File:Cassier's magazine (1904) (14768770062).jpg

Identifier: cassiersmagazi2719041newy (find matches)
Title: Cassier's magazine
Year: 1891 (1890s)
Authors:
Subjects: Engineering
Publisher: New York Cassier Magazine Co.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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tive types of each. In every horizontal engine a wide anddeep gap, forming the jaws for the re-ception of the main bearing, breaks thecontinuity of the frame. The import-ance of strength at this point is fullyrecognised, not only in the proportionsof the massive cap which spans andembraces the jaws, but by the greatspread of the base, which in large en-gines reaches several feet beyond thecentre line of the shaft, the vertical partof the frame extending in a long slopedownwards from the cap to the extremityof the flat base. Ample support is thussecured for the heavy weights, and thefore-and-aft stresses for which provisionmust be made. The strength andweight of the cap is, in fact, out of allproportion if its uses were simply con-fined to keeping the brasses together.Its principal function, however, is to keepthe joints together. Indeed, so importantis the need of making good the gaps inthe frames that main bearing caps of castor forged steel are coming into use. 422 CASSIERS MAGAZINE
Text Appearing After Image:
THE MODERN HORIZONTAL STEAM ENGINE 423 The tubular trunk guide, which formsthe connection between the bed properand the cylinder, is usually of Csection,but sometimes both sides are open forconvenience of access to the crosshead.In the latter case, when the engine runscontinuously in the outwards direc-tion, it is good practice to support thetrunk at the centre of its length by afoot, bolted to the foundation, while forthe heavier work this foot extends thewhole length of the trunk. In a wind-ing engine, or in other engines wherethe crosshead pressure is alternately up-wards and downwards, the upper andlower guides must each be strengthenedby a deep and heavy rib, care beingtaken that the minimum cross-sectionof metal in the trunk is adequate to re-sist the longitudinal stresses. Theguide surfaces are invariably cylindrical,and their diametrical distance apart isgoverned by the ratio of connecting-rodto crank. In the best modern enginesthe end flange of the trunk does notmake a steam-

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