S100 USA Class wheel sizes - different sizes UK and USA

[G-BOAF]

This topic doubtless spans UK Prototype and Overseas prototype (so Mods feel free to move it), but here goes:

 

the SR USA class has, according to the weight diagram, 54 inch diamater wheels

https://en.wikipedia.org/wiki/SR_USA_class#/media/File:S100Design.png

 

The reference case of the SR USA Class is shown here, with the cranks for the rods have spokes visible outboard

https://upload.wikimedia.org/wikipedia/commons/e/ee/SR_USA_0-6-0T_30073_Eastleigh_MPD_70D%2C_August_1966_%289969640295%29.jpg

 

 

However looking at the example preserved in Sacramento, CA, the wheels appear much smaller, with the cranks basically taking all the space between the wheel centre (or center!) and the tyres. This, along with the mk1 eyeball suggest the wheels are smaller. Were there two versions of the original USA Tank? At least two extant examples in the USA show smaller driving wheels, so we're not talking a one off.

 

https://upload.wikimedia.org/wikipedia/commons/1/1b/Granite_Rock_Railroad_10.jpg

And another (less clear, but certainly smaller wheels compared to UK/European based locos)

https://steamengineresource.weebly.com/locomotives-being-restored.html (scroll down about 1/3, to Colebrookdale Railroad #5002

 

I would have thought that rewheeling, while doubtless increasing the power, would have led to other complications like coupling height and ground clearance, as well as involving cost that would have mitigated the purchase of cheap ex-army locomotives.

 

A mystery, or can someone enlighten?

[jim.snowdon]

Two observations -

 

a) looking at the pictures the crankpin boss on the US locomotive is visibly larger than that on the SR example, which might be no more than their having been built by different builders. The ASATC contracted the construction of the S100 locomotives to three different companies and it is not beyond the bounds of possibility that although the key dimensions might all be the same, the three companies all made their own casting patterns to their particular standards and practices.

 

b) is the US example actually an S100 or a predecessor design, much the same way as the WD 0-6-0ST (the J94 to many) is a derivative of the Hunslet 18" design of 1937 (which, coincidentally, had smaller wheels than the design for the War Department)?

 

Jim

[G-BOAF]

Two observations -

 

a) looking at the pictures the crankpin boss on the US locomotive is visibly larger than that on the SR example, which might be no more than their having been built by different builders. The ASATC contracted the construction of the S100 locomotives to three different companies and it is not beyond the bounds of possibility that although the key dimensions might all be the same, the three companies all made their own casting patterns to their particular standards and practices.

 

b) is the US example actually an S100 or a predecessor design, much the same way as the WD 0-6-0ST (the J94 to many) is a derivative of the Hunslet 18" design of 1937 (which, coincidentally, had smaller wheels than the design for the War Department)?

 

Jim

Certainly the Sacramento GraniteRock 10 is listed on the Project 62 database as being USATC 5001

http://www.project62.co.uk/locolocation.htm

So I don't doubt they are genuine S100 locos. Interesting point about the wheel castings. Although closer inspection reveals the spaces between the tyres and brake pivots to be larger on the US than UK example, which further suggests the wheels are smaller.

[Marshall5]

Certainly the Sacramento GraniteRock 10 is listed on the Project 62 database as being USATC 5001

http://www.project62.co.uk/locolocation.htm

So I don't doubt they are genuine S100 locos. Interesting point about the wheel castings. Although closer inspection reveals the spaces between the tyres and brake pivots to be larger on the US than UK example, which further suggests the wheels are smaller.

It may, or may not, be relevant to the perceived differences in the shape of the wheel castings but USATC5001 was built by Porter (1942) whilst all but one of the S.R. ones were built by Vulcan. The odd one out 30074? and the one purchased for spares were the only Porters purchased.  It might be worth comparing photos of those with 5001.

Ray.

[Nearholmer]

Tourret, in "USATC Locomotives" makes no mention of different wheel diameters, and says that all 258 were built to the same US Army specification. He provides a different "original" weight diagram from the one you linked to, his having most of the dimension in inches, rather than feet and inches, the wheels again being 54".

 

But, he also includes a broadside picture of 5001 when it was virtually new, and ...... I think the wheels are smaller than on the weight diagrams. The top of the front wheel is only c2" above the centreline of the valve spindle, whereas on the diagrams, and in photos of others, the wheel seems to rise higher than that.

 

Having gone boss-eyed in the attempt, I can't work out from the, mainly shadowy, B&W photos in the book whether all the other Porter ones are like this, but I don't think so. Maybe there was something odd about the batch 5000-5008.

 

But, notice that the details below the photo of 5002 that you linked to give the wheel diameter as 54", so maybe this is all about subtle tricks played by the height of the camera lens, rather than the size of the wheels. The top of the wheel is about 'eye height' for a man standing on the ballast, so a shift up or down in lens position, of only a few inches would make a big difference to what is perceived.

Edited October 16, 2017 by Nearholmer

[G-BOAF]

Found this picture of 5000 seeming in war condition, also featuring 'smaller' wheels. So maybe it was this batch, which also seems to have a disproportionate number of surviviors in the US. I am convinced the wheel size is smaller as the gaps between the wheels (occupied by the brake hangers) is larger than on the UK/european survivors.

 

http://beutelevision.com/blog2/wp-content/uploads/2017/05/Crissy-Field-USATC-S100-5000-with-hospital-cars.jpg

[PatB]

Maybe it's because the Californian example is H0 ;-).

Edited October 22, 2017 by PatB

[G-BOAF]

Just come across this post by adb968008, which does indicate some differences in the batch that remained in the USA... I will see if he can contribute to this thread...

http://www.rmweb.co.uk/community/index.php?/topic/55185-modelrail-ustc-0-6-0-tank-loco-project-usa/page-20&do=findComment&comment=2402442

[adb968008]

Here’s a line drawing specifically referencing the 5000 batch for the North African theatre..

 

http://www.wikiwand.com/en/United_States_Army_Transportation_Corps_class_S100

Note the drawing refers to 48” centres, not 54”. But 54” diameter wheels.

 

There was an artickle I picked up some time ago referring to the NA campaign and locos being diverted there, and later not required, where the reference to US vs European config was referred to i’ll See if I can dig it out.

Outside chance I may see GRanite Rock 10 in December.

 

Here’s it at Watsonville in service condition (note air pumps,which presumably is a post war US requirement), it’s also oil fired.

 

These are from 1946, so immediately post war.

http://archive.graniterocktools.com/img/content/museum/steam_engines/engine_10.jpg

http://archive.graniterocktools.com/img/content/museum/1940-1949/army_surplus_steam_engine_2.jpg

 

This is its sadder looking sister today..#5014.

 

http://c8.alamy.com/comp/D1JB3G/old-railroad-steam-engine-in-former-gold-mining-boomtown-turned-ghost-D1JB3G.jpg

Edited October 25, 2017 by adb968008

[EddieB]

For what it’s worth, a copy of the Porter works list shows no differences in wheel diameters for 5001-8, but notes that two were delivered as oil burners.