Rocket Surgery on the PRB brass ATSF 3400 Pacific

[randgust]

Well, that's what it has felt like anyway.

I got Ron's 3400 that he'd decided to sell, knowing it wasn't running right and he didn't think he could ever fix it.   Well, I'm a Santa Fe fan, and I've already significantly modified two brass locomotives and lived to tell about it, the Hallmark 4-8-4, and the original Jamco 3400.  Both of those had gone pretty well.

I've had such fun with the Decapod project with full sound and DCC at Altoona, and I have a full 'Fast Mail' train behind PA's now with DCC and sound.   I'd really like another sound-equipped steamer to pull that consist at shows, but the criteria for that has been low-priority, until Ron's chance came by.

The Pecos River 4-6-2's have as good a reputation for a brass locomotive as you can get, both appearance and mechanism.   Worth a shot anyway.   Here's Mark (Spookshow's) page:

https://www.spookshow.net/loco/prb462.html

So, here's why I think it made sense before I jumped off the proverbial cliff of messing with a legacy brass locomotive.....

1)  Ttrak layouts have sharp curves, pretty much eliminating most newer 8-coupled steam locomotives; inside standard T-trak is 11".
2)  Need significant weight to pull a train, although grades are nonexistent.    My Decapod is handling 18 cars easily now.
3)  Should have a mechanism with a reputation for performance, quiet, and well built
4)  Should be ATSF, and the Fast Mail consist is a post-37 one with some streamline baggage, modern steam.
5)  Room for DCC and sound in the tender
6)  Shouldn't be investment grade in pricing

My Jamco 4-6-2 fits all that actually, but getting DCC in it at this point is not really an option, DC is solid. That was an exceptionally difficult project and the fact that it works as well as it does is a really good place to just stop.     I'd rather have a second one that is a non-critical project, and lets face it, it it fails miserably, still looks good as a display model in the case with a story.....

So as usual, this sounded better in my head until I got into it, no fault of Ron, but if you want to follow along on this particular rabbit hole rebuild, should be fun.   I'm only starting this thread when I 'think' it will ultimately succeed, had me going for a while.

As soon as I studied it, the basic project scope here took shape......

1)  really well made.
2)  Ron's right, hot-wiring to the chassis and it runs perfectly.   Motor can be easily isolated.   VERY smooth and quiet in the frame and motor.
3)  AIN'T NO WAY the stock front end is clearing 11" without significant redesign and clearance grinding for the pilot truck, did it to the Jamco.
4)  Pickup system is odd, pilot truck and trailing truck and 2 drivers pickup right rail, tender six wheels pick up left rail
5)  All pickup dependent on 'brass to brass' contacts that naturally corrode
6)  Tender body is huge enough to fit anything, decoder, speakers, wiring harness
7)  Trailing truck is wrong for the 3429 locomotive and also not on straight
  Drawbar connection design is a problem as pulling hard on a curve will naturally 'jack' the lead driver off the outside rails.   I'd attacked this on two previous steamers (Jamco and LL 2-8-4) by redesigning the drawbar to pull from directly behind the trailing driver instead of under the rear cab.   maybe possible
9)  Tender trucks look nice, but getting 12x12 pickup off the tender from Dirk's ATSF N scale models trucks (did that on the Jamco) would be much, much better.
10)  Boiler headlight drilled for one but no headlight, LED should work OK.

So, if you consider brass locomotives either priceless investment media or untouchable works of Asian art, leave now.  This won't be as cool as the Shay thread has become, but the same goals apply - take one of these and make it into a bulletproof runner, but also with sound and DCC.  At the price of some blood and brass. 

[eja]

Good luck !


This should be interesting to follow.  Lots of pictures, please.

[randgust]

OK, well, here's what we're starting with.   There's some changes visible even so far, that multi-colored cable is the new wiring harness for the DCC plan



Link:  http://www.randgust.com/PRB342901.jpg

Good prototype shot of one of the ones with the 'big honkin' tender' :  https://www.rrpicturearchives.net/showPicture.aspx?id=3472040#google_vignette

And here's under the hood.   Note that by simply pulling the bottom motor tab up to the side, the motor is isolated.   The two top wires will connect the new LED headlight.   The red wire 'might' catch the insulated side, for now, nothing.  Two wires to the motor, two wires from the frame sides, two wires to the headlight.



Hot-wiring to the motor and running the chassis sure proved the quality of the parts and assembly.  It's really smooth and quiet, just like Mark says.  Worth the fight.

Link:  http://www.randgust.com/PRB342902.jpg

[kiwi_al]

Hmmm that's got me thinking - Would you be able to measure the drivers across the treads please?

[randgust]

OK, dimensions measured with the trusty micrometer:

Driver diameter .492"  (more or less 80", 78.72")
Over flanges   .532"

Driver tread width (including flange) .073"
Driver tread width (guessing without flange) .057"

[mmagliaro]

You won't regret this, Randy.  As you've already noted, it's a smooth, good-running mechanism, and it is very solidly constructed.
I fixed up a few of these in my repair life.  They run really good even with the original open-frame motors, so I just left them in.  They are geared down well, so they don't run away and have nice start-up. I had to grind clearance out of the insides of the cylinders and underframe so the pilot
wheels would negotiate curves and not short out on the underside.  I hard-wired the drawbar, added about 10g of weight in the boiler, and cleaned all the paint and shellac off all the contact surfaces in the tender, pilot and trailing trucks.    I also ended up added stiffer springs on the pilot or trailing truck in some cases to get more positive tracking and contact.   One thing to watch out for: the #1 crankpin had a tendency to hit the backside of the
crosshead as it slides back and forth.  Some careful filing and bending might be needed there to keep it from locking up.

This will be a nice project.

[randgust]

Thanks for weighing in Max.  Ron warned me that I was in for this on the front truck clearance.   I hit that on the Jamco and had to do some serious grinding but it was ultimately very successful for reliable tracking.   And you showing up gives some legitimacy to the radical changes I'm about to make on this.

A quick check confirmed my suspicions.  Any attempt to put this on 11" radius with a 'stock' model was futile.  The cylinder front edges hit the lead axle, and also rock the inner wheels vertically up off the rail.

The tool I use for this is pretty simple to study this.  I have some sections of Atlas 2521 11" sectional soldered up.  Trick is to put the chassis on it and look at it from underneath so you can see what's binding, overhang, etc.   You can't do this on a layout or would want to.



Link:  http://www.randgust.com/PRB342907.jpg

And you can see just how far over those cylinders are to the track centerline.

So there are two very distinct problems.   First is the clearance on the lead axle, need a lot of cutting like Max said.   The second, more problematic one, is the suspension design of the lead truck.  It is designed EXACTLY like the old HO Tyco Mantua 4-6-2 was that I had as a kid.  Long screw down from the boiler through the CENTER slot on the lead truck, allowing the truck to slide around sideways, and pushed down with a mild coil spring.

Bluntly, this didn't work that well in HO and resulted in a lot of derailments, as it pushes more force on the OUTSIDE wheelsets in a curve and the inside wheelsets can visually lift on a track irregularity or sharp curve.  AND, it also takes weight off the drivers for traction and contact.  It works even less effectively here.  The bugger was that when I cut the cylinders back for clearance I discovered there still wasn't enough lateral movement in that slot to allow the lead truck to move over in an 11" curve, it tipped and the inside wheels lifted.

The Jamco, for as primitive as it was, put the lead truck out on a lever going back to the frame, like a two-axle truck would.  And not surprisingly the Atlas 4-4-0 is the same from Micro-Ace.   So...ow.  I decided to do the radical approach of modifying the entire front end and lead truck to pull that off here. 

Here's the 'new view' underneath the cylinders with the boiler screw removed:



Link:  http://www.randgust.com/PRB342904.jpg

Yes, I cut that much off to clear the lead wheels.  I warned you if you think of these as virgin asian art you shouldn't have come in here.   I used a cutting head on a dremel, after I wrapped the entire mechanism in plastic to keep the brass dust from contaminating everything.  Eye protection required.

Now on to redesigning the entire front truck.

I did check the crosshead clearance against the front crankpins, I've had that issue on other locomotives but this one seems fine.

[thomasjmdavis]

Yes, I cut that much off to clear the lead wheels.  I warned you if you think of these as virgin asian art you shouldn't have come in here.   I used a cutting head on a dremel, after I wrapped the entire mechanism in plastic to keep the brass dust from contaminating everything.  Eye protection required.

I no longer feel at all guilty for anything I've done to zamac and plastic over the past 50 years, to allow for clearance or operation.

Thanks for this thread.  If I ever get my hands on a similar brass loco, I'll know what to look for, and where to start.

[ATSF_Ron]

Wow, Randy! You are quite the brass surgeon. That’s way more surgery than I would feel comfortable with an expensive brass loco. Glad she found a good home. I’ll be watching this with interest!

ATSF_Ron

[randgust]

OK, so the next major modification is the lead truck.   And it's difficult.

The 'long screw' into the lead truck slot was experimented with.  I even milled the slot wider on the truck, didn't work, still wouldn't clear.  Has to go.  But that's an odd screw, not 00-90, and has an interesting shoulder on it too.  Hmmm.

Discovered it WAS NOT steel with a magnet.  OK, then I can mess with it.   I cut if off just off the boiler, and cut a new screw slot in the now shorter shaft with a razor saw.  It actually worked.  I can still hold the boiler on and it clears the new front truck screw.

So getting that out of the way, I can redo the front truck like the Jamco, making a new brass deck sheet, soldering a 00-90 nut underneath, and fabricating a suspension arm back to the first screw on the cover plate - inside.   clearance hole is .050.    And in case you think it will stick out like a sore thumb the 'stock shot' at the beginning of the thread already has the modified front truck under it.  Once painted black, all this messing is invisible.



Link:  http://www.randgust.com/PRB342905.jpg

Note the tiny lead slug by the front axle.    And underneath, more lead, secured with Goo.....  I just hammer soft lead flat and trim it with cutters. 



Link:  http://www.randgust.com/PRB342906.jpg

At this point, I've remounted it and checked it on the static track for clearance and all is good.   Have yet to reassemble and test it in operation.   That comes next.  I'll hotwire the wiring harness for DC to the stock tender.  The only thing I'm testing is the tracking of that front truck.   Not convinced I've got it yet.  I do have some 11" track on the ATSF layout in hidden trackage, that's the constraint in addition to the Ttrak minimum.

As I'm planning on 12x12 pickup in the tender, I'm not concerned about pickup in the locomotive, or at least not until proven otherwise.  That gets the front truck clearance issue out of the way, I hope, and I'm not reinstalling the spring, just letting it roll.  So a tiny addition to traction.

Max, where did you add more weight?   There's a big lead boiler slug in there and 'maybe' some more room behind it around the worm.....???

[peteski]

You can (or at least used to be able to buy) lead flashing in Home Depot or similar hardware store.  It was sold by the foot. It is about 0.040" thick sheet. I bought about a linear foot of it years ago and it should last my N scale need for a lifetime. That way I don't need to hammer lead sinkers flat. 

[mmagliaro]

....
....

Max, where did you add more weight?   There's a big lead boiler slug in there and 'maybe' some more room behind it around the worm.....???

In the "summary" photo below you can see the weight (lead sheet) inside the boiler at the right of the photo. 
Peteski was on the right track.
You can buy lead sheet online in thicknesses from 1/32" and up.  So I have a few 12" x 12" sheets in various thicknesses.  Very easy to
cut and work with.  It's not as dense as tungsten, my favorite weight metal, but it is super easy to fit a lot of it in a flat curved space like the inside of a boiler as I did here.
BTW, this photo reminded me... how's your driver and other wheel gauge?  As you can see in this photo, I had to press mine to get them to the correct gauge.  I also didn't have to do major surgery on the pilot truck, because I wasn't trying to get this to run on 11" curves (egad!).  It handled 15" just fine after I cut back the inside corners of the cylinders, so I left it alone.

[peteski]

I used lead sheet rolled up to extend the original lead weight in PRR H-10 loco.

[randgust]

Wow, Max, that's a further teardown than I've done in the mechanism.   

I considered the driver gauge a hair tight, but have decided to leave it alone until if and when I prove it's a problem.   As I'm not running Atlas C55 anywhere, it may not be.  I noted there is very little lateral movement in the journals, so if the gauge is corrected there may be new curve issues.  And I don't have a proper press anyway to handle a driver that size..

I also think that the reason I'm not having crankpin to crosshead issues on #1 is I didn't correct the gauge.

That's where I thought on the additional weight, thanks for confirmation.

I had such a nightmare on my Decapod with resetting all the drivers after turning them that I resolved to never tear anything apart like that if it was already running perfectly. 

So after I patch this thing up for DC and start testing it, I'll hold on to performing that particular invasive procedure!

[mmagliaro]

Wow, Max, that's a further teardown than I've done in the mechanism.   
...

Well, I was fixing this one up for somebody, and once I got going... well, you know how it is.