Part Symboling Systems


image link-topic-sf0.jpg

1. Introduction

The system of parts identification used by the Mergenthaler Linotype Company (and to some degree by other companies for Linotype or Linotype-compatible parts) evolved into a two-part system which consisted of a part symboling system (usually called a "numbering" system even though the "numbers" were alphanumeric) together with a part naming system.

The symboling (numbering) system began, I believe, as systematic to some degree but soon became arbitrary in practice. The naming system was by design highly systematic.

2. Numbering System

The numbering system employed for the Linotype uses an alphabetical prefix (usually one letter but sometimes two) followed by a one to four digit number. In most later use they were written with a dash separating them. I believe that these part symbols had an origin in a partially systematic approach, but by the 20th century they had become essentially arbitrary.

The origin and principles of this system are not described in any document of which I am aware. It can be partially reverse-engineered, however, based on references in early parts catalogues to the letter prefixes as indicating "Sheets." I presume that these were the presentation drawing sheets on which the parts were first shown in maintenance literature in the 1890s. (But it is also possible that the "sheets" were lists rather than drawings - the use of the term "sheet" in drafting in this period accomodates both meanings.)

The "sheets" cannot, however, be the engineering drawing sheets use for the manufacture of the parts. It would be impossible to represent the hundreds of parts present in some of the lettered "sheets" as real engineering drawing on a single sheet.

3. Naming System

The Mergenthaler part naming system was, by way of contrast, highly systematic. A part with a single number could have many names, depending on its use within the machine. This was articulated by John R. Rogers, writing in the first comprehensive book published by the Mergenthaler Linotype Company on the machine ( Linotype Instruction Book (1926)). It is worth quoting him at length:

Very early in the history of the Linotype it became necessary to designate the different parts of the machine so that the names of these parts coule be used in the manufacture of the machine and by our customers. As there are many parts in the Linotype machine, it was necessary to have a system for naming these parts. The system adopted at first, and which has been in use ever since, is that commonly used by manufacturers of machines having many different parts. The first word designates the main part of the machine to which the part belongs, and the names follow in order so as to designate beyond the possibility of doubt each part. It thus happens that the smaller the part the longer the name. A small bracket on the machine has the following name: "vise jaw left-hand adjusting rod locking pin lift bracket." Whilte this name is very long and clumsy it does actually desribe and locate the bracket so that it is impossible to make any mistake. In addition to the name, each part has a number. The number of the "vise jaw left-hand adjusting rod locking pin lift bracket" is E-1311. It is manifest that these long names cannot be used in ordinary practice. The keyboard keybar is commonly called a keyrod or keyreed. In this book the shorter and more common names are used in the descriptions. This is made necessary by the fact that the regular names are so long and difficult to keep in mind.

As a general rule part numbers are not used [in Rogers' book]. This is because the part numbers have been subject to change during the many years since the Linotype was placed on the market. The proper names and part numbers can be obtained from the catalogues issued by the Company which are revised and brought up to date from time to time, and these catalogues must be used in ordering parts. [original italics by Rogers] (vi-vii)

The hierarchical naming system described by Rogers appears at least as early as the 1905 Mergenthaler Linotype Company catalogue.

This naming system is not fully in evidence, however, in the the 1898 Ottmar Mergenthaler & Company catalogue. For example, in the 1905 MLC catalog one of the names for part B-3 is "Second Elevator Lever Adjusting Bolt." In the 1898 Ott. Mergenthaler catalog B-3 is simply an "Adjusting Bolt and Nut." This suggests, but does not fully demonstrate, that the more elaborate hierarchical naming system dates from some point after 1898. (It doesn't prove the matter because while Ott. Mergenthaler & Co. built the first Linotypes, by 1898 Mergenthaler had fallen out with the NY-based company which controlled the Linotype patents. While Ott. Mergenthaler & Co. continued to make Linotype parts, and continued in many cases to employ the same part numbers, it was a separate company.)

4. Evidence: 1905 Catalogue; "Plates"

At present I have yet to discover these sheets directly. But there is evidence from them in a relatively early Mergenthaler Linotype Company catalogue published in 1905 (which was still 13 years after the introduction of the Model 1 Linotype). This catalog covers the Models 1, 2, and 3. Here is an example from the beginning of "Sheet A":

[click image to view larger]

image link-to-linotype-parts-and-supplies-1905-0600grey-130-sheet-a-rot89p5ccw-crop-tight-sf0.jpg

(From Linotype Parts and Supplies. (NY: Mergenthaler Linotype Company, 1905.) Scanned by DMM.)

The drawings illustrating the parts, however, are not gathered into sheets, but instead into numbered "plates." (There are enough parts in each of the "sheets" that it would be impossible to represent them in one book-format illustration per sheet.)

[click image to view larger]

image link-to-linotype-parts-and-supplies-1905-0600grey-109-plate-71-sf0.jpg

[click image to view larger]

image link-to-linotype-parts-and-supplies-1905-0600grey-130-sheet-a-sf0.jpg

This arrangement of the illustrations into "plates" continued until at least 1923 (the reissue in that year of Catalog No. 22) but was discontinued by at least 1927 (an un-numbered general parts catalog of that year).

Anomaly: The catalog from which the illustrations above were scanned is dated 1905. I do have one earlier catalog which is dated 1903. Curiously, the 1903 catalog does not contain the "Sheet" listings of the 1905 catalog. (Nor does it contain an index by sheet letter, as was the later practice). I can't explain this, but I do have a suspicion: the 1905 catalog was purchased by me from New Zealand. I suspect that even though it carries no indication that it is not a US catalog it might in fact be an earlier catalog than the date on its cover might suggest. (New Zealand and Australia, while technically a part of the sales territory of Linotype & Machinery in England, in practice had a mix of American and English Linotypes.)

5. Evidence: 1898 Ott. Mergenthaler Catalogue

The earliest Linotype parts catalog of any kind which I have seen is the 1898 catalog published not by the Mergenthaler Linotype Company but by Ott. Mergenthaler & Co. (Mergenthaler's own company in Baltimore, by that time estranged from the NY/Brooklyn firm). It is illustrated by arranged photographs of parts. These are identified as "Sheet A," "Sheet B," etc. At times it takes several photographs/pages to illustrate all of the parts of a particular Sheet. (See:

This numbering system was used by the Mergenthaler Linotype Company and by Ottmar Mergenthaler & Co. Its use by Ott. Mergenthaler suggests strongly, but not conclusively, that it originated with Mergenthaler himself.

6. Later Catalogs

With the exception of Catalog No. 22 (a special catalog from 1934 listing parts available for then-obsolete models), later Mergenthaler Linotype catalogs abandoned the organization of drawings in to "plates." Instead, they simply illustrated the parts of the machine on successive pages. The order was that of the "tour of the machine" followed uniformly in all Mergenthaler literature (from assembly counterclockwise around the machine to distribution).

7. Duplicate Parts

In the Mergenthaler system, when the same part was used in multiple locations it still retained a single part number. This was possible because the Mergenthaler approach was only partially systematic. It wouldn't have worked in an approach such as that of Lanston Monotype where the part symbol encoded its location within the machine.

Here is the beginning of the listing for "Sheet A" in the 1905 parts catalog. In this early presentation, a duplicate part such as "A-3" is simply duplicated in the listing. Each instance of it has the same number but a different name (indicating its function).

[click image to view larger]

image link-to-linotype-parts-and-supplies-1905-0600grey-130-sheet-a-rot89p5ccw-crop-tight-sf0.jpg

Here is the equivalent section 52 years later, in Catalog No. 52. The "Sheet" listing has become just an index with no indication at all of a meaning for 'A', 'B' etc. Part A-3 is identified as occurring in three places in the Catalog: pages 48, 142, and 146.

[click image to view larger]

image link-to-mlc-catalog-52-casting-driving-models-5-29-to-36-741-52-A-VV-15X-1957-c2-0600grey-170-sf0.jpg

Here are pages 48 (illustrations) and 49 (listings) which show one of the three instances of part A-3. It is the screw in the lower right corner. (Note that here Mergenthaler is using a single photograph for two purposes: A-3 (where the head is 9/16 thick) and A-880 (where it is 5/16).

[click image to view larger]

image link-to-mlc-catalog-52-casting-driving-models-5-29-to-36-741-52-A-VV-15X-1957-c2-0600grey-048-sf0.jpg

So in this instance, part A-3 is a "Column screw, for mold wiper" rather than a "Motor (Belted) Bracket Support Screw" (1905), a "Cam Shaft Bracket Screw" (1905), a "Cam shaft bracket (l.h.) screw" (1952, pp. 142/3), or a "Motor, geared, bracket screw (for Cline and General Electric motor)" (1952, pp. 146/7).

[click image to view larger]

image link-to-mlc-catalog-52-casting-driving-models-5-29-to-36-741-52-A-VV-15X-1957-c2-0600grey-049-sf0.jpg

Finally, in later catalogs such as No. 52, the MLC did begin to include tables of screws, dowels, nuts, etc. which supply more complete specifications of each part.

[click image to view larger]

image link-to-mlc-catalog-52-casting-driving-models-5-29-to-36-741-52-A-VV-15X-1957-c2-0600grey-161-sf0.jpg

8. Revisions

The Mergenthaler system makes no provision for indicating either incompatible revisions of parts or the engineering revision level of a part.

9. Contingent Parts

The Mergenthaler system makes no provision for indicating mutual contingencies between parts Certain part numbers do indicate assemblies, but I do not yet know if Mergenthaler Linotype would or would not sell the individual parts within assemblies. (I suspect that they would have, though.)

10. Intertype and Star Parts

Mergenthaler sheet letters ran from A through J. The Intertype Corporation adopted a similar system, but started later in the alphabet at R (with one oddball: 'FS'). When Intertype manufactured Linotype-compatible parts, they used their own part numbers, not Mergenthaler Linotype's.

The Linotype Parts Company (an entirely separate firm which later renamed itself "Star Parts" after its trademark) manufactured Linotype-compatible parts, Intertype-compatible parts, parts for Linotypes and Intertypes of their own invention, and complete systems of their own invention which fit into the linecasting environment. When they made compatible parts, they mostly used Linotype or Intertype part numbers. Their overall system, however, is quite complicated and full of exceptions. See: Linotype Parts Co. / Star Parts.

Select Resolution: 0 [other resolutions temporarily disabled due to lack of disk space]