Working Drawings.
From the “plans” made in the office are produced “working drawings”—which represent in detail the work to be done to exact measurement and of material, as indicated, by the pattern-maker, the foundry, the forge, the shop, and finally, by the erector of the completed mechanism.
How to satisfactorily fulfill the directions contained in these drawings, representing only a part of the work, so that it will fit, with needed accuracy, to all other parts of the design, is the task before each separate worker.
It is by means of this division of the process of manufacture through these drawings, that scores and hundreds of men can be employed at the same time upon a single engine or machine; thus, while handwork has been superseded by machines in many quarters, the art of drawing has not been narrowed nor diminished, for no drawings or designs have yet been made by machinery, nor are they likely to be.
It is thus that a good designer and draughtsman “projects” or extends himself, to the advantage of many fellow workers.
The drawing, [fig. 277], shows a simple form of pillar crane: it consists of an upright cast-iron pillar, which is bolted on a cap stone, under which is the foundation plate not shown in the drawing; the boom is of rolled steel, supported by steel tie rods, and provided with rollers at the base; the hoisting gear is shown in broken lines and circles; all as seen in the drawing.
Fig. 278.—Fig. 279.
Fig. 280.
[Figs. 278, 279] and [280] show a drawing of a “hydraulic beam bending machine” in three views; [fig. 280] is a plan, [fig. 278] is an end elevation, and [fig. 279] a side elevation, and a portion of the latter in section shows the interior construction.
Note.—These three views are a practical illustration of drawings for a machine of the following dimensions: this machine has a bed 3 × 5 feet in area, with 27 holes in each side for the bending pins. The frame and cylinders are made of cast iron, the rams of machinery steel, and the slides for holding the bending blocks, of steel casting. The distance between the bending blocks is 17 inches. The cylinders are copper lined, 8 inches diameter, and the rams have a 6-inch stroke. The rams, which are independent and single acting, are returned by counterweights placed as shown under the table. The cylinders can be operated independently from either side of the machine by an arrangement of valves and levers. The machine complete weighs about 7,500 lbs.
Fig. 281.—Fig. 282.—Fig. 283.
The drawing, [page 222], shows three views of a power punching press.
[Fig. 282] is a side elevation.
[Fig. 283] a front elevation.
[Fig. 281] a vertical sectional view; from these views the proportion, general arrangement and disposition of the automatic devices can be easily understood; it may be well to call particular attention to the automatic clutch on the top shaft and the tripping device.
Fig. 284.
This drawing, [fig. 284], shows a side elevation in section of a self-adjusting piston-rod packing.
A is the gland, B is the piston rod, C is a brass sleeve which contains the packing D, E is the cylinder cover, F is a coil spring. It will be seen that the spring F abuts on a bushing in the bottom of the stuffing box and is prevented from scoring the piston rod by stepping over the ends of the bushing and follower. All as shown in the drawing.
The drawing, [fig. 285], shows a sectional view of a large pulley fixed on a “quill,” or hollow shaft: the driving shaft passes through the hollow shaft and is attached to the friction clutch shown at the right-hand end; this friction clutch drives the hollow shaft and pulley.
Fig. 285.
[Fig. 286] shows the mechanism, called the link-motion, employed to reverse an engine, or to enable it to be run in either direction. Many forms of link-motion have been devised, but the Stephenson form, as shown in the figure, is, however, the one in almost universal use.
Fig. 286.
This drawing shows shading and the mode of figuring the parts for identification.
Fig. 287.—Fig. 288.—Fig. 289.
[Figs. 287 to 289] represent a bumping-post for the end of railway tracks, reproduced on an enlarged scale from the columns of the Engineering News.
In addition to the lettering and dimensions, admirably shown in the drawings, the following description is appended to show how printed text and mechanical drawings mutually aid in practical—or commercial—usage.
The unique feature of the arrangement shown, is that the center line of the post does not coincide with the track, thus adapting itself to the nature of the blows of a car-bumper, as received in the single-post style of the mechanism.