Design Features: Pneumatic Pens

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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. The simplest actual filling mechanism is the pneumatic system. And, as it happens, the most complicated filling mechanism ever designed is also a pneumatic system. This article traces the family tree of pneumatic pens from their appearance until the end of the line. Illustrated here is a Crocker lady’s Ink-Tite blow filler from about 1916 — did you know that this pen is the great-grandmother of Sheaffer‘s Legacy?

Patented in 1901 (U.S. Patent Nº 678,947), Seth Sears Crocker’s pneumatic system relies on air pressure to collapse a rubber sac in the pen. This design differs from all other sac-based systems because the others collapse the sac by some mechanical means such as a lever pushing on a pressure bar. In a pneumatic pen, the pen’s barrel has a hole designed to admit air that is then compressed to squeeze the sac directly by its own pressure. Here is the basic pneumatic design, as the inventor used it in his Crocker “blow filler” pens:

Nothing could be simpler. To fill the pen, you immerse the nib and part of the section in ink, blow gently into the nipple at the back of the barrel to compress the sac, and then release. The sac’s elasticity restores the sac to its original shape, drawing ink into the pen. One potential disadvantage of this system is that an open ink bottle is very close to the user’s face, and bubbles in the ink might cause splatters.

Variation I: The Chilton Pen — Blowing into the pen before immersing the nib solves the drawback described above, but still the blow filler is not exactly pleasing to aesthetic sensibilities. There must be a better way to compress the air inside the 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 began marketing a pneumatic pen. Based on a design by David J. LaFrance (U.S. Patent Nº 1,528,379), the Chilton pen was, for all intents and purposes, a true self filler. Here is a Chilton pen.

Note the odd shape of the section. This shape is necessary to accommodate the filler. The extra length of the section requires an extra-long cap that appears ungainly on all but very long pens like the one shown here. The following illustration lays open the Chilton design for you:

As shown here, the barrel slides on the sac guard, sealed by a packing of waxed thread at the end of the sac guard. To fill the pen, you first extend the barrel, admitting extra air into the enlarged interior through the hole in the end of the barrel. Then you immerse the nib and part of the section in ink, cover the hole with a finger, and press the barrel back into position. This action compresses the air in the barrel, and the air compresses the sac. Releasing your finger from the hole allows the compressed air to escape, and the sac fills itself. As you can see in the cutaway above, the design allows for a very large sac, and Chilton pens were noted for their great ink capacity.

Variation II: Chilton’s Improved Model — 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 can be filled with one hand. The second-model Chilton looks like this inside; this image shows the blind cap and sliding metal tube slightly extended:

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 is the Wing-flow, which was adorned with stylish Art Deco metal inlays. The Wing-flow, introduced in 1935, used the second-model filling system.

(Chilton tried a slight variation of the second-model filler, closing the hole in the blind cap and installing a valve that opened and closed a hidden air passage, but the valve mechanism was unreliable, and this version was unsuccessful.)

Variation III: The Vacuum-Fil — In 1934, Sheaffer began selling pens with the Vacuum-Fil system. It should be noted that this system had originally appeared about 30 years earlier on the Onoto pens made by De La Rue in England; Sheaffer’s version (U.S. Patent Nº 1,926,405) was, however, advanced enough to have merited its own patent. It could be argued that the Vacuum-Fil isn’t a pneumatic pen as defined in this article because it lacks a sac. But it does have a single-stroke filler that compresses air within the pen’s barrel, so I consider it sort of an adopted member of the family.

Here is a diagram of a Vacuum-Fil pen with its plunger partially extended:

In the Vacuum-Fil system, the barrel is entirely sealed at the back by a felt packing. Extending the plunger expels air from the barrel by allowing it to flow past the pliable piston-head gasket. Pressing the plunger down creates a strong partial vacuum in the barrel. At the end of its travel, the head of the plunger escapes the bore into a slightly broader space; at the same time, the pointed end of the plunger is pushed sideways by the beveled end of the center feed. This allows outside air pressure to force ink into the barrel. Produced at first on secondary-brand pens such as the Wasp Clipper (shown below) and pens bearing the Vacuum-Fil brand, the system appeared a year later on Sheaffer‘s branded pens. (Wahl-Eversharp also marketed pens with a slightly modified version of the Vacuum-Fil system, and the modern Visconti Power Filler uses the same system with a technology boost to eliminate the problem of packings that ossify when left to dry with ink in them.)

Vacuum-Fil pens were offered alongside Sheaffer’s lever fillers at the same prices. In 1942, when Sheaffer introduced the revolutionary Triumph nib, the system was applied to the new pen models:

Variation IV: Sheaffer’s Touchdown — Chilton’s second model was the direct ancestor of Sheaffer’s Touchdown, which made its appearance in 1949 and marked Sheaffer‘s abandonment of the Vacuum-Fil. 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. 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.

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 added a sac protector. 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 profile and bullet-tapered blind cap, the Touchdown is an attractive pen. As it had done with its Vacuum-Fil pens, Sheaffer made Touchdowns with Triumph nibs and with open nibs. Among the latter type, illustrated above, is this low-priced model, the 1950 version of the famous Craftsman:

Variation V: Sheaffer’s Snorkel — With the rise of the ballpoint, fountain pens began to lose market favor. In an attempt to compete with the convenience and messless filling of ballpoints, Sheaffer adapted the reliable Touchdown system by encasing the sac in a moving “cartridge” at whose end is a small tube that extends out from under the nib. The result was the most complicated filling system ever designed for a fountain pen:

This elaborate but amazingly reliable system, dubbed the Snorkel after the breathing device used on German submarines during World War II, allows the user to dip only the end of the Snorkel tube into the ink. When the Snorkel tube is retracted after filling, the entire outside of the pen is free of ink and does not need to be cleaned. Here are a typical Snorkel, the TM Clipper, and the final Snorkel model, the PFM:

Variation VI: 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:

Variation VII: 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 the back 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:

Epilogue

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.

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