How to hook up a safety chain link to a trailer

Updated February 21, 2017

Trailers serve a variety of uses, from carrying equipment to hauling cars or other vehicles. Trailers are connected to a tow vehicle with a trailer hitch and an electrical cable for brakes and lights. Federal and state laws require safety devices, including brake systems and safety chains. Safety chains are critical devices that prevent loss of control of a trailer should it disconnect from the tow vehicle.

Chock one trailer wheel. Jack up the trailer tongue with the tongue jack or a floor jack. Support the tongue with lumber or blocks.

Attach the safety chain to the trailer behind the tongue with a high-strength bolt, nut and washers. Use bolts with large heads or washers to prevent the safety chain from pulling through the bolt under load. Tighten the bolt and nut with a socket wrench and crescent wrenches.

Adjust the safety chain length to prevent it from dragging on the ground. The chain length should also prevent the trailer from dragging on the ground if it disconnects from the tow vehicle.

Connect the trailer to the tow vehicle. Back up the trailer from side to side and confirm the chain length will permit a 90-degree turn in either direction. This should be the maximum chain length allowed for the safety chains.

Inspect all connections and chain-mounting hardware. Connect the chains every time you tow the trailer.


Always cross the safety chains under the trailer tongue when connecting the trailer to the tow vehicle. The crossed chains will catch the tongue and prevent it from dragging if it disconnects from the vehicle.


State and local transportation laws may regulate the size and type of chains required for towing. Review applicable laws if you are designing your own chains. Many states also require positive locking devices to connect the chains to the vehicle; open "S" hooks may not be permitted. Remove chain links with bolt cutters to shorten the chain. Do not wire or weld the chain together to shorten it.

Things You'll Need

  • Socket wrench
  • Crescent wrenches
  • Wheel chocks
  • Floor jack
  • Lumber or blocks
  • Bolt cutters
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About the Author

Paul Richard began writing in 2002 after a career in chemical processing, refrigerant alternatives and workplace safety. He has written articles for the "Cecil Whig" and "Air Conditioning, Heating and Refrigeration News." Richard holds a Bachelor of Science in chemical engineering from the University of Akron.