Pecos River Brass 4-6-2

[ATSF_Ron]

Tried adding photos but am not tech savvy.  NVM.  I'm getting no results that are helpful.  I disconnected the drawbar, spring, insulating washer, and screw.  Clipped a lead to the now dangling motor wire.  Clipped another lead to the track.  Nothing.  Tried putting the tender on the track and clipped the other lead to the tender post.  Also nothing.  Switched the wires, and nothing.  Put the loco back in the cradle.  Left the one clip on the motor lead and tried touching the other lead to each side of a driving wheel, directly from the power source.  Still nothing.  I give up.  Maybe it's something simple, but I really don't get electricity sometimes.

[mmagliaro]

Don't give up, man.   Brass locos are expensive, and finicky.  You just need to pick a little more.  There really aren't  many things that can be wrong with it.

For reference, here are some photos of this thing disassembled (from other hard-core repairs I have done on these).
First, a whole-engine shot.


Now, focus in on the motor.  I had already ditched the drawbar connection on this and hard-wired it to go straight to the tender,
but the long black wire trailing off to the right would normally be connected to the drawbar.


So, you disconnected the wire from the drawbar, but left it connected to the motor right?
Just touch your power leads to the drawbar wire coming off the motor, marked "2" in the photo, and touch the other power
probe to the other motor brush, or a clean brass spot on the frame, marked "1" in the photo.  It HAS to run.   We know the motor isn't dead.    If it doesn't run, touch the leads directly to the copper motor brush areas.

Once you get that running, do what you just tried.  One probe on the drawbar wire, and the other on each of the 3 drivers on each side.  If you touch the wrong side, it will be a short.  But once you figure that out, try the other side.

My repair notes on the one in the photo say I had to grind away some brass from inside corners of the cylinders to keep the pilot truck wheels from touching them and shorting - pretty common problem on brass steam.

[randgust]

Had the same problem with the Jamco, I really had to murder the inside of the cylinders with a Dremel to get enough pilot truck clearance to prevent shorts between the pilot truck and the cylinders.    I needed to reliably get around 11" radius and an Atlas #5 diverging side.   I had a kink on the approach (point side) of one turnout that finally got so frustrating I tore out all the track and rebuilt it.   No diesels had issues, but steam did.

I used pieces of Atlas curved sectional track on the workbench so I could fit track to the chassis right side up and upside down to see what was going on.    It's too hard to do on the layout and the radius is indeterminate on flex.

[ATSF_Ron]

Ok, here's the latest.  Max, I did as you said in your last post.  Everything worked fine in the cradle.  I also put it on the track and tried touching leads to the parts you mentioned.  It works fine.  Have not tried to put the boiler/shell back on to test as I haven't done the cylinder grinding yet.  Yikes!  I'll definitely be going slow on that step.  My sharpest radius on my layout is 15" on the main.  There will not be a reason to run the loco on anything sharper, such as the switching segments.  Turnouts are #6 and #7.  I've looked at the cylinder clearances with a VERY bright flashlight.  The fronts of the cylinders just barely clear the front pilot wheels, but just the first axle.  The 2nd axle seems to have plenty of clearance.  I'll do some grinding in a bit after I get my nerves geared up.  Or maybe I should do a shot first, haha!

[ATSF_Ron]

randgust, hopefully with a 15" minimum I won't have to do too much grinding.  I have some heavy duty sanding discs for my Dremel.  Let's hope those do the job!

[mmagliaro]

Ah, excellent!

Now, before you mess with grinding the cylinders.... leave the pilot wheels off for now so that doesn't confuse the issue.
If you leave that truck off, it can't short anything.

On the track, with the track power up, you should be able to attach a clip lead to that free wire and touch the other end of the clip lead to the left rail (that's the one the tender picks up from).  It should all work with just one clip lead because the right-hand rail pickup comes from the drivers.

If that works, the next step is to put the drawbar pin back in with its insulator, and connect the motor wire back onto it.  Then clip a lead to the drawbar pin underneath and touch THAT to the left rail.  If that runs,
then hook on the tender and see if THAT runs.

If you get shorts after you put that drawbar pin back in, that pin is surely your problem.  The key is to make sure that the pin, motor wire, and drawbar itself cannot touch the frame in any way.

[Dirk Jan Blikkendaal]

Hi,

Just another 3 suggestions:
1.check if ALL 6 brakehangers behind the drivers have ample clearance and have no chance of touching a driver.......the drivers have quite a bit of play and might touch the brakehanger when moving.... causing a short. 
2. check if all 3 drivers have the insulated wheel on the same side..... the previous owner might have had problems as well and have taken out the wheelsets and not put them back right.
3. make sure the expansion link is POINTING DOWN and the eccentric rod therefore almost horizontal...... there is quite a bit of play is those links and sometimes the expansion link goes UP - almost horizontal - when flipping the engine over...... causing only half a driver revolution (when power applied) and then jamming the valve gear and thus stopping the engine........

found (and solved) all these problems myself the hard way.......... GOOD LUCK and hope you solve the problem one way or another!!
(glad you found my website....)

Dirk Blikkendaal

[ATSF_Ron]

Thank you, gentlemen!  Lots more things to try.  Max, after trying the first step in your last post, the loco does indeed run.  However, it may have a bad solder joint at the copper tab on top of the motor.  If I moved the wire AT ALL, the loco stalled or jittered.  I may replace that wire altogether, as the other end that attaches to the drawbar has always looked sketchy to me.  The only problem is I don't have any wire that small.  I have some a bit larger though, so unless shell clearance is an issue it should be fine.  I'll try that and the other steps and report back.

[mmagliaro]

Thank you, gentlemen!  Lots more things to try.  Max, after trying the first step in your last post, the loco does indeed run.  However, it may have a bad solder joint at the copper tab on top of the motor.  If I moved the wire AT ALL, the loco stalled or jittered.  I may replace that wire altogether, as the other end that attaches to the drawbar has always looked sketchy to me.  The only problem is I don't have any wire that small.  I have some a bit larger though, so unless shell clearance is an issue it should be fine.  I'll try that and the other steps and report back.

If you unsolder that wire on top of the motor, and then solder a new wire to it.... BE QUICK.  You can destroy the brush or brush spring, or the whole plastic nose of the motor if the heat deforms it.  Normally, the best approach is to pry the whole brush holder out and do the soldering while it's out of the motor, and then put the spring, brush, and holder back in.  But if you don't feel comfortable prying out the brush holder, you can solder it in place... Like I said... just be quick.  Don't use any bulky stiff wire in there.  You want something like #22 or #24, stranded.  If you don't have any, now is the time to pause and go get some.  You will always need it for internal loco wiring anyway.

By the way, all of Dirk Blikkendaal's suggestions were excellent.  If you still have shorts intermittently after getting this engine running with engine-and-tender, those will all definitely be things to check.

[peteski]

If you unsolder that wire on top of the motor, and then solder a new wire to it.... BE QUICK.  You can destroy the brush or brush spring, or the whole plastic nose of the motor if the heat deforms it.  Normally, the best approach is to pry the whole brush holder out and do the soldering while it's out of the motor, and then put the spring, brush, and holder back in.  But if you don't feel comfortable prying out the brush holder, you can solder it in place... Like I said... just be quick. 

And don't try soldering "dry" - use non-acidic flux. Not only it keeps the liquid metal clean, it also aids in heat transfer.

[ATSF_Ron]

I ended up reusing the existing wire after reading your post.  I was very quick, and it definitely helped.  However...once the blasted drawbar was connected it went back to the sporadic connection and herky jerky operation.  I can place it back in the foam cradle and it runs fine -  as long as I don't move the drawbar AT ALL.  Any movement, especially in the vertical plane, and it shorts out and stops.  There is probably less than 1mm clearance between the drawbar and the spring which is around the screw.  This is where I've seen the sparking, so that makes sense when there is vertical movement of any kind.  I also checked Dirk's suggestions.  Everything appears ok there.

I'm thinking of just fashioning an entirely new drawbar from styrene and bypassing the damned original all together.  Hardwire the motor to the tender and be done with it.  I have some small pieces of shrink tubing left from another project, so I can even wrap that around the new drawbar with the new wire inside it.  Nice & neat!  I will definitely need to go get some of the smaller wire.  Any suggestions on where to pick that up now that Radio Shack is gone? I have a tone of wiring for track, but nothing small like what you suggest.  I have a local Ace Hardware near me.

[mmagliaro]

I can't fault you on making a new plastic drawbar and just hard-wiring to the tender.  That will solve your shorting problem and get you a 100% solid connection, which you never get with the spring-wire-against-a-post system.
If you are going to use styrene, don't be cheap on the thickness.  While it may be overkill, use the .080" thick stuff.  Styrene can bend and break, especially around the holes where the engine and tender posts have to go.  If you hunt down some ABS or nylon strip
online and cut your piece out of that, it would be stronger.

[ATSF_Ron]

That's exactly what I'm thinking.  I've got a couple thicknesses on hand.  Pretty sure one of them is the 0.80" or close to it.

[nkalanaga]

If you've ever looked at a prototype drawbar, they're not thin!  0.08" wouldn't be out of line, and if you can find a scrap of engineering plastic, the glue-proof stuff like Delrin, that would be even better.  It can be drilled and tapped, and would probably last longer than styrene.

[ATSF_Ron]

Here's something I was thinking about yesterday as I was looking at how to make this new drawbar.  Since I'm removing the engine motor lead from the whole drawbar/mounting screw piece, couldn't I just leave the old drawbar attached, still use it for a connection to the loco, and not even worry about it electrically?  Like I said, I'm not the sharpest tool in the shed when it comes to electronics.  My concern is the drawbar/screw/spring connection and ridiculously tiny clearance between all of that and the frame under the cab (less than 1mm).  If the drawbar is making momentary contact with the frame (even a painted part), that theoretically shouldn't be an issue since the current from the motor wire no longer goes through the drawbar, correct?  Or am I missing something?