'False' engagement of tipping hooks on 'builders' skips

Health and Safety Executive - Safety alert

Introduction:

Skip containers are used widely across the waste and recycling industry.

This safety notice highlights a potential danger whereby fabrication of the skip can result in a lip on which tipping hooks may 'falsely' engage and provides advice on corrective actions.

Background:

It is a common arrangement for skips to be suspended by four chains attached in pairs to two loading arms on the lorry which straddle the skip. The loading arms are hydraulically actuated such that they either rotate forwards to lift the skip onto the lorry or backwards to off-load the skip onto the ground.

To tip-out a skip, the process is similar to off-loading except that a pair of tipping hooks, which are mounted towards the rear of the bed of the lorry, are raised and as the skip is pulled over them they engage on the tipping bar on the end of the skip near its base. As the lifting arms continue to rotate, the hooks hold the front end of the skip such that it begins to rotate and eventually reaches a near vertical position causing the load to slide out of the skip (see photograph 1)

There are no nationally established standards (eg British Standards) for the manufacture of this type of skip which are generally fabricated from steel plate. Often the base plate extends beyond the end plates producing a lip. A hazardous situation can occur if the tipping hooks fail to engage with the tipping bar but instead 'snag' on the lip (see photograph 2). This false engagement of the hooks is not necessarily visible from the operating position and, superficially, will behave like a proper engagement until an angle of tipping is reached whereby the hooks are pushed off the lip.  When the skip is no longer restrained it will swing-out over the back of the lorry, the momentum of which could lift the front of the lorry off the ground.

The potential for the lorry to overbalance is increased where there are shortcomings in the deployment, positioning or function of the stabilisers.

The immediate risk is to the operator because of their close proximity due to the controls being typically positioned at one side of the lorry.

Although there is not a nationally established standard, the Container Handling Equipment Manufacturers (CHEM) Association have produced a technical standard TS14 "Standard Specification for Skip Containers" which manufacturers should find useful. In section 4.6.3 it states, "There must be no projection of the base plate in the area of the tipping hook engagement with the tipping bar thus preventing inadvertent hooking on the skip."

Action required:

• Existing skips should be examined and where a protrusion exists that could give rise to false engagement with the tipping hooks it should be removed from that area and the fabrication made good.
• New skips should be manufactured without a protrusion that could give rise to false engagement with the tipping hooks (in line with the CHEM association standard TS14).
• Instruct driver-operators to perform a visual check to ensure the proper engagement of the hooks on the catch bar during tipping-out.
• Instruct driver-operators to routinely check skips and skip loader vehicles and to report any defects.

Relevant legal documents:

• Health and Safety at Work etc. Act 1974
• Provision and Use of Work Equipment Regulations 1998
• Lifting Operations and Lifting Equipment Regulations 1998
• Management of Health and Safety at Work etc. Act 1999
• Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995.

References:

• HSE (2005) Workplace transport safety, An employers' guide HSG136
• HSE (2003) Safe use of skip loaders, Advice for employees INDG378
• CHEM Technical Standard TS14 Standard Specification for Skip Containers
• CHEM Technical Standard TS16 Vehicles for the collection and transportation of wastes in bulk. General requirements and safety requirements - Skip loaders
• CHEM Code of Practice No. 2 The Safe Operation of Skip Vehicles

Further information:

Health and Safety Executive
Manufacturing Sector (Waste Management and Recycling Team)
Ty Glas
Llanishen
Cardiff
CF14 4SH
Website: Waste management and recycling

Container Handling Equipment Manufacturers Association (CHEM)
David Buxton, Honorary Technical Secretary
3 Berry Close
Faringdon
Oxfordshire
SN7 7FL

Email: [email protected]
Tel: 01367 244992
Website: CHEM - Container Handling Equipment Manufacturers Association (http://www.chem.uk.com)

General note:

Please pass this information to a colleague who may have this Product/ Equipment or operate this type of system/process.