Fig. 3341.
This injector is self-contained, or in other words, it has both steam and check valves, so that it can be connected directly without other fittings, although, of course, it is generally desirable to place another stop valve in the steam pipe, and a check valve in the delivery pipe, so that the injector can be taken to pieces or disconnected at any time. Another important feature of this injector is, that it is operated by a single handle, and that the waste valve is only open at the instant of starting.
Referring to [Fig. 3338], a is the receiving tube, which can be closed to the admission of steam by the valve x. A hollow spindle passing through the receiving tube into the combining tube is secured to the rod b, and the valve x is fitted to this spindle in such a way that the latter can be moved a slight distance (until the stop shown in the figure engages with valve x) without raising the valve x from its seat. A second valve w, secured to the rod b, has its seat in the upper side of the valve x, so that it can be opened (thus admitting the steam to the centre of the spindle) without raising the valve x from its seat, if the rod b is not drawn out any farther, after the stop on the hollow spindle comes in contact with the valve x. d is the delivery tube, o an overflow opening into space c, v the check valve in delivery pipe, and z the waste valve. The upper end of the combining tube has a piston n n attached to it, capable of moving freely in a cylindrical portion of the shell m, m, and the lower end of the combining tube slides in a cylindrical guide formed in the upper end of the delivery tube.
The rod b is connected to a cross head which is fitted over the guide rod j, and a lever h is secured to the cross head. A rod w, attached to a lever on the top end of the screw waste valve, passes through an eye that is secured to the lever h; and stops t, q control the motion of this rod, so that the waste valve is closed when the lever h has its extreme outward throw, and is opened when the lever is thrown in so as to close the steam valve x, while the lever can be moved between the positions of the stops t, q without affecting the waste valve. A latch f is thrown into action with teeth cut in the upper side of the guide rod j, when the lever h is drawn out to its full extent and then moved back; and this click is raised out of action as soon as it has been moved in far enough to pass the last tooth on the rod j. An air vessel is arranged in the body of the instrument, as shown in the figure, for the purpose of securing a continuous jet when the injector and its connection are exposed to shocks, especially such as occur in the use of the instrument on locomotives.
The manipulation required to start the injector is exceedingly simple—much more so in practice, indeed, than it can be rendered in description. Moving the lever h until contact takes place between valve x and stop on hollow spindle, which can be felt by the hand upon the lever, steam is admitted to the centre of the spindle, and, expanding as it passes into the delivery tube d and waste orifice p, lifts the water through the supply pipe into the combining tube around the hollow spindle, acting after the manner of an ejector or steam siphon. As soon as solid water issues through the waste orifice p, the handle h may be drawn out to its full extent, opening the steam valve x and closing the waste valve, when the action of the injector will be continuous as long as steam and water are supplied to it.
To regulate the amount of water delivered, it is necessary only to move in the lever h until the click engages any of the teeth on the rod j, thus diminishing the steam supply, as the water supply is self-regulating. If too much water is delivered, some of it will escape through o into c, and, pressing on the piston n n, will move the combining tube away from the delivery tube, thus throttling the water supply; and, if sufficient water is not admitted, a partial vacuum will be formed in c, and the unbalanced pressure on the upper side of the piston n n will move the combining tube toward the delivery tube, thus enlarging the orifice for the admission of water. From this it is evident that the injector, once started, will continue to work without any further adjustment, delivering all its water to the boiler, the waste valve being kept shut. By placing the hand on the starting lever, it is easy to tell whether or not the injector is working; and, if desired, the waste valve can be opened momentarily by pushing the rod w, a knob on the end being provided for the purpose.