U-Boat Derailments

Phil V
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Post by Phil V » Thu Jul 27, 2006 4:02 pm

Joe, what radius curves are you using? The older "black box" U25B's with the silver wheels and friction bearings can get real twitchy when going through curves. I had a problem with one of mine that was due to the one truck running slightly slower than the other, resulting in jerky movement and causing the slower truck to sometimes lift and derail on curves. Rebuilding the truck cured the problem for the most part for me. Also, if your derailmets are happening all over your layout, check and make sure the wires are not looped under teh mounting "A" frame of the motor block. If one got under there, the truck would loose it's ability to track over roadbed irregularities causing derailments as well

Bennett Greeninger
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Post by Bennett Greeninger » Thu Jul 27, 2006 6:43 pm

I also had a problem with my U25B jumping the tracks , i reworked the motor areas and they now turn like a RS-3, no more problem jumping .ben

[ July 27, 2006, 02:44 PM: Message edited by: Bennett Greeninger ]

Ted Doskaris
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Post by Ted Doskaris » Fri Jul 28, 2006 3:19 pm

Joe,

As to Aristo's U25B derailment (aka "stability problem") it is likely related to that loco's rather odd truck pivot design that is a design that resembles Aristo's passenger car trucks - that being the offset pivot - but the loco has an added plastic adapter plate inclusive of a 4 metal roller arrangement to apparently reduce friction when the trucks pivot. I don't know why this loco was designed this way except for possibly the couplers benefiting from tight curve train operation.

Moreover, it seems some folks with this loco have experienced a wobble or list to one side when rounding curves - maybe because of those rollers falling out or wearing the under side plastic surface of the loco's frame. My U25Bs are still too "new" as to use, so I don't experience any derailments or stability problems at this time. And I do plan to add more weight within the fuel tank area to improve their traction.

The below pictures are of my Union Pacific U25B which happens to have the newer ball bearing type motor blocks.
However, this is not relevant to the offset pivot hardware that the U25B has as this is the same for the older style non ball bearing trucks of my Southern Pacific U25Bs.

The pictures may help with respect to lubrication, however, I would caution the use of Aristo's Electralube given my experience with cracked plastic journals on other Aristo rolling stock.

Again, the Aristo-Craft U25B loco uses an adapter plate with pivot rollers to implement an offset mounting of its 2 axle power truck. This method affords a shorter coupler end overhang (with the trade-off of a bit more belly overhang) that is helpful on tighter curves.

Image


Below are upsidedown views

Image


The Aristo-Craft U25B power truck offset mount adaptor plate includes pivot rollers to reduce friction:

Image


FYI, See the below link for old FORUM topic which had responses with respect to the Aristo U25Bs "stability problem":
"Topic: Triple Heading Aristo's U25Bs with the SD45"

http://www.aristocraft.com/cgi-bin/ulti ... 465#000000

I hope this is of some help.
Ted

[ July 28, 2006, 11:36 AM: Message edited by: Ted Doskaris ]

Greg Elmassian
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Post by Greg Elmassian » Sat Jul 29, 2006 2:36 am

With all the friction points, looks like a good place to have liberal lubrication, and grease would seem to be the right thing, except maybe the roller ends themselves.

How do the rollers mount in the plate? Do they have little journals like wheelsets?

Have you ever disassembled that part and checked how freely they rotate?

Regards, Greg

Ted Doskaris
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Post by Ted Doskaris » Sat Jul 29, 2006 5:58 am

Greg,

I have not yet had reason to take apart my U25B to see how the rollers are attached to the adapter plate.

As to using grease on them, I am sure it would work just fine for operation on my under house layout, but for folks who have outdoor layouts with a lot of dry dust and dirt, it may get into the grease and rollers and result in more trouble.
Perhaps some other FORUM user can contribute their experience in this regard.

Ted

Doug Cannon
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Re: U-Boat Derailments

Post by Doug Cannon » Wed Oct 18, 2017 5:47 pm

Thanks for this thread with heads-up on some of stability issues and fixes. Will dig further for a better described fix 'recipe' !

Just recently acquired a (for a decent pricepoint form a estate) black box GE Demo' unit. The railings were not even put onto the unit yet (NOS, or gently used classification ? ;) ) !

doug c
Last edited by Doug Cannon on Wed Oct 25, 2017 12:05 am, edited 1 time in total.
" G-gauge may not RULE, But it GROWS on Ya !! " djc'99

Ed Headington
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Re: U-Boat Derailments

Post by Ed Headington » Thu Oct 19, 2017 9:25 pm

You will note that U25B trucks have one rigid axle and one axle that pivots left and right. On my U25B's, the flexible axle is the one closest to the center of the engine. I reversed both trucks so that the flexible shaft is on the outer two axles. This significantly improved any derailment issues I have had with my U25B's.

As an additional note, I have learned that my U25B's operate better with the old trucks that have the axles extending into the side rails of the truck.

Ed Headington

Alan Lott
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Re: U-Boat Derailments

Post by Alan Lott » Fri Oct 20, 2017 7:31 am

I don't have any U25B's Doug, but I do have an FA-1. Some while ago Ed H advised me that he reversed the trucks, as detailed here, to good advantage. I have done the same with equal success.
Alan
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Doug Cannon
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Re: U-Boat Derailments

Post by Doug Cannon » Wed Oct 25, 2017 12:34 am

Thank You Gents for the input !

So I guess I'll first look at confirming orientation, if req'd dropping the motorblocks and reverse them .. floppy axles to the hood ends (if i re'd your comments correctly !?) .

I also still have a unopened (yellow box ) PRR unit, also acquired at a terrific $ point, thru a local shops ebay selling (probably 5 yrs ago now) off their purchase of a (usa) HS stock !

I do seem to have a great opportunity (unpack both black'n yellow) to do a comparison of some of those differences in production models I've read about ...


Also Ted D. rolled out a recent how-to tutorial on upgrades to BB motor blocks and weighting;
https://elmassian.com/index.php?option= ... temid=1157
I spotted it on Teds' LSC thread;
http://www.largescalecentral.com/forums ... tor-blocks



later,
doug c


p.s. want to unpack these 2 units ASAP for a photo op', and submit them for upgrading the existing UnCatalog pics (unreal IMHO) :) ! I prefer pics similiar to what I submitted for the CN D'9 and other production items. http://aristodatabase.x10host.com/
Last edited by Doug Cannon on Wed Oct 25, 2017 8:36 pm, edited 1 time in total.
" G-gauge may not RULE, But it GROWS on Ya !! " djc'99

smcgill
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Re: U-Boat Derailments

Post by smcgill » Wed Oct 25, 2017 11:42 am

p.s. want to unpack these 2 units ASAP for a photo op', and submit them for upgrading the existing UnCatalog pics (unreal IMHO :) ! I prefer pics similiar to what I submitted for the CN D'9 and other production items. http://aristodatabase.x10host.com/

This info should be a sticky .. :!:

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