Lonp•r's the vane-shaft in Lempeke's wind-wheel (fig. 9) there is a movable collar, which is connected with the vanes at their outer ends by chains, and by means of horizontal and vertical drawing-rods with another movable collar, which encloses the vertical support and is connected by a chain to a weighted lever suspended from it. As the vanes are fastened to the whips, and as the latter are elastic, there is produced by the described mechanism, through the elastic whips, the loaded lever, and the force of the wind, an inclination of the sails suited to every velocity of the wind. Moreover, it may be noted that the shiftable collar on the vane-shaft acts at the same time on a lever-mechan ism which effects an automatic breaking, while the fork-like lever placed below it admits of a breaking by hand. The vertical driving-shaft is enclosed by a hollow cast-iron column, which is supported by an encir cling ring attached to the four brace-irons firmly secured by screws to the fixed wooden frame. The wheel is turned to the wind. by a vane (not shown in the illustration).
American principle of American windmills differs essentially from that of the above-described European mills. Figure 6 (IL 71) exhibits a self-acting wheel which has the proper amount of speed in ordinary winds; but if the current is too strong, the wheel is forced partially around toward the rudder, in which position it continues to work at a regular speed, and automatically returns to its normal position when the force of the wind abates. If, however, the velo city of the wind becomes very great, the wheel is folded around by the side of and parallel to the rudder, thus presenting the edge of the wheel to the wind, where it remains at rest until the wind-storm ceases, when it again resumes its position face to the wind. The wheel can be stopped at any time by means of the weighted gear-lever, to which is attached a wire passing down through the centre of the turn-table and swivel and attached to a lever at the bottom of the tower. By simply releasing the lower lever the weighted lever brings the wheel again into position, ready for working. The operating mechanism of the mill is fastened to the frame or tower by an iron cap covering the upper ends of the timbers, to which it is strongly secured. The wind-shaft carries on its inner end a crank-wheel, which operates a curved bar attached to a connecting-rod.
are two general classes of American wheels, which are known as the " open wheel " and the " solid wheel." The former is so constructed that each section tilts or turns separately, while in the latter the entire wheel is solidly put together, with the sec tions immovable. Of the latter type, Figure 8 exhibits a twist-slat wheel which has radiating fans or slats set in double rims, and is so con structed that their slant or pitch varies from the centre to the circumfer ence. As the circumference of a wheel travels a greater distance, and consequently faster, than the parts nearer its centre, the flatter the fans or sails are laid at this point the less resistance there is to the rotation of the wheel; and by giving the slats a longitudinal twist nearly uniform width of slats may be used, which gives to the wheel the greatest surface-area for receiving the impulse of the wind.
The " so called (fig. 5), is constructed on the turbine
principle, which is that a current of water in its descent will follow a curved surface and reach a given horizontal plane in the same time that it would take to pass over a gravitating curve, although the actual distance of the former curve should be much greater than that of the latter. In accordance with this principle, the wind does not lose its force on its first contact with the buckets of the wind-whccl, but, like the current of water following a curve, continues its impulse until it escapes from the periph eries of the buckets. The latter, which are made of smooth, solid iron, are firmly bolted to the flattened ends of iron pipes, which form the spokes of the wheel and are laterally and diagonally stiffened by tie-rods. The hub is fitted and secured to the shaft by set-screws and bolts. The vane-socket is hinged to the turn-table, which is connected by a rod with an eccentric attached to the turn-table by a vertical bar. The leverage obtained by the vane through the peculiar arrangement of the eccentric holds the wheel to the wind; and when the wind, by reason of its extra pressure during a storm, forces or shifts the wheel around parallel with the vane, the lever age brings it again into position, thus making the engine entirely self-reg ulating. There is also provided a brake, which prevents the revolution of the wheel when "out of wind." The power is transmitted from the main shaft by a crank-wheel and a connecting-rod combined with a bent lever, which is connected with the vertical rod.
The Challenge I1Ynchni11 (Jl. 72, jigs. 1, 2) differs from all others in that it has two power wind-wheels and two small wheels that operate a screw which keeps the faces of the power-wheels perfectly to the wind at all times. The two power-wheels are connected with separate shafts, both in the same line, and turn in opposite directions, carrying the main driv ing-gear at the end of each shaft, which centres the turn-table. These gears engage a centre pillion in the turn-table, communicating the power of each wheel to opposite sides of the pinion, thereby driving it in the same direction. From this point the common system of shafts, pulleys, and belts is brought into use to reach the machinery to be driven. The two small,Nyheels on each side of the power-wheels are attached to one shaft, transversely to the power-wheel shafts, and both aid in operating a screw or worm, which engages a segment that encircles the chair or bed plate upon which the turn-table, with all the mechanism, rests. When the wind radiates from a line parallel to the face of these wheels, it acts upon them, and they revolve until the screw traverses the circle segment sufficiently to bring the wheels into line with the wind; when this is accomplished, they rest. The power-wheels are then at a perfect right angle to the wind, and they cannot change from that position except by a change of wind to act upon the side wheels. The mechanical construction of this wheel is such that uniformity of power and of speed is maintained in all degrees of wind above the minimum by the adjustment of a weight upon a lever in reach of the operator, the power being commensurate to the resistance of tie weight according to its adjustment on the lever.