THE UNITED STATES RAILWAY ADMINISTRATION (USRA) WAS A GOVERNMENT-ESTABLISHED COMMITTEE OF RAILROAD OPERATORS, EQUIPMENT BUILDERS AND GOVERNMENT OFFICIALS, WHOSE PURPOSE WAS TO COORIDINATE THE OPERATIONS OF AMERICAN RAILROADS DURING THE FIRST WORLD WAR.  IN ADDITION TO OPERATIONS, THE USRA WAS TO OVERSEE THE DESIGN OF A SERIES OF "STANDARD" LOCOMOTIVES AND ROLLING STOCKWHICH MADE USE OF COMMON COMPONENTS IN ORDER TO MAKE EFFICIENT USE OF STRATIGIC MATERIALS.  ONE OF THE MOST COMMONLY USED USRA DESIGNS WAS THE 2-8-2 MIKADO SERIES OF WHICH SOME 2,250 LIGHT AND HEAVY MIKADOS WERE BUILT FOR USE ON AMERICAN RAILROADS.

THE USRA HEAVY MIKADO WAS CONSTRUCTED FOR RAILROADS WHICH NEEDED A LOCOMOTIVE WITH GREATER TRACTIVE FORCE THAN THE LIGHT MIKADO AND WHOSE RAIL AND ROADBED WAS CAPABLE OF HANDLING THE HEAVIER AXLE LOADING OF THE HEAVY MIKADO.  THE USRA HEAVY MIKADO UTILIZED THE SAME RUNNING GEAR AS THE LIGHT MIKADO WITH STIFFER SPRINGS AND LARGER CYLINDERS.  THE HEAVY MIKADO'S BOILER WAS OF THE SAME LENGTH AS THE LIGHT MIKADO BUT WAS 10 INCHES LARGER IN DIAMETER IN ORDER TO PROVIDE EXTRA WEIGHT AND STEAMING CAPACITY FOR THE 27 X 32-INCH CYLINDERS.  WITH EXCEPTION OF THE BOILER, BOILER ACCESSORIES AND SMOKEBOX, THE USRA HEAVY MIKADO WAS IDENTICAL TO THE LIGHT MIKADO AND USED THE SAME CAB, TENDER, AND OTHER MISCELLANEOUS FITTINGS AS ALL OTHER USRA-DESIGNED LOCOMOTIVES.

USRA HEAVY MIKADOS WERE USED BY A LARGE NUMBER OF RAILROADS IN ALL AREAS OF THE COUNTRY, AND MANY RAILROADS HAD MIKADOS OF SIMILAR DESIGN AND CONSTRUCTION TO THE USRA DESIGN.  ALMOST 1,000 HEAVY MIKADOS AND COPIES WERE BUILT AND SERVED ON 23 RAILROADS (NEW).  RAILROADS PURCHASING USRA HEAVY MIKADOS ARE LISTED BELOW (ABBREVIATED).
 
 

AGS	CNOTP	L&N	NKP	P&WV	W OF A
A&WP	ERIE	MILW	OMAHA	SLSF	W &LE
CNJ	FW&D	MONON	P&LE	SLB&M	WP
CB&Q	GN	MP	PMCK&Y	SOU

THE RAILROAD WAREHOUSE USRA HEAVY MIKADO IS SCALED TO THE LARGER 1.6" SCALE WHICH IS PROPER FOR 7 1/2" TRACK GAUGE AND PROVIDES A LARGER, HEAVIER LOCOMOTIVE AT LITTLE ADDITIONAL COST TO THE BUILDER.  THE HEAVY MIKADO CAN BE CONSTRUCTED FOR OPERATION ON EITHER 7 1/2" OR 7 1/4" GAUGE TRACK AND CAN BE FIRED ON COAL OR DIESEL FUEL.  THE BOILER IS ALL STEEL CONSTRUCTION AND STEAMS FREELY, ALLOWING AMPLE STEAM FOR PULLING HEAVY TRAINS AND OPERATING ACCESSORIES.

USRA HEAVY MIKADO LOCOMOTIVE SPECIFICATIONS
 
 

OVERALL LENGTH-LOCOMOTIVE OVER-CAB...........	82 1/2"
OVERALL LENGTH-TENDER...........................................	53"
OVERALL LENGTH-LOCOMOTIVE AND TENDER......	132 1/2"
OVERALL WIDTH-LOCOMOTIVE..................................	16 3/4"
OVERALL WIDTH-TENDER.............................................	16 1/4"
OVERALL HEIGHT-TO TOP OF STACK.........................	24"
OVERALL HEIGHT-TO TOP OF CAB..............................	23 1/2"
OVERALL HEIGHT-TENDER............................................	20"
CAPACITY  OF BOILER-RUNNING LEVEL...................	8.1 GAL.
CAPACITY  OF TENDER..................................................	21 GAL
FUEL...................................................................................	OIL, COAL
VALVE GEAR.....................................................................	WALSCHAERT PISTON
LEAD & TENDER WHEEL DIAMETER............................	4 3/8"
TRAILING TRUCK WHEEL DIAMETER..........................	5 3/4"
DRIVER WHEEL DIAMETER............................................	8 3/8"
WORKING PRESSURE......................................................	125 psi
BOILER SHELL DIAMETER	11 5/8"  Outside Diameter
CYLINDER BORE & STROKE..........................................	2 3/8" X 4"
VALVE STROKE................................................................	15/16"
LOCOMOTIVE WEIGHT...................................................	900 LBS
TENDER WEIGHT..............................................................	400 LBS
WEIGHT ON DRIVERS......................................................	640 LBS
TRACTIVE EFFORT (DRAW-BAR PULL)........................	170 LBS
MINIMUM TRACK RADIUS.............................................	40 FT

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