Winterization Hatches

[GP-9_Man11786]

I've noticed that older Geeps tend to have winterization hatches over one of their cooling fans. I was wondering what purpose it served. Why don't modern locomotives have them?

[trainfan1221]

Some of them did, notably GP7 or 9 types.  Not all of them though, I think railroad preference and maybe climate were a big factor.   I do believe that occasionally some more "modern" units had them,I have seen SD40-2 locos with them and others.  I believe one railroad that used to do this was SOO line.

[Railway Man]

I've noticed that older Geeps tend to have winterization hatches over one of their cooling fans. I was wondering what purpose it served. Why don't modern locomotives have them?

The purpose of the winterization hatch is to redirect hot air back into the engine room to increase the ambient temperature and reduce risk of coolant freezing and fuel gelling.

EMDs E, F, GP, and SD series locomotives use A.C. motor-driven cooling fans (except the FT which had mechanically driven fans).  The cooling fans are controlled by a thermostat.  When the locomotive is just starting and cold, or idling and outside temperatures are cold, the coolant temperature is low and none of the fans need to operate.  As coolant temperature increases, the fans turn on sequentially to increase air flow across the radiator cores and reject heat into the atmosphere at a higher rate.  When the locomotive is at full load all the fans will soon turn on.  Typically the #1 cooling fan -- the furthest to the rear of the locomotive (but the closest to the front of the engine as the engine is backward in the locomotive) is the first one to turn on, but the cooling fan control panel allows this order to be changed at the railroad's discretion.  The winterization hatch is placed over the #1 fan.  It consists of nothing but a manually operated damper with a winter/summer setting and a plenum to redirect hot air back down through the roof of the locomotive into the engine room.  With the damper in the summer position the damper is open and the fan works normally, pulling outside air across the radiator where it absorbs heat, and exhausting it into the atmosphere.  With the damper in the winter (closed) position all the exhaust heat from the #1 fan re-enters the engine room.  As the engine gets hot in the winter, the other fans activate and work normally to exhaust heat to the atmosphere.  The winter/summer setting is changed by the roundhouse forces at the appropriate time of year.  In the summer it must be open as all the fans will be needed to cool the engine.

In general only EMDs with open, non-pressurized engine rooms such as Es, Fs, SD7-SD24 and G7-GP20 were equipped with the winterization hatch as the subsequent EMDs with pressurized engine rooms and centralized air supply system do not have engine rooms that are wide open to the outside air.  Some pressurized EMDs operating in very cold climates such as Canada and Alaska, however, have winterization hatches.

GEs had pressurized engine rooms from the beginning (except the experimental units) and do not require this feature that I am aware of, but I never turned wrenches on a GE.

RWM

[CShaveRR]

I've noticed that older Geeps tend to have winterization hatches over one of their cooling fans. I was wondering what purpose it served. Why don't modern locomotives have them?

An inaccurate generalization.  CNW's SD60s (which I believe were a cancelled Soo Line order) were equipped with winterization hatches.  I've lost track of them after UP unloaded 'em, but that ought to be a spotting feature.

[beaulieu]

Soo Line and Oakway SD60s had them as built, most have been removed from both groups.