. Machinery and processes of the industrial arts, and apparatus of the exact sciences. ermittent and jerkingaction of the press, as operated by a forcing pump, had the effect ofdetermining fracture of the masses compressed before the limit of theirresisting power to dead pressure had been reached. The perfectly steadyaction of the sterhydraulic press completely remedied this imperfection,and eliminated the irregularities which had disturbed the exactness ofthe determinations. The ordinary form of the press with vertical movement is shown inFig. 6, annexed. In this figure, a manometer appears a
. Machinery and processes of the industrial arts, and apparatus of the exact sciences. ermittent and jerkingaction of the press, as operated by a forcing pump, had the effect ofdetermining fracture of the masses compressed before the limit of theirresisting power to dead pressure had been reached. The perfectly steadyaction of the sterhydraulic press completely remedied this imperfection,and eliminated the irregularities which had disturbed the exactness ofthe determinations. The ordinary form of the press with vertical movement is shown inFig. 6, annexed. In this figure, a manometer appears attached to the press, to serve asan indicator of the degree of compression. This is important in experi-ments on the resistance of materials to crushing weights. 200 PARIS UNIVERSAL EXPOSITION. There is one consideration which requires attention in presses con-structed on this principle, when it is necessary that the piston shall havea large movement. As the quantity of cord accumulated on the pulleyincreases, the resistance to the driving force increases in virtue of the Fiff. Desgoffe & Olliviers Sterhydraulic Apparatus. enlargement of the radius by which it acts. And this unfavorable effectoccurs at that part of the course where the pressure on the piston isgreatest ; and where, accordingly, the mechanical advantage of the motivepower ought rather to be increased than diminished. To provide forsuch cases, the inventors have devised the form of construction shownin Fig. 6 of Plate Y, above referred to, where the pulley is smaller butthe chamber is elongated, and a second pulley is introduced at the oppo-site extremity 5 the cord being in this case rolled about both the pulleys,while much the larger part of its mass occupies the interval betweenthem. A case may however occur, in which a very large piston may have tomake so long a course, as to render it inconveuient or practically impos-sible to meet the exigency by the expedients thus far described: inas-much as the quan
Size: 1733px × 1442px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, booksubjectmachinery, booksubjectscientificappa
