Platform lifts (vertical lifting platforms), like traditional passenger lifts, provide access between floors. They are hydraulically, or electrically powered and usually operate over two to three floors. They are normally operated by hold to run buttons and are slower than a conventional passenger lift. A door at each landing stops persons gaining access to the lift well, which should not open unless the platform is at that landing.
What happened
During a recent investigation, the HSE have gathered evidence of tampering and “inappropriate maintenance” to door switches or unlocking zone bypass switches, leading to doors at landings being able to be opened when the platform is not at that landing. This has subsequently allowed people access to the lift well when the lifting platform was not at the same landing, putting them at significant risk of falling from height or being crushed.
Three specific incidents concerning the use of Nami-lift 400 platform lifts installed between September 1999 and December 2006 raised particular concern as these lifts incorporate Bowden cables (a flexible cable used to transmit mechanical force or energy by the movement of an inner cable relative to a hollow outer cable housing) to control the door locks, which are more susceptible to incorrect adjustment. It was also identified that wear or inappropriate maintenance can lead to:
- Bent door lock switch contacts – The contacts on door lock switches have been bent to increase the switch contact force; however, this can prematurely signal to the control system that the door is locked, allowing operation of the lift platform when the locking pin is only partially engaged with the latch plate.
- Shortened door lock pins which do not provide adequate engagement with the door lock plate, allowing the door to be opened.
- Incorrect adjustment of Bowden cables.
- Missing screws securing door locks and latch plates.
- Poor adjustment of unlocking zone bypass mechanisms, meaning that the switch remains permanently activated, allowing the platform to travel between floors with the landing doors open.
- Damage to doors and door frames resulting in poor door alignment.
What needs to be done
Lift maintenance companies should:
- Ensure maintenance activities are undertaken by competent personnel; in line with the manufacturer’s instructions and / or guidance; and in accordance with a safe system of work.
- Ensure maintenance of the safety elements of the lift do not affect its safe operation.
- Ensure modifications intended to keep a lift operating which may result in unsafe operation are not be carried out under any circumstances.
Owners and operators of vertical lifting platforms should:
- Review maintenance and inspection procedures to ensure that these tasks are carried out by persons competent to do so.
- Introduce simple tests into daily checks (carried out by a competent person) for the lifts to confirm that:
- Landing doors cannot be opened when the platform is not at the same level and;
- The platform cannot travel without the doors closed and locked.