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. 18.
CARRIER.

Fig. 19.
CARRIER.

The Carrier.

—We have frequently spoken of the carrier, which contains the mail and other parcels that are transported from one office to the other. In Fig. 13, showing the sub-post-office apparatus, we see one of these carriers being despatched by the attendant and another being delivered from the tube. In Fig. 15 several carriers may be seen standing on the floor. Fig. 18 shows a carrier with the lid open, ready to receive a charge of mail, and Fig. 19 shows the same closed, ready for despatching. The construction of the carrier is shown by the drawing, Fig. 20. The body of the carrier is steel, about one-thirty-second of an inch in thickness. It is made from a flat sheet, bent into a cylinder, riveted, and soldered. The length outside is eighteen inches, and the inside diameter is five and one-quarter inches. The front end is made of a convex disk of steel, stamped in the desired form, and secured to the body of the carrier by rivets, with the convex side inward. It is necessary to have a buffer upon the front end of the carrier to protect it from blows that it might receive, and this buffer is made by filling the concave side of the front head with felt, held in place by a disk of leather and a central bolt. The leather disk is made of two pieces, riveted together, with a steel washer between. The steel washer is attached to the head of the bolt. The carrier is supported in the tube on two bearing-rings, located on the body of the carrier a short distance from each end. The location of these rings is so chosen that it permits a carrier of maximum length to pass through a bend in the tube of minimum radius without becoming wedged. This is a very important feature in the construction of carriers, but does not appear to have been utilized in other systems.

Fig. 20.
MAIL CARRIER.—PHILA.

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The bearing-rings are made of fibrous woven material, especially prepared, and held in place by being clamped between two metal rings, one of which is riveted to the body of the carrier. Of course these rings wear out and have to be replaced occasionally, but their usual life is about one thousand miles. The rear end of the carrier is closed by a hinged lid and secured by a special lock. The lock consists of three radial bolts that pass through the body of the carrier and the rim of the lid. These bolts are thrown by three cams, attached to a short shaft that passes through the lid and has a handle or lever attached to it upon the outside of the lid. This cam-shaft is located out of the geometrical centre of the lid in such a position that when the lever or handle is swung around in the unlocked position, it projects beyond the periphery of the lid, and in this position the carrier will not enter the tube. When the lid is closed and locked, the lever lies across the lid in the position shown in Fig. 19, and when the carrier is in the tube it cannot become unlocked, for the lever cannot swing around without coming in contact with the wall of the tube. This insures against the possibility of the carriers opening during transit through the tube. The empty carriers weigh about nine pounds, and when filled with mail, from twelve to fifteen pounds. They have a capacity for two hundred ordinary letters, packed in the usual manner.