Engines; Motors and Batteries; Fuels

267. Gasoline Engines. A gasoline engine (Fig. 151) should be operated out of doors or in a well-ventilated room, except in cases where the exhaust pipe is carried thru the wall of the building to the outside. The fumes may cause illness, or even death, to any one staying in the room.

A gasoline engine should be mounted on a substantial base of concrete or heavy timbers, or on a well-built truck, and should be put in good order before the woman or girl begins to use it. The engine must be level. If more than one device is attached to it, be sure to use the right pulleys on the engine and the machine to be operated. An engine is usually equipped with pulleys of two or more sizes. The size of the wheel on the washing machine or vacuum cleaner must be of a size to make the desired number of revolutions per minute.

268. Figuring Speed of Pulleys. For example, if the speed of the engine is 425 revolutions per minute and the diameter of the pulley on the engine is 12 inches, and the machine is to be run at 150 revolutions per minute, have a pulley on the machine of a diameter which equals 425 times 12, or 5,100 divided by 150, or 34 inches.

It would be more convenient to have a smaller pulley on this machine. Since there is a smaller wheel on the engine which, we will say, is 6 inches in diameter, put the belt on the smaller wheel, and then a wheel only 17 inches in diameter will be needed on the machine.

269. Operating the Engine. One person should be responsible for the care of an engine. Starting the engine is usually too heavy work for most women. Since a man usually starts a gas engine which the women are to use, it is more important that they know how to stop the engine and to recognize when it is not running properly. A cold engine can be started easier if warmed with hot water.

Running an engine which is out of order may damage it seriously. Have some one show you how to operate your engine. Stop it when not running properly.

270. Points in Caring for Engine. The following are points to keep in mind when operating an internal combustion engine:

1) Black smoke issuing from the exhaust pipe means there is not enough air in proportion to fuel.

2) When an engine misses more explosions than it should, or backfires, the cause is likely to be too much air in the fuel.

3) If the mixture of fuel and air is in the proper proportion, but there is too little of it, the engine will have no power.

4) Premature ignition may be caused by deposition of carbon or soot on the walls of the cylinder; the compression being too high for the fuel used; overheating of the piston, or exhaust valve, or of some poorly-jacketed part.

5) Using too much or a poor quality of lubricating oil, or a mixture too rich in fuel, causes deposition of carbon on the cylinder.

6) The use of too much cylinder oil is indicated by a blue smoke issuing from the exhaust.

7) Pre-ignition, or a bearing out of order, or the engine not being securely fastened to its foundation, causes pounding.

8) Too much water in the oil used for fuel causes white smoke to issue from the exhaust pipe. This may be caused by a leaky jacket on gasoline engines.

9) Stop the engine by shutting off the supply of fuel. Open the switch to the ignition system. Close the lubricators and oil cups, and turn off the jacket water.

10) In cold weather, drain off the jacket water to prevent freezing.

11) Always leave the engine clean and in order to start again.

12) For safety, belts and wheels should be boxed in wherever possible.

Fig. 151 should be studied closely for a better understanding of the engine.

271. Generating Electricity for Homes. Water motors, kerosene, gas and gasoline engines are the sources of power commonly used to generate electricity for private homes. A device for generating electricity is called a dynamo (Fig. 152). The electricity generated is either used directly while the engine is running, or it is stored in storage batteries. From here it is conducted thru wires and used for lighting, heating and turning motors to do work.

272. Batteries. Batteries are used mainly where a small amount of current is needed, as on oil or gasoline engines, to make the spark to ignite the gasoline or oil, and in lighting gas and acetylene lamps, and for some door bells.

There are several kinds of batteries, as liquid, dry-cell and storage.

273. Liquid Batteries. In liquid batteries, electric current is generated by means of direct chemical action between an acid and two other substances, one more easily attacked by the acid than the other (Fig. 153), such as zinc and copper. This forms a simple cell, one form of primary battery. When the chemicals and metals in a primary battery are exhausted, they can be replaced with new metal or solution.

274. A Dry-Cell Battery. A dry-cell is another form of battery. In these, the moisture of the acid substance is absorbed by some material like plaster-of-Paris flour or blotting paper, so that it can act on the metals or carbon in the cell and still make a cell easily transportable. The absorbed moisture in dry cells slowly evaporates, and then they become worthless. These batteries are usually thrown away after they have been used and have ceased to generate electricity.

275. Storage Batteries. Storage batteries differ from primary batteries in that current must be supplied to them from some outside source, such as a dynamo. They can be recharged again after the current in them has been used (Fig. 154).

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The engines for private homes where a light plant is used are adjusted to charge batteries at the proper rate—but the owner should charge these batteries at regular intervals. They can be charged only by direct current.

Never allow the storage battery to run down to a voltage lower than 1.15 per cell. This reading is taken from the voltmeter supplied with the plant.

Storage batteries should be tested by a hydrometer for the specific gravity of the electrolyte or liquids in them. Instructions for this and for correcting the specific gravity accompany the plant. Take care to preserve them.

Dynamos for home use are almost automatic. Run the dynamo to renew the batteries when using electric irons or other devices calling for more current than the lighting fixtures. Each plant is designed to carry a certain load of equipment. Exceeding this, damages the plant.

Place electric motors and dynamos in a dry, cool, clean place.

276. Some Uses for Electric Motors. Motors are now used on sewing machines, washing machines, dish washers, vacuum cleaners, wringers, fans, refrigerating systems, pumps, grinders, freezers, churns and separators. They are made either for direct or alternating current. When purchasing a motor, be sure to designate the type of current with which it is to be used. Select motors of the right size to operate the machine. It costs more to operate a large motor on a small device than a small motor.

277. Definition Tables. A British thermal unit is the amount of heat required to warm one pound of water one degree Fahrenheit.

The flash point of an oil is that temperature at which it will form an inflammable vapor. The accompanying table shows amount of heat generated from a number of sources.

The total heat in a gallon of kerosene is greater than that in a gallon of gasoline because the kerosene is heavier than the gasoline. A gallon of gasoline will give on an average but about five-sixths as much total heat as a gallon of kerosene. This is approximately true, whether the heaviest grades of kerosene are compared with the heaviest grades of gasoline, or the lightest grade of kerosene is compared with the lightest grade of gasoline.

Distillate is the refuse left from the distillation of petroleum.

The flash point of kerosene may be between 70 and 150 degrees Fahrenheit, depending upon the grade. For illuminating purposes, do not use kerosene with the flash point lower than 120 degrees Fahrenheit.

The flash point of gasoline is 10 to 20 degrees Fahrenheit; that is, gasoline will form an imflammable vapor at temperatures as low as this.

Between 60 and 70 per cent of the common fuels are utilized in the generation of steam for heating purposes.

TABLE SHOWING GENERATION OF HEAT

*One pound ice in being melted will absorb 144 B. T. U.