Popular Science Monthly/Volume 18/December 1880/Domestic Motors I
THE situations in which a motor of comparatively small power can be used with advantage, and in which it is a necessity even, are already very numerous and are constantly increasing. Not only has it a proper place in the workshop, in the business house, and on the farm, but in the household as well it has a wide range of utility. The need for such a machine in our homes, created by the sewing-machine, has been strengthened and increased by various other appliances in use or coming into use, while such devices as fans for cooling rooms in summer and ventilating them in winter further add to the requirement. In suburban and country residences, and on the farm, the primary need is for pumping water, and this alone renders a light and economical power almost indispensable. For the performance of most of the other mechanical operations upon the latter it is also of the utmost value. In the field of small industries the uses to which such a motor can be turned are as numerous as the varied occupations of the workers. The necessities of numbers of amateurs further increase the range of activity for such a power. The kind of machine that is suitable to the varied needs of these different classes of users necessarily differs in each. In most trades the demand for power is for one of from two to five horse and above, and on the farm a serviceable machine could not generally be much if any less; but in the household that desired is rarely above one horse, and generally under it. A more complicated machine can, moreover, be used with success in the workshop than in the household, as in the latter it would generally
be in the care of attendants but little, if any, skilled in the use of machinery. Certain general conditions are, however, common to all. The work for which it is needed is generally of an intermittent character, and this necessitates a machine that will always be ready for work, or that can be made ready with but little trouble at short notice, and that is no expense, or but very small expense, when not being used. It needs further to be perfectly safe, economical in use, of low first cost, and to require but little care, and that of a kind which can be given by unskilled labor.
The attempts to make a machine that would answer to these varied requirements have been many, and they have been crowned with greater or less success. Though it can not be said that the ideal motor has been produced, still there are at present made and on the market a number of machines of real merit, and some of great excellence, that are all well adapted to the needs of users of light power, including the householder. While in large manufacturing only two machines—the water-wheel and the steam-engine—can be used, for the purpose of these small powers the range is much greater. Wind and water, steam, hot air, gas, and electricity, are all suitable and are all to a greater or less degree available. I propose in these papers simply to make a brief description of some of the more promising and successful machines now on the market, and give such information regarding the sizes in which they are made, cost of working, and prices, as will be of value to the householder and others having use for such a power.
Though the windmill is one of the oldest of the appliances by which man has sought to turn to his use the powers of nature, it remained until a comparatively recent period a very crude and cumbersome machine. In the earliest form, the wheel was fixed so that it could only turn when the wind was in the right direction; and later, when it was made movable, the shifting had still to be done by hand as often as the wind veered. Successive improvements were, however, slowly made, the chief ones being the addition of a rudder-vane placed directly behind the wheel in a vertical plane at right angles with its face, and a centrifugal governing device by which the canvas sails were furled and unfurled as the wind varied in strength. The pressure of the wind upon this vane automatically shifted the wheel into the wind, and the action of the governor presented to it a greater or less surface of the sails, securing a uniform velocity with varying wind-pressure. Even with these great improvements the windmill remained a clumsy affair until it was developed by American skill and ingenuity into the present very serviceable machine. As now made it is light and strong, and entirely automatic in answering to the varying direction and pressure of the wind. The canvas sails have given place to light wooden slats arranged radially around the wheel at short distances apart, and the whole mechanism has been simplified and vastly improved both in construction and design. The tower is an open-work structure of wood or iron, easily erected and taken down when desired.
Two methods of regulating the extent of wheel-surface exposed to the wind are now in use, the one acting by centrifugal force as in European mills, and the other by the direct pressure of the wind against a side-vane. In centrifugal mills the wind-wheel consists of a number of radial arras firmly secured in a metal hub, with sections between them pivoted so that they can swing into a position in which the ends of the slats only are exposed to the wind. They are held in the plane of the wheel by a counterweight, and thrown out of this position by the action of a ball-governor. This governor may be placed in various positions on the wheel, and act upon the movable section directly or through the medium of connecting rods. In one form of wheel the balls are placed upon the framing so that when the wheel is at rest they hang down upon its face, but as it revolves fly out, and in doing so turn the sectors. The angle at which the wheel-surface is exposed to the wind is thus altered with every variation in its velocity, and the motion of the wheel consequently kept nearly uniform, in a manner similar to that of a steam-engine. When the wind attains a velocity greater than a certain number of miles an hour, the action of the governor keeps the slats in the position in which their ends are alone exposed to the wind. The velocity at which the wheel will completely close can be regulated by the counterweight, which is movable on its arm by means of appropriate connecting rods, from the base of the tower.
This method of regulation has been found to answer very well in practice, but it has several grave objections. The construction is necessarily such that there are a large number of joints on which the wear is very considerable; and with so many movable parts the liability to derangement is greatly increased. The failure of any of the parts during a high wind would endanger the safety of the wheel, and perhaps cause its destruction. The second form of mill, that using the vane-governor, is much simpler in construction, has fewer parts, and is consequently more durable. It is, therefore, to a considerable extent supplanting the older form. The wheel in it is solid—that is, without movable sections—and is turned about a vertical axis in such a way that its angle with the direction of the wind varies with the pressure of the latter. The devices by which this is accomplished vary somewhat in different mills, but the method is essentially the same in all. In one, a small vane, placed back of the wheel, is hinged upon the frame of the large rudder-vane, and when the wheel is at rest hangs vertically downward. It is connected by means of rods with the wheel in such a way that, when the pressure on this exceeds a certain amount, the vane will be raised toward an horizontal position. In so moving it turns the wheel by suitable mechanism toward the rudder-vane, when the pressure of the wind is sufficiently great the small vane is raised to an horizontal position and the wheel swings parallel with the rudder. The whole apparatus, wheel and rudder, then becomes simply a weather-vane, is exposed as little as possible to the wind, and is in the best position to escape injury when this is very high.
The wheel can be adjusted to close at any desired wind-pressure by means of a sliding weight upon the arm of the small vane. It may be turned by hand edgewise to the wind by a chain passing to the ground. The working parts of another vane-governor mill of excellent design are shown in Fig. 1. A portion of the wind-wheel is represented at L L, the rudder-vane at M, and the small governor-vane at N. This latter is in a plane parallel with the face of the wheel, at a slight distance back of it, and extends beyond its edge. The wheel is supported upon an iron frame, 1, which turns within the tubing 17 and the additional bearing 18. The wheel-shaft passes through the
bearing 2 and gives motion to the pump-rod by a crank, 10, as shown. To one side of the frame 1 a weighted lever is pivoted, which terminates in a toothed segment. This gears with a curved rack on the frame of the rudder-vane, so that, moving the lever upward, the rudder and wheel approach each other. The chain 35 passing over the pulley 20 allows this to be done by hand when desired, through a lever upon the lower end of the rod 25. This movement is the one which takes place when the wind-pressure upon the small vane is sufficient, the wheel swinging round toward the rudder-vane an amount proportional to the pressure. When this pressure is great the wheel swings parallel with the rudder and presents only its edge to the wind, as in the case of the other vane-mill. The weight 13 is movable upon the lever 26, and the wheel is therefore capable of nice adjustment.
Windmills have gone very largely into use in the Western States, where the wind can be counted on with tolerable certainty. They are also used to a considerable extent in the East, both in the country and in the cities. Makers of wheels claim that in most localities they will work up to their full power seven hours out of the twenty-four, and a good portion of the remaining time will give some part of their full capacity. When a steady and continuous power is required, either at a definite time or whenever you happen to want it, the windmill is not suitable; but for all uses in which such conditions do not hold, such as pumping water, it is admirably adapted. It is for this purpose employed on railroads, the farm, country seats, and to some extent in cities where the water-pressure is insufficient to carry the water to the upper stories of buildings, as many as five hundred being employed in New York City alone for this purpose. On the farm it would seem that a mill might be employed for a variety of purposes besides the pumping of water. Such operations as sawing wood, chopping feed, and perhaps churning, might readily be done by wind-power, by timing them to the periods when experience showed it could best be depended upon. With a well-constructed automatic mill of from two to five horse, such work could probably be performed with less trouble than in any other way. The only expense after the first cost is that for repairs and lubrication, neither of which is large. The power of any wheel depends, of course, on the velocity of the wind. They are usually rated with the wind at twenty miles an hour, and on this basis the powers of those made range from one eighth to forty horse, the smaller size being eight and a half feet in diameter and the latter sixty. The first cost of a good mill is from twenty-five to fifty per cent, higher than a steam engine of corresponding power, with boiler.
While the windmill is peculiarly well adapted for pumping and allied purposes, it is not at all suited to most of the uses for which a small power is required. Water-power, on the other hand, is excellently adapted to such uses. Water-wheels are simple, easily managed, and the most efficient of known motors. They are especially suitable for use in the household, and, where sufficient water can be procured under a proper pressure, are at once the cheapest and most convenient motor for the shop. Water-wheels of large power, such as are required in manufacturing operations, can only be used in particular localities; but those of comparatively small power can, owing to the very general introduction of water under pressure into buildings in cities and towns, be used in very many places. As, however, the supply that most waterworks are capable of furnishing is not at any time greatly in excess of the demand, wheels adapted for use upon house-pipes have to be, first of all, economical of water. They should also be constructed so that they are not liable to injury by water freezing in them, and be of low first cost. Several different wheels, designed to meet these requirements, are now made, and have been more or less widely introduced. One of the best of these, and one which has met with considerable favor in the market, is that shown in Fig. 2, the invention of Mr. O. J. Backus. It is exceedingly simple in construction, and has proved very satisfactory in use. It consists of a light but strong wheel, carrying buckets or vanes upon its rim, against which a jet of water impinges. The wheel is inclosed in an iron casing in which it revolves freely, the only points at which there is any friction being the bearings of the shaft. The manner of using the water constitutes the special feature of the motor, and is one that peculiarly adapts it to use on service-pipes, as it reduces the consumption to a minimum. In the wheels used in manufacturing, whether of the turbine or other pattern, motion is imparted by the continuous pressure of a considerable body of water. In this the motion is due to the successive impacts of a small jet having a high velocity, which allows of considerable work being performed with comparatively little water, as the striking force of the jet is utilized. In the smaller sizes of these motors, those capable of running a sewing-machine, the water jet is but one sixteenth of an inch in diameter, while in the largest machines it does not exceed half an inch. A steady and uniform motion of the wheel is attained by placing the buckets very close together, so that the impulses follow each other in rapid succession. The water enters the wheel-casing at one side and escapes at the bottom, traversing but one quarter of it. As there is nothing to impede its flow, none can remain in the wheel and freeze in cold weather. The motors are manufactured in sizes varying from seven to forty-five inches' diameter of wheel, and from about one eighth to eight horsepower. The power obtained depends of course upon the pressure of the water, but they are designed to run at any pressure above fifteen pounds per square inch. This is easily obtained, as at most places where there are water-works there is a pressure of from twenty to forty pounds, and at some a much higher one. The manner of applying the motor to a sewing-machine is shown in Fig. 3. Perfect control over the supply of water is given by a valve operated by a treadle, which enables the operator to stop and start the machine as readily and quickly as by the ordinary foot-power. This method of regulating the speed of the machine has the great advantage that only the amount of power required is at any time used, thus saving the water to the utmost.
In a similar manner it can be used to drive any sort of light machinery, scroll-saws, dental engines, jewelers' lathes, coffee-mills, etc. One of the uses to which it is peculiarly well adapted is the blowing of organs. By a very simple mechanism the performer is given complete control over it, so that the bellows may be kept continually full. Among the heavier uses to which it has been applied are the running
of printing-presses and the lifting of merchandise elevators in business houses. To all these uses it is in every way adapted, as it is always ready for use, is no expense except when running, needs no care, and is without danger. The extreme simplicity of the motor enables the makers to place it on the market at a very low first cost, varying from fifteen dollars in the case of the seven-inch to two hundred and seventy-five in that of the forty-five inch double wheel.
The cost of operating these motors depends upon the locality in which they are used. In New York and Philadelphia the insufficiency of the water-supply prevents their use at all, but in most other places in this country they can be used at but nominal rates. The average charge made by water-boards is from fifty to seventy-five dollars a year per horse-power, while for those used on sewing-machines the charge varies from three to six dollars. The cost for organs is between twelve and twenty dollars for the same time. When the motors are used for business purposes, their owners can usually get special rates depending upon the time they are actually employed. This price per horse-power is not greater than that of steam-engines of large size, and is very much less than the cost of any other form of motor of small power. This price is, however, based upon a condition of water-service which could not hold were the motors much more largely used than at present. The greatly increased demand for water that this would make would necessarily raise the price charged, but it could be very much increased and still leave these motors the most economical of small powers.
Another wheel of a somewhat peculiar construction, invented by Mr. Talley, is capable of being used either as a turbine or an overshot. The water is applied in such a manner that it strikes the wheel in a thin sheet, the sheet being undulating and wave-like in form, and impinging edgewise upon the wheel. The circumference of the wheel is provided with buckets set so as to make an angle of thirty degrees with the radial lines. The flanges forming the sides of the buckets are scalloped out to allow the water to freely escape when the wheel is employed in the former way. The wheel is set eccentric to its casing, approaching it closely on the inlet side. The casing in this portion has a number of curved channels terminating in the face opposite the buckets in a sinuous slit from which the water issues upon the wheel. The inlet-pipe enters this wave line chute at the top of the casing, and the water is distributed throughout it by ducts terminating at different points. A valve at the top admits the water to one or more of these ducts as desired. The wave-line slit in the casing is wider near the top and gradually narrows toward the bottom, so that there is a greater weight of water on the wheel at the upper part, and the water issues with a higher velocity lower down. The sheet of water exerts a continuous pressure upon the wheel instead of moving it by successive impacts as in the case of the former motor. An outlet in the base allows the water to pass oft' when the wheel is used as an overshot, and one in the side of the casing provides an exit when it is used as a turbine. The wheel is said to be quite economical of water, and to run easily.
For light pieces of machinery, such as the sewing-machine, various sorts of spring motors have from time to time been devised, though none of them seem to have been brought into use. They are not properly motors, and are really quite valueless for the purpose of power, unless it be very slight, as that required in clocks. They are capable of giving out but a small amount of the power expended in winding them up, and, as this labor has to be done by hand, are very uneconomical. A weight is a much better device, and yields a large per cent. of the power expended in raising it when it falls. Such an arrangement is, however, a thoroughly impracticable one, as a simple calculation will show. It takes about four hundred foot-pounds per minute to drive a sewing-machine, so that to run one an hour a weight of a fifth of a ton would have to fall sixty feet. The only practicable way of utilizing gravity for motive power is by the water-wheel, where the weight can fall continually, and the cost of raising it again is a minimum.