Beam trolley drop

Description of Incident

Incident 1

A manual gear trolley was reported to be partially disengaged from the monorail. No activity was carried out around the location at the time of discovery. Potential drop of 2.3 meters for a 52 kg weight.

Incident 2

A trolley was installed on the beam above a pump for its maintenance. The end stop was tested by the lifting team from the ground (i.e. 6 meters below) running it towards the edge. The trolley did stop yet there was no visual observation of its contact with the end stop. The following days, in the course of the maintenance activity, the trolley fell down on a nearby platform (3 meters below the beam). None of the 4 personnel presents in the vicinity were injured. Potential drop of 3 meters for a 40 kg weight.

Why it happened?:

In both cases it appears that the manual geared trolley when reaching the end of the beam was not stopped by the beam stopper due to the fact that the mechanical stopper was not wide enough to make contact with the trolley itself.

Good Practice Guidance

• Ensure that endstoppers are fitted on beams. Beams fitted without endstoppers shall not be used and marked accordingly onsite.
• Based on available documentation, ensure that the width of the endstoppers is adapted to the size of the monorail bottom flange and to the type of trolley.
• In all cases, ensure that the functional test including a visual check of endstoppers effectiveness is carried out after each trolley installation. Include this test within the site procedures