Learn about the MMA Locomotive defect that set the stage for the Lac-Mégantic wreck

Post by Jon Flanders, retired rail machinist.

“Non standard repair” of the broken out bore housing the cam bearing of the Lac-Mégantic locomotive that caught fire and led to the disaster is the understatement of the century. Take a good look at what the capitalist profits above all mentality looks like. Without strong unions behind the maintenance forces on the railroads standing in the way of “repairs”like this, expect more Lac-Mégantics.

“Following the accident, the locomotive consist was moved from Lac-Mégantic to a maintenance facility in Saint John for examination. A partial engine teardown of MMA 5017 was conducted (see Engineering Laboratory Report LP181/2013 for complete details). It was determined that the cam bearing had fractured when the mounting bolt was over-tightened after the cam bearing had been installed as part of a non-standard repair to the engine block. This temporary repair had been performed using a polymeric material, which did not have the strength and durability required for this use (Photo 14). Failure of the cam bearing reduced the engine oil supply to the valve train at the top of the associated power assembly. The decreased lubrication led to valve damage and eventually to a punctured piston crown. The damaged valves and piston crown allowed engine oil to flow into the cylinder and the intake and exhaust manifolds. Some of the engine oil collected in the body of the turbocharger. The engine fire later occurred in the exhaust stack due to the build-up and ignition of engine oil in the body of the turbocharger.”

from: http://www.tsb.gc.ca/…/rapp…/rail/2013/r13d0054/r13d0054.asp

Photo 14. Polymeric material applied to cam bearing bore and fractured cam bearing Photo of the polymeric material applied to cam bearing bore and fractured cam bearing

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