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Baldwin Locomotive Works : Search For Baldwin Drawings

Understanding Baldwin Class Numbers 

The bulk of the Baldwin drawings, ink on linen paper, were drawn for steam locomotives between the years of 1900-1920. Below is information about the pdf inventories of Baldwin drawings in DeGolyer Library.

The first column, labeled “Index #” is the identification (filing) number for the drawing. The second column, labeled “Road Name,” is the alphabetical listing of the railroad companies, individuals, or agents who purchased the locomotives. The column labeled “Date,” is the date on the drawing. The columns labeled “Baldwin Class Number,” represent the Baldwin Locomotive Works identification number for that specific engine.

In addition, the listing has been cross indexed according to the Baldwin class number. This class number has been divided into three fields or sections to aid in sorting by that number.

The three sections are:

number of wheels and the number representing the size of the cylinder

letter representing the code for the driving wheels

number indicating that locomotive's sequence in the class list


Baldwin Class Numbers:

The Baldwin Class number was a rather complicated classification system initiated in 1842 and used until sometime around 1940. For example, the class number for the Nevada-California-Oregon Railway can be described in the following manner.

10-24 D 35

35 = Indicates the 35th locomotive in the class.

D = 3 pairs of driving wheels

24 = Number representing size of cylinder

10 = Indicates a total of 10 wheels

The initial number is the total number of wheels of all kinds under the locomotive

The second number indicates the cylinder diameter in inches, the cylinder diameter being obtained by dividing the classification number by 2 and adding 3 to the quotient. The above classification number of 24 indicates a cylinder diameter of (24 ÷ 2) + 3 = 15.

A fraction, 42/68 indicates a compound locomotive having two sizes of cylinders.

The letter designation indicates the number of pairs of coupled driving wheels.

"A" = special class of high speed geared locomotive with one pair of driving wheels. Also rack railroad locomotives.

"B" = one pair of driving wheels.

"C" = two pairs of coupled driving wheels.

"D" = three pairs of coupled driving wheels.

"E" = f our pairs of coupled driving wheels.

"F" = five pairs of coupled driving wheels.

Double letters = articulated locomotives having more than one set of coupled driving wheels.

The last number(s) in the class number identifies a specific locomotive within the class.

Order Copies of Baldwin Drawings

Requests for drawings should be emailed to with the index number of the drawing(s). A staff member will email the researcher to let them know the format of the reproduction available and cost estimate. Small drawings are digitized and only offered as a bitonal bitmap file for download. Oversize drawings are only available as a print copy and are mailed to the customer. After the researcher confirms their order, the library will send an email with a link to pay by credit card. Orders are usually processed within three weeks.

Erecting Drawing

White Pass & Yukon locomotive 61 erecting drawing
White Pass and Yukon #61 erecting drawing

Collection of Baldwin Locomotive Works records
Mss 61

Detail Drawing

Saint Louis Kansas City & Colorado Number Plate
Saint Louis Kansas City & Colorado Number Plate detail drawing

Collection of Baldwin Locomotive Works records
Mss 61