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OSHA Hazard Information Bulletins
Hitachi EX3500 and EX1800 Hydraulic Excavators Equipped With Front Shovel Attachments

March 22, 1996




  • Acting Director
  • Directorate of Technical Support


  • Hazard Information Bulletin - Hitachi EX3500 and EX1800 Hydraulic Excavators Equipped With Front Shovel Attachments

The Directorate of Technical Support issues Hazard Information Bulletins (HIBs) in accordance with OSHA Instruction CPL 2.65 to provide relevant information regarding unrecognized or misunderstood health hazards, inadequacies of materials, devices, techniques, and safety 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 thorough evaluation of available facts, literature and in coordination with appropriate parties. HIBs are used as an outreach tool for accident prevention.

The Mine Safety and Health Administration (MSHA) forwarded to the Occupational Safety and Health Administration (OSHA) a draft Program Information Bulletin informing MSHA enforcement personnel and mine operators of a potential failure of bolt flanges utilized on the hydraulic system of the Hitachi EX3500 and EX1800 Hydraulic Excavators equipped with front shovel attachments. Recently, a hydraulic spool on a Hitachi 3500 Excavator was projected from its valve body, killing a miner. The Hitachi Construction Machinery (America) Corporation (HCMA) is presently assisting MSHA in investigating this incident. The purpose of this HIB is to familiarize OSHA personnel of the MSHA incident and to assist in recognizing similar situations at other workplaces.

Although the investigation has not yet been finalized and the cause of the bolt failure has not been determined, Hitachi decided to begin a modification program immediately on October 30, 1995, in consultation with MSHA. This program is intended to eliminate the possibility of a similar occurrence.

The program primarily consists of:

  1. Requiring that the four bolts be replaced by an authorized Hitachi dealer/representative. It is strongly recommended that operators do not attempt to replace the bolts themselves;
  2. Placing guards on the switch valve assembly;
  3. Asking that operators who wish to make some type of immediate interim correction do get guidance from an authorized dealer/representative.
  4. Asking that operators do not attempt to tighten the old or new bolts beyond recommended torque, as this could increase the likelihood of bolt failure.
  5. Although there is no guarantee that there will be an obvious indication that one of the bolts is failing, a hydraulic oil leak around the end cap could indicate that a potential fatigue failure is in process. If this should occur, immediately contact an authorized dealer/representative for instructions.

According to Hitachi, all bolts have been replaced, or are scheduled to be replaced, on all Hitachi EX3500 and the EX1800 machines operating in the United States. Guards have been installed on all EX3500s and on 90 percent of the EX 1800s. All EX1800 owners have been notified of the advisability of installing guards and several have elected to schedule this modification with routine maintenance procedures in the near future.

This bulletin may be used for accident prevention and outreach purposes. Please distribute this bulletin to all area offices, State Plan States, Consultation Projects and appropriate local trade and union groups for their information.

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