. Railway master mechanic . inclinationof its edges corresponds to that of the ports of theprincipal valve. As in all similar constructions, theonly function of the riding valve is to fi.\ the point ofcut-off, the principle of the this case,being that of the Meyer cut-off. The time of steamadmission is varied by displacinglhe valve laterally,by the use of a system of levers controlled by a levermoving along 51 notched quadrant beside the lire-box. In consequence of this lateral displacement,and because of the obliquity of the ports already al-luded to, the cut-off valve, whose
. Railway master mechanic . inclinationof its edges corresponds to that of the ports of theprincipal valve. As in all similar constructions, theonly function of the riding valve is to fi.\ the point ofcut-off, the principle of the this case,being that of the Meyer cut-off. The time of steamadmission is varied by displacinglhe valve laterally,by the use of a system of levers controlled by a levermoving along 51 notched quadrant beside the lire-box. In consequence of this lateral displacement,and because of the obliquity of the ports already al-luded to, the cut-off valve, whose eccentric is keyedon at ISO degrees from the crank pin, is located atthe beginning of the stroke, nearer the port whichit is to close, in proportion as it is drawn more to-wards the right hand side of the engine, a positioncorresponding to a shor admission. The division ofthe ports into two parts along its length, has for anobject the reduction, as much as possible, of thesize of the main valve and of the riding cut-off. In. order to facilitate the introduction of the steaminto the ports of the valve, hollows are cut into theface of the valve which increase the actual sectionof the passage at the end of admission, as in theTrick canal. The peculiarity of this method of distribution itwill be seen consists in the obliquity of the edges ofthe exhaust jxjrt and of those of the exhaust cham-ber of the valve. This obliquity permits the amountof inside lap to be varied when the valve is movedsidewise to vary the admission, permitting theamount of compression to be controlled at the valve is drawn to the left the admissionincreases and the steam distribution continues up tothe point where the cut off valve no longer closesthe ports. Hut this leaves a very slight opening;it is desirable, therefore, that the admission shouldnot be carried thus far in order to avoid a pronounc-ed wire drawing of the steam and a too decided fallin pressure at the point of cut off. If the valve i
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Keywords: ., bookcentury1800, bookdecade1870, bookidr, booksubjectrailroadcars
