Kumata Brass Patients are being healed!!!!! Update

[u18b]

I thought I'd start a new thread instead of digging up an old one.

New video is up!  About three minutes. 

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or go to my website-   www.u18b.com

Making progress on my work with Kumata brass locomotives.

Special thanks to Bob Bufkin (Centipede), Roger Holmes (EP-2 Bipolar), and Bryan Busset (New Haven Washboard) who graciously loaned me their locos.

The main objective for me was to take the shell off and study the mechanism-  and I have learned SO much from this.   I have- and will continue- to work with Spookshow to help improve info for his site.

But each of these guys graciously also gave me the opportunity of tinkering with the loco.  Each said that he was not "collecting" the piece but wanted to RUN it.  So if I could get it running better, then more power to me.

The irony is that out of all KMT locomotives, these three are among the most expensive.  While you could always get a good deal, these three locos rage from just under $700  to over $1,000.  Thanks guys for trusting me with these.  The irony is they are all expensive and all were some variation of crapola.  But they are such greatly unique prototypes-- that's what keeps their demand so high.

Well, I at least improved every one of them.

The Centipede is really such a poorly designed loco.  It is INHERENTLY designed to have minimal tractive effort on the few drivers it has.  Arrrgggghhhh!
I got Bob's running "fairly well".  It will at least pull some freight (sometimes they won't even pull themselves!).  I'm not quite finished with this one.  I may try a few more things.

The New Haven Washboard is one of the later (and thus you would think more advanced) locos KMT made.  But wait until you see the video.  I cannot describe how incredibly awful it sounded.  And it was in mint condition.  Bryan has had it in a box for almost 25 years.  Now it runs very well.

but the best was the Bipolar.  This loco ALSO had horrible design flaws which I was able to overcome.  Like the Centipede, the Bipolar is so poorly engineered that it could barely run.  it WOULD run by itself, but would slip with any amount of pressure.  Now it will pull 20 or more 50' cars and is unbelievably smooth and quiet.

The Washboard and the Bipolar are on their way back to their owners.  I hope they will post something (good or bad) when they get them.   Feedback is good.  And as I said, I think I'll tinker with the Centipede a bit more.

I am up to 50 pages on The Kumata Primer- and I still have to write up the Washboard.  After the experience of the last month, it may be 100 pages before I'm finished.  But my goal is to have the most exhaustive resource on these models for N scalers.

The original thread is here:
https://www.therailwire.net/forum/index.php?topic=29600.0

[u18b]

I would still love it if some people might want to help me out in this project.

So here is what I have already studied and therefore do NOT need.
RS-2
Trainmaster
B&O EA/EB
EP-2 Bipolar
Centipede
NH Washboard starter set (though, I would love to photo the ADD-ON two cars.  Anyone have them?)


Here is what I would love to borrow (remember- all Kumata/Japan,  not Samhongsa/Korea):

EMD SD40-2, Hallmark/Kumata (Japan)

Alco RSC-2 (or 3?  Not sure), Hallmark/Kumata (Japan)

Alco RSD-4/5, Hallmark/Kumata (Japan)

EMD E3/6A & E3/6B, Hallmark/Kumata (Japan)

EMD E5A & E5B, Hallmark/Kumata (Japan)

EMD E1A & E1B (Super Chief), Oriental Ltd/Kumata (Japan)

New Haven Washboard Add-on cars

PRR Electrics, NJ Intl/Kumata (Japan)  (there are about 5 all total)

Budd Silverliner, NJ Intl/Kumata (Japan)

And remember, I will only study the mechanism if that is all you want me to do.  I'll do nothing else unless you want me to.

Thanks for reading.

[Roger Holmes]

Wow!  Got my Milwaukee Road  Bi-Polar back from Ron and just watched it walk away with 27 MT and FVM freight cars.  It surely could pull more but I only had a few minutes for testing.  No more shelf queen.

Thanks Ron!

[nstars]

I agree with Ron, that the Centipedes are terrible running locomotives. Fortunately my brother was able to replace the existing chassis with a new ones and both my Centipedes run really well. With the sound in I'm really happy.

Marc

[Bob Bufkin]

Who makes Baldwin sound chips?

[nstars]

We used the Loksound micro V4 decoder. You can hear the loco in this video.

Marc

[u18b]

I agree with Ron, that the Centipedes are terrible running locomotives. Fortunately my brother was able to replace the existing chassis with a new ones and both my Centipedes run really well. With the sound in I'm really happy.

Marc

Marc, I have spent countless hours tinkering with a Centipede--- and I'm a pretty persistent fellow,   but I just could not perfect it.   They inherently designed this 4-axle truck to be out of balance.  It is just too hard to overcome the poor work of the designers.

[u18b]

Who makes Baldwin sound chips?

Bob, I tried to call you yesterday (Friday).  Give me a call when you get a chance.
(I'll try again in case you don't have my number).

Ron

[u18b]

Here is some information from my research in this project.

Why the Centipede is crap so hard to optimally tune.

Let's start with the EP-2 class Bipolar- which also has 4-axles.
The power truck only touches the frame at the drive axle (circled in red).



Now in this side image of the Bipolar truck, the powered axles are 1 and 2.  3 and 4 are dummy idlers.  As long as 3 and 4 float at least a LITTLE bit, then all of the weight for this truck is transmitted to axles 1 and 2 (yellow arrow).



But did Kumata design the Centipede the same way-  no!   

Here is a power assembly/truck for the Centipede.
There are a few things to note.  The weight of the shell is on the bolster (circled in red).  But actually, the pilot truck is attached with a screw that sticks up and is rounded on the end (circled in yellow).  This screw tip can slide on the shell underside.   You should also note how the motor weight will shift the balance point to the rear over the idlers.  Also, see the little bend in the brass sheet frame that extends from the power truck forward over the pilot truck and holds the coupler-- note that this frame can be bent up and down.



Ok, why can't we get good traction in a Centipede?  Just look.



The entire line of the truck/power assembly is the purple line.
The powered axles are in red.
The bolster is the big X and is thus a pivot point.

So the weight of the shell is mostly at the pivot point (blue arrow).  Notice that the IDEAL situation is when the focus of the weight is DIRECTLY over the middle of axles 1 and 2.  But in the Centipede, the weight is BEHIND axle 2-  which takes weight off of driven axle 1.

The motor weight will trend toward tipping the truck toward the rear (A).

But the weight of the forward section will trend to tip the weight toward B.  Hmmm.
But the screw at point B-  if the frame for the pilot truck and coupler is bent to high, then the shell will press down on point B and tilt the truck forward.

So should the frame be bent that the shell does not touch?   

Also note that the pilot truck has a spring which places a small upward pressure at point B. 

So how in the world do you balance ALL of these factors so that the weight distribution is at its maximum at the driven 1 and 2 axles???   

I have no idea.  You would be a better modeler than me.   

This is why (in my humble opinion) the Centipede is hopeless and if I owned one, I would throw away the motor and totally repower this shell with a Kato or Atlas chassis.

[delamaize]

So, the question I have is could the power truck portion be "Flipped" within the sideframe?

[u18b]

Mike,
I would say yes.  But....

The sideframes of course do nothing. (the wheels are not attached to them)
The truck frame itself is a rectangular piece of Zamac.
The sideframe piece is connected to the truck frame in the dead middle of each end.  You can see the screws.  One is a little hidden in the wires under the motor and the other one is the forwardmost one in front of the worm bearing.

So, yes, I suppose to could remove those screws and rotate the guts of the truck.

However, since the bolster brace is not in the dead middle spot between axles 2 and 3, then when you rotate everything, the bolster will be in the "wrong place."  Of course, it only goes one place onto the shell, so what would happen is the whole truck would be moved forward to much.

Right?

[delamaize]

Mike,
I would say yes.  But....

The sideframes of course do nothing. (the wheels are not attached to them)
The truck frame itself is a rectangular piece of Zamac.
The sideframe piece is connected to the truck frame in the dead middle of each end.  You can see the screws.  One is a little hidden in the wires under the motor and the other one is the forwardmost one in front of the worm bearing.

So, yes, I suppose to could remove those screws and rotate the guts of the truck.

However, since the bolster brace is not in the dead middle spot between axles 2 and 3, then when you rotate everything, the bolster will be in the "wrong place."  Of course, it only goes one place onto the shell, so what would happen is the whole truck would be moved forward to much.

Right?

you got my brain working now....wish I had one to tinker with....

[u18b]

hahahaha.


NO!  Don't do it!!!!!

 

[wcfn100]

Maybe modifying on the bolster design would help.  I can't picture it this late at night, but I'm thinking something like a weight distribution hitch on a trailer which 'moves' weight forward off the tongue.  Maybe you could trick it into thinking the center was between the 1 and 2 axles.  I think though, there would have to be an additional friction point for some sort of spring.


Jason

[u18b]

If I was on the Kumata design team.... what I think they should have done is...

1.  Made a truck basically like the EP-2 class Bipolar.
2.  Except place the gear tower in the CENTER of the truck, so now axles 2 and 3 would be powered, and the weight would be right on the center of the truck.
3.  Do away with the brass sheet that connects to the pilot truck.  Why isn't the pilot truck and pilot/coupler just connected directly to the shell?  It should not involve the 4-axle power truck.


but given what we have....
1.  The loco comes with 4 powered traction tire wheelsets.
2.  Some one who is REALLY good could find a way to cut into the truck frame  to make room for more gears and make axle 3 powered.  The extra idler gear between axle 2 and 3 could come from an extra wheelset.

When that was done, then the bolster would be more or less over the MIDDLE of the powered wheels.

The number one problem is the bolster screw goes THROUGH the motor frame/holder and INTO the truck frame.  So you would probably lose the screw hole. 
But maybe the screw could screw into the Motor frame/housing instead.