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Alert 12 - Swing stage scaffold—use of girder trolleys

This alert is to advise of a potential risk with the use of girder trolleys on swing stage scaffold.

Girder trolley


There is a potential safety risk with the use of girder trolleys on swing stage scaffold. Care is needed in the assembly process otherwise there is a danger to workers who are suspended on the scaffold.

Whilst operating a swing stage scaffold a worker noted that a girder trolley had become partly dislodged from a monorail support beam. This was caused by insufficient force being applied to spacer washers on the bolt which is centred between the two side plates of the trolley girder. This allowed the side plates to spread apart under load.

Girder trolleyAn investigation revealed that the nut used to compress spacer washers on the bolt shaft had been tightened only to the end of the thread on the shaft and not tightened against the washers. The spacer washers appear to have obscured the view of the end of the thread and this has tricked the workers during the assembly process.

Girder trolleySafety issues

  • To correctly install the trolley there must be sufficient force applied to the washers. This will stop the device spreading apart when placed under load. 
  • A specific quantity and/or length of washers must be used to ensure there is sufficient thread available to tighten the hanger pin nut and support the side plates under load.

Action required 

  • Assess your workplace to identify the number, types and manufacturer of girder trolleys in or available for use.
  • Consult with the manufacturer/supplier regarding the correct installation arrangement including the minimum number of spacer washers.
  • Ensure that workers have the minimum competency to install a girder trolley. High Risk Licence Rigger Basic is required for all load applications and Advanced Scaffolder if the girder trolley is being used in conjunction with a swing stage scaffold.
  • Girder trolleyProvide all workers that install such a device with this information, instructions and training so that all girder trolleys are installed, inspected and maintained in a safe condition when in use.
  • Obtain advice from a qualified engineer to ensure the correct force has been applied to the spacer washers. You may wish to use visible indicators (such as a spring washer) to clearly show compression has occurred and that the integrity of the device is sound.

Further information

Please contact Comcare's Regulatory Services team on 1300 366 979 or via email.


Page last updated: 04 Nov 2013