Mechanical Devices in the Home

PART IX

Sundry Devices

CHAPTER XXXII

Dumbwaiters and Other House Furnishings

228. Dumbwaiters and Window Adjustments. Dumbwaiters and elevators are used in homes where the kitchen is on a different floor from the dining-room.

The simplest ones are a set of shelves counterbalanced by weights. When the elevator is raised, the weights drop down, and when it is lowered, the weights rise.

Window weights hung over a pulley in the top of the window sash work on the same principle as dumbwaiters—the weights help in raising the window. The only care needed is to replace the rope when worn.

Another window pulley is made of metal like that in a clock spring (Fig. 127). The spring is drawn out when the window is lowered, and the weight of the window is just enough to hold it, so very little force is needed to raise the window, as the spring is pulling on it, too.

229. Check Valves. Check valves are made to prevent doors from slamming. They are used in offices and public buildings, and, occasionally, in homes (Fig. 128). One kind contains glycerine and castor oil, which move from one compartment to another as the door is opened and slowly flow back as a spring pulls the door shut.

The other kind is operated by compressed air and a spring. The air causes the steady action of the door stop. Another type of pneumatic hinge is attached to a door which is hung so that it would naturally swing shut. When the door is opened, the air is exhausted from part of the hinge. After it has been opened, the slow equalization of the air inside the door stop and outside allows the door to close slowly without slamming.

230. Door Fastener. A door fastener (Fig. 129) is a small device which has a strong spring on the inside. When the spring is released, it pushes down on a rod which is capped with rubber. When down, this comes in contact with the floor and holds the door in place. To change the position of the door, a small lever is used to lift the rod and compress the spring, thus releasing the door stop from contact with the floor.

231. Window Shades. Window shades are equipped with a spring in one end of the roller to aid in raising it. At the end of the spring is a flat bar which is held in position by the bracket on which the shade is hung. Small catches hold the curtain when it is at the desired position (Fig. 130). If the spring becomes weak, draw the curtain down. This compresses the spring. Stop so that the clamps always fall into place to hold it. Then remove the curtain from the brackets and roll it up by hand. Place it back on the brackets. It can then be raised or lowered as wanted, and will work with more power. Take care when doing this not to wind the spring so tight that it will draw the curtain clear around the roller, thus letting the spring unwind or breaking the spring.

232. Hinges. There are some hinges which should be of interest to women. These are the ones for doors which swing only one way, and for those which swing both out and in (Fig. 131).

233. Sliding Doors. When sliding doors slip off the slide, they may be replaced. They are hung like a barn door. There is a metal track above the door between the walls. The door is hung on this track by pulleys which slide along the track. Sometimes, by accident, these pulleys are slipped from the track. The door then must be lifted so that the pulley can be set back on the track. Usually the door needs to be lifted but a fraction of an inch and then pushed a little to one side or the other to get the pulley into place.

CHAPTER XXIII

Sewing Machines

234. Different Types of Sewing Machines. There are two types of sewing machines in use—the chain-stitch and the lock-stitch. Sewing machines are made to run by hand, foot or mechanical motor power. This makes no difference in design or care of the stitching part of the machine. Motor and foot power run the machine faster than hand power.

The treadle of the foot-power machines swings on pivots. These should be kept oiled and clean from lint and thread. The large and the small wheels for the belt should be oiled at the axle.

235. Lock-Stitch Sewing Machine. A lock-stitch sewing machine (Figs. 132 and 133) consists of shafts and wheels which move the needle, feed plate and bobbin. The top thread is guided from spool to needle thru a tension so that only the needed amount passes forward each time the needle is raised after the thread has caught in the cloth.

When there is a difference in the size of the thread used on the machine, the tension must be adjusted to fit the thread, unless the tension is automatic. If the tension is not properly adjusted or the machine threaded properly, the thread will either break, tangle at the needle point, or draw the top thread tighter than the bottom one (Fig. 134).

A longer stitch is needed for coarse thread than for fine thread.

236. Feed Plate. A device below the needle called the feed plate (No. 34, Fig. 132) shoves the cloth faster or slower under the needle, according to its adjustment, thus making a longer or shorter stitch. This device is a rough plate which moves backward each time the needle is raised, and forward again when the needle comes down. While moving backward, the rough surface moves the cloth, but it drops slightly below the level of the table as it moves back into place, so does not affect the cloth. For short stitches, it moves with a short stroke, and for long stitches, with a long stroke. If the feed plate becomes gummed with lint and oil, the machine will not make even stitches and may fail to move the cloth. Sometimes it will fail to stitch. Improper threading may break the needle thread. Too tight a tension may break it. Too coarse thread for the size of the needle may break the needle. A bent, blunt pointed or incorrectly set needle may break.

237. Bobbins. There are two styles of bobbins used on lock-stitch sewing machines—the shuttle bobbin (Fig. 135) and the round bobbin (Fig. 136), depending on the particular type of machine used.

238. Shuttle Bobbins. In shuttle bobbins, there is a long iron spool on which the thread is wound. This is put into the bobbin with the twist in the direction indicated in the book of directions for the machine being used, and the thread is drawn thru the slits and holes in the bobbin which govern the tension of the lower thread (see Fig. 135).

Put the shuttle into place and draw the thread up over the feed plate (Fig. 137). The machine moves the shuttle backward and forward, and as this happens, the needle is timed to drop down, leaving a loop of thread in such a position that the bobbin passes thru it. In rising, the needle pulls the loop up tight, and as it has passed thru the cloth, this cloth comes in between the thread from the bobbin on the under side and the thread from the spool on the upper side, which have been interlocked by the bobbin having passed thru the loop of thread from the spool as the needle carried it down below the cloth. This is called the lock-stitch (Fig. 134). The spool bobbins also pass thru the loop left after the needle has passed downward.

————

239. Chain-Stitch Machine. In the chain-stitch machine (Fig. 138), the shaft turns a device which draws a loop of thread thru each foregoing loop, thus making a stitch similar to crocheting, but having the cloth interlocked with the stitch. The needle carries the thread and makes it tight or loose as needed. The feed plate carries the cloth under the needle.

There is a tension to govern the thread. As a single thread is used in making this stitch, no bobbin is used. The tension must be tight enough to draw the loop of thread about the cloth, or else the thread will tangle.

240. Cautions for All Machines. Machines should be kept well oiled, and they must be kept free from thread and lint, for these are the things which give trouble in machines. Never try to draw the cloth under the needle any faster than it is pushed along by the feed plate under the presser foot. Pulling on the cloth bends the needle from the exact path which it should follow.

Move the treadle with a smooth, even motion—a jerky motion wears out operator and machine. Use only the best sewing-machine oil. Poor oil gums the parts of the machine. Clean the machine every day it is in use. Take care to set the needle in its proper position, and fasten it firmly in place.

241. General Instructions. Thread the machine exactly according to instructions. If not properly threaded, it will fail to stitch—the thread will tangle. If the bobbin is not properly threaded, it will not have the proper tension, and the machine cannot sew as it should. The bobbin thread will break if it is not properly threaded thru the bobbin case. It will also break if the bobbin tension is too tight (No. 14, Fig. 138).

Always regulate the stitch and the size of needle for each size and kind of thread used. A table for this usually comes with each machine, or is often stamped on the machine. Select the thread suitable to the material. The number of a needle is marked on the shank. Needles made for one kind of machine will not always work on another.

An automatic tension should not be changed or meddled with. Some tensions must be adjusted to the thread. Follow directions coming with the machine for adjusting tensions. Remove any thread which has become entangled in the mechanism of the machine.

Never use a bent needle. A bent needle drops stitches on a chain-stitch machine. Soaping the needle helps it to go thru goods difficult to penetrate.

When a machine runs hard, it needs oil or has become gummed up with poor oil. When gummed, clean with kerosene oil. Thread or ravelings wound about the axles of the wheels also makes the machine run hard. Learn to use the attachments of your machine—take care that they do not become bent.

The lock-stitch does not rip easily.

The ends of the thread of chain stitches should be carefully fastened. If started from the end where the seam was completed, the loop stitch may be easily unraveled and thus save time when mistakes are made in sewing or when garments are being made over.

CHAPTER XXXIV

Automobiles

No lengthy treatise on automobiles can be given here, but a few facts of general information are well in order.

Each car has its special features, but the basic principles of operation and control are the same for all makes. Let us consider, first, the control of the machine on the road.

242. Starting the Motor. Open the throttle from one-fourth to one-third way, to permit entry of plenty of gas into the motor. Set the time control about as far down as the throttle. Turn on the ignition switch and turn the motor with the starter.

A cold motor may demand use of the choker before starting, but, again, too free use of the choker floods the carburetor with a rich, non-explosive mixture which can be removed only by use of the starter. Should the motor flood too easily, or should it take too much choking, have the carburetor readjusted. Common mistakes in starting the motor are (1) too free use of the starter, which is injurious to the battery; (2) starting with the timer set too far down, causing back-fire. Occasionally, a novice attempts to start a car with the gears set and the brakes on. With the motor started and running smoothly, shift the gears into low and take off the brake. Let the clutch back gently to prevent the car from starting with a jerk. In shifting gears, the throttle should be kept down to prevent the motor from racing upon releasing the clutch. (3) A common mistake is the attempt to shift gears with the clutch not entirely released. (4) Still another error is the failure to release the brake on starting, resulting in everything from a stalled motor to a stripped gear.

A difficult place to start a car is when stalled on a hill. This is done by holding the machine with the foot brake, throttling the motor with the hand lever, and slowly releasing brake and engaging clutch simultaneously.

243. Driving the Automobile. In driving, many things should be observed. The oil pressure gauge or indicator should be noted from time to time to see that the motor bearings are getting proper lubrication. The speed of the motor should be such that the battery is being charged rather than discharged, as is likewise shown by an indicator on the dash. This is especially important when using lights at night. Keep timer lever in correct place to prevent overheating.

The general rule for driving is—keep to the right side of the road, the only possible exception being when passing a vehicle going in the same direction; then go around on the left.

Stop before crossing railroad tracks, and drive slowly when approaching cross roads. In turning corners to the left, make the turn beyond the center of the cross road. Do not use brakes against the motor—release the clutch. Do not use the brake too forcibly; it will cause injury to rear tires and skidding. On slippery roads, make it a rule to use chains and drive slowly.

244. Care of Car. Under this heading, a few general rules may be given. Do not persist in running a machine when out of order. Never drive when the lubrication system is working imperfectly. Lack of cylinder oil will ruin a motor in a short time. Make it a rule to look at oil gauge before starting. Care of the battery consists largely in keeping it charged and filled to the proper level with distilled water. Tires should be kept inflated at all times. In case of trouble, never run on a flat tire, as it will soon be worthless under such treatment. Never drive a machine while out of order—stop and have repairs or adjustments made.

CHAPTER XXXV

Lawn Mowers; Incubators

245. Operation and Care of Lawn Mowers. The wheels of the lawn mower permit it both to move easily over the ground and turn the knives which cut the grass (Fig. 139).

This means that they must be kept well oiled to work easily—that the shaft of the wheel must not become wrapped with grass, weeds, string or wire. Most machines are made adjustable, and the knives are set to allow them to pass close enough to the plate at the bottom of the mower to clip the grass as if the machine were a pair of scissors. Keep the knives properly adjusted in relation to this plate. Do not let them come so close that they touch the plate but very lightly, nor be so uneven that one end cuts grass, while the other misses the plate so far that it will not cut.

If the knives are kept properly adjusted and the mower is not abused by trying to cut wires, stones, or by being stored where it becomes rusty, it will seldom need sharpening.

Keep all bolts tight.

246. Storing Mowers. When storing for the winter, grease the knives with a heavy coat of unsalted lard, or cover them with some other protective material.

247. Scissors and Shears. In popular language, there is no distinction made between scissors and shears. Technically defined, scissors are less than six inches in length. Any similar cutting device of greater length is called shears. Both are devices used for cutting cloth, paper, pruning trees, and many other purposes. They consist of two knives riveted together at some point between the handle and the point of the blade. The two blades are so adjusted that as the open scissors are closed, they touch lightly as they pass each other until the tip is reached. When the scissors are closed, the blades should touch only at rivet and tip. Scissors not so adjusted will not cut well, even the the blades are very sharp. Dropping scissors often bends the blades. Blades may be straightened as well as sharpened, and thus make good metal scissors like new.

248. Principles Upon Which Incubator Works. A device for hatching chickens is called an incubator. In order to hatch chickens, the incubator must keep an average temperature of 102-1/2 degrees Fahrenheit. The thermometer should be placed in the center of the tray and on a level with the top of the eggs. The temperature of 102-1/2 degrees Fahrenheit must not vary greatly during the incubation of eggs.

The incubator must also permit of suitable ventilation and control of the moisture in the eggs.

There are incubators heated with hot water and others with hot air. The air or water in those commonly used in homes is heated with a kerosene lamp.

The device consists of a heating unit, a regulator or thermostat which, acting upon a valve or damper, regulates the admission of heat into the insulated box containing the trays of eggs, ventilators and a thermometer (Fig. 140).

249. The Body of the Incubator. The box-like body of a good incubator is set on strong legs which raise it to a convenient height. The trays slide into the box on cleats about two or three inches from the bottom of the body. They fit so that a slit about two inches wide is left between for the chickens to drop down under the tray as they hatch. Usually this is near the door. If the door is furnished with a glass to admit light, the chickens are attracted toward light and fall thru the slit.

The walls of the incubator are usually double so that air can be let in without making a draft. Dampers in the side of the machine regulate the admission of air. Ventilation both regulates the amount of air circulating in the incubator and the amount of moisture. Air from a damp room keeps the eggs moist. Air from a dry room dries them.

250. Incubators Heated by a Lamp. Choose a lamp which holds enough oil to last for twenty-four hours. Good lamps are usually made of metal and as plain as possible (Fig. 141).

The burner furnished with them is an ordinary lamp burner carrying a straight, flat wick. Metal chimneys are used, there being enough mica in one side to permit the flame to be seen. The chimney extends into a metal chamber containing the hot-water pipes, or into a chamber thru which air is taken and heated by the chimney. The fumes from the burning oil pass out into the room and not into the incubator. The heated air passes thru ducts into the incubator. These are often constructed of wood.

251. The Wick. The wick most generally found practical is the cotton wick, such as is used in ordinary lamps. It should be kept clean and renewed often. The lamp should be kept filled regularly. The wick must always be kept trimmed even, to prevent smoking.

Incubators heated by electricity have the heating unit placed either above or below the trays of eggs. The current is controlled by a thermostat.

252. Thermostat. The thermostat also raises the damper over the top of the lamp and air heater (Fig. 142), when the incubator reaches the temperature for which it is set, and lowers it when the temperature falls. When the damper is lifted, the heated air passes out into the room and not into the incubator. As soon as the incubator cools below this temperature, the thermostat contracts, letting the damper drop in place to retain the heat and direct it into the incubator. The thermostat works the same when a gas flame is used instead of a lamp. In electrical machines, the thermostat operates the switch, admitting much, little or no current, as is needed to maintain 102½ degrees Fahrenheit.

253. The Thermometer. A thermometer is placed in the incubator to guide the operator in regulating the temperature. It guides him in adjusting the thermostat and the heating device; that is, it shows him when to turn the wick of the lamp up or down.

Lamps should never be turned high enough to smoke. Smoke and gas in the room are likely to get into the incubator and harm the growing chicks.

254. Operation of Incubator. Set the incubator level; it is constructed to work on the level. Heated air rises—if the incubator is not level, the highest point will get most of the heat. It should be set in a dry room or dry cellar, which is well ventilated and well lighted. There should be no artificial heat in the room which is not regular. An uneven temperature gives difficulty in managing the heating of the incubator. The room should be free from dust.

Adjust the incubator and run it for two or three days to see that it is operating at a constant temperature before putting in the eggs.

Use only the best grade of oil, and use the same kind of oil all thru one hatch. Change in oil may necessitate a change in regulators which is not safe while the eggs are in the incubators.

Start the incubator with a good, clear, high flame in the lamp, so that it can be turned lower as the germs in the eggs begin to grow and generate heat.

Start the incubator at 100 degrees Fahrenheit, and by the second day, it will reach the temperature of 102 degrees.

Violent fluctuations of temperature in the incubator are dangerous and should be avoided.

Accuracy in reading temperatures and in adjusting the thermostat and ventilators is essential. Fill the lamp and turn the eggs regularly. Cleanliness is important. Disinfect the incubator between hatches, and air it well. Cresol soap and water make a good disinfectant for incubators. Turn and handle eggs with clean hands.

To know whether the incubator has the proper amount of moisture supplied, weigh the trays before filling, weigh after filling. At the end of the fifth day, weigh tray and eggs again, subtract the tray weight, which is constant, from the weight of the whole, and note the difference between this weight and the original weight of the eggs. If 100 eggs have lost 8.38 ounces, or 4.17 per cent of their weight, the moisture is correct.

If they have lost too much weight, give more moisture or less ventilation, but, remember, that pure air is essential to incubators, so do not shut off ventilation entirely.

If not enough weight is lost, open the ventilators, and, if necessary, for the next hatch, place the incubator in a drier place.

255. Egg Tester. An egg tester is a device for looking thru eggs to ascertain whether or not they are good. It consists of some device to keep all bright light away from the eyes except a few bright rays shining thru the egg. The hole should be about an inch long and three-fourths of an inch wide. A metal chimney with one such opening in the side used in a darkened room serves as an egg tester. A large piece of cardboard tacked over a sunny basement window is sometimes used, the hole being cut in the cardboard (Fig. 143).

Hold the egg between the finger and thumb before the opening. Look at the egg as the light shines thru it. Fig. 144 shows how good and bad eggs look when viewed in egg tester.

CHAPTER XXXVI

Typewriters

256. Construction of Typewriter. The typewriter is a machine for printing letters (Fig. 145). The letters making the imprint are attached to shafts which can each swing to one point. Care should be taken to strike one key at a time, as they are all made to reach the same point, and contact with each other may cause bent shafts. If a shaft becomes bent, the letter attached to it will not swing to the desired point, so will be out of alignment, or will fail to leave a mark, since the imprint is made on a roller and the letter hits only the nearest part of the surface. The shaft may have one, two or three letters on it. This is made possible by the use of the shift key which raises or lowers the framework to which the roller is attached, so that when the machine is in normal position, one set of type on the keys will be imprinted, and, upon the holding down of a shift key and simultaneously striking a letter, another set of type will make the imprint. On some typewriters there are two shift keys, allowing three sets of characters to be used. The motion of the keys turns a small wheel which shoves the roller from right to left, and, also, turns the spools of ribbons so that a new bit of ribbon comes under the letter each time a key is struck. If the ribbon did not move, the letters would soon cut a hole thru it. This ribbon carries the ink which reproduces the imprint of the letter. When the end of a ribbon is reached, most machines reverse its direction so that it again winds onto the spool from which it has just unwound. On other machines, it is necessary to release the bar which controls the spools to reverse the winding of the ribbon.

257. Special Features of Typewriter. Learn how to use the attachments on the typewriter to get the greatest service from it. If a machine is equipped with tabulating keys, much time is saved by using them for the indentations instead of working the space bar until the desired place is reached, or by using both hands to release the carriage and move it to its desired place. Some machines are equipped with a key marked "ribbon" key. This key, when pressed, lowers the ribbon so that no impression from it is made on the paper. When the ribbon is removed, stencils may be cut with the letters for mimeographic work. These are only two examples. There are many automatic aids on each make of machine.

258. Interchangeable-Type Typewriters. On these machines, the type is not placed at the end of a shaft, but the complete set of letters is put on a semi-circular plate which is attached to a wheel which brings the desired letter to the point wanted when the key is pressed (Fig. 146).

The change of type can be made very easily so that with the proper semi-circular plate any one of several languages may be written on this kind of typewriter regardless of the characters used to represent the letters.

Charts of the keyboard are furnished with each set of letters to guide the operator in writing. This machine requires the same general care as other typewriters.

259. Care of Typewriters.

1) Read the directions for cleaning and oiling the machine. Keep them for future reference.

2) Do not attempt to take the machine apart. Only readjust parts for which such directions are given.

3) Use only the best grade of typewriter oil, and oil only where indicated. The average machine does not require oiling oftener than from ten to fourteen days.

4) Brush the entire machine each day before using. This prevents the accumulation of oil and dust, which retards the free action of the machine, and rusts or clogs the bearings and other parts.

5) Use a stiff brush to clean the type. If the type has become gummed with ink from lack of care, moisten the brush with alcohol or gasoline, and brush it until clean. Avoid cleaning the type with a sharp instrument, if possible, as it mars the edges. However, in case of the letters having an enclosed parts, such as c, d, e, b, g, p, a, s, c, q, it may require the careful removal of the deposit with a pin. After this treatment, the type should be well brushed. Keep machine covered when not in use. With proper care, a machine should stay in good order indefinitely. If, in any way, any part of a machine is out of adjustment, have an expert readjust it.

260. The Hectograph. The hectograph is one of the simplest devices for obtaining duplicate copies of written work (Fig. 147). It is a sheet like heavy paper or pad of jelly-like substance on which a reversed copy of the writing can be made and from which copies can be taken. The original copy is written with hectograph ink on smooth paper by hand, or on a typewriter, and allowed to dry. This copy is placed face downward on the hectograph pad, which has been moistened and rubbed to insure the contact at all places. It is allowed to remain here for three or four minutes. More time is required in cold weather, as the absorption of ink by the pad is slower. The paper is then removed, leaving a reversed impression on the hectograph plate. Copies are then made by placing dry paper on the impression and removing them instantly. Twenty copies may be taken. The plate should be washed in lukewarm water immediately after use. The hectograph plate should be about the temperature of an ordinary room; chilled plates produce faint prints. Never use cold water on the plate. Keep pen flowing freely when writing the original copy, by wiping it frequently. Keep the hectograph covered when not in use.

261. Mimeograph and Multigraph. The mimeograph (Fig. 148) is a more complicated device for reproducing duplicates than the hectograph, but more copies may be made at faster speed on this machine and the stencils may be saved for making more copies later. A stencil (tissue paper, usually blue, fastened to a sheet of equal size waxed cardboard) is cut by a typewriter. This is done by removing the ribbon and allowing only the outline of the type to cut thru the tissue which has been saturated with "Dermax," a liquid wax which is brushed over the surface of the waxed paper, and the tissue paper carefully smoothed out upon it. Some stencil paper or waxed sheets do not require this treatment of "Dermax"; instead a tissue or silk sheet is placed under the stencil paper. When the desired wording is cut, the cardboard is torn off at the perforated line, leaving the four holes which attach the stencil to the roller of the mimeograph machine. First see that the pad on the machine is well inked, and then fasten the stencil to the pins at the top of the roller and with bar at the bottom, seeing that it is smooth.

Set the adjustment which indicates the number of copies turned out, so that it is not necessary to count them while printing. (Full directions are printed on this adjustment.) Place the paper on the feed board, far enough down for the sheets to come in contact with the rollers which feed them in, and turn the handle. If the proportion of space at top is greater or less than desired, set the attachment for regulating the space. Full directions are printed on each attachment of most machines. See that the ink tank which is located inside the cylinder is kept full of the best ink. Ink the pad by pushing the brush across the inside of the perforated cylinder.

Multigraphs differ from mimeographs in that they print the copy from type instead of thru a stencil. The type is set in a cylinder that is covered by an inked ribbon. Manuscripts printed by a multigraph look more like typewriting than those printed by a mimeograph. When turning out less than a thousand copies, the mimeograph will be found more economical on account of the small amount of time required in preparing the stencil.

Questions for Part IX

PART X

Motors, Fuels, and Gas Plants

CHAPTER XXXVII

Treadles and Water Motors

262. Definition of Motor. A motor is a device for utilizing the power stored in gasoline, electricity or elevated water for doing work. The structure of the motor depends upon the source of its power, as does its name. Besides the motor, there is a treadle, or foot-power motor, used in the home.

263. The Treadle. The treadle is a small platform, which rocks on two pivots. As the treadle is rocked, it moves a rod attached to its outer edge, upward and downward. This rod is then attached to a wheel a short distance from the hub, so that the upward and downward motion of the shaft turns the wheel. When a belt is attached to the wheel, it will run a sewing machine or other small device.

264. Water Motors. Water motors are commonly used in the household on washing machines and pumps (Figs. 149 and 149-a.) At least twenty-five pounds of water pressure is required to run an average-size washer. More pressure is advantageous. The motor may be, and often is, attached to tanks in which water is held under pressure, and used to pump water from a cistern or well.

265. Selecting a Water Motor. Before purchasing any device to be operated by a water motor, ascertain how much water pressure you have available. Under enough pressure, the water from a faucet will give power enough to a small-sized water motor to run a washing machine, sewing machine or small feed grinders. These motors are usually less than one-half horse power.

266. Two Types of Water Motors. One type of water motor is made up of a piston and valves in a cylinder (Fig. 150). The water pushes the piston to a certain point when a valve opens and lets out the water. The piston then moves backward until it automatically opens another valve, letting in more water, which, in turn, pushes the piston forward and again to the point where the first valve opens. The motion of the piston must be strong enough to do the work. About twenty-five pounds of water pressure is required in moving the piston forward when attached to a machine which might be operated by hand by a woman.

Another type of water motor consists of cups or fans on the rim of a wheel. As the water flows over the wheel, it pushes it around, thus giving it power to do work provided there is enough pressure behind the water (Fig. 150-a).

CHAPTER XXXVIII

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.