Again we are indebted to Mr. Vic Wintermantel of Box 4200, Bellevue, Pitts burgh 2, Pa., for getting us the Patent Office description of the Arnold Valve Gear. Sometime ago he furnished the Geiser Valve Gear description that operated with a hand wheel and belt. We know you will aprreciate this work. Mr. Wintermantel is a successful flour broker and an authority on valve gears.
To All Whom It May Concern:
Be it known that I Bishop Arnold, a citizen of the United States, residing: at the city of Auburn, in the county of Cayuga and State of New York, have in vented certain new and useful Improvements in Steam-Engine Valve-Gears, of which the following is a specification.
B. ARNOLD., STEAM ENGINE VALVE GEAR., No. 298,438., Patented May 13, 1884.
Heretofore among the defects in the valve-operating mechanism of steam-engines has been the condition that the reversing mechanism was constantly subjected to wear while the engine was in operation a fact noticeable with the various link-motions and that in consequence of wear and lost motion in the valve-gears and actuating mechanism the movements of the slide-valves become deranged, which causes variations in the throw and lead of the valves, and unequal admission and distribution of steam. Again, the parts have generally been numerous, complicated, and costly to construct.
The object of my invention is to pro vide in the valve-operating mechanism of a steam-engine a reversing mechanism, in combination with a variable cut-off, for controlling the admission and distribution of steam to the cylinder that stall be simple and cheap to construct, durable and efficient to operate, with ready means of adjustment in case of wear or slight imperfections of workmanship, with the parts so arranged and operated that the throw of the eccentric may be varied, and in which the reversing mechanism is not subjected to wear when the engine is in operation. I attain these objects by the mechanism illustrated in the accompanying drawings, in which
Figure 1 is a plan view of the entire device. Fig. 2 is a vertical longitudinal section of the same- Fig. 3 is an end view of the eccentric and disk, showing the shaft in section. Fig. 4 is a diagram illustrating the throw of the eccentric. Fig. 5 is a horizonal cross-section of the eccentric through the dotted line x x shown in Fig. 3. Fig. 6 is an end view (next to the eccentric) of the disk. Fig. 7 is an edge view of the disk. Fig. 8 is a view of the strap having trunnions, and adapted to fit the peripheral rib on the sliding sleeve. Fig. 9 is a horizontal section of the sliding sleeve, showing the rack connected thereto. Fig. 10 is an edge view of one of the ways attached to the disk, and Fig. 11 is a plan view of the sliding sleeve and the rack connected thereto.
Referring to the letters upon the drawings, in aid of a detailed description of my improvements, D indicates the driving-shaft of an engine, and A an eccentric of peculiar construction connected to the shaft in a particular way, and, as usual, rotating with the shaft. This eccentric is in practice connected in any suitable way with the slide-valve of a steam-cylinder for opening and closing its ports; and I have not illustrated such connecting or valve mechanism be cause it is well understood and forma no part of my invention.
My invention consists in the peculiar construction of the eccentric and its connected parts upon the shaft for securing the useful results above recited, and is succinctly summed up in my appended claims.
My eccentric is an annulus or short hollow cylinder, having cast within it at one side a segmental body of metal, d, provided with inclined teeth N, and having at one end suitable shoulders, supports, or guides B, adapted to admit of a sliding motion of the eccentric, in a direction transverse to the axis of the shaft.
C indicates a disk or other suitable support for guide ways O P, of any suit able character, secured to the disk by dowel-pins Q (see Fig. 10) and screw bolts R, or otherwise, and adapted to receive or serve as bearings or support for the guides O P, and to sustain the eccentric and admit of its transverse sliding motion, as above mentioned, so as to shift its position and vary its eccentric city to the shaft. The disk C may be provided with a hub, T, and a set-screw, e, for securing it to the shaft, or it may be otherwise fixed to the shaft in any suitable way.
It will be observed that the eccentric has no connection of any of its parts directly to the shaft, and that it is only indirectly connected to the shaft through the instrumentality of the disk C and the guide ways O P and guides B. The result is that while it always rotates with the shaft and disk it may be slid back and forth at will transversely to the shaft, or it may be adjusted transversely to any desired position with respect to the shaft, and there fixed by means of a set-screw, f, and operated in that position as long as required.
In order to cause the shifting of the eccentric at will, when the set-screw f is not screwed down to hold it at a given point, I provide a sliding rack-bar, L, having inclined teeth M, adapted to mesh with the inclined teeth N of the eccentric. This rack-bar is fitted into a suit able longitudinal slot in the shaft, (see Fig. 2,) and may be provided with any suitable means to enable an engineer to reciprocate it in its slot. It will be seen that as the rack-bar is moved back and forth along the shaft, it will cause the eccentric to slide back and forth trans versely in its ways an other words, in a direction at right angles to that of the movement of the rack-bar. This will en able the engineer to instantly adjust the eccentric in any desired position with reference to the shaft, and it is obvious that the valve operation by the eccentric will be affected in its movements accordingly.
While, as above stated, any suitable means may be adopted for sliding the rack-bar back and forth, I prefer the means illustrated in the drawings, where is shown a sliding sleeve, F, secured to the rack-bar by means of set-screws g, and having a double-inclined annular projection or peripheral rib, G. Around this sleeve and rib is provided a fitting strap, H, having a V-shaped groove, and composed of two parts united by screw-bolts h, as shown. Tins construction of the sleeve and strap may be modified at will; but it is well adapted to retain a lubricant, exclude dust and dirt, and admit adjustment by means of the screw-bolts When worn. The strap H is provided with trunnions J, to connect it with the bifurcated arms of a bell-crank lever, K, or such other suitable mechanism as may enable it to be easily controlled by an engineer.
S indicates a section of a lever, which may be. employed to move the bell-crank lever, and consequently the sleeve, rackbar, and eccentric. It will be observed that the shaft turns the sleeve within the strap H, and that all of the parts except the strap and its operating-levers revolve with the Shaft. The result is that, by means of the levers just de scribed, an engineer is given perfect control of the position of the eccentric with reference to the shaft. He can set it and retain it at a given point, or he can move it back and forth within the range of its sliding capacity at will. The longitudinal motion of the sliding sleeve F upon the shaft D is changed by means of the connected rack L, having inclined teeth M, meshing in corresponding teeth. N, in the eccentric A to a transverse or diametrical motion of the eccentric upon the face of the disk C.
It is to be understood that the con struction and relations of the eccentric and its connections to the shaft are such that the center of the eccentric must always be away from the center of the shaft a distance equal to the amount of lap and lead of the valve. In Fig. 4 the distance from the center of the shaft D to line a b indicates a distance which may be assumed to be equal to such lap and lead in a given case.
In order to take up lost motion and compensate for wear or imperfections of workmanship, I provide adjustable stops E, consisting of set-screws provided with jam-nuts, as well shown in Fig. 3. Those set-screws project into the hollow part of the eccentric on opposite sides of the shaft, and are adjusted to define the proper limit of sliding movement of the eccentric in its supports. At its mid-position and least eccentricity, the eccentric, having an amount of throw equal to the lap and load of the valve as it is moved in either direction from this
position When in motion, acquires an amount of throw and the valve a corresponding amount of travel equal to the desired opening of the ports. Consequently, steam may be cut off at any desired point of the stroke by shifting the eccentric, and if it is then shifted back to the opposite side of its mid position the steam acting on the piston is released, and the port opened for ad mitting steam to the apposite side of the piston, thereby reversing the motion of the engine.
Having thus described the construction and operation and advantages of my invention, what I claim, and desire to se cure by Letters of Patent, is
1. An adjustable and shifting eccentric, in combination with a revolving shaft and disk, and a sleeve and rack bar sliding longitudinally on said shaft for the purpose of actuating said eccentric, said sleeve having a peripheral rib and strap provided with trunnions, and adapted to fit the sleeve, and of such a shape as to retain oil, exclude dirt, and admit adjustment when worn, as de scribed.
2. The combination, with the shaft D, of eccentric A, provided with inclined teeth and guides B, and disk C, provided with guideways O P, and the rack-bar L, substantially as set forth.
3. The combination of the shaft D, the sliding sleeve F, provided with the V-rib, the strap H, adapted to fit the same, and connected by trunnions to the bifurcated arm of the bell-crank lever K, the rack liar L, and the eccentric A, each provided with inclined teeth, and the latter provided with guides B, and the disk C, provided with the guideways O P, as shown and described.
In testimony whereof I have hereunto subscribed my name this 20th day of April, A. D. 1883
Witnesses: A. O. Jahrens, Bernhard N. Sternberg.