Farm Mechanics Part 7

PORTABLE FARM ENGINE AND TRUCK

[Ill.u.s.tration: Figure 111.--Portable Farm Engine. This engine is permanently mounted on a low wheel truck wagon. The saw frame is detachable and the same truck is used for spraying and other work.]

A convenient arrangement for truck and portable power for spraying, sawing wood and irrigation pumping, is shown in the accompanying ill.u.s.tration. The truck is low down, which keeps the machinery within reach. The wheels are well braced, which tends to hold the outfit steady when the engine is running. The saw table is detachable. When removed, the spraying tank bolts on to the same truck frame; also the elevated table with the railing around it, where the men stand to spray large apple trees, is bolted onto the wagon bed.

Spraying never was properly done until the powerful engine and high pressure tanks were invented. Spraying to be effective, should be fine as mist, which requires a pressure of 150 pounds. There may be a number of attachments to a spraying outfit of this kind. A pipe suspended under the frame with a nozzle for each row is used to spray potatoes, strawberry vines and other low down crops that are grown in rows. When not in use as a portable engine it is blocked firmly into place to run the regular stationary farm machinery.

HYDRAULIC RAM

The hydraulic ram is a machine that gets its power from the momentum of running water. A ram consists of a pipe of large diameter, an air chamber and another pipe of small diameter, all connected by means of valves to encourage the flow of water in two different directions. A supply of running water with a fall of at least two feet is run through a pipe several inches in diameter reaching from above the dam to the hydraulic ram, where part of the flow enters the air chamber of the ram.

Near the foot of the large pipe, or at what might be called the tailrace, is a peculiarly constructed valve that closes when running water starts to pa.s.s through it. When the large valve closes the water stops suddenly, which causes a back-pressure sufficient to lift a check-valve to admit a certain amount of water from the large supply pipe into the air-chamber of the ram.

After the flow of water is checked, the foot-valve drops of its own weight, which again starts the flow of water through the large pipe, and the process is repeated a thousand or a million times, each time forcing a little water through the check-valve into the air chamber of the ram.

The water is continually being forced out into the small delivery pipe in a constant stream because of the steady pressure of the imprisoned air in the air-chamber which acts as a cus.h.i.+on. This imprisoned air compresses after each kick and expands between kicks in a manner intended to force a more or less steady flow of water through the small pipe. The air pressure is maintained by means of a small valve that permits a little air to suck in with the supply of water.

[Ill.u.s.tration: Figure 112.--Hydraulic Ram. The upper drawing shows how to install the ram. The lower drawing is a detail section through the center of the ram. Water flows downhill through the supply pipe. The intermittent action of the valve forces a portion of the water through another valve into the air-chamber. Air pressure forces this water out through delivery pipe. Another valve spills the waste water over into the tailrace. An automatic air-valve intermittently admits air into the air-chamber.]

Water may be conveyed uphill to the house by this means, sometimes to considerable distance. The size of the ram and its power to lift water depends upon the amount of water at the spring and the number of feet of fall. In laying the small pipe, it should be placed well down under ground to keep it cool in summer and to bury it beyond the reach of winter frost. At the upper end where the water is delivered a storage tank with an overflow is necessary, so the water can run away when not being drawn for use. A constant supply through a ram demands a constant delivery. It is necessary to guard the water intake at the dam. A fence protection around the supply pool to keep live-stock or wild animals out is the first measure of precaution. A fine screen surrounding the upper end of the pipe that supplies water to the ram is necessary to keep small trash from interfering with the valves.

THE FARM TRACTOR

Farm tractors are becoming practical. Most theories have had a try out, the junk pile has received many failures and the fittest are about to survive. Now, if the manufacturers will standardize the rating and the important parts and improve their selling organizations the whole nation will profit. The successful tractors usually have vertical engines with four cylinders. They are likely to have straight spur transmission gears, and a straight spur or chain drive, all carefully protected from dust. And they will have considerable surface bearing to avoid packing the soil. Some tractors carry their weight mostly upon the drive wheels--a principle that utilizes weight to increase traction. Other tractors exert a great deal of energy in forcing a small, narrow front steering-wheel through the soft ground. Any farmer who has pushed a loaded wheelbarrow knows what that means. Some kerosene tractors require a large percentage of gasoline. The driver may be as much to blame as the engine. But it should be corrected.

[Ill.u.s.tration: Figure 113.--Tractor Transmission Gear. Spur gears are the most satisfactory for heavy work.]

Manufacturers should do more educational work and talk less about the wonderfully marvelous and marvelously wonderful. Salesmen should study mechanics instead of oratory. Tractor efficiency should be rated practically instead of theoretically. The few actual reports of performance have emanated from tests with new machines in the hands of trained demonstrators. Manufacturers include belt power work among the virtues of farm tractors, and they enumerate many light jobs, such as running a cream-separator, sawing wood, pumping water and turning the fanning-mill. Well, a farm tractor can do such work--yes. So can an elephant push a baby carriage. If manufacturers would devise a practical means of using electricity as an intermediary, and explain to farmers how a day's energy may be stored in practical working batteries to be paid out in a week, then we could understand why we should run a 20 horsepower engine to operate a cream-separator one hour at night and another hour in the morning.

[Ill.u.s.tration: Figure 114.--Straight Transmission Gear, forward and chain drive reverse, for traction engine.]

CHAPTER IV

DRIVEN MACHINES

FARM WATERWORKS

Every farm has its own water supply. Some are very simple, others are quite elaborate. It is both possible and practical for a farmer to have his own tap water under pressure on the same plan as the city. When good water is abundant within 75 feet of the surface of the ground the farm supply may be had cheaper and better than the city. Even deep well pumping is practical with good machinery rightly installed. Farm waterworks should serve the house and the watering troughs under a pressure of at least 40 pounds at the ground level. The system should also include water for sprinkling the lawn and for irrigating the garden. If strawberries or other intensive money crops are grown for market there should be sufficient water in the pipes to save the crop in time of drouth. These different uses should all be credited to the farm waterworks system pro rata, according to the amounts used by the different departments of the farm. The books would then prove that the luxury of hot and cold running water in the farmhouse costs less than the average city family pays.

_Three Systems of Water Storage._--The first plan adopted for supplying water under pressure on farms was the overhead tank. The water was lifted up into the tank by a windmill and force pump. Because wind power proved rather uncertain farmers adopted the gasoline engine, usually a two horsepower engine.

The second water storage plan was the air-tight steel water-tank to be placed in the cellar or in a pit underground. The same pump and power supplies the water for this system, but it also requires an air-pump to supply pressure to force the water out of the tank.

The third plan forces the water out of the well by air pressure, as it is needed for use. No water pump is required in this system; the air-compressor takes its place.

[Ill.u.s.tration: Figure 115.--The Farm Pump. It superseded the iron-bound bucket, the slimy old bucket, the malaria-lined bucket that hung in the well, but it wore out the women. Oil was never wasted on its creaking joints. Later it was fitted with a stuffing-box and an air-chamber, and the plunger was. .h.i.tched to the windmill.

To the right are shown two kinds of post-hole diggers. The upper digger is sometimes used to clear the fine earth out of the bottom of a hole dug by the lower digger.]

_Suction-Pumps._--The word suction, when applied to pumps, is a misnomer. The principle upon which such pumps work is this: The pump piston drives the air out of the pump cylinder which produces a vacuum.

The pressure of the atmosphere is about fifteen pounds per square inch of surface. This pressure forces sufficient water up through the so-called suction pipe to fill the vacuum in the cylinder. The water is held in the cylinder by foot-valves or clack-valves. As the piston again descends into the cylinder it plunges into water instead of air. A foot-valve in the bottom end of the hollow piston opens while going down and closes to hold and lift the water as the piston rises. Water from the well is forced by atmospheric pressure to follow the piston and the pump continues to lift water so long as the joints remain air-tight. The size of piston and length of stroke depend on the volume of water required, the height to which it must be lifted and the power available.

A small power and a small cylinder will lift a small quant.i.ty of water to a considerable height. But increasing the volume of water requires a larger pump and a great increase in the power to operate it. The size of the delivery pipe has a good deal to do with the flow of water. When water is forced through a small pipe at considerable velocity, there is a good deal of friction. Often the amount of water delivered is reduced because the discharge pipe is too small. Doubling the diameter of a pipe increases its capacity four times. Square turns in the discharge pipe are obstructions; either the pipe must be larger or there will be a diminished flow of water. Some pump makers are particular to furnish easy round bends instead of the ordinary right-angled elbows. A great many pumps are working under unnecessary handicaps, simply because either the supply pipe or discharge pipe is not in proportion to the capacity of the pump, or the arrangement of the pipes is faulty.

[Ill.u.s.tration: Figure 116.--Hand Force-Pump. Showing two ways of attaching wooden handles to hand force-pumps.]

[Ill.u.s.tration: Figure 117.--Rotary Pump. Twin water-chamber rotary pumps take water through the bottom and divide the supply, carrying half of the stream around to the left and the other half to the right. The two streams meet and are discharged at the top.]

[Ill.u.s.tration: Figure 118.--Section of Rotary Pump.]

_Rotary Pumps._--A twin-chamber rotary pump admits water at the bottom of the chamber and forces it out through the top. Intermes.h.i.+ng cogs and rotary cams revolve outward from the center at the bottom, as shown by the arrows in Figure 118. The stream of water is divided by the cams, as it enters the supply pipe at the bottom, and half of the water is carried each way around the outsides of the double chamber. These streams of water meet at the top of the chamber, where they unite to fill the discharge pipe. These pumps operate without air-chambers and supply water in a continuous stream. They may be speeded up to throw water under high pressure for fire fighting, but for economy in ordinary use the speed is kept down to 200 revolutions, or thereabout. Rotary pumps are also made with one single water chamber cylinder. The pump head, or shaft, is placed a little off center. A double end cam moves the water. Both ends of the cam fit against the bore of the cylinder. It works loosely back and forth through a slotted opening in the pump head.

As the shaft revolves the eccentric motion of the double cam changes the sizes of the water-pockets. The pockets are largest at the intake and smallest at the discharge. Rotary pumps are comparatively cheap, as regards first cost, but they are not economical of power. In places where the water-table is near the surface of the ground they will throw water in a very satisfactory manner. But they are more used in refineries and factories for special work, such as pumping oil and other heavy liquids.

_Centrifugal Pumps._--The invention and improvement of modern centrifugal pumps has made the lifting of water in large quant.i.ties possible. These pumps are constructed on the turbine principle. Water is lifted in a continuous stream by a turbine wheel revolving under high speed. Water is admitted at the center and discharged at the outside of the casing. Centrifugal pumps work best at depths ranging from twenty to sixty feet. Manufacturers claim that farmers can afford to lift irrigation water sixty feet with a centrifugal pump driven by a kerosene engine.

The ill.u.s.trations show the principle upon which the pump works and the most approved way of setting pumps and engines. Centrifugal pumps usually are set in dry wells a few feet above the water-table. While these pumps have a certain amount of suction, it is found that short supply pipes are much more efficient. Where water is found in abundance within from 15 to 30 feet of the surface, and the wells may be so constructed that the pull-down, or the lowering of the water while pumping is not excessive, then it is possible to lift water profitably to irrigate crops in the humid sections. Irrigation in such cases, in the East, is more in the nature of insurance against drouth. Valuable crops, such as potatoes and strawberries, may be made to yield double, or better, by supplying plenty of moisture at the critical time in crop development. It is a new proposition in eastern farming that is likely to develop in the near future.

[Ill.u.s.tration: Figure 119.--Centrifugal Pump. This style of pump is used in many places for irrigation. It runs at high speed, which varies according to the size of the pump. It takes water at the center and discharges it at the outside of the casing.]

[Ill.u.s.tration: Figure 120.--Air Pressure Pump. Pumping water by air pressure requires a large air container capable of resisting a pressure of 100 pounds per square inch. This ill.u.s.tration shows the pressure tank, engine, air-compressor, well and submerged pump.]

_Air Pressure Pump._--Instead of pumping water out of the well some farmers pump air into the well to force the water out. A double compartment cylindrical tank is placed in the water in the well. These tanks are connected with the farm water distributing system to be carried in pipes to the house and to the stock stables. Air under a pressure of from 50 to 100 pounds per square inch is stored in a steel tank above ground. Small gas-pipes connect this air pressure tank with the air-chamber of the air-water tank in the well. A peculiar automatic valve regulates the air so that it enters the compartment that is filled, or partly filled, with water, and escapes from the empty one so the two compartments work together alternately. That is, the second chamber fills with water, while the first chamber is being drawn upon.

Then the first chamber fills while the second is being emptied. This system will work in a well as small as eight inches in diameter, and to a depth of 140 feet. It might be made to work at a greater depth, but it seems hardly practical to do so for the reason that, after allowing for friction in the pipes, 100 pounds of air pressure is necessary to lift water 150 feet. An air tank of considerable size is needed to provide storage for sufficient air to operate the system without attention for several days. Careful engineering figures are necessary to account for the different depths of farm wells, and the various amounts of water and power required. For instance: The air tank already contains 1,000 gallons of air at atmospheric pressure--then: Forcing 1,000 gallons of atmospheric air into a 1,000-gallon tank will give a working pressure of 15 pounds per square inch; 2,000 gallons, 30 pounds; 3,000 gallons, 45 pounds, and so on. Therefore, a pressure of 100 pounds in a 1,000-gallon tank (42 inches by 14 feet) would require 6,600 gallons of free atmosphere, in addition to the original 1,000 gallons, and the tank would then contain 1,000 gallons of compressed air under a working pressure of 100 pounds per square inch. A one cylinder compressor 6 inches by 6 inches, operating at a speed of 200 R.P.M. would fill this tank to a working pressure of 100 pounds in about 50 minutes. One gallon of air will deliver one gallon of water at the faucet. But the air must have the same pressure as the water, and there must be no friction.

Thus, one gallon of air under a working pressure of forty-five pounds, will, theoretically, deliver one gallon of water to a height of 100 feet. But it takes three gallons of free air to make one gallon of compressed air at forty-five pounds pressure. If the lift is 100 feet, then 1,000 gallons of air under a pressure of forty-five pounds will theoretically deliver 1,000 gallons of water. Practically, the air tank would have to be loaded to a very much greater pressure to secure the 1,000 gallons of water before losing the elasticity of the compressed air. If one thousand gallons of water is needed on the farm every day, then the air pump would have to work about one hour each morning. This may not be less expensive than pumping the water directly, but it offers the advantage of water fresh from the well. Pure air pumped into the well tends to keep the water from becoming stale.

[Ill.u.s.tration: Figure 121.--(1) Single-Gear Pump Jack. This type of jack is used for wells from 20 to 40 feet deep. (2) Double-Gear, or Multiple-Gear Pump Jack. This is a rather powerful jack designed for deep wells or for elevating water into a high water-tank.]

[Ill.u.s.tration: Figure 122.--Post Pump Jack. This arrangement is used in factories when floor s.p.a.ce is valuable. The wide-face driving-pulley is shown to the left.]

[Ill.u.s.tration: Figure 123.--Three Jacks for Different Purposes. At the left is a reverse motion jack having the same speed turning either right or left. The little jack in the center is for light work at high belt speed. To the right is a powerful jack intended for slow speeds such as hoisting or elevating grain.]

[Ill.u.s.tration: Figure 124.--Speed Jack, for reducing speed between engine and tumbling rod or to increase speed between tumbling rod and the driven machine.]

[Ill.u.s.tration: Figure 125.--The Speed Jack on the left is used either to reduce or increase tumbling rod speed and to reverse the motion. The Speed Jack on the right transfers power either from belt to tumbling rod or reverse. It transforms high belt speed to low tumbling rod speed, or vice versa.]

_Pump Jacks and Speed Jacks._--Farm pumps and speed-reducing jacks are partners in farm pumping. Force-pumps should not run faster than forty strokes per minute. Considerable power is required to move the piston when the water is drawn from a deep well and forced into an overhead tank. Jacks are manufactured which bolt directly to the pump, and there are pumps and jacks built together. A pump jack should have good, solid gearing to reduce the speed. Spur-gearing is the most satisfactory.

Bevel-gears are wasteful of power when worked under heavy loads. Power to drive a pump jack is applied to a pulley at least twelve inches in diameter with a four-inch face when belting is used. If a rope power conveyor is used, then pulleys of larger diameters are required to convey the same amount of power.

Only general terms may be used in describing the farm pump, because the conditions differ in each case. Generally speaking, farmers fail to appreciate the amount of power used, and they are more than likely to buy a jack that is too light. Light machinery may do the work, but it goes to pieces quicker, while a heavy jack with solid connections will operate the pump year in and year out without making trouble. For increasing or reducing either speed or power some kind of jack is needed. All farm machines have their best speed. A certain number of revolutions per minute will accomplish more and do better work than any other speed. To apply power to advantage speed jacks have been invented to adjust the inaccuracies between driver and driven.

IRRIGATION BY PUMPING

The annual rainfall in the United States varies in different parts of the country from a few inches to a few feet. Under natural conditions some soils get too much moisture and some too little. Irrigation is employed to supply the deficiency and drainage, either natural or artificial, carries off the excess. Irrigation and drainage belong together. Irrigation fills the soil with moisture and drainage empties it. Thus, a condition is established that supplies valuable farm plants with both air and moisture. In the drier portions of the United States, nothing of value will grow without irrigation. In the so-called humid districts deficiency of moisture at the critical time reduces the yield and destroys the profit. The value of irrigation has been demonstrated in the West, and the practice is working eastward.