Texas & Pacific 4-8-2 "Mountain" Type Locomotives

Introduction

The Texas & Pacific purchased five 4-8-2s (road numbers 900 through 904) from the American Locomotive Company in 1925. These "Mountains" were designated as Class M-1 and had 27 x 30 cylinders, 73" drivers, a 210 psi boiler pressure, a tractive effort of 52,500 lbs and weighed 360,500 pounds.

In 1928, another five 4-8-2s were delivered. This time, they came from the Baldwin Locomotive Works and were designated as Class M-2 and assigned road numbers 905 through 909. These locomotives were very similar to the Class M-1s except for an increase in total weight. Later, the boiler pressure of these last five oil burners was raised to 225 psi, which increased the tractive effort to 57,300 pounds.

There are no surviving T&P "Mountains".

Roster by Richard Duley

ClassRoad NumbersYear BuiltBuilder
M-1900-9041925ALCO
M-2905-9091928Baldwin

Class Details by Steve Llanso

Class M-1 (Locobase 229)

5 built in 1926 by Alco and described in Railway Age Gazette. Data from T&P 1 - 1950ca Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Firebox had combustion chamber and two Nicholson Thermic Syphons of 70 sq ft total heating surface, boiler fitted with Elesco feedwater heater. The Baldwin engines of 1928 had some slight differences; see Locobase 8511.

Al1 ten 4-8-2s handled the long-haul passenger trains such as the Sunshine Special, the Texan, and the Southerner.

Class M-2 (Locobase 8511)

Data from T&P 1 - 1950ca Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. See also DeGolyer, Vol 80, pp. 664+. Works numbers were 60551-60555 in July 1928.

The first five Mountains procured for passenger service by the T & P came from Schenectady in 1926 (See Locobase 229). The current entry describes the later five that arrived three years later. Like the M-1s, the M-2s had fireboxes whose heating surface area included 119 sq ft (11.05 sq m) in the combustion chamber and two Nicholson Thermic Syphons adding 70 sq ft (6.5 sq m).

The Walschaert valve gear operated 14" (356 mm) piston valves with 8" (203 mm) travel. Also like the M-1s, the M-2 boiler was fitted with the Coffin feedwater heater. The differences between the two classes were admittedly small: a slight increase in grate area and, consequently, in firebox heating surface and a more substantial reduction in superheater area.

Al1 ten 4-8-2s handled the long-haul passenger trains such as the Sunshine Special, the Texan, and the Southerner. The T & P was an early adopter of an all-diesel motive-power roster and the last steam run of any sort came in 1951.


Specifications by Steve Llanso
ClassM-1M-2
Locobase ID229 8511
RailroadTexas & Pacific (T & P)Texas & Pacific (T & P)
Whyte4-8-24-8-2
Road Numbers900-904905-909
GaugeStdStd
BuilderAlco-SchenectadyBaldwin
Year19261928
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase20'20'
Engine Wheelbase43.25'43.25'
Ratio of driving wheelbase to overall engine wheebase 0.46 0.46
Overall Wheelbase (engine & tender)84'84'
Axle Loading (Maximum Weight per Axle)61400 lbs61500 lbs
Weight on Drivers245500 lbs245600 lbs
Engine Weight360500 lbs361400 lbs
Tender Light Weight280100 lbs291666 lbs
Total Engine and Tender Weight640600 lbs653066 lbs
Tender Water Capacity14000 gals14000 gals
Tender Fuel Capacity (oil/coal)6000 gals6000 gals
Minimum weight of rail (calculated) on which locomotive could run102 lb/yard102 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter73"73"
Boiler Pressure210 psi225 psi
Cylinders (dia x stroke)27" x 30"27" x 30"
Tractive Effort53477 lbs57296 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.59 4.29
Heating Ability
Firebox Area404 sq. ft409 sq. ft
Grate Area80.30 sq. ft81.12 sq. ft
Evaporative Heating Surface3768 sq. ft3774 sq. ft
Superheating Surface1110 sq. ft1032 sq. ft
Combined Heating Surface4878 sq. ft4806 sq. ft
Evaporative Heating Surface/Cylinder Volume189.53189.84
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1686318252
Same as above plus superheater percentage2074122085
Same as above but substitute firebox area for grate area104353111350
Power L12027820802
Power MT728.40746.91

Reference

Credits

Introduction and roster provided by Richard Duley. Class details and specifications provided by Steve Llanso of Sweat House Media.