112 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Apuii, 



of disc-valves for conijiound-cvliinler enj^Incs, so as to effect tlie 

 same result as by the slide-valves above-mentioned, and in arranjf- 

 iii;r ea<-h valve to be raised by a separate tappet (or by <ither ine- 

 <:hanical means), so that any one valve can be closed without inter- 

 ierinfT with anv of the others; by reason of which arrangement 

 any amount ot' expansion or comprossion of steam in either tlie 



' 



Fit. 1- 



F^g. 2. 



high or low-pressure cylinder can be effected. Fig. 1 represents a 

 vertical section of a low-pressure cylinder, together with the 

 steam-passages, so arranged that by one valve-box, six openings, 

 and two common, single, hollow sliding-valves, they are adapted 

 to serve both tlie high and low-pressure steam-cylinders ; and 

 jig. 2 is a transverse vertical section of the passages through the 

 line 1, 2, showing also the position of the cylinders, a indicates 

 tlie admission and exit openings for the top of the high-pressure 

 cylinder; and a' the opening for similar purposes to the bottom 

 of the high-pressure cylinder; and ft, and 6', the ports for the 

 admission and escape of steam to or from the top and bottom of 

 the low-pressure cylinder; c, and c', the passages to the con- 

 denser; r/, and (i', steam-passages to the high-pressure cylin- 

 der; p, ajid (.", the Imllow sliding-valves ; and ./J and./"', the lap 

 or covering for the condenser-ports c, and c'. The action of this 

 arrangement is as follows : — Steam being admitted from the boiler 

 to the valve-box a, enters at d (when the valves are in the posi- 

 tion shown), and passes thence by the passage g, to the top of the 

 liigli-pressure cylinder 6, where, having performed the downward 

 stroke of the engine, the position of the valves /»,/»', will be re- 

 versed, and the steam will return by the passage g ; and the open- 

 ing d (as well as the port e'), being now covered by the valve 

 /»', the steam will be conducted thereby below the piston of the 

 low-pressure cylinder r, and, on a subsequent stroke taking place, 

 it will escape tlirough the valve /»', to the port/', and thence by 

 a suitable passage to the condenser. For the upward stroke of the 

 engine, the port rf' will be uncovered by the valve A, and steam 

 will enter, passing by the passage^', to the bottom of the high- 

 pressure cylinder, and by the change in the valves it will escape 

 from thence by the passage ^r', through the valve A, into the top 

 of the low-pressure cylinder c, where, having performed its office, 

 it is exhausted by the condenser through the passage j\ which, in 

 its turn, will be covered by the valve h. The ports/", and/', are 

 always covered either by the valvee A, and A', or by their pro- 

 jecting-pieces j, andi'. Fig. 3 represents a vertical section of a 

 valve-case, together witli the requisite passages, by which arrange- 

 ment one valve-casing, five openings, and one double hollow slide 

 are made to serve for two high-pressure cylinders and one low- 

 pressure cylinder, these being arranged, in the drawings, one on 

 either side of the low-pressure cylinder, to which the slide-case 

 and slides are attached ; the different valves, openings, and pas- 



sages are lettered severally, as in the last figures, and to which 

 the description thereof will be equally applicable, as tlie steam is 



conducted precisely in the same man- 

 ner as in that case. Fig. 4 is a ver- 

 tical section of a low-pressure steam- 

 cylinder, with its valves and openings 

 so arranged that by one valve-box, 

 eight openings, two plate expansion- 

 valves, and two common, single, 

 hollow slide-valves are adapted to 

 serve one high-pressure steam-cy- 

 linder, and one low-pressure steam- 

 cvlinder. Fig. 5, a section through 

 tiie line 3, 4, showing the arrangement 

 of the passages, with the relative 

 position of the two cylinders. A, 

 rejuesents the valve-case ; B, the 

 high-pressure cylinder ; C, the low- 

 pressure cylinder ; a is the opening 

 in the valve-face, which is connected 

 with the top of the high-jiressure cy- 

 linder by the passage fc, which passage 

 also serves to convey the steam from 

 the top of the high-pressure cylinder 

 B, to the bottom of the lovr-pressure 

 cylinder C. a' is the opening in 

 admission of steam to the bottom of the 

 passage 6 ' communicating thereto ; this passage 



FiK. .1. 



the valve- face for the 

 cylinder 15, the 



•i^Z^^^^^S^^Z. 



c ? 



a 



Fig. 4. 



Fig. 5. 



serves as a communication between the bottom of the high- 

 pressure cylinder B, and the top of tlie low-pressure cylinder 

 C. These openings a, and a', are covered altern:itely by two ex- 

 pansive plate-valves p, and C ; which valves are furnished with 

 suitable apparatus for varying the amount of expansion, and are 

 placed on the same rod as the valves rf, and rf', which are for the 

 purpose of controlling the direction of the steam in its entrance 

 and exit to and from the low-pressure cylinder C. p, ande', are 

 the steam-passages to the cylinder C, and /, and / ', the openings 

 in the valve-face to the condenser ; i/, and 3', are the openings in 

 the valve-face to the steam-passages 6, and 6'; and A, and A", the 

 laps of the slides rf, and rf', for the purpose of covering the 

 openings /,//, .9', and/'. Steam being admitted to the valve- 

 Jacket from the boiler, at a high-pressure, it enters at a, to the 

 passage ft, which is filled as far as 3' ; tliat opening being covered 

 by the lap of the valve rf', it is conducted thereby to the top of 

 the high-pressure cylinder B, where, having ])erfornu'd the down- 

 stroke of the piston, the position of the valves will become changed, 

 the steam in the top of the cylinder B, will escape by the passage 



