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District 8 - Coal Mine Safety and Health
Info-Grams and Close Call Accidents

Close Call Graphic
Department of Labor
Mine Safety and Health Administration

Close-Call Info-Gram
MAY 2002

Erratic Movement of Miner
Switch Magnet Reversed

Recently, after routine maintenance of a TX-3 remote-control unit, a close-call incident occurred at a District 8 underground mine. During the maintenance shift, the remote-control unit's cover plate and membrane were removed. This was done to clean the switch wells and the rest of the unit. As the repairman removed the tram switches, a tram-lever magnet fell out. He reinstalled the magnet into the switch, but in a reverse direction. (Reversing a switch magnet will cause the corresponding miner track to move in the wrong direction.) After cleaning, the repairman reassembled the remote-control unit. He then checked the machine for proper operation by briefly actuating, (bumping) the control levers. At the beginning of the next production shift, the continuous miner operator started to move the machine forward. When the operator placed the controls in the forward direction, the miner tracks moved in opposite directions. This caused the continuous miner to slue around rapidly. The continuous miner operator was in a safe location; therefore, he was uninjured by this unexpected movement of the miner. The switches were Revision-B switches, and they are noted with a green marking.
Remote-Control Unit and Tram Switch
  • If Magnet is removed or falls out Replace the Switch, and test functions for proper operation.
  • When operating continuous miners, continuous miner operators should position themselves in safe locations before moving their machines.
  • When continuous miners are being moved, ensure that all persons are beyond the miner's turning radius.
  • Remotes can fail or malfunction at any time! Always be prepared for the unexpected.
  • The manufacturer is distributing redesigned switches for these remote-control units. The tram lever stems are gray, the magnets have retaining clips, and the tram lever boots are stepped.

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This file was last updated on 01/15/2003

This information was provided by concerned miners in an effort to eliminate accidents. Accident or "close call" information within District 8 may be shared by contacting the MSHA office at (812) 882-7617.