After the clay is tempered in ring-pits, it is covered with large battened panels, made of light pine wood nailed together, the object being to keep the clay moist, and prevent it from drying on the top before it is used. The laborers in the brick-yards like the clay tempered in ring-pits, as they can go in separate gangs at any time and commence work without waiting for a complement of gangs, which has to be done when pug-mills are used for tempering.
It is no unusual thing for brick-yard gangs, in the hot season of the year, to commence their task at about twelve o'clock at night, when the moon gives sufficient light, and have their work of moulding done before seven o'clock in the morning. Ring-pits facilitate this more than does any other mode of tempering the clay.
The invention of Mr. Henry Aiken, of Philadelphia, Pa., is shown in Figs. I I, 12, 13 and 14, and the main object of his invention is to dispense with complex driving-gearing, and to apply the power more advantageously than usual. A further object is also to simplify the devices by which the radial move ment of the tempering-wheel on its shaft is effected, and to so construct the same that a vertical movement of the wheel is allowed without danger of throwing the operating mechanism out of gear. These objects are attained in the manner which we will now proceed to describe, reference being had to the drawings, in which Fig. t t is a plan view of a clay-pit with Aiken's improve ments ; and Figs. 12 and 13 and 14, sections on the lines I 2, 3, 4, 5,6, Fig. 11, respectively.
A is the pit, in the centre of which is a vertical standard, a, and to the top of the latter is adapted a loose sleeve, x, carry ing two pulleys, b and d, the former of which receives power from any adjacent shaft—for instance, that shown at c—while the pulley d transmits this power, by means of a suitable belt to a pulley, e, carried by a vertical shaft, f, adapted to bearings at the outer end of the radial arm, B, the inner end of which turns on the central post a. From the outer end of the arm B projects a short shaft, B', carrying a loose traction-wheel, D, the periphery of which is adapted to the rim of the pit and a worm-wheel, g, on the hub of the traction-wheel, gears into a worm, h, on the shaft f (See Fig. 12.) For the sake of economy, it is preferable to make the wheel D comparatively light, and to increase its traction power by hanging upon the outer end of its shaft a box of clay or other cheap weight, E.
The arm B is connected to the outer end of the shaft F, which carries the tempering-wheel I, by means of the link i and rods j j, and the tempering-wheel is hung to, or forms part of, a sleeve, .7, so adapted to the shaft F that it can be moved from or towards the centre of the pit, this movement being effected, as usual, by means of the double rack M and pinion N, the di rection of the movement depending upon whether the upper or lower rack is in gear with the pinion. Instead of rotating the pinion N from a central shaft by means of spur-gearing, as usual, however, it is secured to one end of a spindle, in, adapted to bearings at the inner end of the arm B, and carrying, near its opposite end, a worm-wheel, P, the teeth of which engage with a worm, S, secured to the stem a. (See Fig. 13 and dotted lines, Fig. 14.) When power is applied to the shaft f at the outer end of the arm B, the traction-wheel D is caused to revolve, and travels around the rim of the pit, carrying with:itIthe arm B, and con sequently the shaft F and tempering-wheel I, while at the same time the movement of the worm-wheel P around the worm S on the central stem a causes the rotation of said worm-wheel and the operation of the mechanism which effects the radial move ment of the tempering-wheel.
It will be evident that by the above-described arrangement the power required to effect the movement of the tempering wheel is applied more directly, and with less loss by friction, than when this power is applied to the inner end of the temper ing-wheel arm by means of gearing from a central rotating shaft, while the use of the simple traction-wheel D at the edge of the pit obviates the necessity of locating costly and incon venient mechanism at this point.
By the use of the fixed worm S on the stem a, and the worm wheel P carried by the arm B, the said wheel P can be caused to revolve at the required speed without the intervention of the usual system of gearing, which is complicated and expensive, and causes loss of power by friction.
It will be observed in Figs. I I, 13 and 14 that the inner end of the shaft F is pivoted to the shaft m, which carries the pinion N for operating the rack M, so that when the tempering-wheel rises or falls, owing to inequalities in the bottom of the pit, the centre of movemnnt will be at the shaft m, thus preventing the risk of throwing the rack out of gear with the pinion, which this movement causes in machines of this class as usually con structed.