Fig. 142 shows a charging elevator devised by the McKelvey Machinery Company. The bucket is raised and lowered by the same engine by which the concrete is mixed, and operated by the same man. The capacity of the charging bucket is the same as that of the mixer. In Fig. 143 is shown an automatic loading bucket which has been devised by the Koehring Machine Company for charging the mixers made by them. The bucket is operated by a friction clutch, and is provided with an automatic stop. In using either make of these charging buckets, it is necessary to use wheelbarrows to charge the buckets, unless the materials are close to the mixer.
343. Transporting Concrete. Concrete is usually transported by wheelbarrows, carts, cars, or derricks, although other means are frequently used. It is essential, in handling or transporting con crete, that care be taken to prevent the separation of the stone from the mortar. With a wet mixture, there is not so much danger of the stone separating. to the difference in the time of setting of Portland cement and Natural cement, the former can be conveyed much farther and with less clanger of the initial setting taking place before the concrete is deposited. When concrete is mixed by hand, wheelbarrows are generally used to transport the concrete: and tho are very often used also for transporting machine-mixed concrete. The wheelbarrows used are of the same type as shown in Fig. 140. About two cubic feet of wet concrete is the average load for a man to handle in a wheelbarrow.
Fig. 144 shows a cart of the Koehring make, for transporting concrete. The capacity of these carts is six cubic feet. One man can push or pull these carts over a plank runway. The run way consists of two planks, each 8 to 10 inches wide, fast ened together with 1-inch by 6-inch cross-pieces, a n d made in sections so that they can be easily handled by two men.
When it is neces sary to convey con crete a longer dis tance than it is economical to do so by wheelbarrows or carts, a dumping car run on a track is often used. Fig. 145 shows a steel car for this purpose. The capacity of these cars is from 10 cubic feet to 40 cubic feet, and the track gauge is from 18 inches to 36 inches. Both end and side dumping cars are made.
If a large amount of concrete is to be deposited near where it is mixed, derricks are frequently used to convey the concrete. A coin bination of car and derrick work is easily made by using flat cars with derrick buckets.
344. Boilers. Upright tubular boilers are generally used to supply steam for concrete mixers and hoists operated by steam engines,when they are isolated. For the smaller sizes of mixers, the boilers are on the same frame as the engine and mixer. Fig. 12S shows a McKelvey mixer, and boiler mounted on the same frame. In a similar manner the boiler is often fast ened to the same frame as the hoisting engine. This arrangement
cannot be used for the larger sizes of mixers and hoists, as they are too heavy to be handled conven iently.
When it is pos sible, the mixer and hoists should be supplied with steam from one centrally located boiler. A portable boiler is then generally used.
345. working Plant. Aportable wood working plant can very often be used to advantage in shaping the lumber for the forms when a large building is to be erected. The plant can be set near the site of the building to be erected, and the woodworking done there. The machinery for such a plant should consist of a planer adapted for surfacing lumber on three sides, a rip saw, a crosscut circular saw; and in some cases a band saw can be used to advantage. Usually, the difference in cost between surfaced and unsurfaced lumber is so small that the lumber could not he surfaced in a plant of this kind, for the difference in cost; but perhaps it would be more uniform in thickness. In such a plant the rip saw and the crosscut saw would be found to be the most useful; and if reasonable care is taken, this ma chinery will soon pay for itself. It is often cult to get work done at.a planing mill when it is wanted; and if a con has his own wood working machinery, he will be independent of any planing mill. A plant of this kind can be operated by a steam or gasoline engine or an electric motor.
346. Plant for Ten=Story Building. The plant used by Cramp & Company in constructing a reinforced-concrete building for the Boyertown Burial Casket Company, Philadelphia, will be described, to show the arrangement of the plant rather than the make of the machinery used. The building is SO feet by 120 feet, and is ten stories high; also, there is a mezzanine floor between the first and second floors. This building is structurally of reinforced concrete, except that the interior columns in the lower floors were constructed of angles and plates and fireproofed with concrete. The power plant for the building is to be located at a level of about seven feet below the basement floor. The hoisting shaft is built in the elevator shaft located in the rear of the building. The hoisting tower is constructed of four 4 by 4-inch corner-posts, and well braced with 2 by 6-inch plank. Two guides are placed on opposite sides; also one on the front, Fig. 146. The front guide was made in lengths equal to the height of different floors of the building. Fig. 146 shows the location of all the machinery, all of which is of the Ransome make. The con crete was discharged directly from the mixer into the bucket, which rested at the bottom of the elevator shaft. At the elevation where it was desirable to dump the concrete, the front slide was taken out, and the concrete was dumped automatically by the bucket tipping forward. The bucket rights itself as soon as it begins to descend.