Parker Fountain pens are simple devices. They have very few parts, and the parts of any given pen are very much like those of most other pens. One of the most strikingly different pens is the Parker Vacumatic. This article describes how the Vacumatic’s filling system is unique. The illustrations represent a pen with the Speedline filler; this pen would have been manufactured between 1937 and 1941. The illustrations depict a pen with its proportions altered for illustrative purposes.
the Vacumatic has a section that screws into the barrel. The nib and feed are pressed into the section. In addition, a breather tube is inserted into a hole drilled into the back end of the feed, and a smaller hole is drilled to connect the breather tube with the feed’s air channel. This system allows an unimpeded flow of air to the back end of the barrel, and it also provides the path through which ink is drawn into the pen when the filler is operated.

The Filling System: The next figure shows a larger view of the Vacumatic’s unique and revolutionary filling system. Although Parker advertised the Vacumatic as having no rubber sac for ink storage, the pen nevertheless does have a rubber diaphragm. The diaphragm is exposed to the ink supply, and — like a sac — can ossify.

The diaphragm is deeply cup-shaped, with a small pocket at its closed end. In the pocket is a small pellet of hard rubber or plastic. To install the diaphragm, a small tool is used to push the pellet into the hole at the end of the tubular aluminum plunger. The rubber of the diaphragm is stretched so that it will fit through the hole, which is just small enough to keep the pellet from popping out when the rubber is not being stretched. The open end of the diaphragm is then folded back and fitted around the tapered portion of the inner collar. No adhesive is required.
After the diaphragm is in place, the filler unit is inserted into the back end of the barrel and secured by the retaining collar. This step is also performed without adhesive. Because the retaining collar is threaded at both ends, it must be tightened with a special tool that screws onto the threaded portion that will remain exposed. This threaded portion receives the blind cap.

The retainer strip passes through slots in the inner collar and the plunger, to provide a stop against which the spring rests. The retaining collar secures the inner collar in place and also prevents the retainer strip from sliding sideways and coming out of its slots. The pinkish plug (not called out) is a relatively tight fit into the plunger; it is blocked by the retainer strip and forms a cushion for the diaphragm where it is compressed by the pellet.

Depressing the plunger compresses the spring and distends the diaphragm to drive air out of the barrel. Releasing the plunger allows the spring to extend, relaxing the diaphragm to draw ink in through the breather tube.

These notches are at the outer end. By depressing the plunger and turning it slightly clockwise, the user locks the plunger in its depressed position.

Beginning in 1942, Parker used a redesigned filler in order to conserve critical war matériel. This newer filler is much simpler in design. Its plastic plunger is smaller in diameter than the aluminum plunger. The spring in the newer model fits outside the plunger. It is attached to the plunger at the end nearest the diaphragm, and its other end is made so that it rests on the back end of the inner collar. Depressing the plunger stretches this spring.