(This page revised October 9, 2015)
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In 1931, the Conklin Pen Company of Toledo, Ohio, broke the mold. Two years earlier, Pelikan of Germany had introduced the world’s first successful piston-filling fountain pen, and now it was Conklin’s turn. The Nozac, whose name meant “no sack,” entered the marketplace and did quite well. This article describes how the Nozac’s filling system works. The illustrations depict a pen with its proportions altered for illustrative purposes. Photographs of the external appearance of the Nozac are shown in Profile: The Conklin Nozac.
The Nozac’s nib and feed are quite ordinary, as described in Anatomy of a Fountain Pen I: A Typical Lever Filler. But from there back, the Nozac is unique among American pens. The figure below shows a cutaway view of the pen with its piston halfway along the barrel:
Like Pelikan’s pen, the Nozac uses a helical cam (a long-pitch screw) to move the piston along the barrel. (The “threads” are cut into the operating shaft instead of protruding from it; and there are dimples in the piston shaft, as described below, that ride in these threads.) The piston knob is secured to the operating shaft by means of a crosswise metal pin that fits into a hole drilled through the shaft and the knob after they are assembled. (Conklin drilled the hole for the pin only partway through the knob; there is therefore only one hole. If repair of the piston mechanism requires its disassembly, the repairer must drill a matching hole from the other side of the knob in order to drive the pin out.)
But unlike Pelikan’s differential (double-action) design in which the piston knob screws itself away from the barrel as it is turned to drive the piston toward the proximal end of the barrel, the Nozac’s knob is secured by washers on the operating shaft and does not move longitudinally. This design (U.S. Patent No 1,902,809) is referred to as a single-action mechanism. Shown here are a portion of the patent drawing and an enlarged view of the piston unit shown in the illustration above. Note that the patent drawing illustrates a pen with a separable blind cap covering a smaller knob for operating the mechanism. Conklin never implemented this design in an actual piston-filling pen, but the twist-actuated All-American bulb filler uses it. (The All-American was a Conklin sub-brand, with lever-, plunger-, and bulb-filling models.)
This illustration, in which the piston is retracted fully toward the distal end of the barrel, shows the operating shaft assembly: brass shaft, brass washers, cast aluminum retaining collar that screws into the distal end of the barrel, piston knob, and crosswise steel pin. It also shows clearly how the front end of the piston shaft is assembled. Two flanged collars, placed back to back, hold the cork seal between them and are then secured to the proximal end of the shaft by means of an adhesive that also seals the joint against leakage. The shaft, being a tube, requires a plug at its end, in the form of a small sheet metal piece dimpled to resemble a British army helmet of the First and Second World Wars.
The piston shaft is a thin-walled metal tube with two dimples near its distal end to serve as “threads” that engage the screw shaft. (You can see the dimples clearly in the partial illustrations above and farther down the page.) The tube is actually formed from a sheet metal strip and seamed along its length. The seam is made in the same manner as a felled seam in clothing, as shown to the left here:
This seam serves a dual purpose; not only does it close the tube, but it also functions as a key, running in a notch on one side of the hole in the wall at the middle of the barrel, as shown to the right above, to keep the shaft from rotating as the screw shaft is turned. (As shown here, Conklin actually made the wall with two notches in it, possibly for greater ease of assembly.)
The cross-section views earlier in this article show a barrel with what appears to be an integral wall between the front and back halves. Many Nozacs were built like this, with the wall solvent-welded into the barrel; but Conklin also produced Nozacs whose barrels were in two parts, jointed in the middle. In these pens, the clear front half of the barrel screws into the colored back half, and the wall is a separate part that fits into notches in the end of the front half and rests against a shelf in the back half as shown here:
Pens made like this were much easier to assemble. The aluminum retaining collar installs from the rear, but the tool to install it is a pin spanner inserted from the front of the barrel to engage two notches on the front edge of the collar. (These notches are visible in the illustration above.) With a one-piece barrel, it was necessary to install the collar and then solvent-weld the wall into the barrel. With a two-piece barrel, the barrel half into which the collar screws was shorter and easier to handle; and the wall no longer required solvent welding. On the other hand, labor was cheap, and the more complex parts were somewhat more costly to manufacture. It's not really clear whether these pens were more or less costly than those with the one-piece barrels — but they are much less common. And restorers today crow with glee when presented with the two-piece version because it is possible to restore a dead piston seal simply by unscrewing the pen into halves. (It’s not even necessary to remove and reinstall/reseal the section.)
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