Safety alert on scissor lift table chocks

WorkCover NSW has issued a safety alert on scissor lift table chocks following a fatal incident when a person was crushed beneath a scissor lift table while repairing the hydraulic system. The alert provides information about a potential crush hazard that exists when working on scissor lift tables. An investigation found that the maintenance chock, used to hold the table in the raised position, could be released without first having used the hydraulic system to lift the table off the chock. If the hydraulic system is not holding the load of the raised table, this action could cause the scissor lift table to collapse suddenly.

Contributing factors

When performing maintenance or repairs on scissor lift tables, the following factors can contribute to an injury:

• Failure to develop safe systems of work for the task.
• Failure to correctly implement the manufacturer’s instructions.
• Inadequate training or supervision for those performing the task.
• Performing work in a location that restricts access to the system components.
• Releasing the maintenance chock before the load is taken by the hydraulics.
• Scissor lift table chocks.

Action required

Employers, workers, designers, manufacturers and controllers of plant should note the following recommended actions for minimising the potential for injury when performing maintenance on scissor lift tables:

• New scissor lift tables should be designed so that the maintenance chock cannot be released if it is still supporting a load - eg, by interlocking, or by designing the chock so that it is held in place until the table platform is raised (eg, a double-action mechanism). 
• Employers should instruct workers not to release maintenance chocks until the hoist has been raised free of the chock, thereby verifying that the load is supported by the hydraulic system.
• Controllers of plant should ensure that scissor lift tables are positioned in a location that provides safe access and egress for maintenance and repair work.
• Employers undertaking repair and maintenance work on hoists (especially at sites remote from their main place of business) are to ensure safe work procedures are developed, implemented and communicated to workers.
• These procedures should take into account the conditions where the plant is located and the instructions from the manufacturer’s operating manuals.
• Employers must ensure that workers are trained and competent to carry out repair and maintenance work allocated to them by ensuring they have the necessary skills, knowledge and experience required, and assessing their ability to perform the tasks in accordance with safe work procedures.
• Employers should verify that repair and maintenance tasks are conducted in accordance with safe work procedures.

For further information, see AS1418.8 - 2008 Cranes, hoists and winches - special purpose appliances.