METHOD OF MANUFACTURING BRICK 



173 



New York brickmakers use a Steadman. It consists of a 

 cylindrical flat box about three feet in diameter, within which 

 two concentric wheels with iron arms revolve at a high rate of 

 speed ; the clay being thrown around between these is quickly 

 broken up. If the clay is charged in too moist a condition it 

 will not be thoroughly pulverized, at the same time it must not 

 be charged too dry and thereby prevent the particles in the 

 green brick adhering together. After passing from the disin- 

 tegrator the powdered clay is carried by an elevator to the upper 

 story where it is discharged onto a long screen inclined at an 

 angle of about 45 degrees. The material which has been ground 

 fine enough passes through the sieve and down into the hopper 

 over the molding machine. The tailings fall into a hopper at 

 the lower end of the sieve and are carried back to the dis- 

 integrator. 



Now comes the molding, the manner in which it is done char- 

 acterizing the process. The molding machine consists of a massive 

 frame of forged steel about eight feet high. Three feet up from the 

 ground is the delivery table, sunk into which is the press box. 

 Connected with the hopper above the machine by means of two 

 canvas tubes is the charger. This latter slides back and forth on the 

 table. It is filled on the backward stroke and on its forward stroke 

 lets the clay fall into the mold box. The charger then recedes 

 to be refilled and at the same time a plunger comes down press- 

 ing the clay into the mold. As the upper plunger descends a 

 lower plunger which forms the bottom of the mold moves upward, 

 so that the clay receives pressure from above and below. The 

 upper plunger then rises, and the lower plunger ascends until 

 the lower surface of the brick is even with the table. Again the 

 charger comes forward, shoving the green brick forward on the 

 table, the lower plunger drops and the mold box is once more 

 filled with clay. The faces of the mold are of hard steel heated 

 by steam to prevent adherence of the clay. Air holes are also 

 made in the dies, but are apt to become clogged up. The pressure 

 from above is applied by a toggle-joint arrangement, and it is 

 claimed by the manufacturers of the Boyd dry clay presses that 

 the pressure exerted on each brick is 150 tons. One to six bricks 

 can be molded at a time, according to capacity of machine. On 

 a four-brick machine about 20,000 are molded in a day. As the 



