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Filling System Histories: Pneumatic Pens

Reference Info Index | Glossopedia  ]

This article originally appeared as two parts in the October 2016 and February 2017 issues of PEN WORLD Magazine.

What’s the simplest filling mechanism ever designed for a fountain pen? If you guessed eyedropper, you’re wrong. The eyedropper system isn’t actually a filling mechanism as such, it’s more like an empty vessel waiting for ink to be replenished. It doesn’t self-fill; you fill it.

The simplest true self-filling mechanism is the pneumatic system. And, as it evolved from its humble beginnings, it turned into the most complicated filling mechanism ever designed, too. Let’s look at this fascinating filler’s family tree.

The Original Pneumatic Filler

It began with a brilliant idea by a clever gent named Seth Sears Crocker. He reasoned that if air pressure could force something (ink) into a pen sac, air pressure could force something else (air) out first. He could do away with Conklin’s clunky crescent and fill a fountain pen by air pressure alone. On July 16, 1901, he received a patent for a design that did just that: a blow filler.

Patent drawing

U.S. Patent No 678,547 shows how he did it: by making a small hole (callout 5 in his drawing) in the back end of the barrel. Blowing gently into this hole compressed the sac to expel air, and releasing the pressure allowed the sac to re-expand. If the user immersed the nib end of the pen in ink before releasing pressure, the pen would fill itself with ink. Nothing could be simpler. To move the scene of the action farther from the user’s face, he located a hole at the end of the pen’s cap (callout 7) as well; with the cap posted, the pen would be just a little longer. This could be important if you forgot and immersed the pen before blowing. Illustrated here is a Crocker ladies’ Ink-Tite blow filler from about 1916. Unable to add a hole in the end of this pen’s cap because of the ring mount, Crocker added a small nipple to the end of the barrel as shown in the 3-D cutaway drawing.

Fountain pen Magnifying glass
Pen cutaway

The Chilton Pen

Blowing into a pen before immersing the nib solved the drawback described above. Still, the blow filler was not exactly pleasing to aesthetic sensibilities, and one might further argue that the blow filler was not a real self-filler. Someone needed to invent a better way to compress the air inside a pen.

Enter Crocker’s son, Seth Chilton Crocker, and his elegant solution. In 1923, the younger Crocker formed his own company, the Chilton Pen Company, and in 1924 he began marketing a pneumatic pen based on a design by David J. La France (U.S. Patent No 1,528,379, issued March 3, 1925). Shown here is a first-generation Chilton pen.

Fountain pen
Fountain pen

Note the odd shape of the section. As shown in the photos above and in the 3-D cutaway drawing below, this shape was necessary to accommodate the filler’s sac guard, a metal tube. The extra length of the section required an extra-long cap that appeared ungainly on all but the longest Chiltons.

Pen cutaway

AAs shown here, the barrel slid onto the sac guard, sealed by a packing of waxed thread at the back end. To fill the pen, you first extended the barrel, admitting extra air into the enlarged interior through the hole at the end of the barrel. Then you immersed the nib and part of the section in ink, covered the hole with a finger, and pressed the barrel back into position.

This action compressed the air in the barrel, and the air compressed the sac. Releasing your finger from the hole allowed the compressed air to escape, and the sac filled itself. As you can see in the cutaway above, the design allowed for a very large sac, and these pens were noted for their great ink capacity.

Evolving to the Wing-flow

But the sliding barrel, with its long extension, made filling a little clumsy; you needed to use two hands. This problem soon yielded to an even more elegant design. In 1927 Chilton’s engineers turned the mechanism inside out. With the barrel securely attached to the section and the metal tube sliding inside the barrel and attached to a blind cap for purchase, the pen could be filled with one hand. This design was actually a simplified version of a design patented by Julius Abegg a decade before La France’s clumsier system (U.S. Patent No 1,134,936, issued April 6, 1915, and assigned to the Picard Importing Company).

Patent drawing

This design, which is better proportioned because it does not require an overlong section, continued in production until Chilton ceased operation as a company in 1941. Arguably the most attractive pen model that Chilton produced was the Wing-flow, which was adorned with stylish Art Deco metal inlays. The Wing-flow, introduced in 1935, used the second-model filling system.

Fountain pen Magnifying glass
Fountain pen Magnifying glass

Internally, the second-model Chilton looks like the 3-D cutaway drawing below; this image shows the blind cap and sliding metal tube slightly extended. Note that the sac protector in Abegg’s design has been eliminated as unnecessary:

Pen cutaway

In 1932 and 1933, Chilton tried to further automate the second-model filler’s operation with two designs that closed the hole in the blind cap and used a valve to open and close a hidden air passage (U.S. Patents Nos 2,017,109 and 2,017,110, both issued in 1935), but both valve mechanisms were unreliable, and these versions were unsuccessful.

Like many other pen companies, Chilton fell on hard times in the latter 1930s. 1935’s Wing-flow hadn’t been enough to save the company, and by 1939, when the company introduced its elegantly minimalist Golden Quill model at the New York World’s Fair, the end was nearing. By 1941 it was all over for the innovative company.

Sheaffer’s Touchdown

With Chilton’s demise, no one was left to carry the banner for pneumatic pens — but, as the old adage has it, “What goes around comes around.” In the 1930s, the W. A. Sheaffer Pen Company had introduced a plunger filling system that it called Vacuum-Fil. It worked well, but it was a little fiddly to make, and over time it could develop a leakage problem — especially if the user allowed ink to dry out in the barrel by leaving the pen unused for a long period. It was even more fiddly to repair. Something better was needed, but that something needed to be novel and easy to operate.

The story picks up again after World War II. Throughout the war, Sheaffer continued to use its venerable Vacuum-Fil plunger filler. After the war, however, or probably even during the conflict, Sheaffer’s engineers were hard at work developing a new filling system — new for Sheaffer, at least. The Touchdown, which made its appearance in 1949 and marked Sheaffer‘s abandonment of the Vacuum-Fil, was directly descended from Chilton’s second model. Sheaffer solved the problem of automatically opening and closing the air passage by punching a hole in the sliding tube (now called the Touchdown tube) near its open end and pressing a dimpled “channel” into the tube at its junction with the blind cap (U.S. Patent No 2,610,612, issued September 16, 1952):

Patent drawing

Because the Touchdown has a much freer seal between the Touchdown tube and the barrel, the blind cap screws into the end of the barrel to secure it against inadvertent pulling. The following illustration shows the pen with the Touchdown tube partially extended.

Fountain pen

Extending the Touchdown tube creates a partial vacuum in the pen. To keep the sac from distending and then disgorging a large quantity of ink when pressure is readmitted as the Touchdown tube‘s hole passes the O-ring, Sheaffer restored the sac protector that Chilton had removed from Abegg’s design. On the downward stroke, pressure builds until the dimple near the blind cap passes the O-ring; then pressure is released and the sac can draw in ink.

With its smooth torpedo-shaped profile (below, upper) and bullet-tapered blind cap, the Touchdown is an attractive pen. As it had done with its Vacuum-Fil pens, Sheaffer made Touchdowns both with the “TRIUMPH” point and with open nibs. Among the latter type, as illustrated in the 3-D cutaway above, is the low-priced model shown here (lower), the 1950 version of the famous Craftsman:

Fountain pen Magnifying glass
Fountain pen Magnifying glass

Sheaffer’s Snorkel

With the rise of the ballpoint, fountain pens began to lose market favor. To compete with the convenience and messless filling of ballpoints, Sheaffer’s engineers adapted the reliable Touchdown system to create the most complicated filling system ever designed for a fountain pen. They encased the sac in a moving “cartridge” at whose end is a small tube that extends out from under the nib. They moved the blind cap’s threads to the Touchdown tube, to engage with mating threads on the sac protector. Unscrewing the blind cap allows a spring to push the “cartridge” forward, allowing the user to immerse just the tip of the Snorkel tube in the ink. The pen then fills just like a Touchdown. Screwing the blind cap down again retracts the cartridge, leaving the entire outside of the pen free of ink.

Fountain pen

This elaborate but amazingly reliable system (U.S. Patent No 2,769,427, issued November 6, 1956), was dubbed the Snorkel after the breathing device used on German submarines during World War II.

Patent drawing

Here are a typical Snorkel, the TM Clipper, and the final Snorkel model, the PFM:

Fountain pen
Fountain pen

Cheaper Touchdowns

Although Sheaffer abandoned the complicated Snorkel system in 1963 with the withdrawal of the PFM, the Touchdown went on, continuing into the late 1960s. To make a less costly version, Sheaffer adapted the system in its 1960s Imperial I by using a short fat sac and a solid piston that extends only half the length of the barrel. Esterbrook also marketed a model of this design, called the Safari and shown here. I have found no patents relating to this system.

Fountain pen
Pen cutaway

Sheaffer’s Legacy

The last gasp of the pneumatic filler, so to speak, came in the 1990s with Sheaffer’s introduction of the Legacy line. The Legacy and Legacy II are combination pens, with a cartridge/converter system that also functions as a modified Touchdown. The Touchdown sac and sac protector are combined in a removable cartridge that is externally similar to Sheaffer’s venerable squeeze converter. The Legacy version has a hole in its distal end; there is no opening in the side for a pressure bar, and there is of course no pressure bar. Unscrewing and extending the blind cap at the back of the barrel reveals the Touchdown tube. Here is a Legacy:

Fountain pen


In 2003 Sheaffer withdrew the Legacy II, replacing it with the Legacy Heritage, a standard cartridge/converter pen, and pneumatic fillers became history.

The information in this article is as accurate as possible, but you should not take it as absolutely authoritative or complete. If you have additions or corrections to this page, please consider sharing them with us to improve the accuracy of our information.

This article is also available as a chapter in The RichardsPens Guide to Fountain Pens, Volume 3, an ebook for your computer or mobile device.

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