I say nearly, it being evidently most prudent to make the gudgeon a little more than less in diameter, and to make allowance for wearing. EXAMPLE. Suppose a water-wheel to weigh 12 tons, O cwt. 3 qrs. what ought to be the diameter of a cast-iron gudgeon, sufficiently strong to support the wheel? 12 tons 240 cwt. 3 qrs. The cube root of 240.3 = 6.221 Answ, That is, the diameter of the gudgeon should not be less than 6. diameter. It ought to be rather more, to allow for wearing, &c. See B, in the first table of gudgeons. 157. As the weights of wooden waterwheels cannot be accurately known, without a good deal of calculation, it is desirable to have some more ready method for practical purposes. The weights of overshot, or bucket wa ter-wheels, will be to one another nearly as their circumferences, or diameters and breadth. I say nearly, because the arms will make large wheels heavy in rather a greater proportion. Hence the following rule is formed on the direct proportion of the sole and buckets adding one-half of the diameter increased in the duplicate ratio or square of the diameter. For wooden water-wheels, multiply the diameter in feet by the width also in feet, to which add the square of half of the diameter. The cube root of the sum will be nearly equal to the diameter of the gudgeon in inches. EXAMPLE. Suppose a wooden water-wheel 12 feet diameter and 7 feet wide, (see E in Table II of Gudgeons.) which = 120 = the cube root of 4.932424; that is the gudgeon should not be less than about 5 inches diameter. Explanation of Table II of Water Wheels. 158. All the columns, except No. 10, are the same as in Table I.* The column 10 shews the result by Rule II. * In these tables the weight of the wheel B is different. I suppose the first table to be the correct one, but the difference is inconsiderable. (Ed.) SECTION III. Of Cast-iron Gudgeons for various Pur poses. 159. Taking it for granted that the cube root of the weight of a water-wheel, in hundred weights, is nearly equal to the diameter in inches of a cast-iron gudgeon, sufficiently strong to support such wheel, the following table of the diameters of gudgeons, and the weights which they may be supposed to sustain, is formed. may be of use for finding the diameters of journals in all cases of stress arising from lateral pressure, such as grindstones, intermediate spindles, &c. where the pressure can be ascertained, as well as water wheels.* It Explanation of the Table of Cast-iron Gud geons. 160. Column 1 contains the diameter in inches, from 1 to 11 inches. * See Art. [B. 151.] |