189. Mail Chutes

Office buildings, apartment houses and hotels are now so generally provided with the U. S. Mail chutes, that some reference seems to be required to the limitations under which these modern conveniences may be obtained. A vertical fall is absolutely necessary, and the restrictions of the Post-Office Department require that the chute shall be accessible throughout its entire length, and under no circumstances run behind a partition or wall, or through any room or part of the building which is not accessible to the general public. Where the construction of the building is to be entirely fire-proof, angle irons are usually erected to support the chute, which being made in removable sections, to comply with the Post-Office regulation, requires this or equivalent support.

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In the accompanying plate, Fig. I shows a front elevation of the chute, with a base at floor level, and a cap at ceiling for a finish with the surrounding work, and a bracket for support of chute between floors. Fig. 2 is a plan of the saddle, which is of cast iron and secured to the beams with two bolts at e. The chipping pieces on saddle at a may be trimmed off to suit any flange width. To this saddle are secured the continuous wrought-iron or steel angles b, as shown in Fig. 3 and previously mentioned, and which must be perfectly true and straight. To these angles the chute is secured, c being the line of chute in Fig. 2.

190. Folding Gates

These gates are constructed of channel iron or steel upon the principle of the well-known "lazy-tongs" pattern, and may be made as light as 1/2-inch channel, or as heavy and strong as desired. Their chief advantage being that they fold close, and may be turned out of the way, occupying but little space in their working.

Elevation, Fig. 1, in the plate on page 122, is the gate across the opening or entrance; also the gate closed.

The two channels A are placed as shown, and joined at top with an ornamental cast-iron tip E. When the gate is opened, the channels slide on the bar C which is at top and bottom of gate, and the pins at G move down and up in the channels (see pin B); with a stationary pin joining the channels together. When the gate is folded the channels are close together on the cross-bar C, which bar then drops against the folded gate. The gate is then swung round out of the way on the eye D which is secured to the wall.

Fig. 2 is a simple gate of the "lazy-tongs" pattern. The cross-bars are of flat iron, and work on the pins at F and close into the channel, and are then swung around against jamb.

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The slots in channel are required for the rising and falling of the pins as the gate opens and closes. The diagonal bars in large gates of this pattern may be of channel or small angle bars placed back to back.

191. Box Slides

Box Slides are used for sliding boxed goods from sidewalk to lower floors in warehouses and stores. The principal supporting bars, composing the outside frame, are made of 3 X 3 X 3/8-inch angle irons. The distance D between these angles, as shown in the section in plate, being the effective width of the slide, can be made any width to accommodate opening on sidewalk and size of boxes requiring handling. At right angles to this frame, and riveted or bolted underneath it, are cross-pieces of the same size angle irons, for the support of the half-oval strips which extend parallel with the outside frame. These strips are secured to the cross-pieces by countersunk rivets which are smoothed off for the free sliding of boxes. They should be placed from 4 to 6 inches apart between centres, depending somewhat on the size of boxes. The smaller the boxes the closer the bars should be set. At foot of slide (see side view at F) a plate of black sheet iron (No. 12 gauge), about 4 feet long by the width of the slide, should be secured, to prevent the wearing of the floor by the constant sliding of boxes. Sometimes the slide extends to a cellar under basement; in that case uprights of 3 X 3 X 3/8-inch angle iron should be placed for the support of frame near the middle of length, as shown in section under frame.

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Care should be taken in laying off the pitch of slide that the distance A is sufficient to clear any size of box. G is a section of vault-light frame on which frame of slide is secured. B represents the height of basement.

The half-round bars have a radius of three quarters of an inch.

192. Hanging Ceilings

Hanging Ceilings are used in all fire-proof buildings under roofs of iron. To make the ceilings level in upper story, they are suspended from the roof beams by hangers of wrought iron. As the weight to be borne is simply that of iron plastering and lathing, the hangers are made as small as will practically stand a hole being punched through. Generally 1/2-inch-diameter. bolts are used, with hangers of 1 1/4 X 1/4-inch flat iron, bent as shown in sketch, to take the flange of roof beams. In the detail, the main bars of ceiling run parallel with the roof beams; the hangers supporting them are then placed about 5 feet apart, while the small T iron D rests on and is secured to the main bars. Section A gives the hanger double, with a T iron for a main supporting bar; section B is a single hanger for a double angle bar. If porous terra-cotta blocks are used, the small T irons D are generally placed 25 inches apart between centres. If wire cloth or wire lathing is used, they may be much lighter and be four feet apart. The T-iron and double angle-iron principal supporting bars are usually made of 3 X 2 X 5/16 inch angles, and are placed about 4 feet 6 inches apart between centres. The bolts in hangers are 1/2 inch in diameter.

If the ceiling area is of considerable dimensions, the principal bars may be punched out the shape as shown at E, the smaller T Irons passing through them and secured on every third bar with 5/16-inch-diameter bolts.

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A simpler and more economical maimer of arranging the principal supporting bars, if wire lathing is required, is to secure the hanger to a single angle iron and bolt to this, and flat under it, another angle extending at right angles, then secure the wire lathing by wire clips over the lower angle.