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Re: PC: GP38/GP40 "blower hatch"

> GP20's and SD24's also had the buldge  on the left side of hood
> indicating unit was turbocharged where as non-turbo GP18 and SD18 did
> not have the bulge and both models used the same frames and bodies.
> EMD also made "all" GP30's appear as if they were dynamic brake
> equiped even though some lacked the feature. That did not mean they
> had dynamic brakes. Turbochargers on all EMD roadswitchers is behind
> the cab. None of the EMD data I have indicates this buldge to be used
> for air to traction motors.

There was a difference in the carbodies of EMD locomotives starting
with the GP30s and SD35s. These units and the ones following them had
the blower duct. It was not a round bulge like on the SD24, or a 
square, louvered bulge like the GP20, but a vertical duct that stuck
out from the hood to carry air to the duct which ran on the walkway
on the fireman's side of the locomotive. The blower bulge on GP30s
and later doesn't resemble the turbocharger bulge on the GP20 and SD24.
See the following picture 


from the PC web site. The blower duct bulge has the faded PRR Keystone
on it. Follow it down and see how it runs into the tractor motor blower
duct on the walkway. The duct goes forward and dumps out air onto the
tractor motors roughly underneath the cab and battery box. It also
extends back to the handrail stanchion under the "CR" stencil, where
is blows the air onto the rear tractor motors. The following view from
the rear of a GP40 also shows this:


Now let's take a look at a GP20. There's a photo of a AT&SF one at:


This has the turbocharger bulge on the side, but notice that it's a
different shape than a blower bulge. Also, it has louvers for cooling
the turbocharger, which you wouldn't have if the bulge was an air
duct, like on GP30s and later.

A note on the GP30's--the enclosure on the top of the hood was part of
the styling of the locomotive (back when they cared about locomotive
styling). You could tell if a unit had dynamics or not--the units with
DBs had a grille at the top of the hood, while the non-DB units did
not. Compare photos of PRR and NYC GP30s as an example. (I couldn't find
any web photos of non-dynamic equipped GP30s to show as an example.)
Hope this helps!


Jerry W. Jordak               The boxcars and flatbeds, whistle blowin' steam
mailto:jer@smellycat.com      That was yesterday
http://prozac.cwru.edu/jer/   Now those big trains don't come anymore
Acts 16:31   <><                  -- Restless Heart, "Big Iron Horses"

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