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issue; this forming die being secured on hinges, in less than one minute it can be swung open and the stone knocked out, when the die is closed and the machine again started.

It is not very often that, in working good brick-clays, stones larger than the thickness of a brick get into the machine, and very seldom one larger than the opening to the screw; so that it is but seldom that the manufacturer is troubled with stones that will not pass the screw.

Small stones occur much more frequently, and pass freely through the machine, being buried in the bar of clay and passing to the cut-off. When a stone is buried in the bar of clay at the line of severance, the spiral knife must either cut through it, be broken, or some provision be made by which the blade will not be injured. The first is not prac ticable, as the stones are often very hard; and to break a knife every time it should happen to strike a stone would render the machine useless.

In order that the spiral knife should not be affected by stones, the shaft to which it is secured is held in position by gravity and counterweighted, so as to adjust 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, it rides up on the obstruction, and when passed falls, by gravity, to its original position, thus escaping injury, and not interrupting the continuous operation of the machine.

These spiral blades are made of steel, and will cut off, in good smooth clays, from two to five millions of bricks, and in stony clays from one to two millions. These blades are

secured to the drum by a spiral clamp, and can be replaced in a few moments.

Fig. 74 shows a plan view, partly in section, of the Chambers brick-machine.

After moulding, the next step in the production of machine-made bricks is the drying, and this can be accomplished by either natural or artificial means.

The natural means is to place the bricks in the sheds and dry them by the atmosphere.

In large daily productions of bricks it is found very difficult to dry the stock in sheds, which, being large and covering a great area of land, makes the cost of wheeling the bricks to and from them very great. In addition, the bricks, after being placed in the sheds, are liable not to dry, and as they can be set in the kiln in a damp condition only with a positive certainty of losing them, valuable time would be

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lost and great annoyance caused. Altogether, the first cost for brick-driers, cars, and tracks, is more than for common drying sheds and barrows, but the saving in the cost of handling the bricks much more than compensates for this. The expense for fuel and attendance while the bricks are in the driers should not be charged wholly against them, as time and fuel are largely saved in the burning.

The great advantage in the employment of driers is that the work can be continued throughout all seasons of the year, especially in the early spring, when bricks are usually higher than at any other period of the year. The effective system of heating the driers by steam coils, alluded to in Chapter VII., can be applied if desired.

In all works producing bricks in large quantities by machinery, it is much cheaper in the end to place the bricks directly upon cars and carry them to suitably constructed driers erected for the purpose of expeditiously extracting a portion of the surplus moisture from the stock.

The drier, shown on page 214, is controlled by Messrs. Chambers Bro. & Co., of Philadelphia, Pa., and consists of six or more brick flues, about forty feet long, three-and-ahalf feet wide at bottom and two feet at top, and four feet high, built of bricks, with a railroad track through each flue, slightly descending from the machine, with fire-grates and doors at lower end, and stack at the upper end of the drier.

Each flue has an iron door, sliding in iron grooves and counterpoised by a weight at either end, so that the flue is readily opened and closed for the admission and exit of the cars loaded with either the green or dried bricks.

From the grates, upon which coal, coke, or wood is burned, the results of combustion are conveyed along and near the bottom of the tunnel to near the stack end, and are allowed to escape gradually, through perforations or slots, up, under, through, or between the bricks on the iron cars.

In addition to the gases from combustion a large amount of air is admitted over the furnace into the flue, which becomes heated, and when distributed through the bricks by means of the adjustable flue, takes up the moisture from the bricks and carries it off through the stack.

The cars are constructed of iron, and are designed so that the slats can be turned up and over on the next one, and the "off-bearers" from the machine, and the "tossers" in the kiln can stand within the body of the car, close up to their work, for loading and unloading the bricks. This is an improvement of far more value than would at first appear, for by standing so.conveniently to the work, both to the off-bearing frame of the machine and to the hacks on the car, one hacker or off-bearer is enabled to perform much more work than he would do if compelled to lean over the width of the car.

The boxes on these cars are made with friction-rollers in them, and run without lubrication.

They travel so lightly that a boy will transport four hundred and forty bricks on one of them with greater ease than a man will push a wheelbarrow load on the best-designed barrow.

At each end of the flues is a transfer or switching car, which transfers the loaded cars from a single track, running

from the machine, on to any one of the six tracks running into the flues; and in like manner from any one of the six flues to the track running to the kilns.

The loaded cars are transferred into any one of the kilns by means of transfer cars, and the empty ones returned to the machine by a return-track, outside of the flues.

The whole of this arrangement may be under an inclosed building, and quite comfortable to work in at all seasons.

The cars are moved to the side of the machine, where the bricks are hacked on them direct from the off-bearing apron, and require no more handling until ready to "toss" in the kiln. One man will hack from 20,000 to 25,000 bricks upon these cars, ready for drying, direct from the machine, in ten hours.

The loaded car is then run on to the transfer car, and from thence into any one of the flues, where a current of heated air (an artificial summer breeze) is forced through them, the steam from the bricks near the fire condensing on the surfaces of the cold ones, and preventing checking or cracking, while the bricks absorb the heat from the steam.

When the bricks directly over the fire are dry, the car is run out to the kiln to be set, a fresh car being put in at the upper end, pushing the others down, and bringing another partially dry car immediately over the fire, and so on.

One ton of anthracite coal will dry 25,000 bricks, but the dryer saves a large proportion of coal in the burning of the bricks (as we have before stated), and saves handling the stock twice-once in hacking or laying on the floors, and once in reloading on barrows to be wheeled to the kilns.

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