Pecos River Brass 4-6-2 part 2

[mmagliaro]

Peteski's got you on the right track with the ohmmeter.  Dollars to doughnuts, you will get zero ohms between that drawbar and the frame, which is a short.



Look at it.  It looks really suspicious.  That brass nut and lug on top look like they are screwed down almost to the frame, if not right on it.  I think I see a plastic washer under the nut, but I can't tell.  And that lug that points off to the side should be bent UP slightly so it cannot be touching the frame.

Also, be aware that the drawbar pin/screw go through a plastic bushing in the hole in the frame, so that the screw doesn't touch the frame inside the hole where it goes through.  It's very easy for that bushing to be cracked, missing, or partly disintegrated, and if you bend on the drawbar with the screw in there, you can easily make it touch inside the hole.

What about underneath?  Can that spring wire on the top of the drawbar in any way graze against the frame?

The right way to fix this is to, yes, a) confirm that the drawbar screw is shorted to the frame (zero ohms).  Then b) take off the nut, pull out the screw, and make sure that NOTHING METAL on the top, bottom, or inside the hole can touch the frame.  Not the screw, nor washers, nor spring, nor nut.  Everything in that post assembly has to be insulated from the frame.  Yes, you can make a plastic drawbar to solve this, but I prefer an insulated metal one if you can make it work right, because they are generally more robust.

[mmagliaro]

Here's a pic of one of these that I worked on.
Note that clear/white insulator inside the screw.  It has a flange on the bottom of it, so the spring can't touch the frame,
and the screw and spring cannot touch each other or the frame.  and it goes INSIDE the frame hole and should poke out the top
of the hole slightly, so there's no way the screw can touch the frame.  And by the way, this photo also shows that this
one had that kooky upward bend in the drawbar itself, so they must have commonly been that way.

[ATSF_Ron]

Thanks Peteski, and yes, that little connector nut is a royal PITA.  I got lucky today though and used some scotch tape to hold it still and in place.  Got it the first time!  I'll probably replace the metal drawbar with my plastic one.  It's about twice as thick as the metal one.

So my meter shows no change when I touch the drawbar and frame with the two leads.  I wiggled the drawbar a few times and retested.  Same result.  Metal drawbar is now off.  However, I will still need to use the connecting nut or the screw will just drop out.

Max, thank you for the pics and info!  I have enclosed a few of my own showing the same area.  The little white plastic piece that surrounds the screw appears healthy.  I wasn't able to see any splits or cracking, and the bottom flange looks good as well.  I understand the superior strength of the metal drawbar, but that thing has been a nightmare for me from the get-go.  It's outta there, LOL!  Hopefully I can report back with some success tomorrow.









This last pic is the side of the nut that touches the frame.  Max, I'll give that little tab a slight upward bend to help insure there's no shorting to the frame.

[peteski]

Ron, since you fixed the problem with the drawbar pivot screw, why not keep the metal drawbar?  If not, make sure not to throw the metal drawbar away.  Either keep it in the loco's box (if it has one), or tape it to the tender floor or even inside of the tender. That way the next owner will be able to restore the loco to its original configuration.

[mmagliaro]

I agree, your plastic bushing looks fine.  So, with the drawbar removed, if you put the engine and tender on the track, and you touch
your motor wire to the tender drawbar screw, does the engine run? 

[ATSF_Ron]

Max, I'm not following you.  I don't have the ability to put the engine motor wire onto the screw as the wire is soldered to the tender peg.  And even if I could, the damn screw has gone into the abyss.  45 mins and still searching...At least the tiny nut that goes on top of it is still stuck to a piece of scotch tape.  That's the only way I can hold it to attach to said screw.  NOT a fun project!

My plastic drawbar doesn't work well either.  Even the "skinny" end that the screw is supposed to go into is too thick.  I filed it down as thin as I dared, but the screw still isn't long enough to reach through to the nut.  It barely goes on, even with the thin metal drawbar.  I have no idea what the drawbar problem can be.  Other than bending it to a more horizontal angle, everything else about it appears normal under my optivisor.  The stiff wire that presses against the tender peg is still firmly soldered in place.  I was able to put a slight bend on the tab of the nut that fits on the end of the screw, so hopefully I can find the screw and test to see if THAT is the issue.  Once fixed, I'm NEVER going back into this thing! LOL!

Peteski, I never throw any parts away, good or bad.  Although at the moment I'm pretty tempted to put this PRB loco in a blender!  -___-

[ATSF_Ron]

I found the missing, screw and got everything reassembled. Still have a shorting issue. I give up. I’m past the point of frustration with this thing. I also feel like I don’t have the electrical troubleshooting skills to deal with it appropriately.  Depending on how my Southern Pacific C9 repair goes, I may send this loco off to the same guy for repair. I feel like the two issues are very similar with these locos.

[peteski]

I found the missing, screw and got everything reassembled. Still have a shorting issue. I give up. I’m past the point of frustration with this thing. I also feel like I don’t have the electrical troubleshooting skills to deal with it appropriately.  Depending on how my Southern Pacific C9 repair goes, I may send this loco off to the same guy for repair. I feel like the two issues are very similar with these locos.

Ron, you know exactly where the problem is: the pivot for the drawbar.  It is actually a mechanical problem (some metal part of that assembly is contacting the metal frame, causing a short circuit).  With your Optivisor and strong light you should be able to see where the short occurs.

But if you feel that it is too much to deal with then sending it out for repair might be a good option (to end the troubleshooting frustration replaced with slightly lighter wallet).

[ATSF_Ron]

Thanks Peteski.  These gremlins frustrate me to no end.  Maybe after leaving it alone for a few days I'll have another look.

[Mike C]

@ATSF_Ron    Take an old plastic Credit of Insurance card and make the drawbar from it . Much thinner and still strong enough to do the job .      Mike

[ATSF_Ron]

Ooh, Mike C, I like that idea! I’m sure I have an old one somewhere…

[peteski]

Ooh, Mike C, I like that idea! I’m sure I have an old one somewhere…

Just don't lose any more small parts!   Maybe do the work in a large thin clear plastic bag?

When I work on my projects I wear a jewelers apron.  Basically an apron where the bottom end is fastened (with Velcro) under the workbench.  If something rolls off the workbench it is captured by the apron covering my lap.  Of course that doesn't help with springs that "sproing" and fly off in some random direction.

[ATSF_Ron]

Peteski, I like the jewelers apron idea. Even assembling couplers those dang parts go airborne!

[peteski]

Peteski, I like the jewelers apron idea. Even assembling couplers those dang parts go airborne!

I was lucky enough to have a neighbor who was a seamstress. Unfortunately she passed away several years ago. I bought some fabric and she made the apron for me and sewn a strip of Velcro on the bottom edge. I then put some adhesive strips of the other part of Velcro under my bench.

I guess one could get a regular apron and have a strip of Velcro sewn on.

[ATSF_Ron]

My local Ace Hardware has strips of Velcro on the cheap.  I use them to hold my backdrop sections against the shelf brackets.  I'm sure I can find a bbq apron or something similar that'll work.  Thanks for the idea!