Fitz Steel Overshoot Water Wheels, Bulletin No. 70, Decmeber 1928, by the Fitz Water Wheel Company
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The Fitz I-X-L Steel Overshoot Water Wheel is the product of three generations of unbroken experience in the design and manufacture of water wheels. It high efficiency is due to its correct mechanical principles and to its careful design and construction. The manufacture of Overshoot Water Wheels was begun by Samuel Fitz, in Hanover, Pennsylvania., U. S. A., in the year 1840. The industry has been carried on continuously since that time on the same site under the management of the son and grandson of the original founder. The earlier Fitz Wheels were, of course built of wood. A number of orders are still being received for iron parts for wooden water wheels, as described later in this booklet, but by far the greater part of the business done today is the manufacture of the all-steel Overshoot Water Wheels, in which the company specializes. The real credit for the invention of the modern Steel Overshoot Water Wheel and for its development into its present highly efficient form must be given to the late John Fitz. [John Fitz, Inventor and Manufacturer. Born April 15, 1847 - Died, April 12, 1914. "He originated the modern Steel Overshoot Water Wheel, and rescued from oblivion one of the most useful principles of Hydraulics."] Very early in his business career he realized the great possibilities of this type of water wheel and he devoted the greater part of his life to the study of its principles and the improvement of its efficiency. How well he succeeded is shown by the high regard in which the Steel Overshoot is held today. In spite of this, we have not relaxed out efforts for further improvements, but are constantly striving for still better results in every detail of construction. The knowledge and experience accumulated by out organization during its long career in the water wheel business forms an ever greater asset than out well equipped modern factory. Most of out employees have grown up with us, and our millwrights and mechanics have been trained in this line from early youth. In reckoning with your water power problems, therefore, we have a vast fund of practical experience to draw from and we are glad to place this freely at the service of out customers. Sincerely yours, FITZ WATER WHEEL COMPANY, J. S. Fitz, President.
The Overshoot Water Wheel derives its power directly from the force of gravity. The illustration shows the principle upon which it works. The weight of the water which is admitted to the buckets, loads one side of the wheel, causing it to revolve. The water should be applied to the top of the wheel at a point about ten inches back of the vertical center line, so that the buckets will fill up just as they pass over the topmost point of the wheel. The diameter of an overshoot wheel should be from 2 1/2 to 3 feet less than the total fall available. By total fall, we mean the vertical distance from the surface of the water in the fore bay or "tank" above the top of the wheel, down to the surface of the water in the tail race or discharge canal, below the bottom of the water wheel. Wheels of all types were formerly built of wood. Many picturesque examples of this method of construction are still to be found in rural districts. The overshoot wheel possessed so many advantages that it soon displaced the other early types of water wheels. Even with all its crude design and ill-suited material, the wood overshoot still persists as a strong competitor of the modern small turbine. The field of the Overshoot Wheel lies in the development of small powers. It is not suitable for use in very large developments on account of the increase in size and weight of the wheel as the head and discharge are increased beyond certain limits. It can be built in any diameter needed up to 60 feet and in any width desired up to a capacity of 3,000 cubic feet per minute in single units. The power of an overshoot wheel depends upon both the diameter of the wheel and the width of the wheel. The larger the diameter of an overshoot wheel, the more power it will develop with the same amount of water. The wider the wheel is made, the more water it will accommodate. The relative power of two wheels of the same diameter is of course in direct proportion to the amount of water each wheel is capable of using, if other conditions are equal. The question of determining the proper size wheel to use for any particular location is one which should usually be left to the judgment of the builder of the wheel. We do not publish any list of sizes of wheels in this booklet for the reason that we prefer to have our customer give us the data, so that we, ourselves, can select the size of wheel he ought to have. For any location within the range of its capacity, the overshoot type of wheel possesses certain decided advantages, over all other types of water wheels, viz.: (1) High efficiency. (2) Adaptability to varying discharge. (3) Simplicity. (4) Reliability. The extent to which any overshoot wheel makes use of these advantages depends largely upon design of the wheel, its accuracy of construction and the material of which it is made. The Fitz Steel Overshoot Water Wheel makes use of the same basic principles as the old wood overshoot, but its superior design enables the Fitz Wheel to develop more than 90% efficiency as compared with the 60% to 70% efficiency of the wood wheel. The reasons for this are set forth in detail later on in this booklet under the heading "Comparison with wood wheels." The efficiency of the Fitz Wheel is not a matter of opinion or guess work. Our wheels are rated according to the results shown by rigid test on Hydraulic Testing Flumes. Developing an efficiency of 90% or more, the Fitz Steel Overshoot is vastly more efficient than any other type of water wheel known. In the smaller installations especially, where the overshoot most frequently competes with a turbine, it is doubtful whether the turbines ever operates with an efficiency higher than 70%. It is true that many turbine builders claim high efficiencies for their wheels, but every experienced turbine user has good reason to know how far the turbines themselves fall short of their makers' claims when confronted with actual running conditions. In every case, where the amount of fall and quantity of flow is suitable for our type of wheel, a Fitz Overshoot will develop at least one-third more power than any turbine working under similar conditions, or 25% more than the best new wood wheel that can be built. The above statements are made without prejudice to the turbine type of water wheel, for we build a turbine wheel ourselves that ranks fully equal to the best on the market. We are just as glad to sell a turbine wheel as we are to sell an overshoot where the conditions are suitable for a wheel of that type, but we will not furnish either kind for a location where we know that out customers' interests require the other.
The development of the overshoot water wheel into its present state of unrivalled efficiency has been the results of many years of thought and effort. Founded in its present location nearly ninety years ago, this firm has been building water wheels continuously during all that time, but it has never ceased to improve and modernize its product. Up until the advent of the modern Fitz Steel Overshoot Water Wheel an efficiency of 60% to 70% was considered remarkably good for small water power plant. Today, practically every recent text-book on hydraulics concedes an efficiency of 90% or more to the "modern steel overshoot water wheel when properly constructed." Proper construction means "Fitz Construction," for no other make of water wheel has approached this high efficiency. Fitz Water Wheels form part of the equipment of some of the greatest engineering colleges and universities of the world. They have been adopted by many railroads and by many of the leading engineering firms in this country for use wherever high efficiency and perfect reliability are the essential requirements in a small water power development.
A ten-foot diameter Fitz Steel Overshoot installed in the Hydraulic Laboratory of the University of Wisconsin has received an unusually thoro series of tests, as described in detail in one of the University's Bulletins. A range of four hundred per cent in variation of the amount of water supplied to this water wheel showed a difference of only 5% in the efficiency of the wheel. We quote as follows from an article in the "Engineering News" of January 2, 1913, by Prof. Carl R. Weidner, Instructor in Hydraulic Engineering at the university of Wisconsin: "To engineers familiar with the variation in efficiency of the turbine at part gate, a glance at the curves obtained from the Wisconsin experiments will be convincing as to the superiority of the overshoot wheel in respect to its adaptability to varying discharge." "The result of the experiments show high efficiencies under a wide range of operating conditions. Reliable test of turbines have been reported yielding as high as 89% efficiency but it is rarely that this figure is obtained in an actual installation. In the smaller plants, especially, where an overshoot wheel would be capable of competing with a turbine, it is doubtful whether the turbines operate with an average efficiency higher than 70%." "Laboratory test of a machine, when properly interpreted, undoubtedly have great value, but it must be borne in mind, that any test so made represents results under the exact conditions of the test. The conditions under which the Wisconsin experiments were performed approached practical conditions very closely. The wheel tested was of a standard pattern taken from the stock of the manufacturers. The structure features are simple, and none of these features, of the wheel itself, were changed during the tests. The results should, therefore, be readily duplicated in actual service, if the wheel is set properly." The published test reports of the university of Wisconsin show the ten foot diameter Fitz Wheel above illustrated, mounted on out bronze lined bearings, yielded an efficiency of 89%, on the water wheel shaft. Later tests of this same wheel, made under the same supervision but with the mounting changed to our self-aligning ball bearings, showed an efficiency of 92%. [Note this was the only water wheel efficiency testing done and report published in this century]
A good water power is a valuable possession and the steadily increasing cost of fuel and labor are tending to make it more valuable every day. It costs at least seventy dollars per annum to produce one horse-power by steam by the most efficient methods. The average cost is much higher; about one hundred dollars usually for a small plant. A gasoline engine is even more expensive for continuous service. With electric power for commercial purposes,selling at 4 cents per kilowatt or 3 cents per horsepower, a single horsepower used for only ten hours' service each day, will cost $90.00 per year, not even including the usual service charges, nor repairs or depreciation in the motor. Electric current for lighting purposes is usually sold thru a separate meter at from 10 cents to 15 cents per kilowatt, adding still more to the yearly bill. This being the case, a water power developing ten horsepower is worth nine hundred to one thousand dollars a year; or the interest on an investment of nine to ten thousand dollars. A sixty horsepower plant in a good location would have an earning capacity of six times the above, for that is what a similar sized steam plant would cost to operate, counting fuel, labor, repairs, interest and depreciation, etc. Figure it out for yourself on the basis of your own expenditures. The power developed at any water power installation depends on three factors, viz.: The volume of water in the stream, the amount of fall and the kind of water wheel used. The first two factors are usually determined by the natural conditions and are nearly always developed to the greatest practicable extent. They fix the potential or theoretical power. The water wheel is the medium by which the potential or possible power is converted into actual profit-earning power. There is a great difference in water wheels. Failure to realize this fact has caused many water power projects to result in disappointment. After spending perhaps, thousands of dollars on the dam, race-way, flume, excavating, etc., to develop a power, it is a very poor policy to sacrifice a large part of the returns by putting in a wasteful, inefficient water wheel. A water wheel of low efficiency may only develop half, or less than half, the possible power of the location. That means a sacrifice of one-half the earnings capacity of the plant. And that is just what nineteenths of the turbines and wood wheels in existence are doing for their owners. The remaining tenth are doing better than this but not one of them is giving anything like the actual power it should give. A man with a valuable water power cannot afford to take an inefficient wheel as a gift. His water power is valuable just in proportion to its earning capacity, and its earning capacity is regulated by the amount of power developed. A wasteful water wheel cuts down the value of the whole plant in proportion to the amount.
A water power plant usually represents not only the investment of a considerable sum of money in the dam, race-way, flume, tail race, etc., but also in the value of the factory which it operates, since that can earn but little without the power. The cost of the best water wheel on earth is but a fraction of the value of the entire plant which depends on it. Too much care cannot be used in the selection of a water wheel. Only the best and most efficient on the market should be considered. That is the only wise and economical policy. By repeated tests the Fitz Overshoot Water Wheel has shown that it will develop at least 33 1/3 more power than the best turbine made using the same amount of water. We are well aware that some turbine builders claim from 80% to 85% efficiency for their wheels and pretend that this is proven by their records in the testing flume. Such claims are absurd. It is true that a few turbines have given a little over 80% efficiency in the laboratory when tested at full gate, but it must be remembered that these were large wheels built regardless of expense and working under the most favorable conditions known. Even in the case of the large turbines, the practical value of these tests may be seen from the fact that no two wheels of the same size and same make would give the same efficiency, and often the same wheel, when tested at different times, would vary considerably. Small turbines, such as out wheel competes with, have never shown good results even in laboratory test. It is well known that conditions are much less favorable to turbines in actual use that to those in the testing flume, and that when you buy a turbine from any builder you don't get near as good a wheel as the one he builds especially to be tested. We know it to be a fact that there is no turbine built today that will develop over 65% to 70% efficiency in actual use, and the great majority fall much below this. See the extracts on the following pages from some leading reference works in regard to this. But it is not enough to merely consider the efficiency of a wheel with a full head of water. It is just as important to know how a wheel will act with a diminished head or scanty supply of water. No stream of water is of the same size at all seasons and a wheel that is not adaptable to varying conditions is useless a large part of the year. This is the point where all turbines, despite the claims of their makers, fail absolutely, for unless they are run a full gate, or nearly so, they will do very little work. The steel overshoot is a model wheel in this regard, as in every other respect, for it will run just as economical at one-fourth gate as at full gate, while when water is plentiful, it can be crowded far beyond its normal capacity. The Fitz Wheel depends only to a small extent upon pressure for its power. It can adapt itself to a wide range of heads. This feature is especially valuable where water is scarce and a large pond is used to store the water over night. Every one knows how unsatisfactory it is to use a turbine where you have to run by heads. Since the turbine depends upon the pressure of the water, when the head diminishes naturally the speed diminishes and also the power. With the Fitz the head can be drawn down almost to the bottom of the race without affecting either the power or the speed. Besides these most important consideration of high efficiency and adaptability to varying conditions, there are five other points that an ideal wheel should possess, viz.: (1) Freedom from clogging and freezing. (2) Tight gate. (3) Perfect balance. (4) Durability. (5) ability to do good work in back water. These points are only to be found in the Fitz Steel Overshoot Water Wheel. The large buckets cannot possibly become clogged with leaves, sticks, or anything else, like turbine buckets, for whatever goes through the gate will pass over the wheel freely. Ice, which causes so much trouble with wood wheels and turbines, has but little effect upon the steel overshoot. It cannot form on the wheel as long as it is in motion, for the thin steel readily acquires the temperature of the water passing over it and remains above the freezing point. Even should any ice form on the wheel while standing, a few strokes with a hammer will cause the wheel to ring like a bell and will shiver the ice all off, for there is nothing for it to cling to. The gate of our wheel is simplicity itself. It is tight beyond comparison with turbine gates. The balance of the wheel is very accurate. The wheel can be easily turned by one hand no mater how large it is. As for durability, it leaves nothing to be desired. The first wheels we ever built are still running and are in first-class condition right now. Back water, which will soon stop a wood overshoot, has very much less effect on the Fitz wheel. We usually calculate out wheels to accommodate from one-fourth to one-half more water than the normal volume of the streams which drive them. Consequently at flood periods more water can be used on the wheel, thus overcoming the loss of head in back-water. A careful consideration of the above facts must lead the conclusion that the Fitz Steel Overshot is not only the best water wheel on the market but also the cheapest, for it gives much the best value for the money expended. This wheel utilizes every bit of water to its fullest possible extent. The value of the increased power alone, that it yields, may be worth more every year than the whole cost of the water wheel, to say nothing of its greater durability and more satisfactory service.
The Fitz Steel Overshoot Water Wheel is built entirely of iron and steel. Its high efficiency is due to its correct principles of design and to the high class workmanship and material used in its construction. The word "Overshoot" is simply our arbitrary spelling which we adopted some time ago to distinguish our wheel from the ordinary "overshot" water wheel. For the sake of brevity our wheel is sometimes referred to by its old name, "The I-X-L," or often as "The Fitz Wheel." We do not wish to convey the impression that the Fitz Overshoot is the best wheel for all locations or for all conditions. Our field is in the development and improvement of small water powers. By small water powers we mean those having falls of less than sixty feet and volumes of water smaller than 3,000 cubic feet per minute for single units of wheels. Even within those limits, there are certain conditions to be met with occasionally which call for other types of water wheels. Within its own field, however, there is no other type of water wheel in the world that can compete with the Fitz Wheel. Put your conditions up to our engineers and let us tell you what we can do for you. We will guarantee in every case to greatly improve your power or to let it alone. The site of an overshoot wheel depends largely upon the situation, but we usually make the diameter about 2 1/2 feet less than the amount of the actual working head. The force of the water above our wheel is not lost but acts by its impulse upon the wheel just as it act on a turbine or impulse wheel. In other types of overshoot wheels this force is almost entirely wasted but the shape of our buckets and our method of applying the water to the wheel enable us to utilize this impulse. As will be seen from the cut on page eighteen, the water spurts across our smooth steel chute at a tangent to the crown of the wheel. It enters the buckets a little back of the vertical center line of the wheel and glides along the curved part of the bucket, striking the heel of the bucket at right angles to the radius of the wheel drawn to that point. Thus its power is communicated to the wheel in the direction best adapted to produce the greatest effect. The curve of the bucket is not the same in all sizes of wheels. It is varied to suit the particular requirements. Proper allowance is made in all cases to permit the exit of air from the bucket when water is entering. The shape of the bucket is such as to retain the water until all possible power is taken from it. The water is actual retained in the buckets almost to the level of the surface of the tail race. The housing if the steel overshoot, instead of coming flush with the buckets as in a wood wheel, are extended so as to prevent any water splashing over the sides. Thus not a drop of water is wasted and the water is discharged in the tail race with all its power extract. Compare the calm stream flowing from the overshoot wheel with the rushing torrent discharged by the turbine and you will see one of our strongest points. Mighty few small turbines get more than 60% or 65% of the energy out of the water that they use, and the momentum of the tail race represents a considerable part of the remaining 35% or 40%. Practically no power is wasted by friction in the bearing of our wheels. Fitz Wheels are so perfectly balanced and run with so little friction that a little child can turn the largest wheel we ever built, with one hand. Thus we are able to transmit undiminished to the jack shaft, nearly all of the energy we have extracted from the water. With each wheel we usually furnish our "water-tight" iron gate and steel "chute." Our iron gate is a very valuable feature. On small streams in very dry weather, it is essential to save all the water possible. A wood wheel or a turbine will often allow enough water to leak away at night through its defective gates, to run a Fitz Overshoot for several hours a day. The Fitz gate consists of two parts, a smoothly planed iron frame, and a movable slab which is both planed and scraped to insure a very accurate fit. It is tight and at the same time it is almost perfectly trouble-proof. The chute is the steel trough which carries the water from the gate to the buckets of the wheel. This piece is necessary in every case, in order to apply the water to the wheel at the proper tangent. The object of all wheels is to utilize the weight of falling water and to develop power thereby. The Fitz Wheel does this in the most direct manner and therefore with the least loss. Turbines and other wheels, aim to develop their power in an indirect manner by reaction or impulse caused by pressure. To give even moderately good results they must be geared to run at certain speed, under a certain pressure and using a certain amount of water. Since the overshoot depends mainly on the positive weight of the water and only in a small degree on impulse, it can run fast or slow, with high head or low head, at full gate or fractional gate with equally high efficiency, and developing power in exact proportion to the amount of water used. The motion of the Fitz Overshoot is slow. In order to drive fast running machinery the wheel should be equipped with suitable gearing. Later on in this booklet, the reader will find a number of plans showing approved methods of connecting up various kinds of machinery to our wheels.
Fitz (I-X-L) Steel Overshoot Water Wheels are shipped "knocked down" in sections easy to handle. The rim or "buckets" comes in from eight to twenty sections, according to the diameter of the wheel. Every piece is carefully marked or numbered and we furnish full printed instructions for assembling with each wheel, as well as a blue-print drawing showing the setting. The arms are numbered to suit the pockets of the flanges to which they belong. The sections of the rim and the segments of the gear are likewise numbered to correspond with their respective positions. We can furnish a skilled mechanic from our factory to install our wheels when wanted, but our careful method of marking an the perfect "fit" of each piece makes it very easy for the purchaser to install the work himself. The center flanges or hubs are made of cast semi-steel with dove-tailed pockets to receive the arms, and are keyed on the shaft with two keys each. To these flanges are bolted the arms, which are of the best Open Hearth steel. The bolts and rivets used in our wheels are selected with great care. They are absolutely the best that can be bought. For specially heavy service we make our bolts out of nickel-chrome-vanadium steel. Patented Nut Locks are used wherever necessary. Our gears are cast from semi-steel in our own foundry and are much stronger and tougher that cast gearing.
With a large stream of clear water which never varies in volume, and with a good fall, a well made turbine will work very satisfactorily. It is true that the efficiency of small turbine water wheels is always overrated, very few of them in practical use giving over 60% of the power they should develop, but of course where there is an abundance of water it is not necessary to be economical. But on a light stream, or wherever it is desirable to get the full power from the water, they are failures. The capacity of a turbine is unhangable. If you have more water than you need, it is wasted. If less, it will hardly turn the wheel. The reverse is true of the Fitz, as its adaptability to varying conditions is one of its strongest points. When water is scarce it will develop the full percentage of power, while with an abundance of water the wheel can be crowded far beyond its normal capacity. A turbine depends for its power upon the reaction or impulse of the water discharged under pressure of the working head. The pressure is due to the weight of the water and is proportional to the working head of water over the wheel. The higher the head the greater the pressure, and hence the velocity of the water discharged. The wheel must run at a certain proportionate velocity, the buckets must be curved at a certain angle, and the water must be discharged in a certain volume in order to do good work. All these points must be right in order to obtain even 60% to 70% efficiency. they are fixed by the volume of the stream to be used and the amount of water secured. Most streams are constantly varying in volume and it is impossible to supply the wheel with the same amount of water or to keep up the same head, so the conditions are seldom favorable for a turbine to reach its maximum efficiency. It cannot adapt itself to the changed conditions of diminished supply or lowered head. Consequently in dry weather, when economy of water is most necessary, the turbine is most wasteful, and will do practically no work at all. Of course we are aware that all turbine manufacturers table their wheels at 80% efficiency, or higher, and that nearly every one claims that he alone has solved the impossible problem of making a turbine to work equally well at partial gate as at full gate. These foolish claims are a result of conditions established many years ago. Since it is the universal custom, the turbine man who did not make such claims could get no hearing for his wheel. The customer has usually no means of testing his wheel and does not realize the outrageous discrepancy between the power promised by the turbine men, and the results actually attained. An interesting side light on some of the losses which make impossible the high efficiency of any turbine wheel is shown by the following extract from a book entitled "Turbine Water Wheel Tests," written by Robert E. Horton, and published (1906) by the United States Geological Survey, ("Water Supply and Irrigation Paper No. 180") page 22: "This waste (of the gross power of the water by the better class of turbines) is due t the following causes: (1) Shaft Friction. (2) Skin Friction on the Guides and Bucket Surfaces. (3) Leakage through Clearance Spaces, etc. (4) Terminal Velocity of the water on leaving the wheel. (5) Production of Swirls or Vortices in the water within the turbine, some of the energy being thus converted into motion which is ineffectual in producing power." Remember that these losses occur in every turbine. Some of them are quite important. Take for instance the one item of leakage through only one of the clearance spaces. Even a perfectly new turbine wheel has some clearance between the runner and the case. Water escaping through this opening under very heavy pressure and carrying sand and grit, soon enlarges this clearance until it is 1/4" wide or more. Take a 20" turbine inch 24 foot head. That means a stream of water 3.4" thick by 63" (the circumference of the wheel) under a pressure of 24 feet escaping all the time without ever going through the buckets at all. The gate leakage is also a heavy item of loss. The terminal velocity of the water discharged from any turbine is always great and denotes a considerable waste of power. Of course it is impossible to shape the buckets so perfectly as to divert all the energy from the water delivered to them, consequently a large part of the power always escapes to the tail race. Referring again to the cut, the reader will note the swirling motion of the water within the turbine, which occurs even under the most favorable conditions, such as when running at full gate., When the gates are partially closed, the direction of the water is slightly changed and the water no longer strikes the buckets at the proper angle. At such times the swirling motion is much intensified and a large part of the energy of the water is consumed in working against itself. This is one of the main causes of the great loss of efficiency which occurs in a turbine when it runs at part gate. The Fitz Steel Overshoot Water Wheel will deliver at least a third more power than the best turbine using the same amount of water, because it develops its power by utilizing the weight of the water in the simplest and most direct manner possible, instead of indirectly through impulse or reaction, as in the turbine. The water is received from the fore bay in such a manner as to utilize as much as possible of the impulse due to the head in the fore bay, and is retained by the correctly curved water tight buckets until it reaches the center again at the bottom, where it is discharged in a calm stream with all the energy extracted. There is no occasion for loss of power in this process; no splashing, no leaking or spilling too soon. If half the normal quantity of water is used on a Fitz Overshoot wheel it will develop half the power, or one fourth the power with one fourth the water, thus showing that its efficiency is unimpaired by the changed conditions. No power is lost by friction, for a child can turn our largest wheel with one hand. On an ordinary stream, in the course of a year's run, the Fitz Overshoot will do nearly twice as much work as a small turbine. It will give a third more power than the turbine at full gate, and at partial gate it will give two to three times the power, depending upon the quantity of water used. A great deal of trouble is experienced by turbine users in hilly or sandy localities where the frequent floods and freshets wash down great quantities of sand and grit, which are very hard on their wheels. The leaves, sticks and other trash which get into the buckets and choke up the narrow vents are also a constant annoyance and frequently stop the wheels. The turbine flume, if built of wood, requires constant attention and repairs. The gates are invariably leaky after a few months' use and waste a great deal of water. The complicated construction of some turbines make them particularly apt to get out of order, but they all give more or less annoyance in this regard. None of these troubles have any effect whatever upon the Fitz Steel Overshoot. There is nothing about it to break or get out of order. Every part is exposed to view and easily accessible, but the only attention required is to oil the bearing occasionally. The gate is as near perfection as possible for anything which has to work in water, and owing to its simple construction will remain for years just as tight as the day it was put in. The large buckets cannot possibly choke up no matter how dirty the stream is, for anything that will pass through the gate will pass over the wheel without the slightest injury. The condensed experience of thousands of water power owners shows that if you have more water at all seasons of the year than you can use, so that economy of water is no object to you, then you can use a turbine satisfactorily, provided you are not greatly troubled with sand or trash in your stream. But if you want to get all out of your water power that there is in it; to develop the highest efficiency at all times, no matter how low the water is; if you want durability and freedom from repairs; economy and satisfactory results, then the Fitz Steel Overshoot Water Wheel is the only wheel on the market worthy of your consideration.
The wood overshoot still survives as an active competitor of the small turbine in some parts of the country. On a light stream, as well made wood wheel will often give better results than a turbine, but it always falls far short of getting the full possible power from the water. Wood is not a fit material to use in building a water wheel. A high efficiency wheel must be made of metal. Wood overshoots have been built for centuries, but up until the advent of the Fitz, an efficiency of 75% was considered the limit for an overshoot wheel of any kind. Mighty few wood wheels ever approach that efficiency today. The buckets of a wood wheel cannot be shaped to a suitable curve to receive and discharge the water properly. A wood wheel is invariably out of balance and its jerky motion is destructive to good results from the machinery it operated. The constant swelling and drying of the wood soon causes all parts to get loose; the buckets leak; and a considerable proportion of the energy is wasted. In a steel wheel, the buckets can be shaped to suit the design required. The Fitz steel bucket is shaped so as to receive the water at the crown of the wheel with the least possible shock. It retains the water to a point just a little above the level of the tail race. In other words, the water gets to work on a Fitz wheel at least three buckets earlier than it does on other wheels, and it stays on the wheel from three to ten buckets longer, depending upon the diameter of the wheel. A wood wheel gets no benefit from the head of water over the top of the wheel. In order to put the water into the thick straight, wood buckets, the chute is generally slanted a good deal and the water is allowed to "drop" on to the wheel in the manner illustrated on page 31. The water consequently strikes the wheel at an ineffective angle and its energy is dissipated in shock, instead of being communicated to the wheel. This loss is more serious than the casual observer would suppose. In the case of a 14 foot diameter water wheel, for instance, the total head is usually at least 16 or 16 1/2 feet. Two feet of that total head are in the depth of the water in the fore bay over the top of the wheel. If the water wheel does not utilize that 2 feet of head (and a wood wheel never can), then it is wasting 12 or 12 1.2% of the power at this point alone. The illustration of the steel wheel on this page, or better yet, the larger cut on page 18 will show clearly how the water is applied to a Fitz Wheel. Our steel chute is set nearly level. The water guides over the smooth steel with very little loss of friction, and shoots into the steel buckets in a direction just tangent to the crown of the wheel. Its energy is thus applied to the wheel at the most effective angle. The buckets are given just the right curve to enable them to receive the water with the least possible waste of power by "shock." Study the photos on pages 17, 31, and 36 showing Fitz Wheels, photographed while running, and compare these wheels with the splashing, sloppy, leaky wood wheels to be found everywhere. In cold weather, ice gathers on the arms and shaft of a wood wheel, putting it to a terrible strain and often causing it to stop running. Every one who has attempted to cut ice from a wood wheel knows what a difficult and dangerous job it is and how frequently it must be done on a severe winter. Wood is a non-conductor of heat and altho the water which is running over the wheel is usually warmer than the freezing point, the wood wheel will gather ice rapidly along its housings and arms. The water splashing over the sides of the wheel freezes on the shaft and walls. The ice freezes right into pores of the water soaked wood, and is very difficult to dislodge. Ice does not affect the steel wheel, because steel is a good conductor of heat. The steel buckets readily assume the same temperature to the housings and soling, so that no ice will gather on the wheel while running. Even if, thru a leaky fore bay, some ice is allowed to form on the wheel standing idle at night, that ice will wash off the wheel when the water is turned on in the morning. Ice cannot get into the pores of the steel, and hence has no opportunity to cling to it like it does to wood. In very cold countries, we house the wheel in, so as to protect it from the cold winds. The friction of the running water;liberates a certain amount of heat in the wheel room and prevents any trouble from anchor ice. The freedom of the Fitz Wheel from ice of all kinds is one of its strongest points. Neither the turbine nor the impulse wheel can compare with it, in its immunity from trouble with slush ice or frazil ice. Our wheels are in most successful use all along our extreme northern border and in many provinces of Canada, in situations where a wood wheel would be impossible, and where turbines have proven very troublesome on account of ice. About six inches of the fall is usually wasted in the slant of a wood chute and the clearance between the floor of the chute and the inside of the buckets. This space is all saved in a steel wheel. Several inches can be frequently gained at the bottom of the wheel for the reason that the steel buckets require less clearance from the tail race. We build all our wheels to suit the locations where they are to go and are glad to advise out customers as to the proper size to fill their individual requirements. A wood wheel is completely paralyzed by a little back water. Our smooth steel buckets create much less friction than wood buckets when wading in back water. They are ventilated so as to avoid creating a vacuum when discharging the water, and consequently do not suck up water as a wood wheel does. We rate our wheels at the power they develop with buckets filled only 3/4 full. When it is necessary for them to run in back water, the buckets can be filled up full. One of our 17 foot diameter wheels driving the pumping plant of the Hanover & McSherrystown Water Co., near our town, frequently wades in back water to depth of six feet without affecting its work. Water is plentiful at such times and more can be used on the wheel to overcome the loss of head. A water soaked wood wheel weights three times as much as a steel wheel and the friction of the bearing is many times greater. Standing idle for one day, the wood wheel absorbs water on one side and is then out of balance. Its jerky motion wastes both water and power. No machinery requiring a smooth, even speed can be driven successfully with it. It is impossible for a Fitz Wheel to get out of balance. It runs so smoothly that its speed can readily be controlled by the Fitz Automatic Water Wheel Governor. The life of a wood wheel is short, not much over ten years as a rule. The old time wood wheels lasted longer, but the old time material is no longer available, and the old time millwright is fast disappearing. A FItz Wheel will out last a number of wood wheels. The metal wheels built in 1852, at our shops at Martinsburg, W. Va., are still in active service today. The one excuse that a wood wheel has for existence today, is its supposed cheapness in first cost. Even that claim is frequently without foundation. The manifold advantage of steel wheels in every other respect will far outweigh any difference in cost, to the man who is looking for actual value.
A horse-power required to raise 33,000 pounds one foot per minute. To compute the hors-poweer of any stream, multiply the number of cubic feet of water it flows per minute by 62 1/3 (which is the weight in pounds of one cubic foot). Multiply that product by the head (in feet) and divide the product by 33,000. The quotient will be the full horse-power of the stream. Most turbine manufacturers claim that their wheels will develop 80% efficiency, but it is well known that very few of them in actual use will ever reach 70% efficiency, and then only under the most favorable conditions. The Fitz will develop from 90% to 95% efficiency, depending upon the diameter of the wheel; or at least one-third more power than any other wheel using the same amount of water. It will develop just as high efficiency at one-third or one-fourth capacity at it will when run at normal capacity. A turbine will do practically no work at all when run much below full gate, so that in the course of a year's run on a variable stream, the Fitz will develop twice the power of the most economical turbine.
The EFFICIENCY of a water wheel is the actual horse power which it develops with a certain amount of water as compared with the power which it is theoreticall possible to develop with the amount of water. It is impossible to develop the full theoretical power, for there must always be some loss, but the nearer a wheel approaches this performance, the highter the efficiency. Thus when you have calculated the horse power a stream affords by one of the methods we have described, you can depend on nearly 95% of this power if a Fitz is used, or only 60% to 70% if a turbine or wood wheel is used. This difference in efficiency becomes much greater when it is necessary to run at part gate or after the wheel has been used a few years. BACK WATER occurs when the tail race from the mill becomes clogged or choked so that the wheel has to wade in the water it discharges. The greatest care should be exercised to avoid this condition. The JACK SHAFT is the shaft which carries the pinion wheel which gears into the segment gear, or master wheel. The SEGMENT, or SEGMENT GEAR, as the name indicaes, is a gear wheel composed of a number of pieces which are segments of a circle. It is bolted to the arms or housing of the water wheel. The segment gear, as we make it, is quite a different thing from the crude and troublesome device employed on old wood wheels. A PINION is a small gear wheel which gears into a larger one. The MAIN DRIVE PULLEY is the large pully or belt wheel that usually goes on our jack shaft and carries the belt that drives the line shaft to proper speed. The CHUTE is the short trough of wood or iron which conveys the water from the gate to the buckets of a water wheel. It is generally three feet long. A MASTER WHEEL is a large cog wheel that is keyed to the water wheel shaft instead of being bolted to the arms of the water wheel like a segment gear. It can be furnished either in the spur gear type or in the bevel gear type with cogs. The TIGHT IRON GATE that we furnish with out water wheels is an ironregulating gate to control the amount of water admitted to the water wheel and to cut off the delivery of water when the wheel is to be stopped. It is made of cast iron and is simple in design and construction, but we use the greatest possible care in machining it. A good tight gate is of very great improtance in securing the utmost economy in the use of water, and we believe our gate fulfils every requirement in this respect. Our STEEL TANKS and PIPE are almost as far ahead of the old style fore bay as the Fitz is ahead of the wood wheel. Iron pipe is used to convey the water from the dam or race way to the tank, from which it is discharged to the wheel through out water tight iron gate, thus making a complete and permant water tight job. This method of conveying the water is immensely more satisfactory than the use of dirt race ways, which are always breaking out, and wood flumes, which are always rotting. In many cases, too even the first cost is less than that of the leaky wood flumes.
One cubic foot of water...............................62.378 lbs. One cubic inch of water.................................0.36 lbs. One gallon of water....................................8.338 lbs. One gallon of water.............................231 cubic inches One cubic foot of water............................7.476 gallons One pound of water.............................27.7 cubic inches Water falling is actuated by the same laws as falling bodies; passing through 1 foot in 1/4 of a second, 4feet in 1/2 of a second, 9 feet in 3/4 of a second, and so on. Hence its velocity in flowing through an aperture in the side of a reservior, bulkhead, or any vessel, is the same as a heavy body falling freely from a height equal to the distance from the middle of the aperture to the surface of the water. To find the loss of head by water entering a pipe in which the mouth piece is straight, multiply the square of the velocity by .0076 and the product will be the approximate loss in feet. The loss of head by friction in a pipe increases directly with the length, with the square of the velocity, and with the roughness of the pipe. It decreases as the diameter of the pipe increases and is independent of the pressure or head of water. To find the loss in feet: Divide the product of the length and the square of the velocity in feet per second by the diameter in inches and then multiply the quoient by 0.0056 for pipes up to 6 inches dameter; by 0.0047 for pipes between 6 inches and 21 inches in diameter; by 0.0037 for pipes between 21 and 48 inches in diameter; by 0.0028 for pipes between 48 inches to 72 inches in diameter, and by 0.0019 for pipes larger than 72 inches diameter. This formula will give approximate results within at least 10% of correctness for smooth straight pipe. Roughly speaking, the loss of head in 100 feet of pipe is equivalent to one half the velocity squared, divided by the diameter of the pipe in inches. To find the friction head necessary to give a required velocity in an open flume or canal; Multiply 0.001 the lenght in feet by the square of the velocity in feet per second, and by the sum of the two side measurements, the bottom width and one tenth the top width; and finally divide the product thus obtained by the number of square feet in the section of the stream, and this quotient will be the loss of head in the stream in question. One acre foor equals 12 acre inches, equals 43,560 cubic feet, equals 325,829 gallons. A flow of one second foot will produce one acre inch in about an hour. One pound per square inch pressure is equivalent to the pressure of a columm of water 2,31 feet in height. A columm of water one foot in height produces a pressure of .433 pounds per square inch.
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