Fig. 206.
Fig. 206 exhibits two independent pumps. The description of the pump shown in Fig. 205 will apply to the left-hand pump which is a boiler feed pump. The improvement consists in the addition of another pump at the right-hand side; this is a suction force pump with an air chamber and is used to draw water from a well and discharge it into a tank from which it is taken by the other pump and forced into the boiler, as occasion requires.
These two pumps work simultaneously, being driven from the same shaft with cranks set opposite each other. Like the pump previously described this has a tight and loose pulley. The larger sizes are geared, having a pinion on the pulley shaft and a spur wheel on the crank shaft.
These two pumps represent a high service and a low service, the left-hand pump working under high pressure, against that in the boiler and the right one against the head of water in the tank. Each pump has its own separate connections—one or more—to suit the required conditions.
The right-hand pump is double acting; the plunger-rod is guided by a steadiment which holds it in line and preserves this alignment and the power is transmitted through a forked connecting rod. The Table below refers to both these pumps.
Table.
| BOILER PUMP. | DBLE.-ACTING FORCE PUMP. | ||||
|---|---|---|---|---|---|
| Diam. cyl. | Suc. and dis. | Gal. per stroke | Diam. cyl. | Suc. and dis. | Gal. per rev. |
| 21⁄2 in. | 11⁄4 in. | 1—8 | 3 in. | 11⁄2 in. | 2—5 |
| 21⁄2 „ | 11⁄4 „ | 1—8 | 4 „ | 2 „ | 4—5 |