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Re: What prevents modern locomotives from overheating in long tunnels?
Author: Railbaron
Date: 09-07-2018 - 13:44
Trust me, these "new" units do overheat, de-rate, and shut down - there is no avoiding that. The one thing that helps avoid this is speed - get through the tunnel before bad things happen. The newer computer systems also help tremendously as they will control loading to maximize power.
As "Hot Water" pointed out, as units reach predetermined temperatures the locomotives will de-rate in an attempt to maximize tractive effort and avoid overheating. Unfortunately this results in loss of speed, creating more overheating issues. If the unit reaches a high enough temperature, or the oil is thinned due to over-heating, the unit will shut down.
Compounding the problem is that as trains operate through tunnels trailing units are ingesting dirty air from units ahead. This dirty, super-heated air, causes additional loss of power, again compounded by reduced speeds.
For many years up here (Cascade Subdivision on the SP/UP in Oregon) we had an unwritten rule that for the most part crews followed: if you couldn't maintain a minimum 16 mph on the hill you didn't go. There were a few idiots who would go slower and often as a result they'd get "gassed" in the tunnels or even stall shutting everything down; I guess they figured they'd be a hero for getting an over-tonnage train up the hill, never-mind they were sacrificing their, and their conductor's, health.
As "Hot Water" pointed out, as units reach predetermined temperatures the locomotives will de-rate in an attempt to maximize tractive effort and avoid overheating. Unfortunately this results in loss of speed, creating more overheating issues. If the unit reaches a high enough temperature, or the oil is thinned due to over-heating, the unit will shut down.
Compounding the problem is that as trains operate through tunnels trailing units are ingesting dirty air from units ahead. This dirty, super-heated air, causes additional loss of power, again compounded by reduced speeds.
For many years up here (Cascade Subdivision on the SP/UP in Oregon) we had an unwritten rule that for the most part crews followed: if you couldn't maintain a minimum 16 mph on the hill you didn't go. There were a few idiots who would go slower and often as a result they'd get "gassed" in the tunnels or even stall shutting everything down; I guess they figured they'd be a hero for getting an over-tonnage train up the hill, never-mind they were sacrificing their, and their conductor's, health.
