A safety alert has recently been issued by the HSE on the 20th February 2014 regarding tower crane storage. It had been reported that three luffing jib tower cranes have collapsed in high winds. The HSE has made available supplementary guidance as part of the code of practice for the safe use of tower cranes. Luffing tower cranes are cranes that are designed to work near high buildings and in tight spaces. The ‘jib’ is the horizontal arm that extends from the slewing unit, this unit is the engine that sits at the top of the mast and enables the crane to rotate. A luffing crane has a hinged jib (as in photo above). This allows the hook of this crane to move up and down as the jib moves (or luffs). These cranes are advantageous to use in overlapping slewing areas as they don’t require a huge amount of space.

As regards safety in the storage of ‘out of service’ tower cranes, the slew brake must be on and the jib at the correct out of service radius. If the brake is engaged and the jib not at the correct angle, very windy positions could cause the crane to move and swing and so cause damage to nearby structures and/or collapse of the crane. The crane must be stored in such a way that disables it to free slew in high winds.

There are various kinds of cranes including aerial, terrain, truck-mounted, mobile, crawler, floating and luffing cranes, among others. Cranes can cause bodily injuries, fatalities, as well as property damage. So a general safe system of their usage is critical. All tower cranes should be fitted with an automatic safe load indicator. All brakes on the tower crane must be fail-safe and checked periodically as per manufacturer’s instructions. If there is a power loss the brake must be automatically applied for safety. The cabin where the operator sits should be designed to protect them and the lifting machinery should be constructed so it’s easy to use. Means of access to and from the cabin should be easy with guardrails in place. There must be jib stops to prevent the arm of the crane being pulled down over the tower. The installation of the electrical provision for the tower crane should meet the electrically regulations for fixed installations. Tower cranes should have built in devices that prevent damage to the operator(s) and the crane should there be a human error. The condition of the slew drive motors and gearboxes must not have deteriorated so that the crane is prevented from slewing freely. There must be a system in place to warn the operator as to whether the jib is in the correct out of service radius and the slew brake status. The buildings under constructions and other cranes should be checked periodically so that the tower crane is not prevented from free slewing.

The legal responsibilities for the operation of storage cranes include the Provision and Use of Work Equipment Regulations 1998 and the Management of Health and Safety at Work Regulations 1999.

 

Sources   hse   wikipedia    liebherr   labour.gov

 

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