The age-herald., 1901-10-12
BIGGEST WHEEL


 From the Baltimore Sun.
 The Roberts Poole & Son Company, iron founders and machinists, at Woodberry' is about finishing the largest wheel or lts kind in the world. The wheel is 6o rect in diameter, and, with its supports VIII weigh over 100000 pounds. It was or dered by the Calumet and Hecla Mining Company to carry away the refuse from the stamp mills at one of the great mines on Lake Superior.
 The wheel is what Is known as a sand wheel Upon the inner surface of It's rim will be arranged 55O buckets, each meas uring feet inches by feet. AS the wheel revolves each bucket will scoop up it's capacity of earth and refuse, which 1t will dump into a trough at the top or the wheel, whence it will be carried away by the water in sluiceway.
 When the Calumet and Hecla Company decided to order this wheel 1t found that the Baltimore plant was the only one pre- pared to build the giant entirely under cover. One of the first requisites for building such wheel was pit in which part of the wheel might be sunk as 1t was put together, and 1t was found that the Robert Poole & Son Company had one exactly suited to the purpose the pit being 100 feet long, 12 feet wide and 30 feet deep, while the building over the pit is so high that it easily accommodates the huge structure. The order for the wheel was given In June, 1900, and work was at once begun on the various parts according to the plans drawn by MT. 10. D. Leavitt, an engineer of Cambridge port, Mass.
 One of the first considerations in mak- ing the wheel was the strength and safe ty of the axle, and that was ordered from the Krupp gun factory. This axle, or shaft, is by itself an enormous affair. It Is 27 feet long, 32 inches in diameter with . 26-inch hole through the center, end weighs 42,0O0 pounds All of the fir- ishing work on 1t was done in Baltimore
 Because of the enormous size of the wheel 1t had to be built in sections and it was laid off in twenty segments. It con sists of two concentric rims, one on the inside for the purpose of strengthening the entire structure and another outside, consisting of a toothed rim fastened to the inside rim with bolts. No part of the work was as exacting or as interesting as the finishing of the segments, and con- ditions had to be taken into account which would never occur to the lay mind.
 Each segment, for example, had to be finished in practically the same tempera- ture, for had two of them been planned in different temperatures they would not have fitted because of the expansion and contraction of the metal. Great interest was taken in the work by the mechanics connected with the plant, and when the segments were completed there was much speculation as to whether each part would fit perfectly.
 The putting together of the wheel in the shop required several weeks. When it was completed it was found that the parts fitted with really wonderful accu- racy, refiecting great credit upon those in charge of the work. Investigation showed that a line run through the joint of two segments on one side and contin- ued through the center to the joint of the two SeRmentS OH tAC oPPcoAeS SANS was less than one one-thousandth of an inch out of true, or as near as human skill could come to making it absolutely per- feet, the difference being so slight that it would hardly be detected by the most powerful instruments. The outer rim was as perfect as the inner, and so even ly are all the segments laid together that they seem to constitute one piece.
 Running from the hubs on the ends of the shafts to the segments are forty steel arms, built on the principle of bicycle wheel and arranged with special nuts and threads for fine adjustment when the wheel is finally set up at the mine. In or der to fill the contract several pieces of special machinery had to be built to com plete the various parts. One of the most interesting Is that employed to cut down the teeth of the big outside rim until they correspond exactly with the teeth of the smaller wheel by which the motor power is to be communicated.
 Those who have seen an ordinary set of cog wheels are not apt to think that the cutting of the teeth to fit would be diffi- cult, but with a cog wheel 65 feet in di- ameter the proposition is quite different. So carefully is the work being done on