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Ohio State University Extension


Chock and Block

Agricultural Tailgate Safety Training for Operators and Supervisors
Agriculture and Natural Resources
Agricultural Safety and Health Program

Objective: To be able to secure a vehicle or piece of equipment using the proper chock and block method.

Trainer’s Note

To demonstrate the chock and block principles, have the training session in the farm shop or in the field. Give employees the opportunity to demonstrate how they would chock/block equipment if they were using it in the field or working on repairs in the shop. Review the true or false quiz.


Examples of chocks for protecting workers from roll backs.

The purpose of the chock is to pin the wheels and hold them stationary. When unhooking farm equipment from a tractor, make sure the tires on the implement have been chocked to prevent the operator or bystanders from being injured if a roll back occurs. The rear most axle should be the one that is chocked. Tires may need to be chocked in both the front and the rear on some equipment. Operators can be caught between a tractor and the equipment or a piece of equipment and the shop wall because the proper chocking procedures were not followed. It is a simple concept, but many farm employees forget to use this procedure when working with or around equipment. In some cases, workers have been killed or injured because they have failed to follow this procedure.

When loading or unloading bags or pallets from a semitrailer it may be necessary to block freight inside the trailer to prevent the movement. Blocking reduces the chance of a load shift, which can cause a trailer to turn over and damage the cargo or injure a worker. Cargo doesn't have to be round to move, so block all four sides of the cargo separately. Use sound blocking material. Make certain that nails or spikes are long enough and the lumber is thick enough to prevent the cargo from shifting. Other freight should never be used as a block. When working on equipment don't rely on jacks or hoists to support the equipment. They are made to lift, not to support. The equipment should be blocked to support it while you are working on it.

The principal used in both chocking and blocking is the same: securing to prevent movement. Tips to remember:

  • Chock wheels at the rear axle.
  • Block freight inside the trailer when loading or unloading farm supplies.
  • Do not unhook farm equipment that has not been chocked.
  • Never put hands, fingers, etc., between equipment and blocks.
  • Double up and alternate the positioning of blocks while building the platform.
  • Use larger blocks on the bottom. Make the platform as wide as possible.

Review the Following Points

  • Rear axles need to be chocked.
  • Do not attempt to unhook farm equipment that has not been chocked.
  • Freight should be blocked when loading or unloading a trailer.
  • Other freight should not be used as a block. Use proper materials for blocking.
  • Keep hands and fingers from in between equipment and blocks.

About These Modules

The Ag Tailgate Training Series was developed by members of the Agricultural Safety and Health Program in the Department of Food, Agricultural and Biological Engineering. Revised by Dee Jepsen, State Agricultural Safety Leader, with editing assistance by Lisa Pfeifer and Cody McClain.

True or False Answer Key

  1. T
  2. T
  3. T
  4. T

Quiz: Chock and Block



True or False?    

1. There is no need to chock farm equipment before it is unhooked from the tractor. T F
2. The purpose of the chock is to pin the wheels and hold them stationary. T F
3. It is a good safety measure to block cargo inside trailers when loading or unloading. T F
4. When chocking a loaded hay wagon, chock the rear axle. T F
5. Cargo should be blocked separately.   T F





Originally posted Jul 15, 2019.