STANDARD LUBRICATING OIL SYSTEM FOR GEARED TURBINES. 263 



time is being used as a gravity tank. A clear light signal is also connected across 

 each throw of the switch, in order to indicate that the proper tank switch is in 

 operation and also any interruption in the supply of current to the system. 



The magnet operated valve, installed in by-pass line across main throttle valve 

 in steam line to oil pumps, has its magnet terminals connected in parallel with gong 

 and red light signal in such a manner as to open simultaneously with dosing of 

 float switch. 



5. Operating cycle. — When oil level falls about one foot from top of tank, 

 float switch closes, causing gong to ring, and lights red signal lights in engine-room 

 and in chief engineer's room. At the same time magnet valve in by-pass steam 

 line to oil pump is opened, thereby speeding up oil pump, which in turn increases 

 supply of oil until level of oil in gravity tank is again normal. 



When oil is restored to normal level, float switch opens, cutting off gongs and 

 red signal lights, closing magnet valve and causing oil pump to resume normal 

 speed. 



The pump is normally throttled to half speed, or approximately fifty single 

 strokes per minute. The operating engineer should be carefully instructed to con- 

 trol the speed of the oil pumps by means of the throttle valve installed opposite the 

 branch containing magnet valve, and not from the two valves adjacent to the oil 

 pumps. The latter valve should be used only for cutting on or off the oil pump it is 

 desired to operate or hold in reserve. 



Material Specifications for Automatic Electric Alarm System — i. Float 

 switches. — Two enclosed float switches, two poles, open circuit operation five am- 

 peres (minimum), 125 volts, adjustable for maximum distance of 18 inches. 



2. Tank-head brackets. — Two tank-head brackets for mounting float switches 

 on gravity tanks. Material, cast-iron flanges to be drilled for 16^-inch bolts on 

 1 8 J^ -inch diameter pitch circle. Float to be enclosed in tube secured to tank heads 

 and extending down in gravity tank for a distance of 4 feet 9 inches, to prevent im- 

 proper action of float due to rolling of the ship. Tube to be of sufficient diameter 

 to allow free movement of float, and to contain one bearing support for float rod. All 

 screws, etc., to be securely locked by means of copper wire carried through screw 

 heads. 



3. Magnet operated valve. — One magnet operated ij^-inch valve for full 

 boiler pressure and wired for 125 volts open circuit operation. 



4. Alarm panel. — One alarm and operated panel, of black slate, on which are 

 mounted the following: — 



One red light bull's-eye signal equipped with one 25-watt, 125-volt, clear Mazda 

 lamp. 



Two white lights bull's-eye signal each equipped with one 25-watt, 125-volt, 

 clear Mazda lamp. 



One 4-inch gong D. C. 



Two automatic throw-over mechanically interlocked switches, single-pole 5 am- 



