Lionel PW 726 Stall Problem......need some ideas

A eunit dropping out can be caused by a loss of power or a momentary short circuit, which causes a loss of power. You might want to install a high speed circuit breaker, like a post war 91, to see if you can determine which issue might be causing your problem. 

   I would help it through at just under stall speed and watch close for roller issues.

Maybe clean all the turnout rails real well. Scotchbrite them.

You never mentioned which turnouts you use.

The engine may be bouncing over your 027 switches.
Without looking, I think the postwar Lionel 726 has wide rollers. They might be getting lifted from the center rail by other parts of the switches as the engine goes through the switch.

I suggest you make certain the rails on the offending switches are clean, and that nothing is bent.

ROGER1 posted:

 4. I do have a capacitor system on my switches (PW1122 switches ) that eliminates the buzz and sometimes I do have issues with some engines. But I have a power cutoff to the cap system and when I cut the power, the engine still intermittently stalled.

Have you noticed whether this is happening with 1122... or 1122E switches? On the original 1122 switches(one year only) there were issues with getting good ground to some locomotives, and if you are using fiber pins with 1122 switches, this makes it even worse. The 1122E switches require fiber pins, the 1122 does not.

In answer to the above 3 responses.....much appreciated, though.

David......I DO use 91 breakers. They are incredibly fast. I've got 5 amp thermals as "backups" (only because they were on there first). I've got a toggle switch that can take the 91s out of the loop because some engines can cause "nuisance trips". I toggled both ways with this engine and the stalling happened irrespective. So, I don't think it's a short.

Adriatic.......they are PW 1122E switches.  I had emory clothed the rails of the two switches.  Didn't seem to help. It's hard to look under that engine when it's moving, but I did not see sparking. Sometimes, you can see the roller bridge the frog and a side rail to cause a short (which instantly causes a short, which instantly trips a 91). In those cases, I put a dab of Super Glue on the spot (after having put a piece of electrical tape to locate it). But it doesn't appear to be the case here as explained above

CW......yes, the rollers are wide, causing me to suspect the "bridging". But when I swapped out the roller assembly with one from a 736 last nite, it still stalled.

Can the "melt spot" on the drum of the e-unit cause this?  Not alot of options left , I think

Roger

Rob,

Sorry......I didn't see your response as I was typing the above. In the paragraph to Adriatic, I mentioned the 1122E designation.

Ok, let's think about this.  When it goes from forward to neutral that means the e-unit coil lost power momentarily and got it back so it rotated the drum (it is unlikely a melt spot will cause this).  Does the engine roll much further after it loses power?  Turn power off and tilt the engine sideways, where are the pickup rollers when the engine stops?  Photos will help with where the rollers are located.  Does it only lose power on this one switch or other places?  If the engine is running slow enough that it doesn't roll very far then where the rollers are located on the switch is where the problem is at.

Gene Anstine

Gene,

I have been trying to locate the spot. When you use 91 breakers, you end up doing that alot because it doesn't take much to trip them. But this engine rolls quite a bit after the power interruption, so I kind of have to do it by hand.....and then I can't get it to lose the power.  A quandry. 

I did notice that the swivel plate lifts as the engine passes over one of the problematic switches. I put a shim underneath the swivel and it still would stall. 

It may even be stalling on the UCS track in front of one of the switches, but I can't say for sure on that one. Haven't seen it do it there for awhile. 

Might have missed this information. Does it do the same thing running thru the switch in reverse? How about coming from the opposite direction? If you lock it in forward and run thru slowly does it stop as if it lost power?

Roger - this is what happened to me - very similar circumstances - engine rolled over the switch and stopped in neutral - the video shows that I found a loose frog and rivet. I had to remove the back from the switch to tighten, but when done, the problem totally went away.

It sounds like you may have already addressed this, but I thought a video is worth 10k words, so take a peek 

George

You might be onto something there, George. I do have a loose rivet on the swivel. It's always been loose and it causes the outer rail of the frog to lift. I mentioned earlier that I put a shim underneath to see if it helped. It didn't, but I didn't use a thick shim and, the rivet that is loose is not on the frog......it's on the swivel itself. The other nite I was going to bang the rivet down with a nail set to hopefully crush the back side of the rivet tighter. But I'm not exactly sure what's under that swivel. When I do my "cap mod", I don't take off the bottom of the switch.......I drill a window in the base with my Dremel because I've done so many of these that I know exactly where I have to splice in on the underside of the switch. Most times, if a switch is not working out for me.....rough ride, shorts etc.....and I can't repair it without doing a major dismantle......I Ebay another one. Cheap.

I'm going to take a look at that rivet situation later and see if I can tighten it up.  But it's very weird.  There are two rollers on this engine and they are widely spaced. What are the chances that both lose contact at the same time?   And......when I put the collector assembly from one of my 736s on there.....same thing happened. But............I can run both of those 736s through those two switches and they don't stall. Has to be something in the 26 itself. 

Roger

The 1122s are O27 switches - the 726/736 are O engines. Generally, they do navigate O27 ok. However, I have found that the eccentric crank can collide with the switch mechanism lifting the engine up and making navigation around the switch difficult.

BMORAN,

I don't run my bigger engines through the turnout. Only my smaller PW and modern engines are capable of the s turns. One of the biggest regrets I have after getting back into my trains 12 years ago, was sticking with the 027 switches. Big mistake on alot of levels. Changing my layout now would be a royal PITA. So, I deal with it. 

This issue I'm having with this engine is on the straight section of both switches. One of them is much worse with it than the other. But it's only happening with this engine. 

ROGER1 posted:

You might be onto something there, George. I do have a loose rivet on the swivel...…...The other nite I was going to bang the rivet down with a nail set to hopefully crush the back side of the rivet tighter. 

I'm fairly certain that won't work, the whole affair will just flex and dent since there's no solid backing to support a blow.

Most times, if a switch is not working out for me.....rough ride, shorts etc.....and I can't repair it without doing a major dismantle......I Ebay another one. Cheap.

I hear ya! Price vs. effort is a worthwhile consideration. The only reason I went to the trouble was because I had a bunch of them that I got REAALLLY cheap and wanted to learn how to repair and what's inside.

There are two rollers on this engine and they are widely spaced. What are the chances that both lose contact at the same time?

My technique is to get down at track level, grip the engine on both ends, use my left foot to hit the power, then provide "controlled motion" over the switch, back & forth, side to side until it shorts or opens. Usually you can eyeball the exact spot that way. But I'm guessing you have probably done similar already. Some aren't so easy!

George,

Yes.....I've got a very narrow LED flashlight that enables me to see under. But it's very awkward trying to lay across the edge of the layout to do it. Stuff gets smashed. LOL. As for that rivet....I pried up the swivel just a touch and I could see that there's a cut out under there that the bottom rivet head moves along. Whacking it will bend the groove. So, here's what I'm going to do. I opened up my spare switch boxes and found 2 right hand ones that I already wired and have good snap. And two that I haven't touched. So, I'm going to swap one out.   It could potentially open a can of worms. I settled on this group to minimize problems with other engines. So, I'm sure if this solves it for the 726, I'll get nuisance trips  on my 91s with other engines.   It never ends!

I just swapped out one of the switches. No different.  I'm also finding that if I push the engine in neutral over a UCS track or a switch, it moves into forward or reverse suddenly. Must be losing power somehow.  I locked out the e-unit in forward and it did not stall anyplace.   It's also starting to stall at times around one of my turns on uninterrupted track. Can it be the e-unit itself?       It's only happening with this engine and it appears to be a recent phenomenon. I don't run it often, but it never did this before.

Roger

When it moves into forward or reverse suddenly, does the headlight blink (it might be very quick)?
Try locking the e-unit into neutral and look for the blink. Then observe where the collector rollers are located.

You could have a dead roller.
I don't have any reference materials handy, so I am uncertain whether the collector rollers on your engine rotate on axles/rivets, or had nubs on the ends.
If they rotate on axles, I have run across pieces that had so much crud in the center of the roller that no electricity was being conducted. I had to physically remove the roller to resolve the issue. Either clean out the hole with a drill bit, followed by a pipe cleaner with your favorite cleaner (I use mineral spirits), or replace it.
Same goes for the pin or rivet: clean it or replace it.

I suppose you could have the same issue where the arm is articulated at the base, but I have not seen this problem.

CW,

I've got nubs on mine. I removed them yesterday and cleaned the nubs and Dremeled the roller (brush). Didn't effect it. I also hit the spring and spring axle with contact cleaner. 

I'll try that blink test a bit later. Need a break. 

Could it be the e-unit?

CW,

As I don't have replacement rivets for the springs, I may solder on a small wire from the arm to the collector frame and see it there's an improvement.  Although I doubt it since I already tried swapping out the collector assembly for one of my 736s.

No blink when it stops with the e-unit unlocked. I'll try it later locked

Could it be the e-unit?

If there isn't any blink of the headlight, then the e-unit is a possibility. Is the switch handle loose? are the solder joints from the e-unit coil to the terminals good?

But if it was the e-unit, the problem wouldn't be likely to always occur at the same few places.

CW,

The worm turns.........

The lever on the e-unit is tight. It wasn't always that way. Last year, I put a sliver of styrene behind the masonite. Very tight now.     I resoldered the solder points on the unit a couple of nights ago.     

The stalling on that curve is a new thing. All of the stalling, no matter where it occurs, is intermittent. If the engine is going fast, it's not likely to stall, which made me think it was rollers. But swapping out the roller assembly didn't fix it. 

There must be a loose wire someplace.....          But here's another weird thing. I shouldn't get continuity between the short arm of the switch (straight portion) and the next piece of track (inside rail) because there's an insulated pin there. Some switches I do, some I don't in that spot and it seems to change. I have a feeling it's due to the wiring of the capacitor/fixed voltage system. It doesn't seem to effect other engines.

Roger

How is your track for dips? Some times the pilot can get bent or sag lower than specs and ground out on humps or dips in the track. Also it wouldn't hurt to take a gander at the pilot truck.

MidnightWrecking,

The pilot didn't seem to be hitting anything. I've had other engines with cowcatchers that bottom out on frog rails. I did think the rear truck was an issue, so I removed it and ran it again. No change.

Well, whatever is wrong with this engine, it's getting worse. It's stalling now in lots of places on the loop (not just switches). It does not seem to occur when going fast, but at slow speeds it's not going to complete a single loop without stalling now. 

No blinking of the lamp, but something is making that e-unit cycle. Bad coil in the e-unit?

Roger

IS the headlight illuminated when you get no circuit between the e-unit lever and the track?
If you move the test point to a different section of track, is the circuit still open?

Can you temporarily connect a jumper between the e-unit ground terminal, and a ground on the chassis, bypassing the lever?

CW,

A question about what you wrote above.   Do you mean when the engine moves to an area where the e-unit cycles to neutral, is the lamp illuminated?  And if I push the engine off the offending spot, does the lamp change?

If you have a general power pickup problem, the light will blink at the exact same time the e-unit cycles. The off time may be very very brief, so you would have to watch very carefully. It helps to move the engine as slowly as possible.

The light will not go out and stay off unless the e-unit is also off. So no, if the e-unit has cycled, the power was restored and the lamp will be lit.

You may find a spot at which both the light is off and the e-unit is not activated, even though there is power to the track. If so, then you can determine whether it is a problem with the center rail pickup or the outside rail.

In my experience, problems with outside rail pickup are more common in diesels, and small steamers (basically scouts). That doesn't mean those problems cannot occur in larger engines. But I guess they'd be rare.

CW,

I'll check the lamp again later. With the shell off, I had to tape it down to ground it.   I just opened the brush plate to check the brushes (one of the only things I hadn't done, I think). They looked very good, but I did clean out the brush tubes. No change. 

One other thing I noticed that is a bit confounding. Slowing the engine before it enters the problem areas increases the likelihood of a stall. But if I run it at that slower speed (instead of throttling down to that speed), it's not likely to stall. Coincidence, probably. 

Normally, these kinds of things have been relatively easy to track down. Not this one. 

Here is a THEORY to explain that behavior.
When you run at a consistent speed, the rear wheels are going to be pushed to one side by the action of the worm gear.
If you are slowing down in the problem area, the sideways pressure exerted on the axle may be reduced or even reversed, shifting the rear drive wheels to the other side.
If there is significant play in the rear axle, the position of the whole chassis on the track would shift slightly, and might make a difference.

Again, this is just THEORY.

Theory or proven fact......I'm open to anything at this point. I just checked the play in the rear wheels. A full 1/16 inch. That's more than both my 736s and most of my steamers, but my childhood 2035 appears to have more and that runs like silk. But that engine doesn't have a worm.

But that engine doesn't have a worm.

Which means there is nothing pushing the drive wheels to one side or the other.

Does 1/16 seem excessive? Maybe  I could get a shim in there.

Just a thought, are you running the engine alone or with its tender? I had a bad pick up wire on a tender short out intermittently, but happened more on curves and turnouts. I thought it was the track, then the engine, then finally found the shorting wire in the tender. You probably already checked this, but it crossed my mind when reading the post. Good luck!

JD,

Initially, I was running a consist with the tender. Did all the roller work that way. But when I suspected a rear truck issue, I removed the truck and have been running the engine by itself (because the drawbar is gone) and the issue continued.  Whatever is causing it, has gotten worse. 

Thanks!

ROGER1 posted:

...I removed the truck and have been running the engine by itself (because the drawbar is gone) and the issue continued.  Whatever is causing it, has gotten worse...

Hmmmmm...  a poor ground/common connection to the chassis will certainly be exacerbated with the absence of the rear 2 axles / 4 wheels.

Rob,

I'll reinstall it and see what happens. It seemed to do it with truck on and truck off. But the fact that it now occasionally stalls on turns is new. I'll report back on that. Thanks

Roger

Does 1/16 seem excessive? Maybe  I could get a shim in there.

I go by whether anything is rubbing: the backs of the wheels against the chassis or the worm gear rubbing against the sides of the well.
I guess there could be issues with the side rods rubbing too.

I would recommend reinstalling the rear wheels, then add the tender, but I would remove the tender shell and run jumper wires from the tender to the engine - one ground, one center rail - this of course assumes you have a center contact roller on the tender. If the problem persists, it would seem to point to the e-unit as the culprit. If you're familiar with rebuilding e-units, I would do that next. Actually, I probably would have done that a while back just to get that bugger out of the equation. In fact, if I had a different e-unit lying about, I would substitute it in as a quick check.