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OSHA Hazard Information Bulletins
Use of Improperly Sized Wedges and Sockets in Boom Anchor Systems

July 13, 1992




  • Director
  • Office of Field Programs


  • Director
  • Directorate of Technical Support


  • Hazard Information Bulletin - Use of Improperly Sized Wedges and Sockets in Boom Anchor Systems

The Directorate of Technical Support issues Hazard Information Bulletins (HIBs) in accordance with OSHA Instruction CPL 2.65 to provide relevant information regarding potentially unrecognized safety and health hazards; and inadequacies of materials, devices, techniques, or engineering controls. HIBs are initiated based on information provided by the field staff, studies, reports and concerns expressed by safety and health professionals, employers, and the public. Information is compiled based on a comprehensive evaluation of available facts and latest literature. HIBs are normally prepared in coordination with affected parties.

The Hartford Area Office investigated an accident involving a Link-Belt crawler crane. The accident occurred when a wire rope was released as a result of using a wrong wedge in the wire rope socket. The dead end of the wire rope was equipped with wire rope clips but did not prevent the wedge and wire rope from pulling through. The crane was lifting at or near its rated capacity at the time of the accident.

Link-Belt Construction Equipment Company manufactures both fractional (English) and metric dimensioned wire rope sockets and wedges for use with all sizes of wire rope as provided on their product lines. Fractional size, wedges and sockets are made in the United States and the metric dimensioned wedges and sockets are made in Japan.

The key factor in the accident was that the size of the wedge was not compatible to the wire rope that was in use. The wedge was physically smaller than the appropriate size for the wire rope, thereby allowing the wedge and the wire rope to pull through the back of the socket.

Link-Belt has issued to its known customers a technical bulletin in March, 1992 on affected models, tabulating the proper wedge part numbers, socket part numbers and the corresponding wire ropes of metric sizes. Link-Belt stated that the affected model cranes must be checked to ensure that the correct size wedges and sockets are installed.

As conversion to metric is rapidly increasing, compliance and consultation personnel should be aware of the potentially serious hazard of using metric components which are not equivalent to the original English sized ones. The manufacturer must be consulted regarding the proper metric replacement parts.

Please distribute this bulletin to all Area Offices, State Plan States and Consultation Projects.

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