Author Topic: Brass Pecos River 4-6-4 problems  (Read 1663 times)

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woodone

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Brass Pecos River 4-6-4 problems
« on: May 16, 2020, 09:28:01 PM »
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Need some help here and moral support too.
I just did a DCC with sound install on this 4-6-4 locomotive.
Install was pretty much normal.  Being brass I did add all wheel pick up in the tender plus I added wipers on two drivers left side of loco. 
Install was tested and all ran well before being shipped back to its owner.
Got an E-mail from owner telling me the locomotive would not move- I do not know if it ever had sound because the owner just shipped it back to me.
When I received it everything looked good, I tested the decoder and found it to be good. I disconnected the loco from its tender and hooked up some test leads to the motor. That is when I found that the right eccentric was loose and binding the driver. OK so I put the valve linkage back and the main drive rod and put the eccentric arm with screw back in place. Now to test rollers and running. Ran forward for a bit then reversed- locked up again- Looked at the eccentric arm and it was unscrewed and binding again. OK back together and put a little more beef on tightening the eccentric this time. Test again same result. So, more investigating. What I found was that the eccentric was being unscrewed by the valve gear linkage because the arm was soldered to the screw about 10 degrees off. I fixed that and then to the test rollers again. Ran forward for about 10 minutes then reverse the same everything stayed together and ran fine.
OK all back together now with DCC & sound
Test run on layout- went 5 feet and stopped- first thing I looked at was the eccentric It was OK, but the front & second drivers were locked up.
I tried to turn them but fearing I would do damage I took to work bench tested with DC it unjammed and was off running again. Back to layout this time it ran about 60 feet or so, then I reversed it and it backed up about 5 feet and it stopped. Drivers looked up again. This time I had to remove the boiler & cab to get to the motor to free up.
Seems like with DCC the drivers jam up, with DC on test rollers it runs simply fine. any ideas.
Before it heads for a wall? sorry for the long post and poor Me’s.

mmagliaro

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Re: Brass Pecos River 4-6-4 problems
« Reply #1 on: May 17, 2020, 02:45:26 AM »
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I'd strongly wager that DCC vs DC has absolutely nothing to do with the drivers locking up.  Look at the crankpin on the front driver where it goes behind the valve slider as it rotates. You may find that it can jam in the slider every once in a while, just depending on the general slop of the mechanism and where the drivers happen to be when they slide back and forth as it goes down the track.  Running on test rollers or on its back on the workbench is a good test, but the drivers do not shift and move the same way they do on real track.

The next time it jams, inspect the valve sliders and the crankpins behind them.  One of the Pecos River 4-6-4's I fixed for somebody had that problem.  If you find that's the case, write back. I have a close-up photo of a fix for it.

peteski

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Re: Brass Pecos River 4-6-4 problems
« Reply #2 on: May 17, 2020, 10:29:35 AM »
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This was not mentioned yet:  After the running gear jams the best way to look for the culprit is to carefully lift the model off the track (to leave it jammed) then using fine pointy tweezers, or even a sharp pointy dental probe to very delicately try to move every piece of the valve gear.  And I mean *VERY* delicately.  Just barely tough each piece and see if it is loose.  Every moving piece of the drive train should have some play in it.  Well, all except for the jammed one. 
. . . 42 . . .

woodone

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Re: Brass Pecos River 4-6-4 problems
« Reply #3 on: May 17, 2020, 12:02:25 PM »
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Thanks Max.
I don't think that is the problem. While it was jammed up I looked for anything that was causing the bind. I do see what you are talking about, very little clearance on that pin and the slide. While bound up I tried to see if the side rods were free, they were not, but I could not determine which was under compression or stretching on the rods. Seemed like the connecting rods where under load and locking the drivers. Everything else was free.
Could it be that the crank pin on the front driver causes the bind and locks the side rods then falls free?
I will run again and see if I can see anything before removing from track. BTW this seems to be locking up on a curve.
Thanks Peteski, but that is just how I have checked it both times. I know there is something going on, but have not put my finger on it yet.
When I mean locked up, the drivers just will not turn a fraction of a rotation. Twisting on the drivers with tweezers I can't free them. Of course I am not putting that much torque on them, for fear of breaking something. But by going back and forth you would think that would free them.
Thanks for all the pointers. 

peteski

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Re: Brass Pecos River 4-6-4 problems
« Reply #4 on: May 17, 2020, 12:40:19 PM »
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Something also not mentioned: are all the drivers quartered properly?

Also, connecting rods on siderods-driven drivers should not all be in tension (no play at the crank pins). There should be some play in them.
. . . 42 . . .

mmagliaro

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Re: Brass Pecos River 4-6-4 problems
« Reply #5 on: May 17, 2020, 03:41:20 PM »
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Sounds like you are doing the methodical analysis correctly.
So, it only happens on curves?
Is it only in one direction (left or right turn?)

The quartering, as Peteski mentioned, is important.
Other things I've seen on brass steam you might want to check...

When it jams, can the valve sliders both move a tiny bit fore and aft?  Look at the ends of the piston
rods that go in and out of the holes in the cylinders.  Has either one pulled all the way out of the hole,
and then when the piston tries to move forward, jams against the cylinder trying to get back into the hole?


mmagliaro

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Re: Brass Pecos River 4-6-4 problems
« Reply #6 on: May 17, 2020, 03:46:41 PM »
+1
I am posting some photos of the 4-6-4, with some labeling.   These hints may help you find the problem, and they also will provide close-up views to others who might see something.  Note, these are just "other" 4-6-4's I've worked on, not the OP's problem engine.  But these engines did have various jamming problems.







FYI, it would be nice if we could just tighten that gear cover "nice and tight" and be done with it.  But unfortunately, that doesn't produce anywhere near the best performance these engines are capable of.  In fact, the Pecos River 4-6-4 and 4-6-2 are two of the best "out of the box" running brass steam engines I ever saw.  They run smooth and whisper quiet, and can sustain really low speeds, even with the stock motor.  But if you tighten that gearbox all the way, they run a little "bind-ey" and just don't have the top-notch slow start up and running.

woodone

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Re: Brass Pecos River 4-6-4 problems
« Reply #7 on: May 17, 2020, 03:53:00 PM »
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It just takes time- but I sure do not want to get into re quartering.
If the driver is out of quarter, it is very slight. When running on test rollers at an extremely low speed (low voltage DC) I do not see any binding.
With low voltage and out of quartered drivers you will find the motor stalling, when the binding happens, with a higher voltage you normally see a bouncing of the drivers.  But what I am seeing acts like a quartering problem.
just getting frustrated with this. Did a DCC install and never touched the drive or motor except to wire the motor for DCC.
I will wait till the AM to work some more on it. That is when my brain is sharpest. LOL
Yes this has happened on a curve.
piston rods are clear and free.
Thanks for the photos, I will check all the places you have pointed out.

peteski

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Re: Brass Pecos River 4-6-4 problems
« Reply #8 on: May 17, 2020, 04:53:22 PM »
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I re-read your initial post.  You stated:
Install was pretty much normal.  Being brass I did add all wheel pick up in the tender plus I added wipers on two drivers left side of loco.
Install was tested and all ran well before being shipped back to its owner.


So you did test run the model after your modification before shipping it back to the customer.  Was the test done on the same track circuit as you are using now? How exhaustive was the test?  Was is as exhaustive as you are doing now?

If you are now using the same test trackage, and now the loco binds, do you thunk it is possible that something happened to the model when it was in the owner's hands?
. . . 42 . . .

woodone

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Re: Brass Pecos River 4-6-4 problems
« Reply #9 on: May 17, 2020, 09:24:34 PM »
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I tested the loco just before packing it for shipment. I usually set the address and a few other things , like volume of chuff and whistle and will set top speed.This is done on a 3 foot track at my work bench-straight track. Run back and forth a number of times. If I have a problem it will show up on this test track.
To be truthful I don’t see how the eccentric came unscrewed with out ever being run.
The owner told me it would not move, I could never get him to say if the locomotive had sound, indicating to me if the loco was ever powered?
The eccentric with its screw was completely out of the driver. I can’t figure how the eccentric arm got turned about 10 degrees on the screw. The eccentric arm has a small hole in it and slips over the screw and soldered. I had to un-solder the arm, turn and re solder so it was in sync. with valve gear.
So I really don’t know.
The reason for running on the lay out now is to make sure all is well
10 laps around my lay out without problems before it goes home.

A

mmagliaro

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Re: Brass Pecos River 4-6-4 problems
« Reply #10 on: May 18, 2020, 12:10:50 AM »
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Yeah.... it's impossible to know if your customer isn't telling you something.  I've been in that position with repairs.  Was it dropped?  Man-handled?  Who knows?  And it wouldn't do much good to know unless you could 100% prove it.  The only recourse is to just chalk it up to the frustrations and "the gig" of doing repair services, and then just focus on what's wrong with it now.    Better not to dwell on what nefarious things could have caused it.

nkalanaga

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Re: Brass Pecos River 4-6-4 problems
« Reply #11 on: May 18, 2020, 12:29:12 AM »
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If it was dropped, or otherwise abused, it could have been during shipping, and the customer wouldn't realize it.  I've seen boxes arrive at work, looking perfect, and the contents were clearly damaged in shipping.  These were computer/office machine parts, from the original equipment supplier, to their service tech, so I assume they were NOT damaged when packaged.  The parts were also apparently well packed, so they must have really had some rough handling.
N Kalanaga
Be well

woodone

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Re: Brass Pecos River 4-6-4 problems
« Reply #12 on: May 18, 2020, 10:47:03 AM »
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I just want it to run well and move on.
I am really hesitant to dig into re-quartering.
Once I open that up I will be married to it.

mmagliaro

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Re: Brass Pecos River 4-6-4 problems
« Reply #13 on: May 18, 2020, 12:59:24 PM »
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If the engine runs well until it jams, I hightly doubt it's the quartering.  And drivers on brass steam are usually REALLY tight on their axles - so tight that it can be impossible to even press them off.

Are you able to take some really close, sharp photos of the engine on both sides,  and take them when the engine mechanism is free and when it is jammed?  If it runs smoothly at low speed without any periodic hitches in its motion, I would not look for quartering problems at first.

woodone

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Re: Brass Pecos River 4-6-4 problems
« Reply #14 on: May 18, 2020, 02:16:26 PM »
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Every driver looks to be in quarter. This AM I turned the motor shaft a little at a time and then looked for anything that could bind & or jam. I keep rotating and looking at both sides has I rotated the drivers.
What I discovered was that when the eccentric came loose there were more spacers between main piston rod and the connecting rods.
When I first got this back I found two spacers, so I thought it was all that was there. Looking this AM I see that the left side has several More spacers. So this morning I will make a spacer to see it that will cure the problem. Very small spacer so it will take me a bit to fab and then install. Hope that does it.
On things like this its like you can’t see the trees for the forest.
Thanks for all the input.
I will report back, on this!