Class 100 (Locobase 15201)

Data from DeGolyer, Volume 69, pp. 164+. Works numbers were 46492-46493 in September 1917, 46710-46711 in October, 46887, 46960 in November, 53845, 53910 in October 1920, and 56201 in March 1923.

These were duplicates of the TTTs bought by the Union Pacific over several years (e.g., Locobase 6590) with some differences. The class's firebox heating surface area included 99 sq ft (9.2 sq m) in the combustion chamber and 29.5 sq ft (2.75 sq m) of arch tubes. Piston valves measured 15" (381 mm) in diameter. Power reverse gear was Ragonnet Type B.

Water and coal were carried in the usual Vanderbilt cylindrical tender.

The URwy was operated by United States Smelting Company, which retired and scrapped them in January 1953 and April 1955, respectively.

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Class TTT-1 (Locobase 87)

Data from table in 1930 Locomotive Cyclopedia, UP 5 - 1918 and UP 10 -1936 Locomotive Diagram books supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange collection.. See also DeGolyer, Volume 56, pp. 262+ and "2-10-2 Type Locomotives for the UP", Railway Mechanical Engineer, Volume 92, No 6 (June 1918), pp. 321-324. See Richard Duley's detailed discussion of the TTTs in Wes Barris's Steam Locomotive.com website at [], last accessed 26 March 2015. (Thanks to Chris Hohl for his 1 May 2016 email noting tender capacities and weights and for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error. Hohl's 27 April 2020 email supplied the engine-and-tender wheelbase.) Works numbers were 45879-45881, 45957, 45984-45986 in July; 46064, 46170-46171 in August.

These were the first of TTT (Two-Ten-Two) that had similar cylinder and driver dimensions. (NB: Gordon McCulloh emailed Locobase in September 2012 to remind him that the UP would never have called these engines "Santa Fes".) The RME's report said that Superintendent of motive power and machinery C E Fuller and mechanical engineer A H Fetters had the Ogden, Utah-Evanston, Wyoming division in mind. The goal was have a single TTT handle on this section the same tonnage (with ruling grades soon to be 1.14%, compensated for curves) as the Mikados did east of Evanston (ruling grade of 0.81%).

This first group had 32 sq ft (3 sq m) of arch tubes contributing to the firebox heating surface. Nine were fitted with closed-style feed water heaters. Five used Elesco CF-1 Coil Type (5000-5002, 5004-5005) and four had Coffin C-87s (5003, 5006, 5008-5009). The other half had Coffin C-87s (5003, 5006, 5008-5009), which added about 700 lb (317.5 kg) to the adhesion weight.

Firebox heating surface area included 99 sq ft (9.2 sq m) in the combustion chamber and 29.5 sq ft (2.75 sq m) in the arch tubes. 15" (381 mm) piston valves admitted steam to the nearly square cylinders.

Original cylindrical Vanderbilt tender weights and capacities were as follows: 10,000 US gallons (37,850 litres), 17 tons (15.45 kg) of coal, empty weight was 65,000 lb (29,484 kg) which increased to 174,000 lb (78,925 kg) when fully loaded. 5007 was later converted to oil-burning and sent to the Los Angeles & Salt Lake for helper service on the Cajon Pass.

The specification has a little note about wheelbases: "Distance between first and second pair of drivers to be increased 5" [127 mm] to permit of a satisfactory brake design. Driving and total wheelbase to be increased the same amount." Underscoring the impact even a small change could have on such a complex machine, the spec stated that the cylinders were to be move forward 5" and the "smokebox, piston rods and guides to be lengthened the same amount." A key reason for adding length to all these components? It left the valve motion the same "as now shown by Ry. Co's prints."

TTT-2 was assigned to the six engines sent to the Los Angeles & Salt Lake, but quickly diverted in 1918 to another UP subsidiary, the Oregon Short Line; see Locobase 16217.

TTT-3 referred to the five 1919 locomotives from Baldwin, which, as Chris Hohl notes, were oil-fired from the start. Numbered 5010-5014 by the UP, four were transferred to the Los Angeles & Salt Lake in 1928 as their 5526-5529. 5014 remained with the UP. As delivered, their cylindrical Vanderbilt tenders' empty weight was 65,000 lb (29,484 kg).

Retirements began in 1948 and took most of a decade to complete.

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Class TTT-2 (Locobase 16217)

Data from table in 1930 Locomotive Cyclopedia. See also DeGolyer, Volume 56, pp. 294+; and Richard Duley's detailed discussion of the TTTs in Wes Barris's Steam Locomotive.com website at [], last accessed 26 March 2015. (Thanks to Chris Hohl for his 1 May 2016 email noting tender capacities and weights.) Works numbers were 47652 in January 1918 and 47800-47801, 47921-47922, 47965 in February.

Locobase 87 shows the first ten of this class, which were delivered 1917 to the LA&SL's parent Union Pacific as their TTT-1 class. Not quite a year later, the LA&SL ordered these nearly identical TTT-2s with tenders carrying 9,800 US gallons (37.093 litres) of water and 5,200 gallons (19,682 litres) of oil. A note in a roster collection reports that curve limits led the LA&SL to transfer this sextet to the OSL in June 1920. At that point, the oil-burning equipment was replaced by coal-burning grates and the tenders shown in the Locobase specs.

Firebox heating surface area included 99 sq ft (9.2 sq m) in the combustion chamber and 29.5 sq ft (2.75 sq m) in the arch tubes. 15" (381 mm) piston valves admitted steam to the nearly square cylinders.

Original cylindrical Vanderbilt tender weights and capacities were as follows: 10,000 US gallons (37,850 litres), 17 tons (15.45 kg) of coal, empty weight was 65,000 lb (29,484 kg) which increased to 174,000 lb (78,925 kg) when fully loaded.

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Class TTT-3 (Locobase 16218)

Data from table in 1930 Locomotive Cyclopedia. See also DeGolyer, Volume 56, pp. 310+ See Richard Duley's detailed discussion of the TTTs in Wes Barris's Steam Locomotive.com website at [], last accessed 26 March 2015. (Thanks to Chris Hohl for his 1 May 2016 email noting tender capacities and weights.) Works numbers were 51645 in March 1918, 51677 in April; 51763, 51831-51832 in May.

Locobase 16217 shows the six locomotive ordered by the Los Angeles & Salt Lake as oil burners; they had slight changes from the first ten TTTs described in Locobase 87. The next five locomotives, built to the TTT-2 specs, appear in this entry.

As with the TTT-2s, firebox heating surface area included 99 sq ft (9.2 sq m) in the combustion chamber and 29.5 sq ft (2.75 sq m) in the four arch tubes. 15" (381 mm) piston valves admitted steam to the nearly square cylinders.

Original cylindrical Vanderbilt tender weights and capacities were as follows: 10,000 US gallons (37,850 litres), 17 tons (15.45 kg) of coal, empty weight was 65,000 lb (29,484 kg) which increased to 174,000 lb (78,925 kg) when fully loaded. Only the 5014 had been fitted with a feed water heater by the mid-1930s. It was a Coffin C-87 closed style.

The first four (5010-5013) were sold to the LA&SL for helper service on the Cajon Pass. They were converted to oil-burning.

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Class TTT-4 (Locobase 6590)

Data from UP 10 - 1936 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 69, pp. 147+ and "New Pacific and Santa Fe Type Locomotives for the Union Pacific System," Railway and Locomotive Engineering, Volume 34, No 1 (January 1921), pp. 3-4. See Richard Duley's detailed discussion of the TTTs in Wes Barris's Steam Locomotive.com website at [], last accessed 26 March 2015. Works numbers were 53403-53404, 53435-53436, 53465-53466 in July 1920; 53506-53507, 53527-53528, 53558-53559, 53616 in August; 53617, 53647-53648, 53675-53677, 53705-53706, 53746 in September; 53844, 53909 in October; 53943 in November.

Delivered after the first World War, these were duplicates of the first batch (Locobase 87). Baldwin estimated the class's adhesion weight at 300,000 lb (136,078 kg) and total weight of 370,000 lb (167,829 kg).

Firebox heating surface area included 32 sq ft (3 sq m) in four arch tubes and 87 sq ft (8.1 sq m) in the combustion chamber; Baldwin's specifications (used in the table here) showed 29.5 sq ft (2.75 sq m) for the arch tubes and 99 sq ft (9.2 sq m) for the combustion chamber. Cylinders received steam through 15" (381 mm) piston valves.

Many later received feed water heaters. Sixteen were fitted with Worthington-4-BL, three had Worthington-4-AS (5026-5027, 5036), Elesco K-50s went into five (5019-5023), and 5024 used the Coffin C-87.

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Class TTT-5 (Locobase 15996)

Data from DeGolyer, Volume 69, pp. 177+ and OWRR&NCo 2 - 1939 locomotive diagrams supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange Collection.. See Richard Duley's detailed discussion of the TTTs in Wes Barris's Steam Locomotive.com website at [], last accessed 26 March 2015. (Thanks to Chris Hohl for his 1 May 2016 email noting the proper range of road numbers and the original tender capacities.) Works numbers were 55903-55904 in December 1922; 55994-55996, 56077-56080 in January 1923; and 56195-56199 in March.

Continuing in the line of TTTs first described in Locobase 87, this batch of fifteen was assigned to the OWR&N's territory; the cab sides were labeled Union Pacific and the tenders bore the Oregon subsidiary's initials. A few tweaks to boiler proportions were the only real differences. Firebox heating surface area included 96 sq ft (8.9 sq m) in the combustion chamber and 30 sq ft (2.8 sq m) in the four arch tubes. Balanced piston valves measured 15" (381 mm) in diameter. The original tender held 12,000 US gallons (45,420 litres) of water.

At least ten were fitted with Worthington open-type feed water heaters (5400, 5402-5408, 5410, 5414). This same group and the 5401 converted to oil-burning and trailed tenders carrying 5,420 US gallons (20,515 litres) of fuel and weighing 109,260 lb (49,560 kg) empty and 262,620 lb (119,123 kg) loaded.

5408 was transferred to the Oregon Short line in 1928 and renumbered 5314; it was returned to the OWR&N in 1931. Four others--5409, 5411-5413--also went and took OSL road numbers 5315-5318

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Class TTT-6 (Locobase 6591)

Data from 1938 to 1958 Union Pacific Locomotive and Tender Diagrams- Part II (Greater than 70 FT) supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 69, pp. 247+. See Locobase 6082 for a full description of this uncommon valve gear. (Locobase thanks Gordon McCulloh for his 3 February 2012 email asking about the TTTs, which induced a rewrite of several entries.) See Richard Duley's detailed discussion of the TTTs in Wes Barris's Steam Locomotive.com website at [], last accessed 26 March 2015.

Lima works numbers were 6612-6616 in October 1923).

The last five Limas in the TTT-6 class shared every characteristic with the previous 45 locomotives save one: the firebox was completely changed. Grate area stayed the same, but in place of 32 sq ft (3 sq m) of arch tubes, the new firebox had 118 sq ft (11 sq m) of Nicholson thermic syphons. The change increased the direct heating surface by 20%. All five were equipped with Coffin C-87s closed-type feed water heaters.

A Trainorders forum thread headed UP Steam Question and started by "yardclerk" included a 6 December 2006 entry, time-stamped 4:32 AM ([],1299181, last accessed 8 February 2012) in which "4-12-2" offered some reasons for UP's adoption of this gear:

"All of UP's 4-8-2's were built with Young gear, which did possess a number of advantages and in tests clearly demonstrated more power on an otherwise identically equipped Waschaert geared engine. Comments by railroad test forces were along the lines of "The Young engine has proven itself in efficiency, in so far as it could life a much heavier train, without having to take the slack, which the Walschaert engine almost always had to do; and it has proven itself in power, also capacity for making very high speed ....." The same guy also mentioned that "...the ease with which this engine rides, the absence of that lateral vibration, nosing, usually found in most engines." Of course, many other tests were also conducted ... John."

Gordon McCulloh, long-time researcher into things Union Pacific, spelled out in a different way, in a September 2012 email, why the Union Pacific stayed with the Young gear. First he outlined the advantages of using this particular form of constant-lead radial valve gear: "Its primary advantages were two. One, without the eccentric links of Walschaert, dynamic augment was all but eliminated. Two, the valve opening and closing cycles were of very short duration and thus steam flowed much more readily. Graphing the valve position and cycle timing for Walschaert was a long sloping line either opening or closing but the Young gear presents a more box-like form with quick opening and quick closing to and from whatever setting was used. Thus maximum steam pressure could be applied almost immediately with the Young even with a limited throttle opening, thus offering a much higher per-square-inch-pressure without excessive volume and the typical resultant slipping. The throttle was thus able to just keep up with flow without excessive volume."

McCulloh then recounted one problem: "Union Pacific had significant issues with the cross-shaft of the Young gear on both of these classes which led to experiments in 1932/33 on two of their 4-8-2s. One got Caprotti 'poppet' gear and the other was fitted with Walschaert. [That period] being lean times further work on this issue was put off for a while."

Meanwhile, McCulloh reports, another innovation contributed to relief of the dynamic augment problem: "General Steel Castings introduced their Box-Spoke (box-pok) driving wheel circa 1935 and that solved the dynamic augment problem of locos with Walsc haert and thus circa 1939/40 UP began retrofitting all 7000 and 7800 class 4-8-2s with Walschaert gear so they could run much faster."

For the TTT-6s and 7s, "[t]hey just kept patching-at the cross shaft problem (timing of the left valve) on the TTT-6s & 7s and at least one engineer felt the reduction of dynamic augment (pounding) with universal adoption of box-pok main drivers on the TTTs was sufficient to allow continued operation without the complete rebuild and significant expense on the TTT-6s and 7s, especially since by that time they were rebuilding 2-8-8-0 Mallets simple and buying new articulated 4-6-6-4s and 4-8-8-4s. The TTTs were no longer THE heavy 'fast' mainline freight power."

The class divided its feedwater-heater installations into the Coffin closed-system and two types of Worthington open-system heaters. Coffin C-87 heaters were fitted in 5048, 5069-5073, and 5075-5084. Worthington-4-BL heaters went into 5041-5047, 5053-5055, 5057, 5074, 5079 and Worthington - 4S would be found in 5049-5052, 5056, 5058-5068, and the Worthington 5-SA was installed only in 5078.

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Class TTT-6 (Locobase 16220)

Data from DeGolyer, Volume 69, pp. 210+. ( (Locobase thanks Gordon McCulloh for his 3 February 2012 email asking about the TTTs, which induced a rewrite of several entries and Chris Hohl for his 1 May 2016 email pointing out Baldwin's delivery of these locomotives as oil burners and supplying information on weights and capacities. See Richard Duley's detailed discussion of the TTTs in Wes Barris's Steam Locomotive.com website at [], last accessed 26 March 2015. ) Works numbers were 56714-56716 in July 1923.

These were the first Baldwins to use Young's valve gear. (See Locobases 6591 and 230 for discussions of the UP's adoption of Young valve gear.) As in the others, firebox heating surface area included 96 sq ft (8.9 sq m) in the combustion chamber and 30 sq ft (2.79 sq m) in four arch tubes. Balanced piston valves measured 15" (381 mm) in diameter. All three engines were equipped with Worthington 4S open-type feed water heaters.

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Class TTT-6 (Locobase 16221)

Data from UP 10 - 1936 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.. See Richard Duley's detailed discussion of the TTTs in Wes Barris's Steam Locomotive.com website at [], last accessed 26 March 2015. (Thanks to Chris Hohl for his 1 May 2016 email noting the proper range of road numbers and the original tender capacities.) Alco-Brooks works numbers were 64407-64414 in July 1923.

Alco's Brooks works, Baldwin, and Lima all supplied locomotives grouped in the TTT-6 class. These first eight from Brooks went directly to the OSL. They were equipped with 10,500 lb (4,763 kg) tractive effort trailing-truck boosters for a little over five years, but had them removed in 1934. All were retrofitted with Worthington 4-BL open-type feed water heaters.

5306 and 5308 were retired in July 1950. All but one of the rest were withdrawn between October 1954 and August 1956. 6307 was withdrawn in April 1958, but retained for snow-protection duty.

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Class TTT-6 - Alco, Lima (Locobase 16219)

Data from UP 10 - 1936 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.. See Richard Duley's detailed discussion of the TTTs in Wes Barris's Steam Locomotive.com website at [], last accessed 26 March 2015. (Thanks to Chris Hohl for his 1 May 2016 email noting the proper range of road numbers and the original tender capacities.) Alco-Brooks works numbers were 64415-64424 in August 1923. Lima works numbers were 6580-6582 in July 1923, 6583-6604 in August, 6605-6611 in September.

Adding dozens of locomotives to Union Pacific's already considerable TTT stud, this large set of TTT-6s differed from most other TTTs in a) showing less superheater area, b) using Young's valve gear, and and c) not being Baldwins. Locobase doesn't know the order details, but both builders delivered engines in the same months with Lima getting the lion's share.

Most later were equipped with feed water heaters. Among the Brooks decade, only 5040 was fitted with the closed type Elesco-K-50-A bundle; 5048 had the Coffin closed-type C-87. Worthington open-type installations were divided unequally between 4-BL (5041-5047) and 4-S (5049) . Lima's brood adopted Worthington 4-BLs for six locomotives (5053-5055, 5057, 5074, and 5079) and 4S models for twelve (5056, 5058-5068). Closed-type Coffin C-87s appeared on fourteen of the later engines (5069-5073, 5075-5078, 5080-5084)

Two other TTT-6 entries show the three Baldwins, which were produced to a different spec (Locobase 16220), and the last five Limas (Locobase 6591), which had significantly different firebox layouts.

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Class TTT-6/TTT-7 (Locobase 15997)

Data from DeGolyer, Volume 69, pp. 229+. ( (Locobase thanks Gordon McCulloh for his 3 Feb 2012 email asking about the TTTs, which induced a rewrite of several entries and Chris Hohl for his 1 May 2016 email pointing out Baldwin's delivery of these locomotives as oil burners and supplying information on weights and capacities.) See Richard Duley's detailed discussion of the TTTs in Wes Barris's Steam Locomotive.com website at [], last accessed 26 March 2015. (Thanks to James Martino for his 18 July 2022 email supplying details about feed water fitments in this class.) Works numbers were 56769, 56772-56774 in June 1923; 56845-56847, 56897-56899, 56900, 56999 in August; 57030-57032 in September; 57793-57795, 57820-57821, 57826-57827, 57836-57838 in June 1924.

This class mirrored other Baldwin TTT-6s in their specs except for use of oil fuel and the consequent deletion of firebox arch tubes. Thus firebox heating surface area decreased by 30 sq ft, but still included 96 sq ft (8.9 sq m) in the combustion chamber. Balanced piston valves measured 15" (381 mm) in diameter. See Locobases 6591 and 230 for discussions of the UP's adoption of Young valve gear.

A diagram supplied by Gordon McCulloh shows that 5507, 5509-5510 were fitted with the Worthington 4-BL feed water heater. That meant the others in the first fifteen used Coffin C-87s. James Martino noted that the pattern repeated itself in the latter ten as the 5517, 5519-5520 used Worthingtons and the others all used Coffin C-87s.