The 8000 was produced in April 1925 as works number 66169. The 8800-8808 were manufactured in May 1926 with Alco works numbers 66726-66734.
By the Union Pacific's reckoning, these "Overlands" (others called them "Southern Pacifics") weren't particularly successful engines. Their three-cylinder layout - outside actuated by Walschaert, inside by Gresley conjugated valve gear - was mechanically complicated and the wheelbase was too rigid. The center cylinder inclined at 9 1/2 degrees to clear the first axle and drive the second. The outside cylinders drove the third axle. An unusual visual difference from many other locomotives was the straight bottom edge given to the smokebox, which allowed easier access to the third cylinder.
The design used a Worthington 4-BL feed water heater.
Yet, the even bigger three-cylinder 4-12-2s from Alco dominated the prairies a few years later, which suggests that the Overlands suffered as much from being the pathfinders and a foreign road's design as anything else. See Locobase 288 for Alfred Bruce's positive assessment of the arrangement as it operated on the Espee.
In 1942, the class was "remodeled" from a three-cylinder to a two-cylinder type, these measuring 27" diameter by 32" stroke. For the result, see Locobase 13994.
Locobase 289 describes these unusual freighters as they were delivered in their three-cylinder configuration. Wikipedia quotes from James E Boynton's Three Barrels of Steam (Glenwood: Felton) on the problems presented by the floating bushings associated with the center cylinder.
Challenger notes that the 1942 program to remove the center cylinder and its Gresley conjugated link resulted in a noticeably large sand dome over the second and third axles and a fully round smokebox. A raised boiler pressure compensated to a large degree for the lost of cylinder volume.
Used in several regions, the class had joined the 9000s (three-cylinder 4-12-2) on the prairies in Kansas when they began retiring. Most had had the center driver replaced with a Boxpok main driver.
5094 and 5096 were the first to go out of service in 1948, followed by 5098-5099 in 1949. Then came a 5-year delay before 5095 was withdrawn in 1953 with the rest (5090-5093, 5097) retiring in 1954.
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Class||FTT-1||FTT-1 - 2-cylinder|
|Railroad||Los Angeles & Salt Lake (UP)||Union Pacific (UP)|
|Number in Class||10||10|
|Road Numbers||8000, 8800-8808||5090-5099|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||22.50 / 6.86||22.50 / 6.86|
|Engine Wheelbase (ft / m)||44.08 / 13.44||44.08 / 13.44|
|Ratio of driving wheelbase to overall engine wheebase||0.51||0.51|
|Overall Wheelbase (engine & tender) (ft / m)||82.42 / 25.12||84.77 / 25.84|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)||60,400 / 27,397||60,400 / 27,397|
|Weight on Drivers (lbs / kg)||302,000 / 136,985||306,900 / 139,208|
|Engine Weight (lbs / kg)||404,000 / 183,252||405,700 / 184,023|
|Tender Loaded Weight (lbs / kg)||248,600 / 112,763||308,916 / 140,122|
|Total Engine and Tender Weight (lbs / kg)||652,600 / 296,015||714,616 / 324,145|
|Tender Water Capacity (gals / ML)||12,000 / 45.45||18,000 / 68.18|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||5200 / 19.70||5217 / 19.80|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||101 / 50.50||102 / 51|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||63 / 1600||63 / 1600|
|Boiler Pressure (psi / kPa)||210 / 14.50||230 / 15.90|
|High Pressure Cylinders (dia x stroke) (in / mm)||25" x 30" / 635x813||27" x 32" / 686x813|
|Low Pressure Cylinders (dia x stroke) (in / mm)||25" x 28" / 635x711 (1)|
|Tractive Effort (lbs / kg)||77,917 / 35342.60||72,391 / 32836.04|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||3.88||4.24|
|Firebox Area (sq ft / m2)||357 / 33.17||357 / 33.17|
|Grate Area (sq ft / m2)||84 / 7.80|
|Evaporative Heating Surface (sq ft / m2)||5489 / 509.94||5461 / 507.34|
|Superheating Surface (sq ft / m2)||1375 / 127.74||1375 / 127.74|
|Combined Heating Surface (sq ft / m2)||6864 / 637.68||6836 / 635.08|
|Evaporative Heating Surface/Cylinder Volume||322.04||257.52|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||17,640|
|Same as above plus superheater percentage||21,168|
|Same as above but substitute firebox area for grate area||89,964||98,532|