possible chassis for U30B et al

possible chassis for U30B et al

Postby scaro » Tue Nov 06, 2012 11:12 am

One thing worth considering when thinking of chassis for TT is that the current generation of Atlas HO locos are regaugable to 12mm and narrower. I think they have ‘designed in’ the ability to go as narrow as 10.5mm gauge.

I stumbled on this while trying to find something for an Aussie railcar.

In the Atlas range, the HO scale SD 24/26 , SD35 and SDP35 have 3-axle trucks, spaced at a TT scale wheelbase 9’4½” + 9’4½” The rear axle can be amputated to create a 2-axle truck. 9’4 ½” is right for GE, Alco, FM, Baldwin and other B-B locomotives with the AAR-B truck and similar.

Might be best for hi hood locos as not sure how the gear tower would fare under a short hood.

You would need to substitute smaller wheels -eg, 26” HO NWSL code 88 on a live stub axle.

I suspect the Atlas motor is too fat for TT hood units. Cab units, probably OK. Not sure how the gear towers would fare ... they are about 11m wide. Not too bad.

What might be a good Shapeways product, a chassis designed to take these trucks at various chassis wheelbase lengths and designed for either the Atlas or another quality motor. Plus 4 small spacers to be glued to the truck gear case to ensure the pickups sit at the right posiiton.

With wheels machined to fit, this could even be a motorising kit. In the absence of RTR, a kit of Atlas quality might be a nice feature.

Don't know what these Atlas chassis cost in the US but there must be millions of them about.

May be some simple reason why this wouldn't work ... does anyone know? Can't imagine no one has ever turned an Atlas HO SD upside down and noticed the 'narrowability' at least ...

Ben
Last edited by scaro on Tue Nov 06, 2012 11:59 am, edited 1 time in total.
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Re: possible chassis for U30B et al

Postby ConducTTor » Tue Nov 06, 2012 11:18 am

Thanks Ben. I wasn't aware of this possibility. Everything is still in boxes from the move but once it's out and ready for me to "play" with I'm back on the U Boat. Will look into this path if my current direction turns into a dead end.
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Re: possible chassis for U30B et al

Postby scaro » Tue Nov 06, 2012 12:06 pm

the thing i need it for is a railcar so admit i'm not sure about how it would fare with low hoods. i'll have to remind myself to run the calipers over the SD24 i got and see tonight.
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Re: possible chassis for U30B et al

Postby areibel » Tue Nov 06, 2012 3:53 pm

I'll have to look at them also, but I'm not real optimistic!
I started looking at all sorts of HO and N scale trucks several years back, and the only one I really thought about trying to build was for an N scale Atlas C628. I'd have to go dig that mess out, but I think the axle spacing was right for TT, if you left the center wheelset out. The problem there was the wheels- Atlas didn't make anything close to a 40" TT wheel, and with a 1mm stub shaft you'd need bushings for most anything NWSL sells.
I didn't even consider many HO diesels, so that's why I'll have to look now. Parts are cheap enough directly from Atlas, but liekAlex said the big problem isn't the wheel gauge, it's the gear tower. It might work for a rail car or E/F unit, but for most others they're way too wide. The inside of the GP shell is a little less than 13 MM, so in order to make a radius of less than about 6 feet they need a lot more space to swivel. My best guess for HO was using narrowed Athearn axles and gears in an etched fold up truck/ gearbox with an N scale worm, if I could get it to all fit up together.
Remind me again why we picked this scale? :wtf:
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Re: possible chassis for U30B et al

Postby ConducTTor » Tue Nov 06, 2012 7:25 pm

areibel wrote:The inside of the GP shell is a little less than 13 MM, so in order to make a radius of less than about 6 feet they need a lot more space to swivel.


What he said.

areibel wrote:Remind me again why we picked this scale? :wtf:


Awesomeness? :crazy:
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Re: possible chassis for U30B et al

Postby scaro » Tue Nov 06, 2012 9:06 pm

ConducTTor wrote:
areibel wrote:The inside of the GP shell is a little less than 13 MM, so in order to make a radius of less than about 6 feet they need a lot more space to swivel.


What he said.

areibel wrote:Remind me again why we picked this scale? :wtf:


Awesomeness? :crazy:


ahhh, that's where it comes unstuck. not only room to swivel ... but i'd not appreciated that in the HO atlas chassis the whole gear tower moves while in an N loco the truck tends to pivot in a circular shaft inside the stationary gear tower. oh well, forget that one, unless you're modelling a western australian railcar like i am, maybe.
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Re: possible chassis for U30B et al

Postby j p » Wed Nov 07, 2012 2:54 am

Another possibility: wait 1 month for MTB.
SW1200 production start is scheduled at the end of November.
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Re: possible chassis for U30B et al

Postby ConducTTor » Wed Nov 07, 2012 4:27 pm

^^^ very realistic possibility.
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Re: possible chassis for U30B et al

Postby areibel » Wed Nov 07, 2012 4:53 pm

I'm asking Santa for some 9" wheelbase TT trucks?
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Re: possible chassis for U30B et al

Postby j p » Wed Nov 07, 2012 5:42 pm

areibel wrote:I'm asking Santa for some 9" wheelbase TT trucks?


9" wheelbase? Forget it. That would be too hard even for Santa.
But 9’4” is more realistic, it makes something like 2800 mm and that is Tillig's BR218 which I use for Alco FA.
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