ISBN: 1231088028

Paperback, [EAN: 9781231088029], RareBooksClub.com, RareBooksClub.com, Book, [PU: RareBooksClub.com], RareBooksClub.com, This historic book may have numerous typos and missing text. Purch… More...

Paperback, [EAN: 9781231088029], RareBooksClub.com, RareBooksClub.com, Book, [PU: RareBooksClub.com], RareBooksClub.com, This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1903 Excerpt: ...just as difficult to move the handwheel one way as the other. Therefore the prevalent idea of pressure helping to open a valve is quite erroneous. But, you might object, it is surely easier to push a load down-hill than uphill? Well, it all depends on the nature of the road and its steepness. If the declivity is very slight and the load is skidded--not rolled--it makes practically no difference. And a loaded nut turning on a screw, metal to metal, is an exactly parallel case. The pressure between the threads is so severe that ordinary means of lubrication are of little avail. Probably some relief might result from the employment of ball bearings, and possibly they have been tried; but the load would be too great for the balls and their races to stand long. In addition to the load on spindle necessary to overcome the pressure of steam, comes again the problem of distortion due to unequal expansion, although this defect is not so accentuated as in the case of double-beat valves. When the valve and seat are brought into contact there may be, and there generally is, under the action of steam, one side of the valve which persistently blows, showing that the faces are not now strictly concentric and parallel. This effect is doubtless aggravated by the lack of symmetry in the supporting walls of the valve-box. In a common globe stop-valve for instance (Fig. 11, Plate XIII.) one half of the seat is supported from below, the other half being hung from the portion next the cover. In a right-angled stop-valve (Fig. 12, Plate XIII.) the seat next the outlet branch loses the support of the cylindrical walls of the valve-box. Webs, or ribs, are sometimes cast as shown in dotted lines, to afford additional support, but these do not entirely overcome the defect. The want o..., 1000, Subjects, 1, Arts & Photography, 2, Biographies & Memoirs, 3, Business & Money, 3248857011, Calendars, 4, Children's Books, 12290, Christian Books & Bibles, 4366, Comics & Graphic Novels, 5, Computers & Technology, 6, Cookbooks, Food & Wine, 48, Crafts, Hobbies & Home, 8975347011, Education & Teaching, 173507, Engineering & Transportation, 301889, Gay & Lesbian, 10, Health, Fitness & Dieting, 9, History, 86, Humor & Entertainment, 10777, Law, 17, Literature & Fiction, 173514, Medical Books, 18, Mystery, Thriller & Suspense, 20, Parenting & Relationships, 3377866011, Politics & Social Sciences, 21, Reference, 22, Religion & Spirituality, 23, Romance, 75, Science & Math, 25, Science Fiction & Fantasy, 4736, Self-Help, 26, Sports & Outdoors, 28, Teen & Young Adult, 5267710011, Test Preparation, 27, Travel, 283155, Books<

ISBN: 9781231088029

RareBooksClub. Paperback. New. This item is printed on demand. Paperback. 106 pages. Dimensions: 9.7in. x 7.4in. x 0.2in.This historic book may have numerous typos and missing text. Pur… More...

RareBooksClub. Paperback. New. This item is printed on demand. Paperback. 106 pages. Dimensions: 9.7in. x 7.4in. x 0.2in.This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1903 Excerpt: . . . just as difficult to move the handwheel one way as the other. Therefore the prevalent idea of pressure helping to open a valve is quite erroneous. But, you might object, it is surely easier to push a load down-hill than uphill Well, it all depends on the nature of the road and its steepness. If the declivity is very slight and the load is skidded--not rolled--it makes practically no difference. And a loaded nut turning on a screw, metal to metal, is an exactly parallel case. The pressure between the threads is so severe that ordinary means of lubrication are of little avail. Probably some relief might result from the employment of ball bearings, and possibly they have been tried; but the load would be too great for the balls and their races to stand long. In addition to the load on spindle necessary to overcome the pressure of steam, comes again the problem of distortion due to unequal expansion, although this defect is not so accentuated as in the case of double-beat valves. When the valve and seat are brought into contact there may be, and there generally is, under the action of steam, one side of the valve which persistently blows, showing that the faces are not now strictly concentric and parallel. This effect is doubtless aggravated by the lack of symmetry in the supporting walls of the valve-box. In a common globe stop-valve for instance (Fig. 11, Plate XIII. ) one half of the seat is supported from below, the other half being hung from the portion next the cover. In a right-angled stop-valve (Fig. 12, Plate XIII. ) the seat next the outlet branch loses the support of the cylindrical walls of the valve-box. Webs, or ribs, are sometimes cast as shown in dotted lines, to afford additional support, but these do not entirely overcome the defect. The want o. . . This item ships from La Vergne,TN., RareBooksClub<