Defective Brake Chamber

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R. Scott King, BSME ::::

Case Synopsis: A vehicle operator and her passenger were seriously injured after the vehicle she was operating was struck by a tractor-trailer that had proceeded through a red light located at the bottom of a long hill.  The commercial vehicle operator advised the investigating officers that he had applied his brakes well in advance of the approaching intersection; however, as he approached the bottom of the grade, it became clear to him that he was unable to stop.  He also indicated that his brakes had operated normally in the hours preceding the collision although later admitted he had not encountered a hill as steep and as long as the incident grade.

Expert Analysis: A post-incident vehicle inspection revealed that one of the tractor’s brake chamber mechanisms was “caged”, a term indicating mechanical disablement of a spring brake.  Moreover, the air line leading to that same brake chamber was disconnected and “plugged”, thus effectively disabling all braking from that device.  Both conditions were quite unusual for an in-service tractor, as they are typically associated with temporary, service-related procedures. A review of the vehicle service records, produced during discovery, revealed that the tractor had been serviced during an emergency, road-side repair to remedy a leaking brake chamber.  In particular, service personnel determined the brake chamber was leaking and disconnected it to permit safe travel to the nearest repair facility.  Subsequent testimony, however, revealed that the trucking company, which is responsible for vehicle maintenance, failed to follow through with the required repairs.  Rather, the vehicle remained in use until the day of the incident.

Conclusion: Engineering analysis included a review of the available witness testimony; vehicle service records and specifications; satellite-based vehicle tracking data; information; and site documentation.  Significantly, the satellite data indicated the location on the hill the operator applied his brakes.  This information, along with data describing the truck’s normal braking characteristics, provided the basis for the conclusion that the disabled brake chamber
created abnormally long stopping distances, and was a proximate cause of the incident, thus facilitating a pre-trial settlement.

 

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