Fig. 570.
The regulating hand wheel remains cool, and can be manipulated without injury to the hands. The regulation is very simple, and is quickly adjusted by simply turning the wheel to the right or left, to increase or decrease the pressure. No locking device is necessary, as the wheel will remain in any set position.
The cylinder will not become coated with lime, but will retain its smooth surface over which the piston travels, insuring free action, with no leakage around the piston. The drip is located at the extreme upper travel of the piston, so as to retain sufficient water in the cylinder to prevent any air from coming in contact with leather piston packing. This arrangement insures a tight piston as the leather packing will remain soft and pliable and at the same time the water serves as a lubricant for the interior of the cylinder.
Fig. 571.
The hand wheel can be placed in different positions and all that is necessary to make the change is to take out the bolts and move the regulating hand wheel to the desired position. By this arrangement the engineer can set the hand wheel regardless of the arrangement of the steam piping.
All sizes, including 11⁄2-inch and smaller, are made as shown in style B, Fig. [572], and are not provided with an automatic speed controlling device. This style is made especially for boiler feed pumps and for supply pumps for the street system of hot water heating. They are also fitted with a special valve for pumps working under very high steam and low water pressure.
Fig. 572.