. The railroad and engineering journal . from thatwhich we have described. The principles of operation are, however, thesame in both. We will explain the construction of an indicator hereafter. Vol. LXI, No. 12.] ENGINEERING JOURNAL. 572 vertical lines from these points and thus determine the pres-sure by comparing the length of such lines with the scale A . the line S / measures lo fortieths of an inch, thus show-ing that the absolute steam pressure at S inches of the strokewas 100 lbs. per square inch ; the line 12 I; measures 66-i for-tieths of an inch, thus showing that at t2 in. of
. The railroad and engineering journal . from thatwhich we have described. The principles of operation are, however, thesame in both. We will explain the construction of an indicator hereafter. Vol. LXI, No. 12.] ENGINEERING JOURNAL. 572 vertical lines from these points and thus determine the pres-sure by comparing the length of such lines with the scale A . the line S / measures lo fortieths of an inch, thus show-ing that the absolute steam pressure at S inches of the strokewas 100 lbs. per square inch ; the line 12 I; measures 66-i for-tieths of an inch, thus showing that at t2 in. of the stroke thesteam pressure was 66=^ lbs. At 16, 20 and 24 in. of thestroke the vertical lines measure 50, 40 and 33?; fortieths ;and, therefore, there were that number of pounds of steampressure when the piston was at the point of the stroke measurements c<iuld be made from other points, suchas 2, 6, 10, or any other number of inches of (he stroke. Ofcourse, if we measure from the vacuum line we will have the Fig. 40. Fig. 43 absolute steam pressure, or the pressure above- a vaciiutii, as itis sometimes called ; if we measure from the atmospheric linewe will have the effective pressure, or the pressure above theaUnosphere. Question go. How can we determine the average pressure dur-ing the whole stroke of steam which works expansively ? Answer. This can be determined approximately by the fol-lowing method : In the first place, divide the vacuum line () into any number of equal divisions, say six. From thepoints of division, 4, 8, 12, 16 and 20, which in this case cor-respond with the points which represent inches of the stroke,draw perpendicular lines, which will divide the indicator dia-gram into six divisions. It is obvious that during the time thesteam is working full stroke the pressure is uniformly 100 While the piston is moving from 8 to 12 in., thepressure falls from 100 to 66J3 lbs., so that at 10 in. we have ery nearly the average
Size: 1074px × 2326px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectrailroa, bookyear1887
