The Force Pump

In Type Casting

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1. Introduction

To the typefounder, a "force pump" is simply a device which forces typemetal into the type mold. In every case of practical significance, it is piston-and-cylinder based. In some situations it is driven by a simple hand-lever, while in others it is driven by a spring (or, later, other motive power such as a hydraulic cylinder). It has had three uses, historically:

First, in the last few years of the period of hand type casting it was used in hand casting to achieve higher pressures than were available by simply ladling typemetal into a mold and jerking the mold up by hand. This was claimed by David Bruce, Jr. (who introduced it into practice) to be an enabling factor in the introduction of ornamented types in the Nineteenth Century. The need to use a force pump in this way disappeared after hand casting was supplanted by machine casting in the 1840s (the type casting machines, of course, themselves had force pumps). The period of the use of force pumps for production hand casting is, therefore, very brief - little over a decade, from 1834 to the mid 1840s.

Second, it was used from its introduction until the end of mainstream commercial matrix creation in the late Twentieth Century, by matrix justifiers for trial castings. In this form it was commonly known as the "justifier's force pump."

Third, as suggested above, every type casting machine necessarily incorporates some kind of force pump. In this way the force pump has been an integral part of all machine typefounding from the 1840s until the present day.

2. Confusion

One matter can be initially confusing when looking at images of (justifiers) force pumps and of type casting machines such as the pivotal type caster. These three historical uses of the "force pump" actually encompass two distinct variations on its motion.

In justifier's force pump (and also, I surmise, in the force pump as it must initially have been used for hand casting) the pump's piston is driven down by a long operating lever operated (and powered) by the person doing the casting. Typically there is a spring above this piston which then, when the lever is released, pulls up on the piston and returns the pump to its resting, piston-up, position. The hand of the operator, not the spring, powers the casting stroke.

In the force pump as it was used in type casting machines such as the pivotal type caster the situation is reversed. If we follow the cycle of operation from the point just after a casting stroke has occurred, the piston begins at its lowest position, having been pushed down by the spring as far as possible. The piston is then urged upwards by a cam, compressing the spring. The casting stroke occurs after the piston has reached its maximum height and the spiral cam reaches a drop-off point which releases it. The spring, not the operator, powers the casting stroke.

(The pump in the Thompson Type-Caster uses a tension spring and a lever to achieve the same end.)

The fact that in at least one old photograph a justifier's force pump has been reconstructed out of a pivotal caster does nothing to clarify these matters.

3. Choker Valves

David Bruce, Jr. introduced the force pump into production typecasting in America before the invention of the choker valve. Early force pumps for production, therefore, cannot have had a choker valve.

As it happens, although I can think of no reason why one couldn't build a justifier's force pump with a choker valve, I have found no examples of this. All of the images I've seen of justifier's force pumps lack choker valves; their nozzles are above the level of the metal in the pot.

4. Gallery

A justifier's forced pump in use. At MacKellar, Smiths & Jordan before 1896. Note that this justifier's force pump is converted out of an old pivotal type caster (you can see, for example, the journals in which the main cam shaft formerly ran).

[click image to view larger]

image link-to-mackellar-smiths-jordan-1896-1200rgb-0049-justifiers-force-pump-crop-tight-sf0.jpg

(From {MSJ 1896}. 1200 dpi version.)

Here's a justifier's force pump offered for sale in a catalog, in England in about 1919 by Williams Engineering:

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image link-to-williams-nodis-type-founders-equipment-sf0.jpg

(From {Williams ca. 1919}. 1200 dpi version.)

Here's a film loop of a justifier's force pump in use at American Type Founders in Elizabeth, NJ. It is from their 1948 film Type Speaks!. Note that the pump spring doesn't seem to be doing a very good job of returning the piston. (This is a 37 Megabyte animated GIF image; it may take a while to load, depending on the speed of your net connection. Once it loads, the loop is only a few seconds long and shows, smoothly, one casting operation.)

(From {ATF 1948}.)

5. History

The history of the invention and introduction of the force pump in typefounding is open to some interpretation for a number of reasons. A great deal depends on what you mean by "invent" and "introduce," and what you define as a "force pump." Much of the original source material has been lost, and some of what survives was reported decades after the events. The single most important source, Bruce's memoir, was not published at all until the 20th century and did not receive a proper edition until 1981, 147 years after the events he recounts. Most later treatments consider the force pump primarily as a component of type casting machines; the brief period of production hand casting using force pumps is rarely considered, and the justifier's force pump often ignored. Finally, an element of nationalism creeps in, with American sources favoring Bruce in 1834 and Legros & Grant, in England, favoring other sources.

For what it is or isn't worth, my own opinion at this time is in line with traditional American opinion that the force pump was introduced in 1834 by David Bruce, Jr., initially for production hand type casting.

5.1. Mann and Sturdevant (1831)

patent 1831-01-07

{Legros & Grant 1916}, p. 17.

5.2. Bruce (1834)

5.3. Bessemer (1838)

GB patent No. 7,585 of 1838-03-08.

{Legros & Grant 1916}, p. 17.

5.4. Bruce (1838)

US patent 632, 1939-03-17

{Legros & Grant 1916}, p. 17.

6. References

{ATF 1948} Type Speaks! Narrated by Ben Grauer. Elizabeth, NJ: American Type Founders Sales Corporation, 1948. Produced by Loucks & Norling Studios in Collaboration with G. M. Basford Co.

{MSJ 1896} One Hundred Years. Philadelphia, PA: MacKellar, Smiths and Jordan, 1896.

Although MS&J had been incorporated into American Type Founders at its start in 1892, they were at this time still operating as if they were an independent type foundry. The section on type founding has been reprinted by CircuitousRoot in the General Literature on Making Printing Matrices and Types Notebook.

{Williams ca. 1919} Type Founders' Equipment London: The Williams Engineering Co., Ltd., [n.d., but ca. 1919].

Reprinted by CircuitousRoot in the Typefounders' Equipment Suppliers' Literature Notebook.

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