The Pneumatic Despatch Tube System of the Batcheller Pneumatic Tube Co. / Also, Facts and General Information Relating to Pneumatic Despatch Tubes

by Birney C. Batcheller

Fig. 27.
SENDING APPARATUS.

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Fig. 28.
SENDING APPARATUS.—LONGITUDINAL SECTION.

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The Sending Apparatus.

—We have, in the preceding pages, frequently spoken of the sending apparatus, and have described it as mechanism by which carriers are inserted into the tube. In the Philadelphia postal line this apparatus consisted of a large valve, operated by hand. For an eight-inch tube such a valve would be too large and heavy to be manually operated. Furthermore, that type of apparatus is not suited to an intermediate station, where carriers have to pass through it. To meet all of these requirements we have designed an apparatus, of which Fig. 27 is a side elevation, Fig. 28 a longitudinal section, and Fig. 29 a cross-section. Referring to the longitudinal section, Fig. 28, the sending apparatus is shown inserted into the line of a pneumatic tube, A, A. We have a movable section of tube, B, that can be swung about the large bolt, G, at the top, into and out of line with the main tube, A, A. When the section of tube B is being swung to one side, the air-current has a by-pass through the slots E and F and the U-shaped pipe D. The joints at the ends of the movable section B are packed with specially-formed leathers. Referring to the cross-section, Fig. 29, when the movable section of tube B is swung out of line with the main tube, another and similar tube, C, takes its place. The two movable tubes, B and C, are made in one piece, so that they must always move together. They are connected together at each end by plates, M, that serve not only as connecting-plates, but covers for the ends of the main-line tube while the tubes B and C are being moved. The tubes B and C swing between four plates or wings, L, that extend out on each side of the apparatus. They serve as guards, and, at certain positions of the swinging tubes, prevent the air from escaping.

We will, for convenience, call the system of swinging tubes B and C, with their supports, etc., the swing-frame or simply the frame. This frame is moved or swung from one position to the other by means of a cylinder and piston, H, placed in an inclined position under it. A lug, N, is cast on the tube B, to which the connecting-rod, O, is attached. The cross-head, P, slides upon an inclined guide, Q. On top of the cylinder is placed a controlling valve, made in the form of a piston slide-valve. The piston in the cylinder H is moved by the pressure of the air taken from the main tube through the pipe I. The apparatus is operated by a hand-lever, K. When this lever is pulled, it moves the sliding-head R, and this, through the spring S, moves the controlling valve, if the valve is not locked. If it is locked, pulling the lever simply compresses the spring S. When the controlling valve is moved to the right the air in the cylinder H escapes through the passage V and the port J to the atmosphere, and compressed air from the main tube flows through the pipe I, the passages T and U, to the cylinder H, under the piston, causing the piston to move up the inclined cylinder and swing the frame until the tube C is in line with the main tube. Carriers are despatched by placing them in the tube C, then pulling the lever K, and swinging the frame until the tube C is in line with the main tube. The carrier is then taken up and carried along by the current of air in the main tube.