File:Cassier's magazine (1904) (14765989441).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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very effec-tive form for all but the largest sizes ofengines. Fig. 18 shows a tandem drop-valveengine, and Fig. 21 a-cross-compoundengine of similar build. These en-gines represent Messrs. Marshallslatest practice in the larger sizes, andhave been designed specially to ensureeconomy in steam consumption; theyare of ample strength for steam pres-sures of 150 pounds per square inch,and for piston speeds of 600 feet perminute. The frames are of the usual cylinder bases are well extended later-ally. All of these features tend toproduce stability. The chief interestin these engines, however, centres inthe Marshall vale trip gear, with whichthey are fitted. Figs. 19 and 20 show a cross sec-tion and a part longitudinal section ofthe cylinder in a Marshall engine.Before noticing the gear itself, atten-tion is called to the fine clearance be-tween the cylinder ends and the pis-ton, the exceedingly small lostspace in the valve chambers, andthe excellent natural drainage of 5io CASSIERS MAGAZINE
Text Appearing After Image:
PSV: * THE MODERN HORIZONTAL STEAM ENGINE 511 the cylinder towards the exhaustorifice. The steam and exhaust valve seats,shown in black section, are insertedand held in place by the covers aboveand below them, respectively, with theview of allowing their free expansionand contraction without alteration ofform. The gear here illustrated isknown as the No. 2, and is applied toengines of 16-inch cylinder diameterand upwards. It consists of double-beat lifting or poppet valves, their mo-tion being derived from a rotating lay-shaft driven at the same speed as thecrankshaft by mitre-wheels. Referring now to the cross sectionin Fig. 19, the upper ends of the in-clined eccentric rod actuating thesteam valve gear move in an arc, be-ing connected by a pair of short linksDD, shown only in the longitudinalelevation, to a fixed point in the dash-pot frame. The double-armed leverB, when its outer end is in contactwith the lower limb of the right-angledlever C, is depressed by the descent ofthe ecce

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