NW-5 chassis or GP-7 with AAR trucks? How about both?

[randgust]

I've got a custom build planned for an NW-5, and 'guessed' that the current Bachmann RS chassis was so low and narrow it might work better than some of the prior attempts with very little frame milling.   Getting one in confirmed it, this will work just fine as long as the DCC board goes and is converted to a wired cab mount.  The frame is low enough and narrow enough to clear the narrowest and lowest portion of an SW shell.

But you still have the truck problem.   I've already had a rather painful attempt to make a CF7 out of the Bachmann GP7, which worked, but I'd had good look at the mechanism and was impressed with performance.   And with Mark (Spookshow's) great shots, I took a gamble that the truck sideframes or maybe the trucks were interchangeable between the RS and the GP-7

Well, here's proof.... the truck sideframes are entirely interchangeable, snap right off and right on.   So, if you're building an NW-5 and need Blombergs, or looking for an AAR trucked GP7, here you go.... RS on the left, GP on the right, one sideframe swapped to show the difference.
Yes, Virginia, there were EMD GP7's with AAR trucks under them:  https://www.alaskarails.org/pix/former-loco/JS-1826.jpg 

[GimpLizard]

Hmmm... I wonder if the Blombergs would fit an RS-1 frame. Because I'm thinking the RS-1 short hood and cab would closely match the NW-5, wouldn't it?

GN NW-5 #192
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GN RS-1 #182
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Just replace the trucks, fuel tank, end railings, and long hood. Not an exact match, but "good enough"?

[randgust]

Truck centers are the same - 31'.  But what I was looking for was a cast frame low enough to clear that taper in front of the cab without doing any heavy milling.  And it's not only lower, but narrower.   Bachmann's position of the motor and the drive is so low in the frame gives you a lot of elbow room here.  The motor is actually part way down into the fuel tank, and the motor is actually slightly lower than the gear tower worm shaft center if you study it.

[thomasjmdavis]

Yes, Virginia, there were EMD GP7's with AAR trucks under them:  https://www.alaskarails.org/pix/former-loco/JS-1826.jpg 

Well, yes, there were.  However, in the case of the Alaska units, those are AAR Type A switcher trucks (or look like those to me, and I double checked my Diesel Spotters Guide, also used under some NC&STL and military GP-7s- although I am wondering if maybe the Type A used on roadswitchers might be a bit longer than those used on a switcher), not the type B trucks from an Alco RS unit. Are the switcher trucks also interchangeable? There were GP units that did ride on AAR type B trucks, such as GM&O GP-30s and MP GP-18s.  (and I am almost certain some GP-7/9s also had type B trucks, but I don't have any photos at hand).

[Curtis Kyger]

I wonder whether using the Bachmann frame under an RS1 would allow the RS1 to possibly be modified to become sound equipped.

[GimpLizard]

Well, yes, there were. ... There were GP units that did ride on AAR type B trucks, such as GM&O GP-30s and MP GP-18s.

Wisconsin Central (ex-SOO) GP30's rode on AAR Type B trucks.
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[wazzou]

Usually this practice was a direct result of traded in units and the cost savings realized by equipping the units with trucks from the trade ins.

[cjm413]

Well, yes, there were.  However, in the case of the Alaska units, those are AAR Type A switcher trucks (or look like those to me, and I double checked my Diesel Spotters Guide, also used under some NC&STL and military GP-7s- although I am wondering if maybe the Type A used on roadswitchers might be a bit longer than those used on a switcher), not the type B trucks from an Alco RS unit. Are the switcher trucks also interchangeable? There were GP units that did ride on AAR type B trucks, such as GM&O GP-30s and MP GP-18s.  (and I am almost certain some GP-7/9s also had type B trucks, but I don't have any photos at hand).

The AAR-A trucks were replaced with AAR-B when they were rebuilt with low short hoods

https://www.alaskarails.org/pix/former-loco/DM-1801.html

[thomasjmdavis]

The AAR-A trucks were replaced with AAR-B when they were rebuilt with low short hoods

https://www.alaskarails.org/pix/former-loco/DM-1801.html

Well, serves me right for using a 50 year old reference book.  It has "Omaha GP-20"s, but no Paducah geeps or CF-7s or other later 1st generation rebuilds.

[davefoxx]

Usually this practice was a direct result of traded in units and the cost savings realized by equipping the units with trucks from the trade ins.

Southern Ry. did this and reused Alco trucks on its GP35s.

DFF

[randgust]

One thing I will comment on is that the Bachmann GP is rather unfriendly to a nose chop job unless you want to ditch the DCC board and do a bunch of frame hacking.

Meanwhile, when I really get into this NW-5 project I'll probably put up a thread.   At this point is was a 'will this work?' question, I know it's been done by others here but it's a real struggle on the chassis and I'd suggested to take a look at the Bachmann RS suspecting the sideframes were swappable (i.e. Bachmann would never spend money on two different truck gear towers). 

And I suppose if you wanted a high-nose something with with 31' truck centers and AAR B trucks on it this is one way to get there.

If anybody wants that Bachmann DCC board off of the RS for a repair give me a PM, I'll probably put it up on the auction site in a couple days.

As far as sound on an RS-1, gazing into my crystal ball I see Atlas modifying nearly all of their frames down the road to accommodate sound, love it or not, by hanging a bracket under the motor for the speaker in the fuel tank area.  The new 'standard' motor designs have that bracket and extra contacts built in.   And the S-2 is smaller than an RS1, and they left space for a speaker in the cab.  So it depends how patient you are.   I will say the Bachmann frame is all cast metal in the fuel tank, and the motor is darn low (which was an advantage to me) so you might be able to get it in the cab area, good luck.

[narrowminded]

If anybody wants that Bachmann DCC board off of the RS for a repair give me a PM, I'll probably put it up on the auction site in a couple days.

Here you go!  https://www.therailwire.net/forum/index.php?topic=49370.msg659346#msg659346

What I have learned since that post which brought no responses is that there's a newer version of this where the decoder screws to the chassis.  What I have is the one that clipped in although the chassis could probably be drilled and tapped and then the new style mounted.  Which do you have?

[randgust]

If you look at the first photo you can see that the RS chassis board is 'up in the air' because it's on two pieces of sticky black foam tape.  That is all.

It appears to be the exact same board as on the GP7, which can also be seen as a clip-on on the right.      No screws on these, except that the power  wires are drilled and tapped to the frame with tiny screws.

[Sharky_McSharknose]

Watching for the NW-5's status. The Mass Central NW-5 #2100 (ex-SOU) would be a fun little project, esp. since it may be returning to service after a ~5-year hiatus.

MCER 2100 Palmer Massachusetts March 2010 b by Pete Piszczek, on Flickr

[narrowminded]

If you look at the first photo you can see that the RS chassis board is 'up in the air' because it's on two pieces of sticky black foam tape.  That is all.

It appears to be the exact same board as on the GP7, which can also be seen as a clip-on on the right.      No screws on these, except that the power  wires are drilled and tapped to the frame with tiny screws.

OK, that makes sense as I'm seeing and believing that they had a power pickup problem with the bronze spring tabs not being the most reliable conducting to the chassis material.  I didn't have that issue with mine but I did service them and cleaned the pads.  When running they ran real smooth and quiet with good low speed control.  I wouldn't mind trying it if it's not spoken for.