As the liar of clay issues from the forming-die it passes through a small chamber filled with fine, dry sand, which adheres to the surface, of the brieks. The surplus sand is kept btelc hi the eltandsir by swinging, elastic serapers, which allow the bar to escape with its sand. This sanded surface of the clay bar prevents the bricks from sticking together on the barrows or in the luu•Ics, or on the and improves them in color when burnt. All Play has more or lice Stones in it, and as it is impracticable to pick them all out, there is a necessity of making some pa•ovislon for their removal. If it stone is more than 3 in in diameter, and does not lodge in the stationary lining of clay in the case, it will lodge at the e.ntranne to the expressing screw, preventing the clay from issning t he (lie, when a valve is forced open, through which the stone may readily be removed. If a stone of less diameter than the mouth of the screw passes to that point, it will go through the screw, the openings between the threads being less at the entrance than at any other point ; so that a stone that once fairly enters can not lodge until it has reached the forming-die, where it will lodge if it is larger than a brick is thick, and prevent the proper flow of clay, causing the bar to :Split in two, or only part of the bar to issue ; this forming-die being secured on hinges, it can be swung open and the stone knocked out, when the die is closed and the machine again started. Should an undue pressure be brought upon the machine from a stone lodging in the die, or the clay being too sandy or too stiff, there is a safety-pin holding the eye-bolt that secures the "former," which is cut off by the strain and the former opens. thus in stantly and automatically relieving the machine.
The bricks cut from the continuous bar are sepa rated and carried by an endless belt any desired dis tance, sometimes 22.00 ft. across the yard, from which the bricks may be wheeled to any point most conven ient for "hacking," or loaded directly upon the drier cars, as may be required.
The Spiral Cut-off (Fig. 4), employed in the Cham ber's machine, is a thin blade of tempered steel, secured. to the periphery of n drum, in the form of a spiral, the distance between the blades of which is that required for the length of a brick, and the projection of which gradually increases from nothing at its first end to the full width of the widest. brick to be cut. This spiral knife runs perpendicularly in openings in the links of an endless ehidn, supported upon rollers, the chain be ing so formed as to support the bar of clay from the bottom and one edge; the clay is thus fully supported while being slowly cut off by the long drawing cut of the spiral blades in passing through the openings in the chain. The distance between the spiral blades be ing uniform, the lengths of the bricks are uniform. The ends of the bricks are cut smooth and square. The speed is controlled by that of the clay itself ; hence, no matter how irregular the flow of clay from the (lie, the spiral runs in exact unison therewith, con sequently the uniformity in the length of the bricks. This controlling of the speed of the spiral by the clay is so positive that it will run at any speed, from 3 to 100 bricks per minute, while the machine runs at its regular speed. In order that the spiral knife may not be affected by stones, the shaft to which it is secured is held in position by gravity and counterweighted, SO as to it with just sufficient force to compel the knife to pass through the bar of clay. When the knife comes in contact with any hard foreign substance, as stones, brickbats, or bones, its rides up on the obstruc tion, and, when passed, falls by gravity to its original position.
The Penfield Plunger Brirk-Machine (Fig. 5),
manufactured by Nessrs. J. W. Penfield & Son, Wil loughby, Ohio, is an example of the plunger type of stiff-clay machine. The clay is fed into the drum or tempering-cylinder, in the center of which is a shaft filled with blades, which grind the clay and force it through a port-hole into the pressing' chamber. A plunger device then presses the clay through the die, and on to the cut-off table. It is then cut into bricks by means of a suitable cutter-frame, strung with wires and operated by hand. The mechanical device used to propel the plunger is a steel cam, placed on the main shaft between the upper and lower bed-plates. It ope rates the rollers at the front and rear ends of a sliding frame to which the plunger is attached, giving it alter nately a forward and backward motion at each revolu tion of the shaft. The machines are made either sin gle or double workers—one cam doing the work in either case. The main shaft, cam, and friction roller are of steel, and the machines are built with proportionate strength through out. In this machine, as in that last described, the clay is tempered and molded stiff enough to allow immediate hacking of the brick. Fig. 5 represents a Penfield machine capable of turning out 40.000 bricks per 10 hours, and having the following dimensions: Height of machine, 9 ft. 8 in, ; length of sills, lift. ; width from out to out of sills, 3 ft. 10 in.; extreme width. 6 ft. 6 in.; capacity, 40,000 bricks per 10 hours; estimated weight, 12,000 lbs. ; speed of pulley-shaft, about 145 revolutions per minute; pulleys, 42 in. diameter, 10 in. face; ma chine is hack-geared 42 to 1.
By a change of die in this machine, all shapes and sizes of bricks, especially those of orna mental patterns, can be made. The construction and arrangement of the die, therefore, form a novel and important feature. The back or forming die receives and forms a har of clay with rounded corners. The clay bar then passes through the finishing die, which is slightly square-cornered, and by means of this "slicker" and the process of lubrication the bar is finished and given corners accurately shaped. The lubrication is effected by water, by steam, or by both. For water lubrication the finishing, die is set a short distance ahead of the back (lie, and water (or oil) is allowed to flow between the two dies and upon the day liar. For steam lubrication the finishing and forming dies are bolted tightly together and packed. Steam is then supplied directly from the hailer to the clay bar. In cases where both water and steam lubri cation are desired, two slickers or finishing dies are used, the one next to the forming die being arranged for steam connection, and the front slicker being water lubricating. each being oper ated respectively as already explained. Good re sults have also been obtained with a so-called brass scale finishing" 11 ie in which the outer part of the slicker is an iron casting, into which is fitted (i wooden Ii dug. which in turn is lined with strips of spring brass. This slicker is pro vided with a large number of channels, conduct ing the water• or steam from the outside of the. slicker to the brass scales. thus lubricating t he bar of clay effectively as it passes through the die. In still another form of die each corner of the bar of clay is lubricated separately. and by means of a brass plug at each corner the flow of steam can be regulated or entirely shut off from iiiiy one or more corners at any time desired. Thus. if one corner of the die beeomes clogged, so that the steam does not reach the corner of the bar of clay, causing it to ruffle or tea•, the steam can be shut off from the oilier three corners. This will allow the full head of steam to reach the corner which is clogged, blowing out the obstruc tion.