Electric Hoist Failure

1. RWE npower Safety Information Notice
SI 2011.15: Electric Hoist Failure at Tilbury
Date Issued: 22/08/11 Author: Gordon Clive / External
Please see below for information received via Gordon Clive regarding the recent Electric Hoist failure at Tilbury
which was reported to the HSE as a Dangerous Occurrence.
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On the 2 July, Doosan Babcock staff were lifting steel plates from the +9 foot level (Station floor level) to the
precip level to enable ducting repairs to be carried out. A barrier had been erected and work commenced. Several
loads had been raised without a fault.
The load on the 1 tonne electric hoist was 494 kilos. When the load neared the height required it suddenly dropped
then stopped then dropped again. The load was lowered to the ground and the work stopped until another hoist
could be used. A RIDDOR report was sent to the HSE.
The precip hoists generally only get used during outages. The hoist was inspected in August 2010. This would have
been a visual inspection by the insurance inspector and our lifting specialist.
Konecranes carried out an investigation on the Morris 360 series Electric Chain Hoist.
Findings:
• Stripped hoist and found brake to be in order.
• Found castle nut on clutch had sheared its split pin and undone.
• Found leak on gearbox resulting in gearbox oil level to be low.
• Hoist used infrequently with intervals up to 6 months.
• Hoist on open roof top where it is unshielded to all weather conditions.
Conclusion:
The clutch tension securing nut had become loose, the castellated nut split pin had sheared allowing the nut to
become loose, therefore unable to sustain the load. Konecranes have no previous record of this type of failure on
the Morris 360 series Electric Chain Hoist. How the split pin sheared is unknown.
Recommendations:
• The hoists should have a thorough inspection every 12 months, access provided and covers removed, oil levels
checked and changed. Follow manufacturer’s guideline check sheets for maintenance.
• Hoists on beams where they are exposed to the weather should have weather protection hood fitted.
• The electric motors will have a usage rating assigned to each unit.
• This rating will be made visible to the hoist operator. This will ensure the hoist is not used more than the
specified working times and cause a fault.
SI 2011.15
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2. SI 2011.15
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