K4- Bachmann vs. Trix

[strummer]

Peering into my crystal ball...I see a K4 rebuild project in Max's future...

Mark in Oregon

[mmagliaro]

Well, I'll say at the outset that I have no intention to gut and rebuild one of these because I'm not modeling Pennsy
anymore.   

Now, as for "what I would do differently"...

1. Driver rims - thinner and more like the Kato C55 (as I've mentioned).

2. No way would I put that idler gear between the driver axles.  That is a horrible design.  It should be offset from
the line of the two axles.  Victor pointed this out in the Berkshire and they made the same mistake here.  When an idler
is dead in line with two axles, you have the forces of the two axles pushing on each other through that idler, which makes
for binds and other oddities.  You could only avoid it if that gear and its pivot were made with extremely high precision
that, frankly, Bachmann is not capable of.   If they just offset that gear up into the chassis a little, it would work much better.

3.  I don't own one of these, but I understand that the rear driver isn't pinned to the siderods.  I think that's a mistake.
It's hard to make just 2 drivers work well with one being gear driven and the other going around on the rods
(like #1 and #2 are on this engine).   If that rod were pinned to the rear driver as well, it would really help keep
the rod in a straight horizontal line, which helps for smoother running and quartering behavior.

4. The tender pickup strips inside the tender are the little short ones riveted right to the circuit board.  NO NO NO NO NO!
Short little phosphor bronze strips cannot provide the flex needed to maintain good contact on the truck thumbs without
excessive pressure.  That means that sometimes tender wheels will drag, and eventually, those strips inside the tender will
deform/bend.  Even phosphor bronze cannot keep springing back reliably without deforming if it is too short.
They should have used floor-length strips like they did in the Spectrum tenders (and like the Kato Mikado tender).

5. Traction tire on the rear driver instead of the middle.  Having it in the middle makes you play a game trying
get enough traction on it without having the engine rock and see-saw over it.

6. The motor: Not a fan.  They are using a coreless motor, yes, but it's not a high-end coreless motor.  I admit I'm guessing
on this one, but I bet I'm right.  They aren't putting a nice Maxon or Faulhaber in there with heavy duty bearings.
As such, I'd just as soon they stuck with a sturdy conventional 5-pole motor.

The frustrating thing about this list is that these are all things that Bachmann knows, or should know.  These are all
things that they did in their 2-8-0.

I have to say I have a bad feeling about the way I see engine design going, based on this K4 and on the Berkshire.
It looks to me like they are finding ever-new ways to build the engines more cheaply, and then put a decoder in it
and use that to compensate for the cheap drivertrain.  Yeah, it's got DCC and sound built in, and it is very pretty.
But the bones?   I'm not a fan.

[strummer]

Well, I'll say at the outset that I have no intention to gut and rebuild one of these because I'm not modeling Pennsy
anymore.   
I have to say I have a bad feeling about the way I see engine design going, based on this K4 and on the Berkshire.
It looks to me like they are finding ever-new ways to build the engines more cheaply, and then put a decoder in it
and use that to compensate for the cheap drivertrain.  Yeah, it's got DCC and sound built in, and it is very pretty.
But the bones?   I'm not a fan.

You're no doubt correct on all points. I see this final point as a trend, I'm afraid, in all the scales: more superficial details, and less quality in the basic construction. "Bones", as you put it. Thanks for your thoughtful input.

Mark in Oregon

[chicken45]

That was terrific, Max. Thanks!

[Chris333]

The wide cylinders must be why the pilot looks so small.

[peteski]

The wide cylinders must be why the pilot looks so small.

I think you're right. Dr. Dave just posted a head-on shot of his K4 in the Weekend update thread, and it looks like it has chipmunk-cheeks. 

[kornellred]

I am afraid to state that the chipmunk-cheeks are a reality and not an illusion.  I just put the calipers to my example and the measurement is 0.9 inches, which in N-scale is exactly 12 feet.  The overall width on the K4s measured at the cylinders is 10' 3 1/4".    Sigh.

[dougnelson]

Now I know why I had people being knocked over on my passenger platform.  Oh the humanity.

I guess n scale steam holds less energy than 1:1 steam, hence the larger cylinders. 

[Chris333]

Bachmann probably spaced the cylinders out on purpose so the valve gear would have more space to swing around without binding. They did this on their last few locos as well.

[Dave V]

I think you're right. Dr. Dave just posted a head-on shot of his K4 in the Weekend update thread, and it looks like it has chipmunk-cheeks. 

The Bachmann:



The PSC brass:

[nscaler711]

Dave that's like a Apples to oranges type thing. Lol
Idk, Brass is nice, but alot of brass seems to have more clunky drive systems than plastic models.
Either way they both look like good steamers.
As for the cylinders the brass ones stick out too, but not as "bad" as the Bachmann... But hey ill take that for a smoother operation than something that might sound like a coffee grinder... not saying yours does, but I have seen and heard some brass locos operate, and all I can say is I need ear-pro to watch them. 
They just don't have the sound deadening properties as pot metal and plastic lol.

[peteski]

The Bachmann:

The PSC brass:

Thanks for posting those photos next to each other.  But each is taken from slightly different distance (or zoom level), slightly different angle and height.  So, to my eyes, the K4 cylinders still seem to stick out more than the brass loco's (the chipmunk cheeks).    Plus the K4 pilot seems to be narrower too (exaggerating the effect).  Not that I'm saying it is a bad thing - it is just that the K4 the model looks funny to me when viewed from the front.

[Mark5]

Interesting comparison - overall the brass loco details look chunkier. I prefer the Bachmann appearance wise.

[eric220]

My first reaction to the brass was, "Holy halo, Batman!"

Each has their strengths and weaknesses.  Overall, the "chipmunk cylinders" are the only major chink in the armor on the Bachmann that I can find.

That and the whistle...

[chicken45]

My first reaction to the brass was, "Holy halo, Batman!"

Each has their strengths and weaknesses.  Overall, the "chipmunk cylinders" are the only major chink in the armor on the Bachmann that I can find.

That and the whistle...

That, and the fact it's not designed by Kato. 

Oh, BTW, I forgot to mention that my K4 actually has a Falhaber in it!