Cyclopedia of locomotive engineering, with examination questions and answers; a practical manual on the construction care and management of modern locomotives . n its heavi-st position, but conditions arechanged by the opening of a steam port (and atinstant of cut-off. See Fig. 85), at which time theordinary slide valve is subjected 10 the upward pres-sure of the steam in the cylinder port, ana if properlybalanced in central position would, at this position, bethrown off its seat, but in this valve the port pressure(whatever it may be) has free access to both sides ofthe valve by reason of the
Cyclopedia of locomotive engineering, with examination questions and answers; a practical manual on the construction care and management of modern locomotives . n its heavi-st position, but conditions arechanged by the opening of a steam port (and atinstant of cut-off. See Fig. 85), at which time theordinary slide valve is subjected 10 the upward pres-sure of the steam in the cylinder port, ana if properlybalanced in central position would, at this position, bethrown off its seat, but in this valve the port pressure(whatever it may be) has free access to both sides ofthe valve by reason of the passages through thevalve to the port in the face of the balance plate whichcorresponds with the cylinder port; therefore thepressure in the port has no effect whatever upon thevalve, it being on both sides of the valve face in equaTarea, and pressure, is, therefore, equalized so far as thevalve is concerned, but the pressure in the port of thebalance plate wrould lift the plate off from its seat on thevalve if it was not also equalized, or annulled; thereforea port ring, PR, of proper area to balance this pressure, PISTON VALVES AND BALANCED VALVES 179. 8o LOCOMOTIVE ENGINEERING is placed over each port in the inside of the main ringon the top of the balance plate and is open to the portthrough passage F, Fig. 81, so that a pressure equal tothat in the steam port is always on both sides of thebalance plate, as well as on both sides of the valve,and the port pressure is rendered inoperative on thevalve or on the balance plate. Communication fromthe cylinder port, through the valve and through thebalance plate to the interior of the port ring, P R,cannot be shut off at any time, but is maintainedthroughout the travel of the valve. Therefore thesame pressure that is in the port at any given time isalso on both sides of valve and pressure plate in thesame area, and the port pressure is, therefore, not con-sidered in figuring the main balance for the valve. There is another positi
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectlocomot, bookyear1916
