US535545A - Valve-gear - Google Patents

Description

(No Model.) y Y W. J. LEWIS.

VALVE GEAR. No. 535,545. Patented Mar. '12,1895'.

se a Namen WALLACE J. LEWIS, OF ST. LOUIS, MISSOURI, ASSIGNOR TO THE LEWIS VALVE GEAR COMPANY, OF EAST ST. LOUIS, ILLINOIS.

VALVE-G EAR.

SPECIFICATION forming part of Letters Patent No. 535,545faateaMa1-ch 12, 1895.

Application tiled March 8. 1892.

.To all whom it may concern.:

Be it known that I, WALLACE J. LEWIS, residing at the city of St. Louis, Stateof Missouri, have invented certain new and useful Improvements in Valve-Gear; and I hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, in which- Figure 1 is an elevation of a valve gear embodying my invention, the side frame which supports the gear being omitted, the full lines indicating the connections preferred when the throw of the valve is effected by the piston of the opposite side, and the dotted lines to the left of the drawing indicating the preferred connections when the throw of the valves is effected by an eccentric on the driving axle, and Fig. 2, is a plan View of the parts shown in full line Fig. 1, a portion of the supporting frame being shown.

Like symbols refer to like parts wherever they occur.

My invention relates to the construction of that class of valve gear wherein the movements to overcome the lap and lead of the valve, and the throw of the valve are eected by different forces,-as for instance, the two opposite pistons, or cross-heads, where two engines are employed as in the case of locomotives, marine engines, &c. For purposes of illustration I have shown the novel combinations connected so as to obtain the movement to overcome the lap and lead from one side and the throw from the opposite side, and through the medium of rock-shafts (as in the patent of Matton, No. 285,286, and my own patents, Nos. 331,799 and 355,770); but do not intend the same as a matter of limitation, for said movements may also he obtained'from eccentrics on a driving axle or its equivalent;- and further, the novel combination which embraces the unit of construction may be used with a single engine. I have therefore added to Fig. 1, dotted lines which taken in connection with the description will clearly indicate to any one skilled in the art, how my invention may be applied to single engines as well as double engines, and how the power to move the valves may be applied by eccentrics as 5o well as cross-heads or rock-shafts.

The function of the valve being to regulate Serial No. l124 ,158. (No model.)

the alternate admission and discharge of steam at each end of the cylinder, the valve is accordingly set so as to be at a point beyond the middle of its travel-the required lap and lead-when the piston is at the beginning of its stroke, and in coming to said position the valve overcomes the lap and lead so that the admission of steam may fill the clearance space at the beginning of the stroke of the piston.

The travel of a slide-valve operated by the ordinary link motion is slightly greater during its passage over the middle portion of its stroke than it is at the outer portions thereof.

In order to work effectively and economically either with full boiler pressure or expansivel y, it is desirable that the middle portion of the valve travel should be accelerated and the remainder of its travel correspondingly retarded, and the longer the retarded movement can be maintained consistent with the next following rapid movement, the better will be the results.

To accelerate the middle portion of the travel of the valve and retard the remainder of its travel, I interpose between the valve and its two sources of movement a fioating lever with which said powers are connected, and in order to reverse the engines I provide a movable slide-box and a slide in said box connecting the slide-box with the reversing lever, and interposing the slide between the floating lever and one of said sources of movement, whereby engines having valve-gear of the general character specied may be readily reversed with the exercise of much less power than is now required-and the slide valves may be held atany desired point of cut-off.

There are other, minor, features of invention, all as will hereinafter more fully appear.

I will now proceed to describe my invention more fully so that others skilled in the art to which it appertains may apply the same.

In the drawings, which show the unit of organization or the combination as applicable to a single engine, and which is to be doubled for a locomotive or double engine--A indicates a portion of one side of the frame, and B the cross-head of the piston. Connecting IOO said cross-head B, or its equivalent with' the stem S of the slide valve of said side, is a floating lever 1, which imparts to said valve its movement to overcome the lap and lead; and connecting said floating lever with the arm 3, of a long rock-shaft 4, is a link 2, whereby the throw of the valve on the opposite side is effected.

5, indicates a second long rock-shaft which extends transversely ot' the locomotive frame and at its distant end is connected with the oating lever (l) ofthe opposite engine. Said long rock-shaft 5, is provided with a crank arm 6, through which it is connected by a link 7, with one arm 8 of a short rock-shatt 9, journaled in the frame A, the other arm 10, of said short rock-shaft being connected by a link 1l, with a slide 12, adapted to move in a pivoted guide-box 13, the opposite end of said slide 12, being connected to the floating lever 1, by a terminal link 14, as indicated in dotted lines, Fig. 1. As the shaft 5, has its distant end connected with the floating lever and cross-head of the opposite side, it will be apparent that through the medium of the devices 5 to 14, just described, the throw of valve stem S will be effected from the piston of the opposite side. In case however, it is desired to apply the power to the floating lever by means of eccentrics instead ot' rocksnafts, or to use the devices in conjunction with a single engine, the links 2 and 7, and the long rock-shafts 4 and 5, may be omitted, and an eccentric (5a) and link (7a) as indicated in dotted lines on the left of Fig. 1, may be employed to impart the throw t0 the valve gear mechanism, the floating lever l, receiving its movement to overcome the lap and lead either from the cross-head B, as shown,

or from a second eccentric and link connection similar to that shown in dotted lines.

In order to obtain a simpler and efficient reversing mechanism, and one which will distribute the friction over a larger surface and reduce the power required to operate it, I arrange the slide 12 in a guide-box 13, movably supported as at 16, on a bracket 17-17, secured to pillars a, a, projecting from the frame A. The pivot 16 should be at such a point on the line between the center of the short rock-shaft 9 and the point of attachment of terminal link 14 to floating lever 1, relative to the respective lengths of the slide bar and the terminal link, as Will impart the required travel to the lever 1, equal distances fromiits central position. It is important that the point of attachment (F) of the terminal link to the floating lever should be confined by suitable guides to move in a straight line. In the present device, this action is secured by constructing a cross-head on the floating lever at the F point, the ends of the crosshead having recesses, which confine it to projecting bars on the brackets 17 and 17a.

kIntegral with or connected to the guide box 13, is a pend ent arm 15, by which the rotation of the movable slide box 13 may be effected,

and said arm'is connected by a link fr with a rock-beam R, pivoted as at r2, and thence by an intermediate link r to the reversing lever R.

lVhen through the medium of the reversing lever and arm 15, or their equivalents, the pivoted guide-box 13 is moved into its extreme position, either above or below, the valve will be caused to work at full cut-off, and at intermediate positions a graduated travel and cutott 'will be obtained, while when the slide bar is in the plane passing through the point of attachment of link 14, to floating lever 1, and through the center of short rocker-shaft 9, the travel of the valve will be limited to its lap and lead.

If the rocker arm 10, is above the line and the. slide bar is also raised the floating lever 1, will be caused to move backward, and if the arm 10, is below the line and the slide bar raised abo-ve the line, the floating lever 1, will be caused to move forward.

The operation of the valve gearing hereinbefore described will be as follows: From the cross-head B, or equivalent source, the power which controls the movement to overcome the lap and lead of the valve is applied to the floating lever 1, at 1?, the connection ofthe terminal link 14 with the floating lever as at F, acting for the time being as the fulcrum, so that the lever may be said to be for the time 'being a lever ofthe first order. Next the power which controls the throw ot' the valve is applied to the floating lever at the points F, and P in turn becomes the fulcrum, and the lever one of the third order; but as these two movements, whether the same be derived from eccentrics (5*, tbc.) or from the cross-head B- of opposite sides-do not synchronize, their courses 'are at one moment-in the same direction, and a moment later in opposite directions. When, therefore, the points P and F of the Vfloating lever 1, are moving in the same direction, the slide-valve moves less rapidly or is retarded in its movement, and when the points P and F are moving in opposite directions, the movement of the slide valve is accelerated, with the results and advantages hereinb'efore pointed out.

Having thus described the nature and operation of my invention, what Iclaim, and desire to secure by Letters Paten-t, is-

l. In a valve gear the combination witha floating valve-lever, operated at two separate points by independent movements respectively from each engine of a double engine, whereby an accelerated or retarded motion can be give-'n to the valve, of a reversing lever provided with a slide-box, and a slide in said box connected to said valve-lever by which one of said movements is communicated, whereby the double engine can be reversed and the slide valves thereof held at any point of cutoff desired, substantially as and for the purposes specified.

2. In a valve gear mechanism, the combination with thevalve of a floating lever, connections for actuating the same, the whole ar- ICO IIO

ro 12 and link 14, which connects the slide and floating lever, a pivoted guide box for the slide, and a rock-shaft which actuates the slide; substantially as and for the purposes specified.

In testimony whereof I affix my signature, l 5 in presence of two Witnesses, this 5th day of March, 1892.

WALLACE J. LEWIS.

Witnesses:

D. MCARTHUR, L. B. FISH.

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