Key Imports C-9

[ATSF_Ron]

Hello all.  I recently picked up a 1990s era Key Imports SP C-9.  On the bench it runs like a fine watch.  When I set it on the track there is jittery performance.  It appears the issue is the wiring from the motor to the drawbar area.  Problem is, I can't for the life of me get the boiler/cab shell off the chassis.  I followed Spookshow's recommendations for disassembly.  I removed the pilot and long screw under the pilot.  Also removed the two small screws at the back of the cab.  Everything releases, but something is jamming around the motor area preventing the rear portion from lifting up and off.  It moves maybe 1/4" and then the motor itself wants to lift a bit.  I've jimmied it as much as I dare.  I'm worried about popping wires off if I pull any harder.  One more thing...it looks as though one of the motor wires has wrapped itself around the post of the screw which holds on the draw bar.  Help!  Anyone have a reasonably simple fix or experience working on these?  I've taken many locos apart, including the dreaded MDC/Roundhouse steamers.  Just never encountered a problem like this one before.  Thanks!

Ron

[mmagliaro]

Having taken other Key 2-8-0's apart (not this particular one, however), I know that the back of the cab has a real tendency to get caught on the motor because there is very little room to spare back there.  Are you lifting the boiler STRAIGHT UP off the chassis?   Don't try to lift just the back end up at an angle.

If the engine runs well in a cradle on the workbench, I don't think you are going to find the problem inside.   There isn't much in there,
just the motor leads to the frame and the drawbar.   If you can touch a lead to the drawbar and the live driver side, and it works, the problem is in the drawbar and tender, not the insides.

[ATSF_Ron]

Thank you, sir!  I have seen your work and have much respect.  I think I have narrowed it down to one of two things.  1) Possibly in the drawbar connection to the loco (looks sketchy) or 2) Some exposed wiring at one of the motor tabs I believe may have been rubbin on the brass.  I put some black paint on said exposed wires.  I will post pics after happy hour!  Thank you again.

Also, if the problem is the tender, where is the most likely place to look?

[ATSF_Ron]

Apparently I can't add a pic, according to the message I got.  Anyway, there's a square-ish copper piece at the end of the screw that holds the drawbar to the loco.  Power to the motor attaches to that copper piece.  That's where the sketchy solder joint is.  Difficult to explain without the photo.  I also painted the exposed wiring.  I'll put things back together in the morning and report back.  Hopefully things will operate properly.

[peteski]

Ron, with just 3 posts, your privileges on the forum are restricted.  You need 25 posts for full access.
See https://www.therailwire.net/forum/index.php?topic=43673.0

Sounds like your drawbar mount is similar to the one in this brass loco.

[ATSF_Ron]

Peteski, yes.  It's very similar to the photo, minus the fancy plug.  Going to reassemble things in a bit and see if I fixed it.

[ATSF_Ron]

Well, I had partial success.  It definitely runs better, but it still has what I describe as "jitters" in the low- to slow-speed range.  I'd say 30 scale mph or under.  Clearance is so tight under the motor by the drawbar mounting screw that I thought perhaps there was random shorting happening there, so I put some electrical tape on the bottom of the motor.  No change.  All wheels and track are spotless, so I don't see that as a problem.

One other thought I had is the solder connection between the motor wire and the drawbar.  This is right in top of the little brass square shaped part on the drawbar post under the motor.  Those wires are so tiny and the clearances so tight I'm hesitant to attack that.  Small parts and even smaller screws/fittings are getting more and more difficult to handle at my age (62).  Max?  Peteski?  Any other thoughts on this one?  Max, I know you said you've worked on these before.  How is power transferred from the tender wheels to the post?  Even under my optivisor I don't see the axle tip cups like on the Bachmann 2-8-0 and Kato mike.

Kind of surprised I'm having this much trouble.  I had one of these years ago but had to sell it and some other brass to finance college.  It was possibly the best running steamer I've owned.

[mmagliaro]

The wheels in the tender only conduct on one side.  They are pressed on the axle, and conduct directly to the axle.  The axle points ride inside the sideframes, which on a brass loco are made of, well, brass.  The brass truck frames, specifically the bolster that rides against the underside of the tender, then conducts the circuit to the tender floor.  The drawbar is screwed to the tender floor to carry the current the rest of the way to the motor. 

Things to check:

1. Remove the trucks, and make sure the top of the truck bolster and the spot on the underside of the tender floor are completely clear
of corrosion and paint (yes, paint!  on those brass locos, sometimes they paint EVERYTHING).  Polish those spots with some 2000 grit
sandpaper, even if you have all the corrosion and paint off there.  The smoother those surfaces are, the more slowly they will oxidize again, or attract dirt.

2. Adding weight in the tender helps.  If you've got room, don't be shy about adding 10g or more in there.

2.  If you can get the wheelsets out of the truck frames, use toothpicks and alcohol, or even a small drill bit or a pointy Dremel bit (GENTLY) to clean the insides of the axle cups in the sideframes, where the axle points ride.  Many of those brass tender trucks are completely soldered together, so the only way to get the wheelsets out is to unsolder them (VERY DIFFICULT TO DO AND PUT BACK TOGETHER), or very gently bending the brass sideframe away enough for the wheelsets to drop out (nerve-wracking, because you could break the sideframe right off).
For this reason, this step is probably not something you can do, but I wanted you to be aware of it.
If the truck frames some apart with small screws (some do), then you can get in there to clean the axle cups.

3. The drawbar itself usually has some sort of bent washer or spring between it and the underside of the tender where it screws in.
Make sure that's there, and add a thing NWSL phosphor bronze washer, slightly bent, if it doesn't have anything like that.
Just like the surfaces between the trucks and the tender floor, make sure the spot under the tender where the drawbar attaches is really clean.  It can also go either way - the drawbar/spring/washer/screw end might be under the cab, with the spring wire pressing on a post
coming down from the tender.

Does your draw bar have two wires on it, like a "U" shape, touching the post under the cab?  If it's just a single spring wire pressing on the post, that's another big trouble spot.  One contact point just isn't good enough for reliable contact.   Fixing that requires some surgery.   I usually bend a thin piece of phosphor bronze wire in a long narrow U shape, and solder the bottom of the "U" to the tender end of the drawbar.  Then the two legs of the U press on the post under the drawbar from both sides, and the pickup is a  lot more reliable.  On Peteski's example, the U points the other way, so the tender must have the pin that goes between the two legs of the "U" (visible in his photo). 

BUT DO NOT USE BRASS WIRE for this.  It just bends out of the way and doesn't maintain contact.  The drawbar spring wire must be
either thin steel or phosphor bronze.  I use bronze just because it's easier to solder.

---
Finally, this is the reason people sometimes put Kato or Bachmann all-wheels-live trucks under a brass tender, and then solder fine wires to the truck tabs and route them forward to the motor, completely bypassing the drawbar.  It's just so much more reliable.  Even if the trucks aren't the correct prototype and aren't brass, sometimes reliability trumps accuracy.

[ATSF_Ron]

Wow, that's a lot of helpful info!  Thanks, I'll be trying those one by one to see what happens.  I'll start with the drawbar surgery first, since I have a gut feeling that's where the problem lies.  Cleaning up all of the contacts around the trucks as well.  Taking apart those tender trucks?  Ehhh...might be above my comfort level, so let's hope that's not it!

[mmagliaro]

Taking apart tender trucks on a brass loco is a high-stakes game.  So yes, I would avoid that and see how much improvement you
can get elsewhere.  The drawbar and the contact surfaces between the trucks and the tender underbody are the two biggest things to fix.

[Mike Madonna]

Ron,

Congrats on picking up the C-9.
Max pretty much "covered it" regarding contact points on the tender. I do NOT have this model that was imported by Key. I have several of the earlier Oriental Limited SP "C" class 2-8-0s that have almost an identical chassis (both OL and Key models were made by Samhongsa). These have the "one wire" drawbar set up. I first confirm continuity (with a multi-meter) from the drawbar mounting screw to the wire/tender connection point. Then I take a nylon (not metal) bristle wheel in a variable speed Dremel and polish the drawbar and wire where it makes contact with the tender pin. I have also polished the area that Max spoke of where the trucks are mounted. Lastly, I polish the wheel treads on the tender. This polishing is done at the lowest setting on the Dremel (usually 5K rpm). This loco has the 100-C class Vanderbilt tender correct? The OL Vandy tenders are completely soldered together. The Key may be different. If trying to add weight, this may be a challenge.

[Cajonpassfan]

Max, a great writeup! I have one of these pups on my workbench, still in DC, so one of these days...
But, no point doing a DCC conversion unless the DC operation operation is flawless.
Thank you for the insight.
Ron, welcome to the Railwire, and good luck with that teakettle!
Otto

[ATSF_Ron]

Mike, Otto, Max, Peteski, thanks for the comments!  This is great.  I feel like I am among the "giants" of N scale steam.  This forum is an excellent source of info and advice.  I've been a "lurker" for years but finally decided to start posting.  Hopefully I can get enough posts soon to put up some photos of the small layout I've been working on.  I grew up in SoCal, so my layout is primarily SP/ATSF with a little UP thrown in.

Mike, I also own one of the Oriental 2-8-0s but in UP.  Supposedly the Key models are the better runners, but my UP version from Oriental has had ZERO issues with pickup.  Even with the one-wire drawbar pickup. 

Thanks again guys for the warm welcome and free advice.  I'll be tweaking the C-9 this week and reporting back on results.

BTW, I also have a Pecos River Brass ATSF 4-6-2 with similar pickup symptoms.  Oy vey!

[peteski]

I wonder if the problem is caused by a bind in the mechanism?  Can you place the loco upside down (in a cradle if you have one) then connect a pair of (alligator) test clips to the output of a throttle (power pack), then connect one clip to some exposed metal surface in the loco's frame or shell, and the other one to the drawbar. That will supply power to the motor.  Then check the mechanism operation from stopped to full throttle, and see if there are some sort of hiccups at the low speeds, or if the mechanism runs smoothly at all speeds.  If it runs smoothly (because it is hardwired to the throttle) then the problem *IS* most likely spotty electrical pickup.

[mmagliaro]

The Pecos River 4-6-2 is one of the nicest running ("out of the box" anyway) brass locos I have ever worked on.  Smooth, low gearing, and very good pickup, at least on the ones I have seen.  You made a good choice there - worth fixing!