Uintah 2-6-6-2 vs Mantua 2-6-6-2

[nachoman]

Has anyone ever measured the Mantua 2-6-6-2 and compared the dimensions to the Uintah 2-6-6-2 that it was based off of? Does anyone know what the boiler diameter, boiler length, and cab width are on the Mantua and how they compare to the Uintah locomotive? I have heard Mantua took the Uintah 2-6-6-2 dimensions and "re-gauged" and re-proportioned the engine to a standard-gauge model. Would this be a suitable conversion for Sn3 or even On3 to produce a reasonable model of this locomotive? Not that I necessarily want to tackle such a project, but i am curious as to why it is not a common conversion.

[nkp_174]

I found some info about this...
<!-- m --><a class="postlink" href="http://loggingmallets.railfan.net/models/mantua/d-mantua.gif">http://loggingmallets.railfan.net/model ... mantua.gif</a><!-- m -->

From RLW's Uintah project...
ht: 14'2.5"
len: 46'

I've been unable to find any other dimensions on the internet for the uintah engines.

Based off of the length, the Mantua's are too long for HOn3, but the correct height. The driver size is definitely too big (the biggest 3' gauge drivers I can think of were 48"...I suspect the Uintah's were more like 37"-42". The big downside would be the way too wide driver tires.

I would guess that Sn3 would make the most sense...but Sn3 seems to have fewer people into scratch building locomotives than the other narrow gauge scales.

[nachoman]

It's a given that the drivers would be too big for HOn3. I think the uintah's had 42". I wonder how the boiler diameter scales out. I have seen plans somewhere, either the Gazette or in a book. At least a general erection drawing showing the overall dimensions of major parts.

When I kitbash stuff from standard to narrow gauge in HOn3, I generally target 8' width. I know the cabs of the MDC 2-8-0s I use are about 9" - which is too wide, but within what I consider acceptable for a quasi-freelanced railroad (and being too cheap to afford more expensive brass). The MDC shay I am working on is about 9'3"-9'6" across the cab - and it looks huge coupled to some narrow gauge cars. I am told the Uintah 2-6-6-2s were near 10 feet wide! Considering the extremely sharp curves on the line, I find that astonishing.

[nkp_174]

Yep, 10' width is what I saw on RLW's project page! One of the EBT's combines was 9' wide.

Remember, min turn radii was typically limited by the rigid wheelbase...not the width of the cab or superstructure. The width limitation was about stability and clearances.

[Sumpter250]

This is the best I can come up with, based on measurements of the actual Mantua 2-6-6-2, and the HOn3 SVRY 2-6-6-2 (formerly Uintah 2-6-6-2T)
Driver diameter: SVRY 42" Mantua 52"
Wheel base pilot center to trailer center: SVRY 40' Mantua 46'
Heigth, railhead to top of stack: SVRY 14' Mantua 16'
Boiler diameter: SVRY 69" Mantua 73"
Width (cab): SVRY 9'-9" Mantua 10'

In S scale, The Mantua would have:
Driver Dia. 38"
Wheelbase 33'-6"
Boiler Dia. 54"
Height 11'-9"
Width (cab) 7'-4"
There is no fixed size ratio between the SVRY/Uintah 2-6-6-2, and the "Standard gauge/Mantua" version.
Hope that helps.

[nkp_174]

This is the best I can come up with, based on measurements of the actual Mantua 2-6-6-2, and the HOn3 SVRY 2-6-6-2 (formerly Uintah 2-6-6-2T)
Driver diameter: SVRY 42" Mantua 52"
Wheel base pilot center to trailer center: SVRY 40' Mantua 46'
Heigth, railhead to top of stack: SVRY 14' Mantua 16'
Boiler diameter: SVRY 69" Mantua 73"
Width (cab): SVRY 9'-9" Mantua 10'

In S scale, The Mantua would have:
Driver Dia. 38"
Wheelbase 33'-6"
Boiler Dia. 54"
Height 11'-9"

There is no fixed size ratio between the SVRY/Uintah 2-6-6-2, and the "Standard gauge/Mantua" version.
Hope that helps.

So it is essentially just a caricature of it. Regardless, they are both very nice. 52" drivers seem to be a wise choice since they are typical for a std gauge engine of the time.

Sumpter, thank you very much for providing us with dimensions!

[nachoman]

[quote="Sumpter250"]This is the best I can come up with, based on measurements of the actual Mantua 2-6-6-2, and the HOn3 SVRY 2-6-6-2 (formerly Uintah 2-6-6-2T)
[quote]

<Snip>

Great info. It sounds like converting one to Sn3 would look more puny than converting one to HOn3 would look too large. Perhaps if I find a junker at a train show for a reasonable price, I will get it to play around with. 69" vs 73" bopilers is not a huge noticable difference, but considering when the locomotive is large to begin with, that extra 4" may make it look that much larger. I wonder how it would look in HOn3 by simply milling the frame narrower, putting on smaller drivers, possibly shortening the boiler (if it is too long) and narrowing the cab.

[nkp_174]

Be careful with the plastic. When I took mine apart...the plastic was very brittle.

[Sumpter250]

In these attached photos, the Mantua, as a 2-6-6-2T(std gauge), and the SVRY 2-6-6-2 (3' gauge): Both pictures are taken at the same location, on the dual gauge trestle, on my module.        

The Mantua has a MDC cab, and the tank is also MDC. the trestle helps to establish a size relationship between the two. The mantua does make a nice standard gauge logging loco.

[Sumpter250]

This discussion got me curious, so I measured the drivers of the Bachmann On30 moguls......39", not so far off to use two sets of "mogul" drivers for an On30 outside frame 2-6-6-2T with tender.

[nachoman]

looking at your photos above, the mantua boiler does not that much bigger or longer than the SV locomotive. The prototypes had to be some huge narrow gauge engines. The photos I have seen show them dwarfing the cars they were pulling.

[Sumpter250]

The Sumpter Valley 250, and 251 (former Uintah 50, and 51) were the largest narrow gauge locos operated in the U.S.. There were some equal and larger that were exported.
There were some that would have been larger, and proposals were ongoing, but narrow gauge was declining, and the locos were never ordered. The Uintah engines replaced shays, on Baxter pass, operating on 66 degree curves.
The Mantua is a scale 6' longer, considering the 10" larger drivers (that's 60", or 5' more wheelbase) they are very close, and should be as the Mantua is proportioned up from the Uintah prototype.