Central Pacific / Southern Pacific 4-8-0 "Mastodon" Locomotives of the USA


Class Details by Steve Llanso of Sweat House Media

Class GA/TW-51/TW-1 (Locobase 7253)

Data from SP Menke All-Time Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection, "Heavy 12-Wheeld Freight Locomotive for the Central Pacific R. R.", Locomotive Engineering (March 1895), p. 39, and "Twelve-Wheel Freight Locomotive, Southern Pacific Railway", Engineering News, Volume XXXIII, No 19 (9 May 1895), pp. 298-299. Works numbers were 4257-4258 in January 1895, 4304-4312 in June, 4324-4326 in July.

LEMJ waxed in the enthusiastic affirmation of American industry characteristic of the time in saluting the arrival of this Twelve-wheeler design: "The cut below shows the heaviest locomotive ever built at the Schenectady Works, where 4,233 were turned out before this one.

"This engine may be taken as a good type of the state of the art of heavy locomotive construction for American mountain service, in this year of grace 1895.

"This engine is wanting in nothing to make it safe, economical, and efficient for heavy, hard work."

An insight into the relative merits of various aspects of locomotive design opens up as the author says: "We must commend the designer for not getting enthusiastic about huge ports and long valve travel on this engine. Coal is worth from $6 to $10 a ton on the Sierra Nevada mountains. The big things are where most wanted here--the boiler and cylinders."

2900-2901 were delivered with 51" drivers, but were refitted with 54" drivers by 1905. 2900, 2904-2905, and 2911-2913 remained with the Espee Lines for all of their long careers, which extended beyond the end of World War Two.

The other seven were transferred to the Cananea, Rio Yaqui & Pacific in Mexico in 1904-1907 and numbered in two ranges. 2901 and 2906-2907 received 17-19 while 2902-2903, and 2909-2910 were given 301-304. All seven moved onto the Southern Pacific de Mexico in 1909 with 17-19 being renumbered 450, 452,and 451, respectively and 301-304 taking 453-456. All of these engines were scrapped in 1931-1935.

2911 was scrapped in June 1947, 2912 following two months later. Three were dismantled in 1950: 2904 in January, 2905 in October, and 2900 in November. And 2913 completed the class with her scrapping in January 1951.


Class GB/TW-3 - 30"" compound (Locobase 11139)

Data from Schenectady Locomotive Works, Illustrated Catalogue of Simple and Compound Locomotives (Philadelphia: J B Lippincott, 1897), pp. 121-122. Works numbers were 3772-3774 in September 1892, 3775-3778 in October, 3779 in November.

This set of engines immediately followed the production batch of cross-compounds described in Locobase 13308. Still pursuing the promised savings of water and coal, the railroad increased the LP/HP cylinder ratio to 2.25 and enlarged the boiler. With the end of this batch, the


Class GC/TW-51/TW (Locobase 13308)

Data from Engineering News and Railway Journal, Volume 25, No. 9 (28 February 1891), p. 193. . See also D L Joslyn, "Steam Locomotives of the Southern Pacific," Railroad & Locomotive History Bulletin , pp. 160- 161, supplied in August 2013 by Allen Stanley from his extensive Raildata collection. Works numbers for the new-production engines were 3547 in September 1891, 3760-3761 in June 1892, 3762-3764 in July, 3765-3767 in August, 3768-3772 in September

Although they'd generated good results testing the 1986 (Locobase 11139) beginning in 1889, the Espee's Superintendent of Motive Power H J Small went back to Schenectady two years later for a slightly revised Twelve-wheeled cross-compound. Joselyn contends that Small, who had been, as Joselyn imprecisely puts it, "imported from some eastern road", much preferred Schenectady's cross-compound design to Stevens' simple-expansion locomotives. Small, like many others, wanted to believe Schenectady's claims of an average 15-30% savings in fuel and procured several dozen.

He sent the lead engine of the GF class (Locobase 11138) to be fitted with a two-cylinder cross-compound arrangement. The 367 was specified to use A J Pitkin's intercepting valve, which was designed to improve starting power by allowing live steam into the LP cylinder. Small was convinced by trials and bought several batches of two-cylinder compounds.

Before too long, however, further experience cast doubt on the claims. Savings vanished when engineers failed to close the live-steam feed to the big low-pressure cylinder once the locomotive began moving its train. As a result, says Joslyn, "steam was wasted, and a strain was put on the machinery." Joslyn quotes a report from the Espee's engineering department, which concluded that tests on coal and water consumption locomotives in good condition "did not bear out the savings as listed by the locomotive builders."

Locobase 11139 describes eight more engines of this basic design that were fitted with 30" LP cylinders.

Later modified with a new set of simple-expansion cylinders, the 2945 joined the TW-3 class, see Locobase 7255.


Class GE/TW-4 (Locobase 7256)

Data from SP Menke All-Time Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. Works numbers were 1409-1413 in December 1882, 1414-1433 in January-October 1883.

According to a compilation of Cooke locomotives by B.Rumary (25 Kingscombe, Gurney Slade, Radstock, BA3 4TH, ENGLAND) and supplied to Locobase by Allen Stanley in March 2004, the only Twelve-wheelers built for the Espee by this Paterson, NJ firm were the 25 in a batch produced in December 1882-October 1883.

They don't seem to have succeeded in their service and were scrapped not long into the new century. Most went to the ferro-knacker's in 1902, but 2825 (February 1902), 2814 (June 1905), and 2820 (March 1906)


Class GF/TW-51 (Locobase 11138)

Data from Schenectady Locomotive Works, Illustrated Catalogue of Simple and Compound Locomotives (Philadelphia: J B Lippincott, 1897), pp. 118-119. Works numbers were 2661-2670 in 1888.

This entire class of early Twelve-wheelers was sent to other railroads in 1906. 2801, 2806-2809 were transferred in 1906 to Espee Mexican subsidiary Cananea, Rio Yaqui & Pacific. 2809, 2801 and 2806 took 209-211, respectively. 207 was numbered 104, 208 took 107. Later the set would be renumberd 401, 402, 405-406, and 400. This line was absorbed by the Southern Pacific de Mexico in 1909.

Also in 1906, 2802, 2804-2805 moved to Globe, Ariz, to operate on the Gila Valley, Globe & Northern and were renumbered 5, 3, and 4 respectively. The GVG&N was taken into the Arizona Eastern in 1910.


Class TW-1 (Locobase 11136)

Data from Schenectady Locomotive Works, Illustrated Catalogue of Simple and Compound Locomotives (Philadelphia: J B Lippincott, 1897), pp. 112-113. Works numbers were 4131 and 4140-4141 in June 1893.


Class TW-2-simpled (Locobase 7254)

Data from SP Menke All-Time Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

These Twelve-wheelers entered service in the mid-1890s as cross-compounds (Locobase 11139). By May 1, 1930 (the date of the diagram) they were not compounds and they had relatively small cylinders. TW-2a and TW-2b had slight variations in tube count and thus evaporative heating surface.


Class TW-3 - simpled (Locobase 7255)

Data from SP Menke All-Time Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Several years after the Espee invested in a couple of dozen cross-compound Twelve-wheelers (see Locobase 11139, e.g.), they were simpled along the lines of the TW-2. The TW-2s and TW-3 classes were virtually identical, with the TW-3 having a very slightly larger grate. TW-3bs later had a few more boiler tubes (266), giving a total of 1,899 sq ft of evaporative heating surface.


Class TW-4c (Locobase 7257)

Data from SP Menke All-Time Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

For some reason, some of the TW-4s lost 40 of their boiler tubes at some point while the rest of the design retained its earlier dimensions.


Class TW-6 (Locobase 7258)

Data from SP Menke All-Time Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

TW-6 appears to have designated the pair of Twelve-wheelers that modified from earlier GF locomotives shown in Locobase 11138. The 1889 locomotives numbered 370 and 373.

2954 never left the Espee before being scrapped in October 1935. 2955 was sold in 1906 to the Cananea, Rio Yaqui & Pacifico as their 211.


Class TW-7 (Locobase 8938)

Data from Arthur Mellen Wellington, The Economic Theory of the Location of Railways: An Analysis of the Location of Railways (New York: Chapman & Hall, limited, 1887), 410. Sacramento shops works number was 20 in 1882.

Wellington reports that this Mastodon hauled 20 loaded cars weighing 422 tons up a 2% grade. The National Park Services account of the Sacramento shops reports that this locomotive was so successful that the railroad ordered 25 more from Cooke (see Locobase 7256).


Class TW-8 - cross-compound (Locobase 12592)

Data from "Southern Pacific Schenectady Mastodon," Locomotive Engineering, Volume 12, No 1 (January 1899), p. 29. Works numbers were 4807-4811 in October 1898, 4812-4816 in November.

Schenectady promoted a brief vogue in large, two-cylinder cross-compound engines to several western railroads. These were the last in a series of such engines for the Souther Pacific and they were big and featured the long stroke usually found on 4-8-0s.

They were almost immediately converted to oil-firing. Not too long afterwards, the class received a set of simple-expansion cylinders; see Locobase 7259.

NB: The Missouri Pacific was credited with possibly just one cross-compound of essentially identical dimensions in a 1903 American Engineering and Railroad Journal table. See Locobase 5333.


Class TW-8-simpled (Locobase 7259)

Data from http://www.steamlocomotive.info entry on SP #2914 and from SP 7-1951 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

This class was built originally as cross-compound with 23" HP and 35" LP cylinders, the boiler using 332 tubes and a total heating surface of 3,025.85 sq ft; see Locobase 12592.

Originally delivered as a coal burner but converted to oil-burning soon after its arrival. he class was later converted to the simple-expansion and sometime after its simpling, the class was superheated. That upgrade is shown in Locobase 6290.


Class TW-8s (Locobase 6290)

Data from http://www.steamlocomotive.info entry on SP #2914 and from SP 7-1951 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Originally delivered as a coal burner but converted to oil-burning soon after its arrival. And it entered service as a cross-compound, but was later converted to simple-expansion and some time after its simpling, the class was superheated, a unique event among SP Twelve-wheeler classes. The resulting data is shown here.

The Kern County (Calif) Museum website -- http://www.kcmuseum.org/stories/storyReader$84 (visited 12 Aug 2004) -- summarizes 2914's career as follows:

"One of the largest engines of its time, it hauled freight over the Tehachapi Mountains through the Tehachapi Loop to Mojave and north to Fresno and hauled oil to the west side of the San Joaquin Valley on the Sunset Railway Line to the oilfields in western Kern County near Taft and McKittrick. About 1945 this locomotive was used as a switch engine and ended its career switching cars in the Southern Pacific yards in East Bakersfield."

The class was scrapped in 1949-1953, except for 2914, which was donated to the Bakersfield museum in 1955.

Specifications by Steve Llanso of Sweat House Media
ClassGA/TW-51/TW-1GB/TW-3 - 30"" compoundGC/TW-51/TWGE/TW-4GF/TW-51
Locobase ID7253 11139 13308 7256 11138
RailroadCentral Pacific (SP)Southern Pacific (SP)Central Pacific (SP)Southern Pacific (SP)Southern Pacific (SP)
CountryUSAUSAUSAUSAUSA
Whyte4-8-04-8-04-8-04-8-04-8-0
Number in Class148142510
Road Numbers2010-2023/2900-29131999-2005, 2007/2846-2852/2946-2952367/1951, 1986-199851-75367-376/1951-1960/2845, 2801-2809
GaugeStdStdStdStdStd
Number Built148132510
BuilderSchenectadySchenectadySchenectadyCookeSchenectady
Year18951892189118821888
Valve GearWalschaertStephensonStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase15.50'13.75'13.75'14.75'13.75'
Engine Wheelbase25.33'23.58'23.50'23.92'23.50'
Ratio of driving wheelbase to overall engine wheebase 0.61 0.58 0.59 0.62 0.59
Overall Wheelbase (engine & tender)52.50'49.08'47.83'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers147000 lbs118000 lbs109700 lbs114000 lbs111000 lbs
Engine Weight175000 lbs140600 lbs133000 lbs144100 lbs131000 lbs
Tender Light Weight71800 lbs
Total Engine and Tender Weight204800 lbs
Tender Water Capacity4000 gals4000 gals3800 gals3400 gals
Tender Fuel Capacity (oil/coal)12 tons tons6 tons tons tons
Minimum weight of rail (calculated)61 lb/yard49 lb/yard46 lb/yard48 lb/yard46 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter54"51"51"56"51"
Boiler Pressure180 psi180 psi180 psi160 psi160 psi
High Pressure Cylinders (dia x stroke)22" x 26"20" x 26"20" x 26"20" x 30"20" x 26"
Low Pressure Cylinders (dia x stroke)30" x 26" (1)29" x 26" (1)
Tractive Effort35655 lbs21600 lbs21144 lbs29143 lbs27733 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.12 5.46 5.19 3.91 4.00
Heating Ability
Firebox Area179 sq. ft156.13 sq. ft156.13 sq. ft155 sq. ft156.13 sq. ft
Grate Area34.70 sq. ft31 sq. ft30 sq. ft29.70 sq. ft31 sq. ft
Evaporative Heating Surface2297 sq. ft1935 sq. ft1884 sq. ft2038 sq. ft2053 sq. ft
Superheating Surface
Combined Heating Surface2297 sq. ft1935 sq. ft1884 sq. ft2038 sq. ft2053 sq. ft
Evaporative Heating Surface/Cylinder Volume200.80409.36398.57186.83217.16
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation62465580540047524960
Same as above plus superheater percentage62465580540047524960
Same as above but substitute firebox area for grate area3222028103281032480024981
Power L145203907410238514076
Power MT271.15291.98329.75297.89323.82

Specifications by Steve Llanso of Sweat House Media
ClassTW-1TW-2-simpledTW-3 - simpledTW-4cTW-6
Locobase ID11136 7254 7255 7257 7258
RailroadCentral Pacific (SP)Southern Pacific (SP)Southern Pacific (SP)Southern Pacific (SP)Southern Pacific (SP)
CountryUSAUSAUSAUSAUSA
Whyte4-8-04-8-04-8-04-8-04-8-0
Number in Class381232
Road Numbers2007-2009/2810-2812/2996-29982946-29532833-2844, 2845/2933-29452828, 2830-28311954-1955/2954-2955
GaugeStdStdStdStdStd
Number Built38
BuilderSchenectadySPSPCookeSchenectady
Year1893189218921893
Valve GearStephensonWalschaertStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase15.50'13.50'13.75'14.75'13.75'
Engine Wheelbase25.33'23.58'23.58'23.92'23.58'
Ratio of driving wheelbase to overall engine wheebase 0.61 0.57 0.58 0.62 0.58
Overall Wheelbase (engine & tender)52.75'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers147000 lbs117750 lbs120230 lbs122000 lbs111000 lbs
Engine Weight175000 lbs141000 lbs140800 lbs142800 lbs131000 lbs
Tender Light Weight
Total Engine and Tender Weight
Tender Water Capacity4100 gals
Tender Fuel Capacity (oil/coal)
Minimum weight of rail (calculated)61 lb/yard49 lb/yard50 lb/yard51 lb/yard46 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter55"50"50"56"50"
Boiler Pressure180 psi170 psi170 psi160 psi160 psi
Cylinders (dia x stroke)22" x 26"20" x 26"20" x 26"20" x 30"20" x 26"
Tractive Effort35006 lbs30056 lbs30056 lbs29143 lbs28288 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.20 3.92 4.00 4.19 3.92
Heating Ability
Firebox Area184.90 sq. ft147 sq. ft147 sq. ft155 sq. ft155 sq. ft
Grate Area34.50 sq. ft30.70 sq. ft31.60 sq. ft29.70 sq. ft29.70 sq. ft
Evaporative Heating Surface2347 sq. ft1873 sq. ft1873 sq. ft1757 sq. ft1743 sq. ft
Superheating Surface
Combined Heating Surface2347 sq. ft1873 sq. ft1873 sq. ft1757 sq. ft1743 sq. ft
Evaporative Heating Surface/Cylinder Volume205.17198.12198.12161.07184.37
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation62105219537247524752
Same as above plus superheater percentage62105219537247524752
Same as above but substitute firebox area for grate area3328224990249902480024800
Power L147193908390834663551
Power MT283.09292.68286.64250.53282.11

Specifications by Steve Llanso of Sweat House Media
ClassTW-7TW-8 - cross-compoundTW-8-simpledTW-8s
Locobase ID8938 12592 7259 6290
RailroadCentral Pacific (SP)Southern Pacific (SP)Southern Pacific (SP)Southern Pacific (SP)
CountryUSAUSAUSAUSA
Whyte4-8-04-8-04-8-04-8-0
Number in Class1101010
Road Numbers229 / 29252024-2033/2914-29232914-29232914-2923
GaugeStdStdStdStd
Number Built110
BuilderCP-SacramentoSchenectadySPshops
Year1882189819111916
Valve GearStephensonStephensonWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase15.75'15.50'15.50'15.50'
Engine Wheelbase24.96'26.42'26.42'26.42'
Ratio of driving wheelbase to overall engine wheebase 0.63 0.59 0.59 0.59
Overall Wheelbase (engine & tender)53.15'53.54'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers106050 lbs155000 lbs155000 lbs161000 lbs
Engine Weight123900 lbs192000 lbs192000 lbs201500 lbs
Tender Light Weight63000 lbs
Total Engine and Tender Weight186900 lbs
Tender Water Capacity3000 gals4500 gals
Tender Fuel Capacity (oil/coal)6 tons10 tons tons tons
Minimum weight of rail (calculated)44 lb/yard65 lb/yard65 lb/yard67 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter54"55"54"54"
Boiler Pressure135 psi200 psi180 psi190 psi
High Pressure Cylinders (dia x stroke)19" x 30"23" x 32"21" x 32"21" x 32"
Low Pressure Cylinders (dia x stroke)35" x 32" (1)
Tractive Effort23014 lbs36543 lbs39984 lbs42205 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.61 4.24 3.88 3.81
Heating Ability
Firebox Area182 sq. ft206.50 sq. ft216 sq. ft208 sq. ft
Grate Area25.74 sq. ft35 sq. ft34.90 sq. ft34.90 sq. ft
Evaporative Heating Surface1258 sq. ft3026 sq. ft2815 sq. ft2255 sq. ft
Superheating Surface467 sq. ft
Combined Heating Surface1258 sq. ft3026 sq. ft2815 sq. ft2722 sq. ft
Evaporative Heating Surface/Cylinder Volume127.78393.29219.44175.79
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation3475700062826631
Same as above plus superheater percentage3475700062827758
Same as above but substitute firebox area for grate area24570413003888046238
Power L12676417649199995
Power MT222.52237.59279.86547.46

Photos

Reference


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