A Treatise On The Principles And Practice Of Dock Engineering

CONTINUOUS MIXERS. 69 Taylor’s Mixer.—A later adaptation of the same type of mixer has the revolving chamber in the form of a double cône (fig. 30). “ In mixing concrete the materials are filled into the measuring hopper in the usual proportions; the sliding door is then withdrawn and they are admitted into the revolving mixing cones, to mix dry first; water is then Applied through the hollow supporting shaft. “A few revolutions, say 15, serve to thoroughly mix the materials, and the delivery doors, which are closed perfectly tight while the mixing is Proceeding, being simultaneously opened by the lever and cluteh, the contents are dropped through a shoot into suitable trucks or skips, or directly on to the work in hand. “A one-yard mixer can produce, in ordinary working, 24 cube yards of the very best concrete in one hour at a cost for labour of about 4d. per yard. If fitted with a steam hoist and special service trucks an output of 30 yards per hour of thoroughly well mixed concrete can be guaranteed, the cost being greatly reduced. The machines are made either stationary or portable, and of capacities varying from | to 1| cube yards” (Manufac- turers’ Circular). The machines can also be worked by gas engine or electric motor. They ure supplied by Messrs. Henry Balfour & Co., Ltd., of Leven, Fife. The Taylor mixer has been employed at the Keyham Dockyard extension works, at Barry Dock, at Methil Dock extension, at Seaham Harbour, &c. Continuons Mixers—Carey-Latham Mixer.—In this machine the sand änd ballast are supplied systematically, by means of ascending buckets, to the mixing cylinder (figs. 31 and 32), where they are met by a supply of cement, the quantity of which is regulated by an archimedean screw. The process can thus be carried on uninterruptedly for any length of time. Incorporation is “ carried out in a revolving cylinder in which are fitted inclined blades or vanes, which lift and tumble the materials some 50 times before delivery, first in the dry and afterwards in the wet state. During this process the blades or vanes, which are carried from a central shaft, revolve with the cylinder in the same direction, but at a slightly less speed, whereby they are constantly changing their position, acting as scrapers, and thus prevent the setting of the cement on the blades and inner surface of the mixing cylinder. The water required for the concrete passes through the central shaft, and is sprayed out on the materials as they are tumbled about in the mixer.” The machines are manufactured by Messrs. John H. Wilson & Co., Ltd., of Liverpool, in sizes capable of discharging from 10 to 30 cubic yards per hour. The Carey-Latham mixer has been used in connection with dock and harbour works at Peterhead, Newhaven, Sydney, Hong Kong, Yokohama, Odessa, Bilbao, New York, <fcc.