As was the custom, the first railroad to receive a new wheel arrangement was given the honor of giving of naming it and T&P selected the name "Texas" for the 2-10-4s.
Fifteen more "Texas" type locomotives were delivered from Lima in 1927. These Class I-1a 2-10-4s were given road numbers 610 through 624 and were duplicates of the first ten, except the boiler pressure was raised to 255 psi, which increased the tractive effort to 84,600 pounds.
In 1928, thirty more were delivered fifteen were designated as Class I-1b and assigned road numbers 625 through 639 and fifteen were designated as Class I-1c and assigned road numbers 640 through 654. All thirty were built by Lima and were very similar to the 1927 group except the weight of each was 452,000 pounds.
A final 15 designated as Class I-1d with road numbers 655 through 669 arrived in 1929 to complete T&P's roster of seventy. These last locomotives, built by Lima, were very close copies of the previous class except each weighed 457,000 pounds.
There is one surviving T&P "Texas", number 610 which is owned by the Texas Stare Railroad and is on Static display in Palestine, TX. Number 610 was restored to operating condition and it hauled the American Freedom Train through parts of Texas during the 1976 bicentennial celebration.
| Class | Qty. | Road Number | Year Built | Builder | Notes |
|---|---|---|---|---|---|
| I-1 | 10 | 600-609 | 1925 | Lima | 1 |
| I-1a | 15 | 610-624 | 1927 | Lima | 1 |
| I-1b | 15 | 625-639 | 1928 | Lima | 1 |
| I-1c | 15 | 640-654 | 1928 | Lima | 1 |
| I-1d | 15 | 655-669 | 1929 | Lima | 1 |
Data from table in 1930 Locomotive Cyclopedia, supplemented by data from T&P 1 - 1950ca Locomotive Diagrams Combined supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also "A New Locomotive for the Texas & Pacific", Railway and Locomotive Engineering, Volume 39, No 1 (January 1926), pp.10-12. (Many thanks to Chris Hohl for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error. A 26 February 2018 email from Hohl noted the original boiler pressure of 250 psi.)
This was the class that named the 2-10-4 wheel arrangement and certainly the T & P was one of the largest single users of these enormous locomotives. The firebox had a combustion chamber and two thermic syphons (totalling 98 sq ft/,9.10 sq m), the boiler had Elesco K-50 or K-50A feedwater heater.
Baker valve gear had limited cutoff and actuated 14" (356 mm) piston valves. Other mod-cons included Chambers or American multiple throttle at the front end, Alco Type G reverse gear. Only the first ten (600-609) were delivered with boilers set to 250 psi; the other 60 arrived set at 255 psi, as shown in the specs. Trailing -truck boosters delivered an additional 13,300 lb (6,033 kg or 59.2 kN) of starting tractive effort.
Although they did encounter counterbalancing problems because of their small drivers, Drury (1993) reports that they reaped a 33% increase in speed pulling 44% more tonnage while burning 42% less fuel. Their first duties were on the Fort Worth and Rio Grande divisions over 450 miles (725 km) over the 1.5% ruling grade between Marshall and Big Springs
Procured in five batches:
Class Works Road Year Remarks
I-1 6959-6968 600-609 1925 60,000 lb axle loading
I-1-A 7237-7251 610-624 1927 60,600 lb axle loading
I-1-B 7297-7211 625-639 1928
I-1-C 7314-7328 640-654 1928
I-1-D 7428-7442 655-669 1929 61,400 lb max axle loading
Those that were upgraded with Timken roller bearings on all axles -- 608, 657, 666 -- were redesignated I-2 in 1948.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | I-1 |
| Locobase ID | 99 |
| Railroad | Texas & Pacific (T&P) |
| Country | USA |
| Whyte | 2-10-4 |
| Number in Class | 70 |
| Road Numbers | 600-669 |
| Gauge | Std |
| Number Built | 70 |
| Builder | Lima |
| Year | 1925 |
| Valve Gear | Baker |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 22 / 6.71 |
| Engine Wheelbase (ft / m) | 46.70 / 14.23 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.47 |
| Overall Wheelbase (engine & tender) (ft / m) | 86.67 / 26.42 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 60,600 / 27,488 |
| Weight on Drivers (lbs / kg) | 303,000 / 137,439 |
| Engine Weight (lbs / kg) | 452,000 / 205,024 |
| Tender Loaded Weight (lbs / kg) | 277,166 / 125,721 |
| Total Engine and Tender Weight (lbs / kg) | 729,166 / 330,745 |
| Tender Water Capacity (gals / ML) | 14,000 / 53.03 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 5000 / 18,925 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 101 / 50.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 63 / 1600 |
| Boiler Pressure (psi / kPa) | 255 / 1760 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 29" x 32" / 737x813 |
| Tractive Effort (lbs / kg) | 92,590 / 41998.17 |
| Booster (lbs) | 13,300 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.27 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 82 - 2.25" / 57 |
| Flues (number - dia) (in / mm) | 184 - 3.5" / 89 |
| Flue/Tube length (ft / m) | 21.50 / 6.55 |
| Firebox Area (sq ft / m2) | 473 / 43.94 |
| Grate Area (sq ft / m2) | 100 / 9.29 |
| Evaporative Heating Surface (sq ft / m2) | 5113 / 475.19 |
| Superheating Surface (sq ft / m2) | 2100 / 195.17 |
| Combined Heating Surface (sq ft / m2) | 7213 / 670.36 |
| Evaporative Heating Surface/Cylinder Volume | 209.04 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 25,500 |
| Same as above plus superheater percentage | 32,895 |
| Same as above but substitute firebox area for grate area | 155,593 |
| Power L1 | 28,875 |
| Power MT | 1050.47 |
