Re: NNG: D&RGW 5401 Move
| August 25, 2018 01:19AM |
|
Chris Webster Wrote:
-------------------------------------------------------
>
> My understanding is that is a myth and the real
> difference is the positioning of the fan with
> respect to the radiators. While I'm not a diesel
> expert (just a modeler) here is my understanding
> of how air flows thru the units:
>
> Regular SD40-2: Intake --> Radiator-->
> Fan-->Exhaust
> Tunnel Motor: Intake --> Fan -->
> Radiator-->Exhaust
>
> In a regular SD40-2, the fans are pulling air
> off of the radiator.... while the fans are
> blowing onto the radiator in a tunnel
> motor.
>
> Blowing air onto a radiator provides more
> efficient cooling than pulling air off a radiator,
> which is why EMD reused the design on small units
> (GP15-1 and MP15AC) that were never intended for
> mountainous/tunnel service!
No Chris, Brian is correct.
The GM domestic design upper car body radiators with roof mounted fans were the problem, and like I said in my post previous to your, the major increase in HP of the units was the problem. SP's EMD SD-45X at 4200HP still built the same way with radiators at the top side of the carbody. GE has always done the blow it from down below upwards out the top, likewise on the Tunnel motors the air is drawn off at running board height. Fans are rated at CFM sucking or blowing.
And the GP-15/GP-15T/MP-15 were redesign consolidation using the proven radiator assembly as used on GM's Export line.
Our GE DX's when once upgraded to 3300HP and used in 5-6 unit sets on the 1in33 Otira Tunnel, required to have the Central Equipment Blower air intakes and the Compressor air intakes ducted to get cleaner, cooler air from below the running board height.
see This Comparison Picture of DX and DXC
-------------------------------------------------------
>
>Quote
BrianJ
The tunnel motor variety drew cool
> air from the bottom of the tunnel.
> My understanding is that is a myth and the real
> difference is the positioning of the fan with
> respect to the radiators. While I'm not a diesel
> expert (just a modeler) here is my understanding
> of how air flows thru the units:
>
> Regular SD40-2: Intake --> Radiator-->
> Fan-->Exhaust
> Tunnel Motor: Intake --> Fan -->
> Radiator-->Exhaust
>
> In a regular SD40-2, the fans are pulling air
> off of the radiator.... while the fans are
> blowing onto the radiator in a tunnel
> motor.
>
> Blowing air onto a radiator provides more
> efficient cooling than pulling air off a radiator,
> which is why EMD reused the design on small units
> (GP15-1 and MP15AC) that were never intended for
> mountainous/tunnel service!
No Chris, Brian is correct.
The GM domestic design upper car body radiators with roof mounted fans were the problem, and like I said in my post previous to your, the major increase in HP of the units was the problem. SP's EMD SD-45X at 4200HP still built the same way with radiators at the top side of the carbody. GE has always done the blow it from down below upwards out the top, likewise on the Tunnel motors the air is drawn off at running board height. Fans are rated at CFM sucking or blowing.
And the GP-15/GP-15T/MP-15 were redesign consolidation using the proven radiator assembly as used on GM's Export line.
Our GE DX's when once upgraded to 3300HP and used in 5-6 unit sets on the 1in33 Otira Tunnel, required to have the Central Equipment Blower air intakes and the Compressor air intakes ducted to get cleaner, cooler air from below the running board height.
see This Comparison Picture of DX and DXC
Sorry, only registered users may post in this forum.
488 stops for water at Los Pinos tank on closing day Oct. 1979. Photo courtesy Don Richter
The NGDF was started by Don Richter and is currently operated in his memory by Nathan Holmes and others. Others who have contributed to the upkeep of this board are (in no particular order): Charles McCandless, Everett Lueck, Ted Wilton, Cole Adams, James Bane, John Moellmer, Jon Bentz, Linn Moedinger, lloyd lehrer, Rod Jensen, John Craft, Steven Forney, Herb Kelsey, Bill Ramaley, Russ Sperry (El Russo Loco), Josh McNeal, John West, Jim Armstrong, Bob Bergstrom, Greg Scholl, Blake Forbes Doug van Veelen and Mark Fuller.