. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. d upon is really forced the outlet from the fan be partially throttled, there will be iDut a very slight increase ofpressure in the blast, while the fan continues to run at the same speed ; and if the outlet beentirely closed, the fan will still continue running, ^absorbing much power, but producing no prac-tical effect. Table II.—Dimensions op Common Fans. Diameter of Fan. Width of Vane. ft. 90 lOi 0 36 7 0 10| 1 01 2 Length of Vane. ft. 90 10| 0 610 Diameter of Inltt Opening. ft.
. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. d upon is really forced the outlet from the fan be partially throttled, there will be iDut a very slight increase ofpressure in the blast, while the fan continues to run at the same speed ; and if the outlet beentirely closed, the fan will still continue running, ^absorbing much power, but producing no prac-tical effect. Table II.—Dimensions op Common Fans. Diameter of Fan. Width of Vane. ft. 90 lOi 0 36 7 0 10| 1 01 2 Length of Vane. ft. 90 10| 0 610 Diameter of Inltt Opening. ft. in. 1 6 1 9 2 0 2 3 2 6 3 0 1 0 1 3 1 6. 1 9 2 0 2 4 The best known blower at present is Roots, an American invention, but largely used inEngland, and made here by Thwaites and Carbutt, of Bradford. Roots Blower, as arranged for foundry work, is shown in Figs. 1248, 1249. It has rotarypistons covered with wood lags, by which construction the pistons can be made lighter thancast-iron pistons, and thus take less power, run more quietly, and at twice the speed of the iron 1247. pistons. The thickness of a sheet of paper is the only clearance that is allowed, and, in orderstill further to reduce the clearance, a frictional composition is evenly applied with a brush, overthe surface of the hollows of the rotary pistons, until every portion of the pistons is shown to bein contact. The composition is of the consistency of ordinary paint, and also answers the purpose ofpreserving the wood. The wood used is the finest selected deal, free from knots, thoroughly sea-soned and dried for three years. The lags are held upon malleable cast crossheads with bolts, which,for security, have the bolt ends riveted over the nuts. At the joints of the wood lags is inserted aniron tongue, which runs the whole length of the joints. The end plates are planed, and are pro-vided with bosses, which are bored and fitted with hard gun-metal bushes, forming the bearingsfor the steel shafts. These gu
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectenginee, bookyear1879
