03.08.2011

Safety systems cause local drama

The safety systems on a modern boom lift caused a minor drama in the English town of Grimsby this week after it cut out, trapping two men some 15 to 20 metres in the air.

Unable to operate the machines emergency descent system due to the type of error, the Humberside fire and rescue service had to be called out to bring the men down with one of its platforms. A large crowd of spectators watched the drama unfold

The deactivated lift, a Genie Z80/60 articulated boom owned by rental company Peter Hird & Sons, was being used by the two men to carry out work on the roof of a commercial building that also houses the McDonalds restaurant in one of Grimsby’s main shopping streets in the town centre.
Please register to see all images

The men were working well out of sight of the machine's base

We understand that the men had been operating the machine tight up against the building and were well over the top of the façade and out of sight of the machine’s base.

The operator must then have either slewed, driven the machine forward, or lowered the top boom so that it came into contact with the top edge of the building’s façade, eventually lifting one of the machines wheels off the ground, activating the unit’s safety system and causing a lock-out.

With the lock-out mode activated the machine’s emergency descent system only allowed functions that would return the platform to the ground by the shortest route. This effectively prevented the boom from being raised so that it could be slewed clear of the building.
Please register to see all images

The boom came into contact with the top edge of the building to such an extent that it lifted a wheel off of the ground

Hird technicians were eventually aided by a Genie engineer who managed to override or, rather bypass/’trick’ the system, so that the top boom could be raised bringing the machine’s chassis back into four point contact with the ground, at which point the lock-out system could be reset.

Once the platform was back at ground level a full inspection was carried out and no faults where found. It has now been shipped back to Hird’s depot for a full inspection of the damage done to the boom section and any other structural components downstream that may have been subjected to extra stresses.

Vertikal Comment

This is an interesting case in that a machine in perfectly good working order put its users in a compromising position. Yes it is true it is without question a case of operator error, however in the past two factors would have prevented such a case from causing so much cost and drama.

1. Machine overload or lock-out systems used to allow any function that did not reduce the machines stability. This would often allow an extended boom to be raised but not lowered – the opposite of what occurred here.

2. When CE rules first came into force boom lifts had to have emergency descent system that could lift their booms and slew as well as simply come down. Hand pumps were installed on some models to allow this to happen, even if it was extremely hard and very slow work, the fact is it could be done.

It seems that this is no longer a requirement. There is an argument of course that it is better to take the occupants out of the platform and then worry about bringing such a machine down.

If this had been a higher model however it may have been a real challenge to find a fire platform high enough locally to reach the men.