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Locked More SOU SD40-2 Questions

David Friedlander
 

Hi all,

I'm helping 3rd Rail in another round of drawing review to help finalize the as-built SD40-2 drawings for SOU.  They are planning to only produces models within the first batch, 3201-3208.  I found a few flaws, but plenty of time to get them addressed.

I am curious on four things I came across though, only one of which I need an answer for to help with the review:
1. For my review - Were oval cab vents added to the engineer's side of the cab later on, or were they there from the factory?  Every photo I have says yes and that they were on the right.

Just for my general knowledge:
1. On the engineer's side, There is a curious rectangular box in front of the cab.  Possibly has a lid on top.  What is that for?
2. On the engineer's side, There is a small "box" with a white dot in the center that protrudes from the carbody right where the step in the frame is toward the end of the long hood.
3. On the engineer's side, Next to the jackpad, there is a separate beam that holds a chain.  Is that the brake chain? If not, what is that for?

This image helps illustrate everything I mention: https://www.dxinstalls.com/wp-content/uploads/2017/11/Scaletrains-EMD-SD40-2.jpg (although the cab vent is on the left for this particular model.)

Thanks for the information!

David Friedlander
NY, NY
D. Scott Chatfield
 

>  1. For my review - Were oval cab vents added to the engineer's side of the cab later on, or were they there from the factory? Every photo I have says yes and that they were on the right.

 

> Just for my general knowledge:

> 1. On the engineer's side, There is a curious rectangular box in front of the cab. Possibly has a lid on top. What is that for?

 

I'm assuming you're talking long hood forward.  If so, sounds like the box in question is the Electrial Cabinet Air Filter Box, or ECAFB for short.

 

> 2. On the engineer's side, There is a small "box" with a white dot in the center that protrudes from the carbody right where the step in the frame is toward the end of the long hood.

 

Sounds like the walkway light, which illuminates the step.

 

> 3. On the engineer's side, Next to the jackpad, there is a separate beam that holds a chain. Is that the brake chain? If not, what is that for?

 

Tensioner for the handbrake chain 

 

Scott Chatfield 

 

 
David Friedlander
 

Scott,

Thank you! You understood me completely. Never thought they'd put a light by that step with the walkway lights up above.

Followup:
1. What's the purpose of the ECAFB? Was air pushed into the cabinet to keep the 60's electronics cool?

And if anyone has a close up photo of the wind deflector style used on these units, it would be helpful to ensure the deflector etching is created properly.  It looks like this style has the bottom portion that can open up or fold out, versus just a solid pane of glass from top to bottom. Not sure it's ever been depicted in O-Scale before.

Thanks,
David Friedlander


On Mon, Sep 19, 2022 at 12:18 AM D. Scott Chatfield <blindog@...> wrote:

>  1. For my review - Were oval cab vents added to the engineer's side of the cab later on, or were they there from the factory? Every photo I have says yes and that they were on the right.

 

> Just for my general knowledge:

> 1. On the engineer's side, There is a curious rectangular box in front of the cab. Possibly has a lid on top. What is that for?

 

I'm assuming you're talking long hood forward.  If so, sounds like the box in question is the Electrial Cabinet Air Filter Box, or ECAFB for short.

 

> 2. On the engineer's side, There is a small "box" with a white dot in the center that protrudes from the carbody right where the step in the frame is toward the end of the long hood.

 

Sounds like the walkway light, which illuminates the step.

 

> 3. On the engineer's side, Next to the jackpad, there is a separate beam that holds a chain. Is that the brake chain? If not, what is that for?

 

Tensioner for the handbrake chain 

 

Scott Chatfield 

 

 
D. Scott Chatfield
 

> Followup:1. What's the purpose of the ECAFB? Was air pushed into the cabinet to keep the 60's electronics cool? 

 

It's a second stage of air filtration for the electrical cabinet.  Remember, most of the carbody is slightly pressurized to keep dust out.  The inertial air filter is the loco's primary (first stage) air filter, but it's only about 95% effective on a good day.  A second, large set of filters cleans the engine intake air, but until mid-1967 the electrical cabinet did not have its own filters.  On 40-series EMDs built from mid-67 to 1972, the ECAFB had two tall cylindrical paper filters.  Dash-2s doubled that to four filters.

 

Scott Chatfield 
David Friedlander
 

Thanks Scott! Never really considered that diesel locomotives tried to keep the dust out of the electrical cabinets, but that makes a lot of sense.

David


On Mon, Sep 19, 2022 at 11:35 PM D. Scott Chatfield <blindog@...> wrote:

> Followup:1. What's the purpose of the ECAFB? Was air pushed into the cabinet to keep the 60's electronics cool? 

 

It's a second stage of air filtration for the electrical cabinet.  Remember, most of the carbody is slightly pressurized to keep dust out.  The inertial air filter is the loco's primary (first stage) air filter, but it's only about 95% effective on a good day.  A second, large set of filters cleans the engine intake air, but until mid-1967 the electrical cabinet did not have its own filters.  On 40-series EMDs built from mid-67 to 1972, the ECAFB had two tall cylindrical paper filters.  Dash-2s doubled that to four filters.

 

Scott Chatfield 

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