On EMD units the temperature of the coolant is maintained by controlling the
amount of outside air passing through the radiators. The method of controlling
air flow employs an assembly of temperature activated shutters. The shutters
are opened and closed by pneumatic actuators that respond to a thermostat
inserted in the coolant.
This arrangement is satisfactory in the vast majority of situations encountered
by locomotives. Those situations involving extremely low ambient temperatures
or prolonged periods of idling cannot be satisfactorily handled by shutters
alone. In these conditions a "high idle" is used (notch 3) to generate a bit
more heat. Shutting-down a unit in freezing weather is avoided whenever
possible due to the fact that the entire cooling system must be drained.
Currently no anti-freeze is used in locomotive cooling systems on the RR that
still uses the "B" in its name.
In the "good ol' days" at Aurora RH the units and the boilers were kept running
all night to prevent freezing. Aurora RH, by the late 50's, had no source of
steam except for the E's. A unit was usually backed into no. 5 stall and
connected to RH steam lines to serve the needs of the engine cleaners. (A
member of this list nearly had his auto buried in a pile of bricks that once
was the wall of 5 stall.) As a result of the units and boilers running all
night the 2nd. trick Hostler would be required to fuel and water the engines in
the morning before they headed up to the depot. This was a real pleasant chore
at 0400, in minus 10 to 15 degree weather. If you got a back-flow from the
water connection your coveralls would be frozen STIFF before you could make it
to the RH office.
Karl
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