Plate XV. Types of heavy agricultural machinery. A, B, tile ditching machine; C, threshing separator; D, traction engine and crushed-stone wagon for road-making; E, corn picker; F, steam plowing outfit; G, ditching machine for open ditches led to the general adoption of steam-plowing, especially on the large farms. With the powerful engines now in use, it is possible to plow 30 to 60 acres per day. It usually requires three men and a team to take care of the outfit, an engineer, fireman, and a man and team to haul fuel and water. In ordinary stubble-plowing, when the ground is in good condition, 100 pounds of bituminous coal per acre is a fair estimate of the quantity of fuel required. In California, where steam-plowing has reached its greatest development in this country, the estimated cost per acre is 25 cents to $1, depending on the character of the soil, price of fuel and wages for men. H The area suitable for steam-plowing in the United States includes the larger part of California, parts of Oregon, Washington, Utah, Nevada and Idaho on the Pacific slope; North and South Dakota, Colorado, Kansas, Nebraska, Texas, Oklahoma, Indiana, Missouri, Iowa, Illinois, and most of the Canadian Northwest. In this country, the plow is hitched directly behind the engine and the whole outfit is propelled across the field to be plowed. In England and on water line. water line. Fig. 258. A traction engine boiler showing the engine in place and arrangement of gearing. the continent of Europe where steam-plowing is practiced, two methods are in vogue. The first method requires two engines stationed on opposite sides of the field, each equipped with a winding drum which operates a cable for hauling the plows back and forth across the field. In the second method, an anchor takes the place of one of the engines, and is so arranged that it moves automatically along the head-land when the plows make a trip across the fields. The plow carriage, operated by means of an endless cable, is arranged with a double set of plows, on opposite sides, so that when one set is in the ground the other is tilted out. These outfits, with their special plows and cables, are more expensive than the American, and are not capable of doing so much work. An interesting adaptation of the traction engine occurs in rolling the tule lands of the Sacramento and San Joaquin valleys of California, preparatory to plowing. The main wheels are 9 feet in diam D Fig. 257. A type of traction engine boiler. Direct flue fire-box, universal boiler. Straw chute and brick arch removable for burning coal or wood A traction engine is one that is capable of moving from place to place by its own power. eter, with 16 feet face, while the steering wheel is 6 feet in diameter and 5 feet face. This roller settles the ground 6 to 20 inches, and water is on the large wheels continually. In operating combined harvesters on the Pacific coast, traction engines enable the work to be done at a very rapid rate and very cheaply, running as low as 40 cents per acre. The grain is cut, threshed, recleaned, and sacked in one operation at the rate of 75 to 100 acres per day. In the matter of steam economy, the best grades of traction engines compare favorably with stationary engines of similar design, 25 to 35 pounds of steam per rated horse-power per hour being their usual performance. The majority of traction engine boilers are of the horizontal pattern, with flues 2 to 2 inches in diameter. Figs. 256, 257 and 258 illustrate the leading types. The average amount of heating surface per rated horse-power is 11 square feet, while the average grate surface is one-third of a square foot. All traction engine boilers depend on induced draft for forcing the fire, secured by turning the exhaust up the chimney after the manner of locomotives. The service required of traction engines is of a very exacting nature. They are subjected to the severe shocks and strains of rough country roads, to all sorts of weather conditions, to the evils of bad water and incompetent engineers. When used to drive machinery they are seldom carefully adjusted to the work. Engines of this class must also burn whatever kind of fuel is available, and consequently must be Fig. 259. Driving gear for traction engine. A. main driving pinion; B, differential gear, showing spiral springs to relieve shocks on rough roads; C, main drive wheel. built strongly, have an elastic construction, and be free from all delicate adjustments. The fuels vary in different parts of the country. Wood is used where it is still cheap, straw in the wheat-raising belt, oil in parts of Texas and on the Pacific coast, and coal in other parts of the country. NEEDLE VALVE GASOLINE Internal-combustion engines. Under this denomination are included gas, gasoline, kerosene, crude-oil and alcohol engines. All of these engines work on the same principle and are nearly identical in construction, only slight modifications in design being necessary to adapt any of them to the different fuels. In each case the fuel is first converted into a gas or vapor, mixed with the right proportion of atmospheric air, and then burned directly in the engine cylinder. Gasoline COOLING WATER IGNITOR EXHAUST FEEDER SUCTION PIPE || The power is generally transmitted to the drivewheels by means of spur-gearing, but in a few engines a combination of spur-gearing and chaingearing is used. The elastic construction necessary in engines of this class is secured by springcushioned gears and spring connections between parts where heavy shock is likely to occur (Fig. 259). The driving-gears are usually connected with the main shaft by a friction clutch, though sometimes a positive clutch is used in double engines. All traction engines are made reversible, to accomplish which several devices are used. The link-reverse is the oldest and best known, while the radial armgear and shifting eccentric-gear are also extensively used. The reverse STARTING DAMPER. GASOLINE gear not only con- OVERFLOW PIPE trols the direction of rotation of the engine, but also plays an important part in the economy of its operation when properly handled, A RELIEF COCK COOLING WATER. GASOLINE SUPPLY PIPE CAM LEVER HOOK UP CATCH HOOK UP STOP Fig. 260. Elevation of a vertical three horse-power four-cycle gasoline engine. as by it the cut-off of steam in the cylinder can be adjusted to suit the load. According to the Twelfth Census, in the year 1900 there were 31 establishments in the United States engaged in the manufacture of traction engines. Their total output for that year was 6,132 engines, valued at $6,385,026. Besides this, there were reported 130 road-rollers, which are only another form of traction engine, valued at $130,000. The average life of the traction engine in the northwestern states, when it receives unusually hard usage and is left out-of-doors all the year round, is between seven and eight years. When the engines are housed in winter and taken care of, they last 15 to 20 years. vaporizes at ordinary temperatures and is converted into gas by spraying it into a rapidly moving current of air. Such fuels as kerosene and crude oil, however, vaporize only at high temperatures and must be passed through a hot chamber before they reach the engine cylinder. This hot chamber is connected directly with the cylinder and is heated by the burning gases during each explosion. Internal-combustion engines, called also gas en.gines, or explosive engines, may be divided into two forms, depending on their structure and manner of operation, called fourcycle and twocycle engines. The four-cycle engine operates as fol lows: 1. On the first outward stroke of the piston a charge is drawn into the cylinder. 2. This charge is compressed to 40 to 90 pounds per square inch on the return stroke and ignited before the stroke is completed. 3. The piston moves outward the second time under the impulse of the explosion. 4. On the second return-stroke the exhaust-valve is opened and the burnt gases are expelled. Four distinct operations and two revolutions of the fly-wheel have been required for one explosion in this type of engine, and hence the name four-cycle. In the twocycle engine these four operations take place in one revolution, allowing an explosion to occur on each outward stroke of the piston instead of on alternate strokes, as in the four-cycle type. EXHAUST VALVE SPRING WASHER ceeded it. Since then many inventors have entered the field, and this type of engine has been improved until it has now come to be the most formidable competitor of the steam engine. Up to within a few years ago, gas engines were made only in small sizes, ranging from 1 to 100 horse-power. But at the present time they are built in units as large as 3,000 horse-power, thus not only competing with the steam engine for farm IGNITOR PISTON The temperature of combustion in the gas engine cylinder varies in different types of engines, and is dependent on the kind of fuel, the character of the mixture and the degree of compression. In gas engines the temperature varies from 2,200° to 3,000° F., temperatures high enough to melt the cylinder walls if some provision, such as a wateror oil-jacket, were not made to carry off the excess heat. The working medium, after explosion, in any explosive engine is a mixture of watery vapor, nitrogen and carbon dioxid gas. These are the products of combustion. The high temperature to which they are raised causes a rapid rise in pressure, amounting in any ordinary gas engine to 200 to 300 pounds per square inch at the beginning of the stroke. Either too much or not enough fuel for the quantity of air makes a weak explosive mixture, causes low temperatures, low pressure, lack of power and poor economy. SIGHT FEED LUBRICATOR PULLEY FLYWHEEL CRANKSHAFT BOX - LEFT CRANKPIN BRASSEG CONNECTING ROD BRONZE BUSHINGO DIL BUB-BASE R JACK PINION-14 GOVERNOR BLEEVE GOVERNOR FLYWHEEL The first inter- Fig. 261. Section of the vertical three horse-power four-cycle gasoline engine gasoline engines. Gasoline engines are built in both the horizontal and vertical styles for farm work. The one that is made the subject of illustration, Figs. 260, 261 and 262, is a three horsepower vertical engine designed expressly for the agricultural trade. It is a fourcycle engine and operates as follows: When the piston starts on its first downward stroke a vacuum is formed in the cylinder. Consequently, air under atmospheric pressure rushes through the suction pipe, Fig. 260, takes up a charge of gasoline vapor in passing through chamber C, opens the intake valve against the pressure of the coiled spring and enters the cylinder. On the return stroke this charge is compressed and ignited electrically at the proper moment. Ignition is accomplished through the cam-gear, cam, ignitor-rod and the ignitor-trip which snaps the ignitor-hammer at the right moment to make and break electrical contact between the electrodes inside the cylinder. The governor is of the centrifugal type, attached to the fly-wheel and designed so that when the speed passes a certain point the weights fly outward and operate on the exhaust valve rod, causing the exhaust valve to be held open. Air will |