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Alert 15 - Towing trailers using plant not designed to tow, and trailer landing leg safety

This alert highlights the potential risks when releasing the brakes of a trailer when it is not connected to a prime mover, towing a trailer with plant that is not designed to tow, and designing and using landing legs.

September 2014

This alert highlights the potential risks when:

  • releasing the brakes of a trailer when it is not connected to a prime mover
  • towing a trailer with plant that is not designed to tow
  • designing and using landing legs.

This alert focuses on trailers but similar risks and control measures may apply to other wheeled vehicles. However, this alert does not cover the safety issues involved when loading and unloading trailers with forklifts.


A man sustained fatal injuries in 2012 when he was crushed by a trailer he was working under. He intended to tow the trailer using a crane by suspending the front of the trailer from the crane using chains. While under the trailer, the brakes were released and the trailer moved forward causing the landing leg to fold back to its travelling position. As a result, the front of the trailer fell onto the man, fracturing his leg and spine, and crushing his chest.

Major hazards

The major hazards involved in this task include:

  • The possibility of being crushed by moving wheels, between the trailer and another object, or under the trailer if the landing legs give way.
  • Uncontrolled movements of the trailer or the towing vehicle due to inadequate braking force to control both units.
  • Instability when either the trailer or towing vehicle move relative to the other.
  • The capacity of the landing legs is exceeded—for example, the landing legs don’t have the capacity to support the trailer with a full load.
  • The landing leg can’t be secured into a fixed vertical position.

Contributing factors

  • The brakes of the trailer were released before ensuring the trailer could not move.
  • The air receiver was connected directly to the brake system to release the brakes and there was no way to control the air pressure and supply to the braking system—for example, dumping the air in case of an emergency.
  • The landing gear was not secured in a vertical position, which allowed it to fold to its travelling position.
  • The landing gear was not designed to lock into a vertical position.

Action Required

  • Identify and eliminate the hazards, or control the risks if they can’t be eliminated.
  • To manage risks, use information from the manufacturers, safety alerts, technical standards, knowledge gathered through experience, and site specific safety issues.
  • Consult with all relevant parties, including workers.
  • A person with management or control must take all reasonable steps to ensure that plant is used only for the purpose for which it was designed, unless the person has determined the proposed use does not increase the risk to health or safety.

Related risks and suggested key control measures

  • Plant not designed to tow should generally not be used for towing as foreseeable risks are involved. For example, ad-hoc towing arrangements may well require trailer wheels to freewheel—that is, move with the trailer braking system bypassed.
    In other words using an item of plant not designed for the purpose it is being used for when that involves towing presents many foreseeable risks which need to be adequately managed. These risks include:
    • lack of sufficient braking capacity to serve both units
    • jack-knifing when the brake is applied
    • likelihood of uncontrolled movement of the trailer including swinging movement beneath the suspension point
    • potentially having to increase the working radius of the crane sufficiently to create risk of structural or stability hazards, particularly when using a crane to tow a trailer under ad-hoc situations.
  • Before using plant that is not designed to tow a trailer, whether such action is absolutely necessary should be considered—for example, is it possible to bring the equipment required to repair a trailer to the trailer, rather than tow the trailer to a workshop for repair?
  • Where the need to tow a trailer under ad-hoc conditions is completely unavoidable, trailers that are not connected to a purpose-built towing vehicle should always be secured against unwanted movement at all times—for example, by using a fail-to-safe state braking system or adequate chocks.
  • Trailer landing legs should be able to be locked in a desired position.
  • Trailer landing legs that can’t be locked in the vertical position should be retrofitted with a locking mechanism. The new system should be designed and fitted by a competent person who has experience in trailer design in consultation with the trailer manufacturer. Any associated welding on the trailer should not be undertaken without first assessing and managing the risks from the effects of heat on the strength of the sections to be welded.
  • The locking mechanism on trailer landing legs should be capable of handling the designed loads.
  • The design of trailer landing legs should take into account reasonably foreseeable misuse.
  • Trailers should always be parked on level ground, or parked within incline limitations the manufacturer of the trailer allowed in its design.

Note: The above recommendations do not preclude a mobile crane towing trailer being designed for towing by the crane.

Further Information

This Alert contains safety information following inquiries made by Comcare about an incident or unsafe work practice. The information contained in this Alert does not necessarily include the outcome of Comcare’s action with respect to an incident. Comcare does not warrant the information in this Alert is complete or up-to-date and does not accept any liability to any person for the information in this report or as to its use.

This Alert was developed from material supplied by and is reproduced with the courtesy of WorkCover NSW.


Page last updated: 22 Feb 2019