The good news is, I didn't pay much for it... Steam Question for the tinkerers..

[wm3798]

So I've added an ancient Minitrix 4-6-2 to the retro fleet, and it does show a certain potential to be a successful engine.

But...  Having read the Spookshow review, I'm looking for ways to resolve the pick up issue.  On the one hand, I want to try to keep it as original as possible, but on the other, I want it run reasonably well for its vintage.

Mine is the older model he describes as having the red idler gear, which means higher speeds and slightly jerkier performance.

Compared to the Rivarossi 4-6-2 I recently rehabilitated, it's a hot mess. 

The most obvious problem when it's running is that it makes great contact and roars through the 11" r turns, but it bogs down and barely wants to run through the tangent sections.  Even the really short ones. 

So, upon the inevitable peek under the hood, I noticed two things.  First, the black wire from the tender was missing.  Easy to fix.  I also added another wire from the front truck to supplement the suspect drawbar connection to the front truck.  Both are now hardwired to the motor.  A little conductolube on the axle wipers, and a bit of added weight in the tender improved performance dramatically, but still not comparable to the Rivarossi.

Next, I inspected the wheel wipers on the engine, and everything seemed to be in order.  I schpritzed it with some contact cleaner, and again, a fractional improvement.  But then I noticed one of the traction tires was missing, leaving a groove in the tread of the forward Fireman's side driver...  The review says the traction tires are one of the problems with the pick up system, as only the middle driver on the left side makes contact with the rail, while the other two, despite their wipers, do not due to the tires.
 o I'm wondering, having added another quarter ounce or so of weight under the shell, would it make sense (and be worth the heartache of dismantling the valve gear for even a moment) to just get rid of the traction tires and replace those drivers with properly surfaced treads?  My thought is that the added weight makes the need for traction tires moot, and frankly, there's room under the shell for a bit more if needed.

Again, the combination of added weight to the engine and tender, some conductolube and new wires from the tender have made incremental improvements, but I'd like to solve this final riddle as best I can before I delve into replacing the motor... which while speedy, appears to be fine.

Help me @mmagliaro and @randgust !

Lee

[DKS]

Have you considered a Spectrum tender, or at least the important bits thereof? I've got a few* spares...

*Like, a dozen or more...

[eric220]

Paging @mmagliaro

[Lemosteam]

1. Check the driver gauge and quartering and once set then use a small drop of loctite on the outside of the wheel at the shaft end.  You will need a new traction tire, I have some. 

2: You will need a new traction tire, I have some.  If I recall, the siderods are connected with screws so you should be able to get the siderod to drop off without removing any axles or valve gear

3: there is no easy way to get gear reduction in that engine, inless you can find someone willing to part with the dual reduction gear 9I may have one and be willing to part with it)

[mmagliaro]

The axle and wiper metals on the Trix tender trucks are a never-ending problem.  You can clean and conducta-lube them forever, but the pickup will always be terrible until you get rid of those and either put a Spectrum or Kato tender chassis under there and hard-wire it to the motor... OR... (what I have done on the retrofits), just put new trucks under there and hardwire the pickup "thumbs" from the trucks with flexible soldered wires up to the tender.

Trust me - no amount of weight or tinkering with improved driver pickup is going to make it run any better than "frustratingly".  Added weight in the boiler will help pulling power, but not pickup.

I have a lot more on this to share with you, including photos and info on remotoring and gear reduction... more later.

[wm3798]

Sounds like I might be in the market for some Spectrum tender trucks.
Very helpful, thanks.
Lee

[C855B]

A complete shot in the dark... back when I was repairing first-gen locos in the '70s for an LHS, I had a similar instance with a European steam model (of European manufacture). It would run well on curves, but on tangents it would jump and balk and just be a PITA. In the end, it wasn't electrical, it was a universal joint between the motor and worm. Replaced the U-joint with a flex joint made of wire insulation, and it ran smooth as silk. Don't know why the odd behavior since the relationship between the motor and worm shafts supposedly never moved, but it was fixed by this nonetheless. Very strange.

[mmagliaro]

Okay... major things about the Trix K4, besides the pickup issue I already wrote.
Probably more than you will ever want to know, but here's a "stream-of-consciousness" dump...

This document:
http://www.maxcowonline.com/maxspage/downloads/minitrixK4Overhaul-revision_2.pdf

...is a 36-page, fully-illustrated guide to putting new trucks into the K4 tender, replacing the motor with a Maxon 1320 coreless, and replacing the "red" or "black" idler gear with a special double-gear that improves the gear ratio.

Key facts from that document...

That special double-gear I used was an Eldon Shirey (motorman) special, so you won't be able to get those anymore.
The original red-gear version (which you have), is the worst one.  They later used a black double-gear that had more teeth on the back portion (that meshed with the worm).  So it got a little more gear reduction.  But it was still not very good.

You could just put a Mashima 10x15 in there, if you can find one, or any good 5-pole conventional motor that is 17mm in length or less (unless you are willing to grind out part of the frame with a Dremel, in which case, you could push it to 22mm).  Getting the worm off the Trix motor is difficult without a gear puller, but I can do that part for you if you get stuck.  In fact, I've got a bunch of original K4 motors and I could just pull the worm off one and send it to you.  Just send me a message).

Any 12x17 or shorter motor will drop-in (with a little styrene shimming and epoxy or caulk to hold it in place)
If you are willing to grind the frame a little, any 12x20 will fit and those are a lot easier to find.

Fitting that worm on a new motor is also a trick because the worm isn't bored out to 1.5mm, the standard shaft size of most loco motors.  So you need to bore out the worm from 1.2mm to 1.5.  I can help you there too, if you send me the new motor you want to use (I can just bore our the worm and slip it on).

That red gear.  That's the nasty part.  All the details on changing it are in the document I linked above.  It takes some work.   You can actually make your own double gear by carefully slicing that red gear in half, and then gluing it to a new gear for the "back half", drilling through both gears and inserting brass pins (don't skip this step or they will just shear apart).

If you want the specs...
Red gear is mod 0.4 15 teeth, diameter 6.65mm

If you slice off the back half of it and replace that with a mod 0.3 gear:
0.3 x (28 + 2) = 9.0mm with 28 teeth. 

Formula to calculate diameter = mod x (teeth + 2)

9mm - 6.65 = 2.45mm larger in diameter, or 1.2mm larger radius.  So you need to grind out 1.2mm of space in that cavity where the double gear sits, but it does fit.

OR... 0.3 x (20 + 2) =  6.6 mm
So a 20 tooth, mod 0.3 gear would fit with no frame reaming.  Going from 15 to 20 teeth gets you a 33% speed reduction.

Let's take it a step further.  What if you used a mod 0.2 gear?
0.2 x (30 + 2) = 6.4mm  So that would also fit.   15 to 30 teeth gets you a 50% speed reduction.

Photos and more to come...

[DKS]

Personally, I think a Spectrum tender is about as far as you'd want to go. (Unless I'm wrong--I usually am).

[peteski]

(Unless I'm wrong--I usually am).

Um, I think you wrong about that. 

[mmagliaro]

Making this easier...

https://shop.kkpmo.com/product_info.php?products_id=609&XTCsid=ckj5gkbhuqtaf3bep8s0tcdi62
Buy a mod 0.4 15 tooth gear with a 1.5mm bore, 2mm thick.  (yes, you can select all those options from this place and the beautiful gear will show up at your doorstep in a week or two)

Also buy:
https://shop.kkpmo.com/product_info.php?products_id=347&XTCsid=ckj5gkbhuqtaf3bep8s0tcdi62
Mod 0.2, 30 tooth, bore 1.5mm, thickness 2mm gear.

You will sandwich those two together to make your new double-gear.  Not as hard as it sounds.  Just slip them both over a standard N scale motor shaft, which is 1.5mm, glue them with some ACC.  Then drill two small holes right through both of them (#76 is a good size) and put some .020" wire through the holes, coated in ACC or LocTite).

Finally, you need a mod 0.2 worm:
https://shop.kkpmo.com/product_info.php?info=p802_wormgear-m0-2---2-8mm.html
Mod 0.2 worm, 1.5mm bore, 6mm length, 2.8mm diameter.

IF you want to keep the original motor, then order the worm with a 1.2mm bore.  They have it.

----------------------------------------------------------------------

Now you can make your own double gear without worrying about any reaming, grinding, boring, etc, and it will drop right in.

Here's one I made in "the old days" before I could order ready-made custom gears for this.
This is 1/2 of the Trix red gear + a brass gear I got "from somewhere".  I had to cut the red gear in half with a jeweler's saw, and I had to find some piece of rod that fit it, and then bore out the brass gear to match.... It was ugly.




Then it drops in, in place of the old red gear.  Forgive how ugly this is, but it expresses the idea and it did work.
Yours will be a lot simpler because your gear and mounting won't have to be so cobbled.



===========

Okay... now I'll shut up.  Good luck!

[wm3798]

Man... I've been SCHOOLED!
Thanks for all that information, Max.  Honestly, that is farther than I'm ready to go at this point.  If I was building a PRR fleet and this was the must have engine I needed for regular service with an ops crew that needed reliable engines, I would be all over it like a bad suit.

But in the end, DKS IS right, I'm looking to resolve the basic pick up issues, fix the traction tire, and pull this out of the drawer to run around the loop in the background while I'm working on house plans.  As I've said before, my train layout has gone from being the nearly full time obsession the old Western Maryland was to being sort of like an aquarium...  Little light flickering out of the corner of my eye, noticeable motion by its inhabitants, and a pleasant whirring sound.  If it needs to run a little fast to run smoothly, what the heck!  It IS the Broadway Limited!

With the K4 being offered by Bachmann now, when and if I need to have the be all/end all K-4, I'll pony up the 200 quid and get one.

But Max @mmagliaro , please don't think I underappreciate the work you have put into both this posting AND making old steam mechanisms dance to your tune.  Having grown up during the Dark Ages of N scale, and experiencing the horrors that you have corrected over the years, I swear you are nothing short of a miracle worker.

Lee

[mmagliaro]

Lee,

We are all good and happy.

My intention was to spew out all the important steps, and then let you pick and choose.
Even my massive 36-page "tome" starts out by replacing the tender trucks and wiring to get reliable pickup,
because that is the major step that takes the Trix K4 from being "useless" to runnable.  I urge you to do that step because without, that engine will end up back in the "non-running" drawer sooner or later.   Oh, and as a minor point, replacing the trucks means putting a body-mount coupler on the tender, but that's a good idea anyway.

All that work was stuff I did back when there was no Bachmann K4, and if you were a Pennsy modeler, you had two choices: rework a Kato C55, or rework a Trix K4.

So by all means, do the trucks and wiring, replace the traction tire, and then just sit back and enjoy it.

-- Max

Oh... and thank you.   

[narrowminded]

Man... I've been SCHOOLED!
Thanks for all that information, Max.  Honestly, that is farther than I'm ready to go at this point. 

But Max @mmagliaro , please don't think I underappreciate the work you have put into both this posting AND making old steam mechanisms dance to your tune.  Having grown up during the Dark Ages of N scale, and experiencing the horrors that you have corrected over the years, I swear you are nothing short of a miracle worker.

Lee

Yes, Max.  A lot of people read these threads and your posts are always detailed and helpful to a LOT of folks.  More than you're likely to know.   Thanks for all you do.

[Point353]

If you want an "ancient" N scale PRR steam loco that runs well, then get one of these: