The "Standard" Continuous Mixer is also an automatically measuring machine. It is extra heavy, being built for large capacity and to meet the wants of large contractors. It is supplied with a three-department feed-hopper, and ad justments are claimed to be easily and quickly made.
The hoppers are equipped with rotary cork screw agitators designed to prevent bridging, which force the materials toward the gates. The conveyor belt delivers the ingredients to the mix ing drum in constantly flowing streams. On the interior surface of the revolving drum are longi tudinal ribs by means of which the materials are tumbled over and over while still dry as the drum rotates, gradually approaching the dis charge end. When within fifteen inches of the lower end, a sprinkling device wets to any con sistency desired, the flow of water in greater or less amount being regulated by a thumb-screw: The valve opens to its full capacity as set, by the use of lever under the direct control of the man who feeds the cement, and can be closed in the same manner.
The "Simplex" Mixer is a continuous auto matically measuring machine in which the pocket system of feeding is done away with, and the dry materials are fed in a continuous stream. The cylindrical mixing drum is mounted at an incline, the dry materials entering simultane ously at the upper end, from the hoppers, through the proportioner. Blades attached to the interior of the drum and running parallel to its axis, assist in mixing as the drum rotates. By gravity the materials are carried down to the lower end of the cylinder, where they come under the action of a set of blades attached to a shaft which revolves at a higher speed than the cylin der itself. Here the water is admitted in any quantity desired, being controlled by a valve on the pipe leading from the supply tank to the inside of the drum; and the final mixing takes place.
The "Perfection" Mixer is a machine of the continuous type; but, by stopping the feed and allowing the mixing paddles to continue in opera tion, material can be handled in batches. The
dry materials are fed from separate hoppers in quantities automatically proportioned for any desired mixture. Water is fed through a perfo rated pipe, the supply being controlled by means of a sensitive gate-valve. The mixing paddles are slipped in succession onto a removable square shaft running lengthwise of the mixing trough. They are double-ended; and, as the shaft re volves, one end turns the material over and throws it forward, while the other end turns and throws it back half-way, this operation being re peated about thirty-five times before the ma terial leaves the mixer.
In the "Crescent" Mixer—a machine of the continuous type—the materials are automatic ally proportioned by an ingenious device in the shape of a spool having concave apartments, which is adjustable so as to give any desired mixture. To obviate all danger of damage to the mechanism in case a very large piece of ma terial—as, for example, a stone—should get into the sand hopper or cement hopper, the propor tioners are provided with a "slip-sleeve" ar rangement on the shaft between the boxing; and if the large piece is not ejected through the "safety-gate," the proportioner will stop. The same result will occur if there is excess friction in the mixing trough.
The "Common Sense" Mixer is another con tinuous machine in which the entire process of measuring, dry mixing, wetting, wet mixing, and discharging is automatic. The feeding de vice is similar in its operation to that employed in the "Kent" mixer described above, consist ing simply of a flat plate forming the bottom of the hopper, which plate, as it moves back and forth sidewise, removes successive layers of ma terial from the bottom of the hopper contents alad drops them into the mixing trough. The thickness of these layers depends on the height of the discharge opening, which is set to regu late the proportions of the material being fed to the mixing trough. The hopper walls are con structed with little slope—practically perpen dicular—so that the natural action of gravity in the feeding process is not interfered with by the tendency of damp material to bridge across the hopper. The mixing apparatus is of the single shaft .pug-mill type, the paddles being narrow and sufficiently numerous to chop, stir, and turn the materials thoroughly, both before and after the water is added.