. The railroad and engineering journal . creased perceiitagi; o( friction, in conse-quence of the proportionally smaller stroke, at 20. 30. 50and 65 horse-power, by brake, and running free, revolu-tions 300 per minute- a speed which may also have causedsome increase in frictional resistance, not only in rubbingparts, but by increasing back pressure—gave a friction ofengine measurmg from horse-power unloaded, to 4horse-power at 20 to 30 horse-power, horse-power ai50, and at 65 horse-power, the total friction increasingperceptibly, as assumed by De Panibour, but decreasingin percent
. The railroad and engineering journal . creased perceiitagi; o( friction, in conse-quence of the proportionally smaller stroke, at 20. 30. 50and 65 horse-power, by brake, and running free, revolu-tions 300 per minute- a speed which may also have causedsome increase in frictional resistance, not only in rubbingparts, but by increasing back pressure—gave a friction ofengine measurmg from horse-power unloaded, to 4horse-power at 20 to 30 horse-power, horse-power ai50, and at 65 horse-power, the total friction increasingperceptibly, as assumed by De Panibour, but decreasingin percentage of load, from 16 to , between 20 and 65horse-power. It is very nearly constant throughout thewhole range of power that the engine would be workedunder ordinary circumstances, and may be so taken with-out serious error ; while the adoption of the De Pambourformula would give a value of / so small that its usewould not be attended, ordinarily, with sutBcient increasedexactness to compensate for the additional trouble in- ^ \§=^^. DETAILS OF REDICING MECHAMSM volved in its application. \X. their rated powers the twoengines thus e.\hibit efficiencies of mechanism of about94 and 90 per cent., respectively. The second series of experiments were made * duringthe latter part of last college year, confirming the deduc-tions already given, while some very interesting andoriginal modifications were made in the details of methodand trial. The engine taken for test was a machine re-cently built and sent to the Cornell University for pur-poses of experimental investigation in electrical measure-ment and other work of the college. It is an engine 7inches in diameter of cylinder and 12 inches stroke, ormore exactly, 6^ inches in diameter; the cylinder havingbeen bored slightly under size. The general plan of the ■ By Me Day and W. H. Riley, engine is siiuilar to the lirst of those already described,and, like that, is carefully designed with a view to reduc-ing friction to a minimum
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectrailroa, bookyear1887
