SMITH-VAILE SINGLE PUMP.
Figs. 298, 299.
Figs. 298, 299.
The accompanying sectional view of steam end of the “Smith-Vaile†exhibits some very novel features. So far as the piston and cylinder in this pump are concerned they are not unlike the average first class pump, but with this difference. It has only one set of cored ports, B, B. The supplemental ports, C, C, are drilled.
The main valve, A, is a slide and is moved by a valve piston, D. Almost all the valve pistons as now made are simply plugs turned accurately to fit the holes in the chest and without any means of adjustment to compensate for wear. After these valve pistons become worn they have to be replaced with new ones, but there is a period between the time whenthe valve piston becomes so leaky as to render the action of the pump uncertain and the time when the worn valve is replaced by a new one that the pump is very wasteful of steam.
The valve piston in this pump is provided with packing rings, E, E, which compensate for wear of these parts so that this valve is expected to do efficient service long after a slow valve. The supplemental valve, F, has a reciprocating rotary motion which is communicated to it by the rock arm, G, and pitman, H, connecting with the crosshead, I, secured to the piston rod. It will be observed that the piston rod, J, and the rod, K, of the water end are separated so that should either one give out through wear or accident it can be replaced without sacrificing both, as would be the case if they were solid in one piece. This supplemental valve, F, in general appearance very closely resembles the “Corliss†valve, and its action is somewhat similar, in controlling the action of the valve piston, which will be understood from the engraving without further description. These pumps all have removable water ends and can be rebored or otherwise manipulated without disturbing the steam end of pump. The cylinder can be separated from the foot by removing the bolt, M.
The duplex pump is also shown in the accompanying engraving, where, A, A, represents the steam cylinders, secured to the foot, B, by bolts, as previously described.
The usual slide valves have been replaced by piston valves, C, in this instance and are provided with removable seats, D, D.
These piston valves have packing rings, E, E, also to compensate for wear and the valves are cast hollow to reduce their weight as much as possible consistent with good workmanship, also to serve as ports for steam admission. When these valve seats become worn they may be easily removed and rebored or replaced by new ones, as desired. It will be observed that these ports are very short to reduce the clearance as much as possible, and to secure a more satisfactory cushion. Each valve is operated by the rock arm connected with the opposite engine in the usual way.