Types

The main types of steam locomotives available to the Union Pacific. They are given according to the classification American White Notation.
Wherever possible the images are pictures of official presentation.

Link to list of all the steam locomotives of Union Pacific since 1915 by date

U.P.R.R. N° 3
C'est une 0-4-0 saddle tank c'est à dire que le réservoir d'eau est placé sur la chaudière comme une selle de cheval.

Le type American fut le plus courant durant la seconde moitié du XIX^ième siècle aux USA.

The Atlantic was an engine speed for the passenger service. That is why it had wheels of large radius. She preceded in this role the Pacific that quickly replaced it. They appeared in the 1890s and quickly found themselves inadequate to draw new passenger heavier steel coaches  replacing wooden ones.

Switcher: locomotive for yard operations. The standardized USRA 0-6-0 (only some for the UP) was the smallest model of this normalization, which was enacted during the First World War to save costs.
Plan

U.P.R.R N° 7
Ce type a existé dans compagnie StJ&GI series 40 à 45

Locomotive de vitesse destinée aux trains de voyageurs. Elle succéda les Atlantic(s) et précéda les Hudson(s) (dont aucune ne fut commandée par L'UP) et les Mountain(s) et Northen(s) dans ce rôle.

TTT-1 to TTT-6 class (TTT : two ten two 2-10-2)

Freight service locomotive. The needs of power before needing to use multiple units in several locomotives simultaneously for a convoy of which the quest for power to be replaced by this model. This model preceded the 4-12-2 to be even more powerful.
These are three-cylinder locomotives, then rebuilt in two-cylinder engines to simplify maintenance, in fact, the effort on the rods was otherwise too high.

Class TTF-1 (TTF: four ten two: 4-10-2)

Locomotive for freight trains. This was one of the last attempts to increase the number of axles for locomotive rigid. Indeed the needs of power previously required to use multiple units ie several locomotives simultaneously for a convoy of which the quest for power to be replaced by this model and after that to have articulated locomotive to limit costs.
These are three-cylinder engines with the third attack the second axle from which the largest gap between the first two axles and thereafter. This also allowed not to have a first drive axle elbow that was more fragile (having a bent axle or not remains debated).

This type of locomotive was developed by the Union Pacific on the basic model articulated Mallet. They were built between 1936 and 1943. They correspond to the model Mallet by being articulated, but all cylinders are directly powered by live steam at high pressure while in the model Mallet both are trained by the steam at high pressure and two steam recycle more low pressure. This gave more power to the hook with more consumption of fuel with a lower efficiency that was not the main concern. The articulated model can take tighter curves. The Union Pacific was 105 Challengers and other companies had also. We solved this model of behavior problems in high-speed line for the geared locomotives and then allowed it to build even larger locomotives and fast like the 4-8-8-4 Big Boy.

There were two models which had the second largest centipede tender.

One,  No 3985,  , is kept in working order by the Union Pacific in Cheyenne Wyoming, and is the largest locomotive in running the world. She served excursion tours until 1990.
Sheet

Les 2-8-8-2 de L'Union Pacific proviennent de plusieurs classes.

Une classe propre à l'Union Pacific
OWR&N (appartenant à l'Union Pacific) : classe MC-1 de 1909 : 3 unités :N° 2000-2002

Deux classes utilisées en leasing durant la seconde guerre mondiale provenant d'une part
C&O (Chesapeake & Ohio) : classe H7 de 1924 : 30 unités : N° 3570 à 3599

et d'autre part
N&W (Norfolk & Western) : classe Y3a de 1919: 4 unités : N° 3671 à 3674 récupérée par l'Union Pacific en 1945
Ces locomotives furent utilisées pendant la guerre par nécessité mais n'étaient pas considérées comme assez rapide et ralentissaient le trafic. Leur usage n'a donc pas perduré longtemps près la guerre.

Plus de détails...

Plus de détails...

L'Union Pacific eu 3 Shay N° 59,60 et 61