The following description of this machine and the illustration Fig. 108, are taken from the circular of the makers, Messrs. Stothert and Pitt of Bath.
"It consists of a closed box or chamber, A, revolving on an axle, and of such a form as, when half filled with the materials for making concrete, to cause them to be turned over sideways, as well as endways, four times in each revolution of the chamber, so that, in from six to twelve revolutions (the number necessary being varied according to the weight and nature of the materials), a more perfect mixture is effected than can possibly be produced by hand, or (except in a much longer time) by any other machine."
The dotted lines show different positions of the hopper, and also the mixer after a quarter revolution.
"The mixer is worked by hand or steam power, and is mounted on a trolly of the ordinary railway gauge, and travelled by the same handles that are used for turning it. The travelling gear can, however, be disengaged when the machine has to be taken a long distance by horse or locomotive.
"For filling concrete into a trench, or the hearting of a pier, the machine is supported over the opening, on two balks of timber; a waggon containing the gravel (and cement in bags) follows on the same line. The hopper H, shown in the figure, suspended from a davit, is made to contain the proper measure of gravel for a charge, whilst the bags contain the proper quantity of cement, and a cistern near at hand (filled by a flexible hose) the proper quantity of water. Two men standing on the waggon (the sides of which are generally raised so that it contains about twice the quantity of an ordinary earth waggon) are able to fill the hopper, in the time employed by four men to give the mixer the requisite number of turns. For counting these, a tell-tale is provided, which indicates when the proper number of turns is completed; the mixer is then stopped with the door downwards. The door fastening is released, and the charge of concrete falls into its place, the discharge being instantaneous. The opening of the mixer is then turned upwards as in the figure, the door is opened (through the dotted arc, as shown), the hopper, suspended from the davit, is brought over the opening and at once discharged into it, and the water is run in from the cistern at the same time. The door, which closes water-tight, is then shut, and the mixing resumed, the hopper being meantime refilled for the next charge.
"For making concrete blocks, the hand mixer is mounted on a light travelling frame, capable of being moved from one mould to another, and the materials filled into a large tray, holding from 10 to 15 tone, are lifted on to a raised portion of the travelling frame by the steam travelling crane provided for lifting the concrete blocks.
"With the hand-mixer above described, a gang of six men, with a boy for attending to the water cistern, can make from 30 to 40 cubic yards of concrete blocks, and a larger quantity of concrete in bulk in a trench in a day, of better quality and at a cheaper rate than can be done by shovel mixing; and when the mixers are turned by steam, as at Aberdeen, etc., twice the above quantities are made.
"The mode of applying steam-power varies with the locality and the quantity of work to be done.
"The great advantages of this mixer over others, are its portable shape and self-contained arrangements, which enable it to be easily moved and used in different parts of a work, dispensing with mixing platform and measures; its economy, and above all, the rapid and perfect amalgamation of materials effected by it, producing, for a certainty, with moderate supervision, concrete of superior strength and quality."
The machine just described was invented by Mr. Messent, the engineer of the Tyne Pier works, Tynemouth.
It has been extensively used on the Tyne at the new breakwaters; at the harbour works, Aberdeen; at the Surrey Commercial Docks, London; for the Sulina works at the mouth of the Danube; for the Alexandria Dock works at Kurrachee, etc. eta Le Mesurier's Concrete Machine is shown in plan and elevation in Figs. 109, no. These figures, and the following description of the machine, are from the circular of the makers, Messrs. James Taylor and Co., Birkenhead.
"The figures show the machine ready for working. It may be driven by an ordinary 5 horse-power portable engine. AA are hoppers to contain each about 2 cubic feet, into which the ballast is shovelled, or material from stone crusher (if used) is delivered.
"These hoppers revolve as on a turn-table, and in course of revolution the sand and cement are added.
"When a hopper arrives at B the door is opened, and its contents delivered on to the elevator band, the arrangement of which speaks for itself.
"The supply of water is added as the materials are delivered from the elevator into the revolving mixing cylinder at C.
"The mixer is a plain cylinder of wrought iron, with some dividing plates in it, and is slightly inclined. In travelling through it the concrete becomes thoroughly mixed, and is delivered at D either into a shoot leading direct to its destination, or into barrows for wheeling it away.
Fig. 109. Le Messurier's Concrete Machine. Elevation.
Fig. 110. Plan.
"When barrows are employed a short swivelling shoot is used, transferable from one to the other, so that the delivery is continuous.
"In case of. interruption there is a clutch by which the mixer may be thrown out of gear.
"It will be seen from the drawing that the whole apparatus is portable in two parts; one the turn-table of hoppers, which is constructed on a bogie, and the other the mixer and elevator, the latter being hinged to the frame at E, so that the end F may be raised clear of the ground, and retained so by the clip at G.
"For following up straight work the end F of elevator may be suspended to the bogie under the hopper turn-table, and the whole moved as one machine on baulks of timber.
"In addition to the advantages of simplicity, portability, and efficiency, there is economy, as this machinery will easily produce 150 cubic yards of very superior concrete at a cost of fourpence per yard, including engine power.
"It will thus be noted that the moderate prime cost is very small in proportion to the advantages."
This machine has been extensively used in the new dock works at Birkenhead, and also at Hull.
The Carey-Latham Concrete-Mixing Machine consists of an arrangement of buckets like those of a dredger. These deliver the sand and ballast into a mixing cylinder, where they are met by a continuous supply of cement - the whole are mixed first dry by revolving blocks until they reach the middle of the cylinder, where the water is added through a perforated shaft, and the mixing is completed with the materials in a wet state.
The quantity of sand in proportion to the ballast is regulated by the arrangement of the buckets, that of cement by an archimedean screw. The machine thus measures as well as mixes the materials. It is made in various sizes to deliver from 5 to 70 cubic yards per hour.
The fig. and part of the above description is from the makers' circular.
Ridley's Concrete-Mixer has a fixed inclined cylinder, with a central shaft carrying longitudinal shelves, which lift the materials as the shaft revolves, and mix them together.