Steam & Excursion > USRA Mikado- Standard tender

Initial research is now completed on the USRA tender used for the Mikado and modeling work is now proceeding. This is the text I just put up on my site ( http://trainperson99.home.comcast.net/ ) summarizing my finding:
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One of the high priories of the USRA when designing its locomotives was standardization--the fewer variations in parts, the lower the cost and the ease of maintenance. No where was this better seen than in the locomotive tender.
 
The USRA settled on a single basic design for its tenders, with three variations for water capacity. All were designed for a 16 ton coal load. The two switchers held 8,000 gallons; the light and medium engines held 10,000 gallons and the largest engines having the largest boilers (the heavy Santa Fe and the two Mallet designs) held 12,000 gallons.
 
All the water-bottom rectangular tenders had a Commonwealth cast-steel frame that included the front drawbar pocket, the rear draft sills and the truck center plates.
 
The freight and switching engines (which included the Mikado design) used Andrews type trucks with cast steel side frames made by American Steel Foundries or Buckeye Steel Casting carrying 33" diameter, 2 1/2" wide rolled steel wheels with a 70" wheel base mounted on axles having 6" by 11" journals.. The truck bolsters were fitted with triplet elliptic springs made by Standard Steel Works. Side bolsters were specified for both the front and back trucks. The passenger engine tenders used built-up trucks with 6' wheel base and 36" wheels of either the Barber or the Commonwealth type.
 
About the tender body, Railway Mechanical Engineer, August 1918 said "The tank is the usual type of construction, the corners being formed by 2-1/2" by 2-1/2 angles. The bottom and top plates are 5/16" in thickness, while the sides and ends are 1/4" thick. The tank manhole is 18" wide by 8' in length across the tank. The great length materially facilitates spotting of the locomotive at water plugs."
 
A Franklin radial buffer wedge type was specified between engine and tender. The drawbar between engine and tender was to be straight and a Franklin Unit safety bar was included. The coupler release rigging at the back of tender was specified as Imperial Type "B", Imperial Appliance Co, Chicago Ill.
 
The Westinghouse ET-6 brakes consisted of a 14"x12" Type L tender brake cylinder with JM type expander and #4 brake pipe vent valve with the following flexible joint connections (Franklin Ball joints) between the engine and tender:
--One 1 1/4" for train line
--One 3/4" for independent brake
 
The USRA specified the uses of Creco Third-Point Brake Beam Support and Safety Device by Chicago Railway Equipment Company for all its tenders and freight cars.
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Attached are some quick renders of the back tender trucks (bigger pictures on the web site). Now on to the frame.

Corrections or additions are always welcome.

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Nice work!

I'm just blown away by the work that you've done. Absolutely incredible! Do you intend to have the parts printed in 3D and cast?

warrenpweiss Wrote:
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> I'm just blown away by the work that you've done.
> Absolutely incredible! Do you intend to have the
> parts printed in 3D and cast?

Thanks Warren. I hadn't thought of that, but seeing the Mikado go from a virtual model to a super scale one sitting in the middle of my living room would be nice. The technology is available, with 3d printers....unfortunately "all" I would need is the resources to get it done.

Beautiful work. Don't forget the pin hole in the live lever. (photo #1)

I plan on putting the hole & pin in when I connect the live lever to the brake cylinder. I modeled the levers as a flat slab on their faces. That was how it was shown in the rough assembly drawing I have for this part. Is that normal or are there portions on the faces away from the pins indented to reduce weight?


Also, does anyone know why they used wood boards between the tender's frame and the body? Just curious.

jayR Wrote:
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> I plan on putting the hole & pin in when I connect
> the live lever to the brake cylinder. I modeled
> the levers as a flat slab on their faces. That
> was how it was shown in the rough assembly drawing
> I have for this part. Is that normal or are there
> portions on the faces away from the pins indented
> to reduce weight?
>
> When I was a rip track Carman on the West Rip in Topeka, I worked air brakes. If I needed rods or levers for a repair, I would order them from the Stores Dept. They would send out whatever was on hand, forged from a factory somewhere, or shop made. The forged ones had the recessed areas, stamped from a machine while red hot. The shop made ones were torch cut from a flat slab, and drilled. Then bend at the brake beam end was done while hot, on a brake press. I suppose either would be correct, but the forged ones seemed more common for new equipment. The rod ends & levers seemed harder than the pins. I've seen pins worn 1/3 the way through, making it difficult to drive them out for replacement.