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 Posted - February 13 2010 : 9:49:30 PM
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I've done 4 of these replacements since posting my first on page one. One pinion alignment that I did was a bit tight against the biggest gear and it wore that down. You could see fine dust from the white gear but it seemed to run OK afterwards.
Alco Fan
Edited by - Alco Fan on February 13 2010 9:51:49 PM
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Posted - February 13 2010 : 9:58:36 PM
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Hey NP:
Nice clear explanantion, thanks! So overmeshing would also by bottoming the teeth, create a bending/deflection force on the pins/shafts holding the gears. For the pinion on the deflected armature shaft, it would create sideload increasing friction in the motor shaft bushing, does that sound right?
On Undermeshing you get the equivalent of a slipping clutch. Not enough interface on the driving surfaces of the gears and therefore less thrust?
As to the pinion gear, I was thinking a larger shaft would be better (greater surface contact between shaft and pinion centre hole) but it would also allow for a flat section to create a "keying" to aid the twisting force acting on the gear. That make sense to you?
I'm working my way through the Tyco engine replacememnt threads. I think I'm gonna create a cad drawing of the PT unit. I'm gonna need it for development work, and ultimately for input into a CNC program if a new power truck is developed... In regards to that, I think a good but inexpensive can motor somehow employing a worm drive makes sense... I also think the idea of a belt/chain drive have merit.... what do you think?
Thanks again for the "Gear Epiphany" your explanation provided!
Best,
Gareth
"A is A"
-Aristotle
Law of Identification
Edited by - romcat on February 13 2010 10:47:29 PM
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Posted - February 13 2010 : 10:46:15 PM
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On overmeshing you get the equivalent of a slipping clutch. Not enough interface on the driving surfaces of the gears and therefore less thrust?
I think you mean undermesh. The biggest risk is stripping the teeth, which is almost a certainty if they aren't completely engaged. Overmesh causes excessive friction, strain on the motor, and ultimately wear. And yeah, the post for the big reduction gear on a PT can't take a lot of stress, either.
A flat on the motor shaft with a matching key on the gear would keep it from slipping, but is really overkill, especially if you're talking about making new pinions out of stronger material like brass or Delrin. (NWSL, maybe?) White metal is not good gear material, but it was cheap.
The Tyco Depot
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Posted - February 13 2010 : 10:52:35 PM
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Hey NP:
Thanks for the correction, fixed it.
The reduction gear pin and presumably the idlers, any idea what that metal is?
maybe the keying is uneccesary, but my thought was with a key less pressure would be needed to press fit a new pinion gear on the "arm" shaft?
Brass is btw what I had in mind for new gears. delrin would be possible. What do you see the pro/cons being?
-Gareth
"A is A"
-Aristotle
Law of Identification
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Posted - February 13 2010 : 11:35:36 PM
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The whole PT block is white metal (also known as zamac or zinc alloy), the same stuff Mantua steamers were made of.
Delrin could be risky, given the size of the pinion. Since it shrinks a bit, we could end up with split gear syndrome.  I think brass is the best choice. Keying would work best for Delrin, since it wouldn't have to be as tight a fit. A possible pro for Delrin is that it might be quieter, but there are no guarantees.
The Tyco Depot
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Posted - February 15 2010 : 7:11:43 PM
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Hey Nelson:
Question is then if the gears are brass, what to make the "block" from? I had been thinking brass but not sure with brass gears if thats a good idea? Someting about a memory of using alloy cylinders in a motorcycle engine with iron rings, or vice-versa... must be tired can't remeber the theory!?
-Gareth
"A is A"
-Aristotle
Law of Identification
Edited by - romcat on February 15 2010 8:08:17 PM
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Posted - February 15 2010 : 8:54:27 PM
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Do you really need to make an entirely new block? Couldn't you take existing ones and machine them, maybe use a steel pin or screw for the reduction gear? Lord knows there's plenty of junkers out there, lol.
I'd say brass pinion, then a thicker Delrin reduction gear, with the rest of the gears being original. I think the real weak point was the pinion, and if that wore or moved outward on the motor shaft it stripped the reduction gear.
The Tyco Depot
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Posted - February 15 2010 : 9:24:10 PM
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Hey Nelson:
As i mentioned in another Terp thread, the goal is a parallel one; one involving rewound armature and better manets + regear what I've nicknamed the Orthodox Terp and a Reformed which would mean a new block with a can motor using a worm gear for quieter operation...
I think your idea of a Brass Pinion, and Delrin reduction gear has merit. I would like however to change the gearing to reflect better protoypical speed ranges say max 75 scale MPH.
Finally the thing about a new block is the ease of production. I can design a new truck block I think which can be machined in a way that would allow simplified setup and machining. I intend to concentrate on the Ortho model initially though...
-Gareth
"A is A"
-Aristotle
Law of Identification
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Posted - September 06 2010 : 9:11:09 PM
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Hey guys,
This is great stuff, but what about wiring them? Even basic electronics is not my strong suit.
I'm running into wiring issues now, just trying to get my Alcos running.
Does anyone make a basic wiring diagram for Tyco Alcos? How about diagrams for the re-engined Alcos?
I hope to remotor mine, but I will need a lot of help doing it.
Cheers, Ian
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Posted - September 06 2010 : 11:19:57 PM
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Is this what you are looking for? It was on the HOseeker.net site.
Mike
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Posted - September 12 2010 : 09:12:45 AM
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Thanks Mike, that'll work
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Posted - April 26 2012 : 5:36:26 PM
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Since the topic came up recently I thought I'd ad a pic of the painted model to the original post of a little over two years ago.
I did a 636 shortly after I finished the 430 using a very thin motor to clear the center wheels.
Alco Fan
Edited by - Alco Fan on April 26 2012 5:55:10 PM
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