/67752/preventing-tractor-runover-incidents.

 

 

Sources:

Harshman, W., Yoder, A., Hilton, J., & Murphy, D. (2011) HOSTA task sheet 4.2: Tractor Hazards. Pennsylvania State University. National Safety Tractor and Machinery Operation Program. Retrieved from http://www.extension.org/sites/default/files/NSTMOP%20Task%20Sheets%20Se….

Miller, J. & Fragar, L. (2006) Farm machinery injury: Injury involving tractor run-over. Retrieved from https://sydney.edu.au/medicine/aghealth/uploaded/Research%20Reports/farm….

Smith, D. (2004) Safe tractor operation: Runover prevention. Texas A & M System AgriLIFE Extension. Retrieve from http://agsafety.tamu.edu/files/2011/06/SAFE-TRACTOR-OPERATION-RUNOVER2.pdf.

 

Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
Dee Jepsen, Ohio State University jepsen.4@osu.edu
Dennis J. Murphy, Pennsylvania State University (Has since retired)
Charles V. Schwab, Iowa State University cvschwab@iastate.edu
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu

 

Rollover Protective Structures


Use the following format to cite this article:

Rollover protective structures. (2013). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/66325/rollover-protective-structures.

 

Tractor rollover incidents account for approximately half of all tractor-related fatalities across the country. A rollover protective structure (ROPS) fits on an agricultural tractor and protects the operator in the event of a rollover.

A tractor’s ROPS and seat belt work in conjunction to secure the operator in a protective zone, reducing the operator’s risk of being crushed under the tractor should it overturn. In most situations, the ROPS limits the overturn to little more than 90 degrees.

Although tractors built after 1985 are equipped with ROPSs and seat belts, many farmers and ranchers use older tractors that are not equipped with these safety devices. According to Occupational Safety and Health Administration (OSHA) guidelines, farm and ranch owners are required to have a ROPS and seat belt installed on all tractors operated by employees.

ROPS: Type and Structure

There are three types of ROPS, all of which protect the operator in the event of a rollover:

  • two-post ROPS
  • four-post ROPS
  • ROPS with enclosed cabs

Two-Post ROPS

Tractor with ROPS

(Two-post ROPS. Source: Pennsylvania State University. Agricultural Safety and Health)

The two-post ROPS (pictured above) is the most common type of ROPS. The upright posts are typically vertical or slightly tilted and are mounted to the rear axle. Two-post ROPSs are either rigid or foldable.

  • A foldable ROPS has a specially designed hinge that allows the ROPS to fold to fit in low-clearance areas.
  • You must raise and lock the foldable ROPS after completing activities in low-clearance areas.
    • A foldable ROPS that is not in its upright position will not provide protection during a rollover.

Four-Post ROPS

A four-post ROPS is mounted on both axles and on the frame in front of the operator. Occasionally, a four-post ROPS is mounted to the tops of specially reinforced flattop rear fenders.

ROPS with an Enclosed Cab

Farmall 130A Tractor

Farmall 130A Tractor. Photo Source: Case IH Media Library

Typically, a tractor is outfitted with a ROPS with an enclosed cab by the manufacturer—the tractor’s cab structure is designed to act as a ROPS. As sales of tractors with cabs have increased, ROPSs with enclosed cabs have become more common.

Falling Object Protective Structures

A falling object protective structure (FOPS) is a canopy specially designed to protect the operator from falling objects. FOPSs are especially recommended for use on front-end loaders and when working in wooded areas or other situations that may involve falling objects.

Most FOPS are used on tractors with four-post ROPS or ROPS with enclosed cabs. 

Retrofitting Older Tractors

Most tractors built before 1985 can and should be retrofitted with ROPS and seat belts. Check with your local dealership or manufacturer to determine the availability of ROPS retrofit kits. You may also click here to access the University of Kentucky ROPS Guide to determine whether a ROPS is available for your tractor. You should have technicians at a dealership install any aftermarket ROPS.

ROPS Safety Standards

Do not use a homemade ROPS on your agricultural tractor; it will not provide you with the necessary protection in the event of a rollover and may pose liability issues.

Manufacturers have designed and tested ROPS to meet specific standards developed by the Society of Automotive Engineers (SAE), the American Society of Agricultural Engineers (ASAE)—now called the American Society of Agricultural and Biological Engineers (ASABE)—and other organizations. These standards indicate that a ROPS has passed specially designed crush, static, and dynamic tests that confirm its effectiveness.

ROPS must meet the following standards:

  • SAE J2194
  • OSHA 1928.51

In Canada, ROPS must meet the following standards:

  • Canadian Standards Association (CSA) B352.0
  • Canadian Standards Association (CSA) SA 352.1 
Certification labels identify structures that meet the safety standards required of a ROPS. Some cab structures and bars may look like ROPS, but only ROPS have certification labels.
  • Two- and four-post ROPS should have labels applied directly to the posts.
  • The label on a ROPS with enclosed cab should be located on the edge of the cab door.
Like ROPS, FOPS must meet SAE and ASAE standards. If you are uncertain whether your canopy is a certified FOPS, check with the ROPS supplier or equipment dealer.

ROPS Maintenance

A factory-installed ROPS should never be structurally modified (that is, cut, welded, and so on). Such modifications can impact the integrity of the ROPS and impair its effectiveness in a rollover.

Periodically check the ROPS and seat belt on each tractor for signs of wear such as rust and cracks. Contact the dealership regarding the best way to properly correct any issues.

Resources

Click here to learn about aftermarket ROPS rebate programs available in certain areas of the United States.

 

Use the following format to cite this article:

Rollover protective structures. (2013). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/66325/rollover-protective-structures.

Sources

 

American Society of Agricultural and Biological Engineers (ASABE), 2012. ANSI/ASAE S478.1. Roll-Over Protective Structures (ROPS) for Compact Utility Tractors. St. Joseph, MI. Retrieved from http://www.elibrary.asabe.org.

 

Murphy, D. and Buckmaster, D. (2003) Rollover protection for farm tractor operators. Penn State College of Agricultural Sciences, Agricultural and Biological Engineering. Retrieved from https://extension.psu.edu/rollover-protection-for-farm-tractor-operators.

The Kentucky ROPS Guide. (2010) Southeast Center for Agricultural Health and Injury Prevention, University of Kentucky. Retrieved from http://rops.ca.uky.edu/?utm_medium=301&utm_source=warehouse-page.

 
Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
Jimmy Maass, Virginia Farm Bureau Insurance (Has since retired)
Dennis J. Murphy, Pennsylvania State University – djm13@psu.edu
Charles V. Schwab, Iowa State University  cvschwab@iastate.edu
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu