PUG-MILLS.
Fig. 23 illustrates the No. 2 Pug-mill built by the Frey Sheckler Co. This pug-mill has a shell made of boiler steel, 8 feet long. It cast-iron ends. There are two patterns for ends, at the discharge of mill; in one of them the opening is very large ; this is used when the clay is of a very sticky nature, and also where large capacity is desired. The other one has a smaller opening, and is used where the clay is of a short nature, or where a smaller capacity is wanted. The shaft is made of hexagon hammered steel 33% inches diameter ; the knives are also made of steel, bolted on cast hubs that slip on the shaft. By using a knife of this kind much trouble and expense are saved should the knives have to be replaced. The hubs, fitting on the hexagon shaft, allow the knives to be arranged in any manner desired. Each knife can be set in six different positions, corresponding with the six flat sides of the shaft, and by this arrangement of the knives the clay can be discharged rapidly, or retained in the mill longer, and the tempering controlled in this manner. The knives on shaft outside of the discharge head of mill cut the clay as it emerges through the head, and allow it to fall to the machine or conveyor below. This device makes the flow of clay even to the machine, and cuts the clay in small pieces, so that the machine will take hold of it readily.
The gearing is very heavy, being geared six to one. The builders say : " Our long experience has taught us that wher ever dry clay is desired to be mixed with water in the process of passing through the pug-mill, that an open-top pug-mill is the only safe machine to use. The reason for this is that an open-top pug-mill allows the examination of the clays all along the course, and the introduction of additional water to even it up. Closed pug-mills are only advisable where the clay is
tempered before entering into them, or where it runs perfectly even in moisture in the bank, and requires no additional water. This mill will pug clay for 30,00o to 6o,000 brick in to hours, depending on the nature of the clay and the arrangement of the mixing knives." It is provided with a friction clutch pulley 36 inches in diameter, to inch face. Average motion, 15o revolutions per minute ; weight, 4,200 pounds.
Fig. 24 illustrates a Double Geared Pug-mill made by the Frey-Sheckler Co. in two sizes, viz.: No. 5, to feet long ; No. 6, 12 feet long.
This pug-mill has a shell made of inch boiler steel. The heads are made of cast iron, and of the same pattern as is used in their No. 2 pug-mill.
The shaft is made of hexagon hammered steel inches in diameter ; the knives are made of cast iron and bolted in cast socket hubs that slip on the shaft, the same as in their No. 2 pug-mill. This pug-mill is double geared, made extra heavy and strong. It can be arranged to discharge the clay either from the bottom or at the end.
The capacity of No. 5 pug-mill is for from 50,000 to 50,000 brick in to hours ; No. 6 pug-mill 50,000 to 75,000 brick in JO hours, depending upon the nature of the clay and the arrange ment of the mixing knives. It is provided with a friction clutch pulley 36 inches in diameter, to inch face. Average motion, 160 In 170 revolutions per minute ; weight, 5,700 pounds.