Abstract: The propulsion control system of a diesel-electric locomotive includes means responsive to the respective temperatures of the coolant and the lubricant of the locomotive engine for automatically indicating that the locomotive is in a tunnel if the coolant temperature exceeds an abnormally high magnitude and is higher than a variable reference level that depends on the lubricant temperature. When a tunnel is thus detected, the conventional overtemperature-responsive deration function of the propulsion control system is temporarily suppressed until the coolant temperature rises to a threshold that is higher than the preset overtemperature threshold at which deration is normally initiated.

Abstract: In a diesel-electric locomotive, the power demand of electrically driven auxiliary equipment is automatically increased in response to the temperature of the diesel engine falling to an undesirably low level so as to load the engine when idling and thereby cause it to produce extra heat which prevents abnormal wear and excessive fuel consumption.

Abstract: In a diesel-electric locomotive, maximum speed of the diesel engine is automatically limited as a function of the temperature of the engine lubricating oil so as to prevent damage to the engine, to the engine-driven lube oil pump, and to the external components of the engine lube oil system when the oil is relatively cool and hence very viscous.