Union Pacific Folio Diagrams

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This page was last updated on November 27, 2020.

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Folio Diagram Books

(The following is based on extensive research and analysis by Dick Harley.)

The Streamliner, published by Union Pacific Historical Society:

Q396 - When did the format of the folio/diagram sheets change and why?

A396 - The first diagram sheets in the "new" format are believed to be the steam locomotive diagrams for the 7000 class, which were dated July 1937. A few diagram pages covering the 1930s streamline train locomotives have been found that are dated December 1937. The rest of the steam locomotives were drawn in diagrams dated 7-1-38. A complete book covering locomotives and cars in the 1st through 8th streamline trains was done and is dated 12-1-39. We do not know if any of the streamline train cars were drawn in the "old" format. The initial book of UP freight car diagrams in the "new" format was dated 7-12-41, and the initial book of UP passenger car diagrams in the "new" format was dated 10-27-41. More research is needed to better determine the accuracy of the above information and why this change occurred. (The Streamliner, Volume 20, Number 4, Fall 2006)

Q397 – Back in 2001, class designations for UP freight cars were discussed in the Q&A Column, in Volume 15, Number 3.  Those class designations appear on the UP freight car diagrams.  However, there are no class designations on the UP passenger car diagrams I have.  Did UP passenger cars have "classes" too?

A397– During the Harriman Era in the early 1900s, both freight and passenger cars were designated by a class number.  The freight car classes had three aspects to show car type, capacity, and a sequential series number.  The passenger car classes also had three aspects, but they showed car length, car type, and sequence number.  These class numbers were usually on the early passenger car folio diagrams.  When the format for freight and passenger diagrams was changed in 1941, the freight car diagrams continued to carry the freight car class number, whereas the new passenger diagrams did not.  The reason for this is not known.  Passenger cars built after 1941 do not appear to have a class number. (The Streamliner, Volume 20, Number 4, Fall 2006)

Passenger Car Diagrams

The UP Passenger Car diagrams were apparently renumbered every time a new book was issued between 1941 and at least 1954, so that the pages of the book were in numerical order - a method that leads to all kinds of confusion. Research has not yet found if UP's freight car diagram books were done in a similar manner, but they were not modified as much as passenger cars. Research has not yet found if different engineering groups managed those diagrams, resulting in different methodology.

Compiled spreadsheet data indicates that the diagram books were done on at least ten different dates (the "Drawn" date): 12-1-39 (S-series), 10-27-41, 10-27-42, 1-12-43, 12-10-46, 9-1-49, 10-1-52, 1-15-54, 2-23-55, 10-9-62. Unfortunately, no books from the 1950s have been found.

There are numerous (100+) examples of a diagram number first being used for a heavyweight series of cars in the 1941-1943 diagram series, then reused in the 1946 to1955 diagram series for a completely different series of newer lightweight cars.

When a diagram number was changed, research suggests that the same diagram likely did not receive a new revision letter. There are numerous examples of the diagram being revised (revision letter advanced) and the number changed at the same time.

The Streamliner, published by Union Pacific Historical Society:

Q399 – I have seen UP passenger car models referred to by a UP diagram number, e.g. 69 ft. Harriman Baggage car class P-1-5.  Is that a good way to designate a model?

A399 – In a word, no.  Since copies of the 1941-43 UP Passenger Car Diagram books have been available over the years, many people have used those diagrams and their numbers to define various cars, because that was all they had.  If UP had kept those diagram numbers with those cars, then using a diagram number to define a car would be okay  Unfortunately, UP did not do that.  In September 1949, UP issued a new Passenger Car Diagram book and assigned new diagram numbers to most cars, without changing the diagram revision letter or date, or anything else on the diagram.  Another diagram renumbering occurred sometime in the 1950s, but more data needs to be found to better understand that renumbering.

As for the mentioned 69 ft. Harriman-style Baggage cars on 1941 diagram P-1-5, those cars were originally designated class 69-B-1 when they were built in the 1920s.  There were 57 cars listed on P-1-5 when first drawn 10-27-41.  The diagram was revised 12-10-46 to revision A, including more detailed build date information.  But, in the September 1949 diagram book this diagram was renumbered to P-1-4.  Those cars retained that diagram number until their retirement in the 1960s.  By 1962, there were 55 cars still listed on this diagram.  So, if the model is of one of those cars in the post-1952 yellow & gray scheme, it would correctly be listed as being on diagram P-1-4, not P-1-5.  Listing the revision and revision date would help a lot, but is not definitive.

As an example of the 1949 and 1950s diagram renumberings, we show here diagrams for the OWR&N 69 ft. Harriman-style Baggage & Postal cars 2350-2352.  These cars were on diagram P-2-21 when the 1941 Passenger Car Diagram book was created.  The September 1949 diagram book has them on diagram P-2-25.  Later, in the 1950s (which is still being researched), the diagram was renumbered to P-2-26.  The 2351 was wrecked in January 1946, and the other two cars were retired in 1958.

So, while some passenger cars did retain the same diagram number after one was first assigned in 1941, many did not.  And hence, trying to describe a car by a diagram number alone is often nonspecific and potentially confusing. (The Streamliner, Volume 21, Number 1, Winter 2007)

1920s and 1930s

UP Passenger Car Diagrams, 1926-1938 -- A group of 119 images of sheets of Union Pacific's passenger car diagrams from the 1926-1938 period. Each sheet includes the Common Standard class and specification, which was dropped on later diagrams.

Although the sheets include three sheets for the 45 new lightweight cars for The Challenger train (40 Chair cars, and the five articulated Kitchen-Diner cars), the collection is almost entirely made up of arch-roof and clerestory-roof heavyweight cars.

Streamliners, 1934-1938

UP Streamliner Diagrams, 1934-1938 -- A group of 139 images of diagram sheets for UP's early Streamliner passenger cars. The sheets include updated revisions for individual cars (or groups of cars) that Union Pacific used as part of their early Streamliner passenger trains, known as the 1st through 6th trains, which included the first City of Los Angeles, City of San Francisco, City of Portland, and City of Denver.

These diagrams used the "S" number series and were created and revised in the 1937 to 1942 period. Most were later changed in the early 1940s from their "S" series diagram numbers, to the "P" series diagram numbers used by UP for all of its passenger cars.

After 1941

UP Passenger Car Diagrams, 1941-1967 -- A group of 691 images of diagram sheets for UP's passenger cars. The sheets include updated revisions for individual cars (or groups of cars) that Union Pacific used as part of their extensive passenger operations. The sheets themselves come from four separate diagram books compiled by Dick Harley, plus published sources that include books by William Kratville and Greg Davies.

The entire series of Union Pacific passenger car diagrams were redrawn and reissued in 1941-1943. In 1943 some of the diagrams for the Streamliners (1st through 6th Trains) were changed from their S-series numbers, to a new P-series number.

Please be aware that a large portion of UP individual passenger cars and groups of passenger cars were changed from one diagram number to another diagram number, in some cases at least four different diagram sheets were used by the same car or cars. Union Pacific did not use a classification system for its passenger cars, and using diagram numbers instead will only result in unnecessary confusion. The best reference is by car number and car type, which also changed in many cases over time.