US2075069A - Steam engine - Google Patents

Description

March 30, 1937'. -H. J. TITUs ET Al.

STEAM ENGINE Filed May 14, 1928 5 Sheecs--Sheei'I l bbh, @KN QmQ SW B m, b5 SE w EGKS @gy N bwk. QRN b%\ Sw Q March 30, 1937. H. J. TITUS ET AL STEAM ENGINE Filed May 14, 1928l 5SheetS-Shee1'l 2 INVENT 5 //wd. m BY lul/n ATTORNEYs 5 Sheets-Sheet 5 S TEAM ENGINE H. J. TITUS ET AL Filed May 14, 192B '7L A TT ORNE YS March 30, 1937.

March 30, 1937.v H. J. TlTus ET AL STEAM ENGINE 5 Sheets-Sheet 4 Filed May 14, 1928 s s Nm/ R n. m Jg 4f y B March 30, 1937. H. J. TITUs ET AL 2,075,069

STEAM ENGINE Filed May 14, 1928 5 Sheets-Sheet 5 l INVENTORS BY M4 l ATTONEYS Patented Mar. 3G, i937 UNITEB STATES PATENT GFFICE STEAM ENGINE Application May 14, 1928, Serial No. 277,772

23 Claims.

This invention relates to steam engines and more particularly to a method of an apparatus for equalizing or smoothing out the torque in such engines, and, since it is particularly useful 1 5 in and applicable to locomotives, it will be here.-

in described and illustrated in connection with locomotive construction and operation.

The objects and advantages of the invention will be better understood if certain practical considerations in connection with this art be first set forth.

In multi-cylinder reciprocating engines there is not only the irregularity or inequality in net torque or rotative effort resulting from the con- 5 stant change in thrust of each piston of the engine from zero to maximum, but there are also inequalities as between the several torque peaks themselves in each complete cycle of the engine, which arise largely from the differences in angular position of the connecting rods in the several quarters of the cycle. For example, in a two cylinder engine, with cranks set at the usual 90 angle to each other, there are (in the combined rotative effort curve) four maximum and four minimum, i. e. high and low points, or torque peaks and valleys, in each cycle of the engines operation, but these peaks are not the same. The highest quarterly maximum peak occurs during that quarter of the cycle when the leading cylinder is working on the head end and its crank is in the first quarter revolution from its forwardl center, and the following cylinder is working on the crank end and its crank is in the last quarter revolution toward its forward center.

If the foregoing quarter cycle be termed the rst quarter, and the other quarters be numbered thereafter in succession, the lowest quarterly maximum torque peak occurs in quarter number 3, and the intermediate maximum peaks in the second and fourth quarters, the second peak ordinarily being slightly higher than the fourth. The diiferences between the several minimum torque peaks, i. e., low torque points, are not so great. In locomotives, such torque inequalities result in a tendency of the driving M rough handling of trains in starting.

In connection with locomotive calculations the factor of adhesion ordinarily used takes into consideration the average tractive power developed during a revolution of the drivers. I-IOW- ever, the starting power which a locomotive can actually deliver is governed by the true factor of adhesion which takes inte consideration the maximum power, i. e., the highest torque peak, that may be developed during a complete revolution. Heretofore, in order to increase the average starting power, resort has been had either to the expedient of adding drivers to the engine, or else to increasing the weight on the drivers which allows an increase in the power which can be applied without making the engine more slippery, b-ut with modern locomotives the number of drivers and the weight per driver has about reached the practical limit. It is partly to overcome this difficulty that the three cylinder engine has been introduced, with its increased overlapping of piston thrusts, but even the use of three cylinders will not obviate substantial differences between the peaks of the torque curve.

We propose, by our invention, to increase the average starting power of a locomotive by reducing the factor of adhesion, and this without making the engine more slippery. In fact, by our invention, an increase in the average starting power can be obtained with less tendency toslip than before; or in other words, the true factor of adhesion can actually be increased while what is normally termed the factor of adhesion is being reduced. We accomplish the desired result, and overcome to a large extent the diiiicul ties and disadvantages hereinbefore set forth, preferably by smoothing out the rotative eiTort curve of the locomotive while maintaining the true factor of adhesion constant, thus lowering what is ordinarily termed the factor of adhesion.

In other words we aim by our invention to smooth out the peaks of the rotative effort curve and bring them more nearly in line with the average rotative effort, which makes it possible to increase the said average rotative effort without rendering the engine more slippery.

Furthermore we aim by our invention to improve the operation both of two-cylinder and three-cylinder engines, and to provide simple and reliable mechanism whereby the desired advantages can be easily and inexpensively attained in existing equipment.

More specifically our invention contemplates the provision of irregular steam distribution as between the two ends of a cylinder, and/or as between different cylinders of an engine, as for Cil , the same locomotive when running in reverse motion;

Fig. 2 is a graph similar to Fig. l, but of an'- other rotative eifort curve;

, Fig. 3 is an enlarged longitudinal vertical section through the right-hand of a locomotive valve chest illustrating a cam-operated poppet valve mechanism adapted to carry out the invention;

Fig. 4 is a section taken on the line 4 4 of Fig. Y3.

Fig. 5 is a diagrammatic illustration, viewed from the right-hand side of the locomotive, of certain control mechanism used in connection with the construction shown in Figs. 3 and 4;

Fig. 6 is an enlarged view, partly in section and partly in elevation, of the admission valve cam of Figs. 3 and 4;

Fig. 7 is a perspective view of the cam, showing a shiftable cam element located out of its normal position in order to illustrate the contours of the parts;

Fig. 8 is a vertical section through one of the `control valves of Fig. 5; and

Fig. 9 is a condensed left-side elevational view of a two-cylinder locomotive on which the mechanism of this invention has been applied, oertain parts being shown somewhat diagrammatically.

Referring first to the graphs, it will be seen that in Fig. l we have shown the rotative effort curve of a two-cylinder locomotive having 50% limited cut-oir, through .one complete cycle. The numerals at the left of the figure indicate rotative effort, in thousands of pounds, and those at the bottom the degrees of rotation of the drivers. The crank pin positions are indicated at the top, rotation being clockwise, as shown by the arrow, and the right (leading), and left (following), sides of the engine are indicated by the characters RS and LS, respectively. The lines RCand LC are curves indicating the torque exerted through the right cylinder and crank and vleft cylinder and crank, respectively, and the curve above these two indicates the total torque, i. e., the combined rotative effort.

It will be seen that the mean average torque or rotative effort, in this example, with a valve cut-off of 50% for both ends of each cylinder, is 60,000 lbs., but the torque peaks vary greatly, not only from this average, but also as between themselves, the highest maximum torque peak I, being about 72,000 lbs., which is 19.7% above the mean average, while the other high torque peaks, 2, 3 and 4, are approximately 67,000, 59,000 and 65,000 lbs., respectively. By altering the cut-off, in accordance with our invention, to 43% on the crank end of the left (following) cylinder, and to 60% on the head end of the same cylinder, as indicated on the graph, the highest vpeak I is lowered to about the height oi peak 2, and the lowest high peak 3 is raised to ,o75,oee

about the height of peak 4A. As for the mini" mum or low peaks. while peak 5 remains the same and peak 8 is lowered somewhat, peaks B and 'l are both raised. The improvement, in the lowering of the high peak and the raising of the minimum peak and two of the valleys in the curve, is graphically shown by the shaded areas. The net change in the average rotative effort is a rise to the line a, an increase of about 15,00 lbs, and with less tendency to slip.

It will now be seen that along with a rise in two of the low peaks and an increase in the average rotative effort the highest maximum peak has been reduced from 19.7% above mean to about 9.6% above mean. Added power could now be applied to the cylinders to such an extent a-s to raise the mean rotative eiort to approximately 66,500 lbs., that is, until peak i again reached 72,000 lbs., without rendering the engine any more likely to slip than it was originally.

By reference now to Fig. la, it will be -seen that we have illustrated the operation of the same locomotive, when moving in reverse, and when employing the preferred embodiment of our invention (as hereinafter described). It will be readily understood (as later pointed out in detail) that when a two-cylinder, reciprocating-engine, locomotive is reversed, the leading side becomes the following side and the following side becomes the leading side, considered with reference to the direction of rotation of the crank pins, with a pin on one side of the locomotive leading a pin on the other side by Similarly to the graph of Figure 1, the graph of Figure 1a shows, in a solid line (near the top of the figure) the combined rotative effort curve of a twocylinder locomotive with 50% cut-off at each end of each cylinder, but with the locomotive running in reverse; and showing in dotted lines the modification of that curve by the reversed operation of the preferred embodiment of the present invention.

For convenience of comparison between Figure 1 and Figure la, 'the progression of the graph of Figure 1a has been made to read from left to right, as in the case of Figure l, and the initial crank pin positions (marked RS for right side and LS for left side) are located the same as in Figure l, that is, with the right crank pinion forward dead center, but the direction of rotation is in a sense opposite to that of Figure 41, that is, counterclockwise, as indicated by the arrow.

Since the right cylinder and crank were assumed to be leading in Figure l, it is obvious that the left cylinder and crank will `he leading in Figure la. Now it is clear that since the -modiiied cut-off on the left cylinder of Figure 1 and the uniform cut-off yon the right cylinder `thereof produce the illustrated improvement in forward motion, those relationships must be reversed for reverse motion, if the locomotive is to have the same advantages when operating in reverse as when moving forwardly. Portions of the mechanism later described have been devised to Vaccomplish this reversed modification o'f the cutoif, and in accordance therewith the graph vof Figure la shows the left crank torque curve for 50% cut-off operation (marked H yE for the head end stroke, and vmarked `C E for the crank end stroke), while the curve for the right-hand crank shows in dotted lines the modification obtained by 60% out-off on the head end Vstroke and 43% cut-off Yon the crank end stroke.

The shaded areas show the improvement in the raising of 'the lowest torque peak and associated depressions of the combined rotative effort curve, and the reduction of the highest torque peak thereof; the improvement thus being similar to that shown in Figure l, and sim-- ilarly illustrated, the modification of the curve being indicated by the dotted line portions. Tlie net change in the average rotative effort is a rise to the line a, an increase of about 1,500 lbs., just the same as in forward motion which was illustrated in Figure 1.

From the above comparison of Figures 1 and 1a it will be observed that the normal curve produced at the left crank, in reverse (Figure la) is substantially the same as the normal curve at the right crank in forward motion (Figure l) and that the normal and modied curves at the right crank for reverse (in Figure la) are substantially the same as the normal and modified curves of the left crank for forward motion (in Figure 1) and that the net results, i. e., improvement in the combined rotative effort curve, are substantially alike in reverse (Figure la) as in forward motion (Figure 1); when our invention is functioning in its reversed relationship, according to the direction of motion of the locomotive. There is, however, one major distinction, namely: the benefits from the altered cutoff occur between approximately and 90 and between 180 and 270, in the forward motion (Figure l), that is, they occur substantially in the first and third quarters of a cycle commencing with the right side crank at forward dead center (forward with respect to the locomotive), whereas in reverse the same improvements occur in the second and fourth quarters of the cycle, commencing from the same point, that is, with the right side crank at forward dead center (forward with respect to the locomotive). It might here be noted that below the graph of Figure la we have indicated the degrees of rotation, sep arately as to the right crank and the left crank, identifying a given point in the cycle by the same degree number as employed in Figure l, but reading in the reverse order, since the direction of rotation is opposite.

From the foregoing explanation of Figure l and Fig. la the other graph will also be readily understood. The graph of Figure 2 illustrates the results obtained with a 90% cut-off, twocylinder engine, in which the crank end of the left cylinder has been altered to a '70% cut-olf. In this case the highest peak l has been reduced from 23.6% above mean to 16.3% above mean, Which is about the same as peak 2. An increase in power could now be applied to this engine sucient to increase the average rotative effort by about 8,000 lbs. with no greater tendency to slip than before the alteration in the cut-off.

In applying the invention to a two-cylinder locomotive engine we have provided an oscillating-cam-operated poppet-valve apparatus. The poppet valve device, while herein shown merely for illustrative purposes-other valve devices being applicable--has the advantage of full opening of the ports even at short limited maximum cut-offs.

Referring now to the illustrative embodiment, Figs. 3 to 9 inclusive, it Will appear that we have devised a modified form of Lentz valve mechanism, arranged to carry out the invention on a two-cylinder engine. Figs. 3 to 8 illustrate the construction for the right hand side of the engine, (embodying in this instance the following crank); While Fig. 9 shows the locomotive from the left-hand side (having the leading crank).

In this construction the usual valve rod connection I5 is made to the arm I6a of cam-shaft I9 which extends into the valve chest I1. This shaft carries the usual exhaust-valve cam controlling the exhaust through outlet 2 which is thus oscillated by the usual valve motion mechanism (a known example of which is shown in Fig. 9) in a manner known in the art, which will not here be enlarged upon. Pipe I8b is the usual lubricator pipe for cylinder I 8a.

The admission-valve cam 22, also carried on shaft I9, controls the admission of steam through inlet 23 and steam chamber 25, by means of the annular poppet valves 25, 26, controlling ports 2'! and 28, respectively, at the two ends of the cylinder lBa. These valves, as ordinarily used, are slightly overbalanced for closing, and in addition have adjustable springs 25a and 26a to insure seating when steam is entirely cut off from the steam chamber 24, as when the engine is drifting. The valves are controlled by cam 22 through the intermediation of their respective stems 29, 30, and cam-engaging rollers or followers 29a, 30a.

Cam 22 has no-t only the usual high and low surfaces 3l, 32, with intermediate sloping surfaces 33 and 34, each of the latter of which in the ordinary construction controls both the admission and cut-off for its particular end of the cylinder, but in our construction this cam is also equipped with additional cam elements comprising tWo movable segments 22aI and 22a', mounted on bars 22e slidable in guides 22h, providing additional cam surfaces 3m, 3m, and slopes 33a and 34a respectively.

Upon oscillation of the cam assembly, means of the ordinary valve motion, in timed relation to the piston stroke, the cam slopes 33 and 34a control the cut-off and slopes 33a and 34 the admission of valves 25 and 26, when the movable segments 22a and 22a are operating. At times when the movable segments are not operating, the cut-off and admission are both controlled by slope 33a for valve 25, and by slope 34 for valve 26, thus giving substantially equal admission and equal cut-olf for the two ends of the cylinder.

In the ordinary Lentz construction, the surface 33a is a fixed part of cam 22 and normally controls both admission and cut-off through valve 25 and port 21; and surface 34 controls the admission and cut-off through valve 26 and port 28, either valve being wide open when its cam follower rides on cam face 3|, and entirely closed when its follower rides on face 32. In our construction, on the other hand, where a later cutoff is desired on the head end of the cylinder (i. e., the following cylinder, as shown in Figs. 3 and 4) and an earlier cut-off on the crank end, the surface 34 is the admission point for value 26, and the surface 33a the admission point for valve 25 while the surfaces 34a and 33 provide the requisite cut-off points, respectively, for the two valves. This is accomplished by the periodic shifting of the segments 22a and 22a in their guide-ways causing surfaces 3| a to shift into and out of registry with cam surface 3|.

For the shifting of the cam segments, each is provided, at the respective ends of its sliding bar 22o with an inner and an outer bevel surface, 35 and 36, respectively, adapted to contact in alternation with co-operating beveled cam shifters 35a and 36a. When the segment 22a` for the head end of the following cylinder (Which is the segment shown at the right in Fig. 3) is i.) shifter 35a, a similar cavity 38 is engaged by the plunger 39 to position the segment in its Operative position in line with the cam follower.

A4 similar shifting action takes place in the operation of the segment 22a' for the crank end l5 of the following cylinder (which s the left hand segment shown in Fig. 3), but it should be particularly noted that this segment, as shown in dotted lines in Fig. 4, is mounted adjacent the outside end of its sliding bar 22C, so that when the segment is moved inward by its shifter 36a.

the surface 3|a of segment 22a will be in line with cam face 3| and the cam follower 29a, and when 22a is moved outward by its shifter 35a its surface 3|a will be out of line with face 3| l5 and follower 29a.

In other words, the cam segment 22a at the right in Fig. 3, which is for the head end of the cylinder on the following side of the locomotive, when actuated by shifter 36a is moved in- Si) ward, out of line with the xed cam surface 3| (to the position shown in Fig. 6); while the cam segment 22a at the left in Fig. 3, which is` for the crank end of the cylinder, when similarly actuated by its shifter 36a is moved in- 35 Ward, into line with the fixed cam surface 3| (to Ythe position shown in Fig. 4). Therefore, upon oscillation of the cam and the periodic Shifting of the segments, surfaces 33a and 34 `determine the admission points for the steam,

o and surfaces 33 and 34a the cut-off points, thus giving admission at the normal time at each end of the cylinder and giving a late cut-off and an early cut-off, respectively, at the head end and crank end of the cylinder. The result is, of

45 course, the desired unequal steam, and consequently power, distribution as between the two ends of the cylinder, while approximately (though not exactly) equal or balanced distribution as between the two cylinders of the engine,

50 in any complete cycle, is maintained.

For reasons which will hereinafter appear, each shifter member 35a is movable in guides 46, and is held outward or forward in operative position by a motor device comprising a piston 4| acted on by fluid pressure admitted to a cylinder 42 through a suitable pipe 43 (see Fig. 4). A spring 44 is provided to move the cam shifter 35a to inoperative position when the air or other fluid pressure is cut off from the cylinder 42.

Obviously, when the locomotive is running backward the following side becomes the leading side and vice versa. Since, in accordance with our invention, the leading side should have equal cut-offs at each end, the following side for forward motion must be altered to give equal cut-offs for reverse motion. Therefore, when running in reverse, the fluid pressure should be cut off from the cylinders 42 to permit the cam Shifters 35a to move inward into inoperative position under the influence of their springs 44. Cam segments will then be moved inward by the fixed cam shifting faces 36a, the segment for the head end of the cylinder being held by its plunger 39 in the position shown in Fig. 6, and

il the crank end 'segment 22a being held by its plunger 39 in the central position shown in Figs. 4 and 7 with its surface 3|a in line with cam surface 3|, thus giving substantially equal cutoffs on both ends of the right cylinder, which is now the same as the left cylinder.

Fluid pressure should now be admitted to the motor devices 42 on the left (leading) side of the engine, which, for reverse, has become the following side, to give unequal cut-offs to the two ends of the cylinder on that side.Y The cylinder and valve structure for the left side of the engine, it should be understood, is similar to the structure hereinbefore described, and therefore the left side (see Fig. 9) is shown only in outline.

The air, or other fluid pressure, admitted to the cylinders 42, may be controlled in any suitable inanner but we prefer to employ some means under the inuence of the reversing mechanism of the locomotive, for example pilot valves 45, 4B, actuated by movement of the locomotive reverse lever 41, as shown in Figs. 5, 8 and 9. Such pilot valves for controlling compressed air are Well known in the art, and an example can be found in Peters Reissue Patent No. 16,483, dated November 2,3, 1926. In the arrangement here shown, when the reverse lever 41 is moved into forward position, the trip member 48 actuates the plunger 49 of pilot valve 45 `(see Fig. 8) to open said valve an-d admit uid pressure, from a suitable source of pressure, such as air tank 5|, through pipe 52 and pipe 43R, to the pipes 43 (shown in Fig.'4) there being one such pipe for each motor cylinder 42, which actuates the pistons 4| to move cam Shifters 35a into operative position. These shifters, together with shifter surfaces 36a, then cooperate with the cam segments 22a and 22a to slide the latter back and forth, all as previously described, thus giving the cylinder the desired unequal cut-off as between its two ends.

When the reverse lever 41 is moved into reverse position, the member 48 is disengaged from plunger 49 to shut oi the air supply and permit exhaust of the air from cylinders 42 on the right hand side of the engine, and engages plunger 50 of valve 46 to admit air through pipe 52a and pipe 43L to the cylinders 42 on the left hand side of the engine, which, as before said, when running in reverse, becomes the following side, (in our present example). The left side of the locomotive is shown fragmentarily in Fig. 9, with the various parts of 'our novel structure illustrated in their association with the ordinary running gear and valve motion mechanism. It might here be noted that the operating connection between the reverse lever 41 and the valve gear is illustrated only diagrammatically, as this may take any usual form, including, if desired, a power reverse gear. The left-hand piston, main rod and crank pin are indicated at LP, LR and LC;I and the corresponding parts for the right side are diagrammatically indicated at RP, RR and RC.

In practice it may be desirable to have an irregular distribution of power only when the locomotive is working at late cut-offs, as in starting, and to have ordinary distribution when the engine attains higher speeds, whether operating forwardly or in reverse. We have therefore shown the trip 48 on the reverse lever as being comparatively short, so that when the reverse lever is taken out of the corner, as it is termed, the pilot valve will close and exhaust the air out of cylinders 42, springs 44 will retract cam Shifters 35a, and segments 22a and 22a. will move to their idle position, thus yielding substantially identical cut-offs between thev ends of each cylinder and between the cylinders. However, it is obvious that we may make the engaging arms of trip 48 of any desired length, so as to maintain the irregular distribution of steam even until very early cut-oils, if desired.

From the foregoing detailed description of Figs. 3 to 9 inclusive, it will now be quite evident how we obtain the advantages illustrated in, and described with reference to, the graphs of Figs. 1 and 1a, which illustrate the forward and reverse operation of the locomotive. It will further be evident that the invention is particularly advantageous because the benets from the change in cut-off are obtained without the necesf sity of altering the normal crank angles and without any change in the other valve events, and further without altering the valve travel or port opening. In addition, by the control system employed, the modified cut-ofi can always be obtained on the following cylinder, whether operating in forward motion or in reverse; and a hooking back of the reverse lever after the locomotive gets under way automatically restores both ends of both cylinders to equal cut-off, resulting in the desired equality of power output at high speeds.

A portion of the benet results from the earlier cut-off on the crank end of the following cylinder, and a portion of the benefit results from the later cut-off on the head end of the following cylinder. Where the mechanism, as here shown, is capable of producing both these results, there is a very substantial improvement in the operation of the locomotive, and the steam pressure may actually be stepped-up, if desired, without rendering the locomotive any more slippery than it was originally.

From Fig. 2, hereinbefore considered, it will be evident that it is possible to attain a portion of the advantages of the mechanism even on a locomotive of very late cut-off when in full gear position (having, for example, a cut-olf at 90% of the stroke) by providing an earlier cut-olf at the crank end of the following cylinder.

In view of the foregoing it will be evident that, by an unequal steam, and consequently power, distribution, we obtain a marked improvement in the average rotative effort at slow speeds, so that the locomotive will have less tendency to slip, or so that the average tractive eifort may be increased substantially without any greater tendency to slip.

We claimz- 1. In engine mechanism of the character described, a valve chest, valve actuating means therein including movable cam means having a segment movable with relation thereto, and stop means co-operating with said segment to move it periodically upon movement of the cam means.

2. In engine mechanism of the character described, a valve chest, valve actuating means therein including movable cam means having a segment movable with relation thereto, and stop means co-operating with said segment to move it periodically upon movement of the cam means, together with control means for said stop means.

3. In reversible engine mechanism of the character described, a valve chest, valve actuating means therein including movable cam means having a segment movable with relation thereto, and stop means co-operating with said segment to move it periodically upon movement of the cam means, together with control means for said stop means under the inuence of the engine reversing mechanism.

4. In reversible engine mechanism of the character described, a valve chest, valve actuating means therein including movable cam means having a segment movable with relation thereto, and stop means co-operating with said segment to move it periodically upon movement of the cam means, together with control means for said stop means under the influence of the engine reversing mechanism and adapted to render said stop means inoperative at high speeds of the engine.

5. A single-expansion double-acting steam locomotive engine having a plurality of cylinders with their pistons, respectively of substantially equal diameters and equal strokes; for each cylinder, main steam distribution valve mechanism and steam portage controlled thereby and opening into the two ends of the cylinder; valve gear means operatively connected with said mechanisms for actuating the same in timed relation with the stroke of the pistons and setto effect a predetermined nominal or maximum normal cut-oilc of a given predetermined percentage value of the piston stroke which is substantially identical at both ends of each cylinder; the valve gear means having reversing apparatus for reversing the direction of operation of the locomotive; cranks to which the pistons are operatively connected, said cranks being angularly set one to another and the connecting means between the pistons and their cranks being thus positioned to assume relatively different angles at various points in the cycle of operation of the locomotive engine, whereby marked differences in the combined rotative effort of said plurality of cylinders considered together occur at different points in the cycle of operation of the locomotive engine, so that the combined rotative eiort curve presents substantial differences between the high and low points thereof; mechanism for reducing the spread between some of the high and low points of the combined rotative effort, during the lower range of operating speeds of the locomotive, including means for altering the effective cut-off point of said distribution valve mechanism at one end of one cylinder as compared with said predetermined normal cut-off of the distribution valve mechanism at the corresponding end of another cylinder without altering the total stroke of the valve mechanism; said means being so arranged that the total work of the cylinders may be increased to produce a higher average tractive power without lowering the true factor of adhesion of the locomotive; and means for rendering said alteration of cut-off ineffective during the higher range of operating speeds of the locomotive.

6. A single-expansion double-acting steam locomotive engine having a plurality of cylinders with their pistons, respectively of substantially equal diameters and equal strokes; for each cylinder, main steam distribution valve mechanism and steam portage controlled thereby and opening into the two ends of the cylinder; valve gear means operatively connected with said mechanisms for actuating the same in timed relation with the stroke of the pistons and set to effect a predetermined nominal or maximum normal cut-off of a -given predetermined percentage value of the piston stroke which is substantially identical at both ends of each cylinder; the valve gear means having reversing apparatus for reversing the direction of operation of the locomotive; cranks to which the pistons are operatively connected, said cranks being angularly set one to another and the connecting means between the pistons and their cranks being thus positioned to assume relatively different angles at various points in the cycle of operation of the locomotive engine, whereby marked differences in the combined rotative effort of said plurality of cylinders considered together occur at different points in the cycle of operation of the locomotive engine, so that the combined rotative effort curve presents substantial differences between the high and low points thereof; mechanism for reducing the spread between some of the high and low points of the combined rotative effort, during the lower range of operating speeds of the locomotive, including means for altering the effective cut-off point of said distribution valve mechanism at one end of one cylinder as compared with said -predetermined normal cut-off of the distribution valve mechanism at the corresponding end cf another cylinder without altering the total stroke of the valve mechanism; said means being so arranged that the total work of the cylinders may be increased to produce a higher average tractive power Without lowering the true f factor of adhesion of the locomotive; and means for obtaining a like effect by a similarly altered cut-off in reverse operation.

7. A single-expansion double-acting steam locomotive engine having a plurality of cylinders with their pistons, respectively of substantially equal diameters and equal strokes; for each cylinder, main steam distribution valve mechanism and steam portage controlled thereby and opening into the two ends of the cylinder; valve gear means operatively connected with said mechanisms for actuating the same in timed relation with the stroke of the pistons and set to effect a predetermined nominal or maximum normal cutoff of a given predetermined percentage Value 0f the piston stroke which is substantially identical at both-ends of each cylinder; the valve gear means having reversing apparatus for reversing the direction of operation of the locomotive; cranks to which the pistons are operatively connected, said cranks being angularly set one t0 another and the connecting means between the pistons and their cranks being thus positioned to assume relatively different angles at various points in the cycle of operation of the locomotive engine, whereby marked differences in the combined rotative effort of said plurality of cylinders considered together occur at different points in the cycle of operation of the locomotive engine, so that the combined rotative effort curve presents substantial. differences between the high and low points thereof; mechanism for reducing the spread between some of the high and low points of the combined rotative effort, during the lower range of operating speeds of the locomotive, including means for altering the effective cut-ofi point of said distribution valve mechanism at one end of one cylinder as compared with said predetermined normal cut-off of the distribution valve mechanism at the corresponding end of another cylinder Without altering the total stroke of the valve mechanism; said means being so arranged that the total Work of the cylinders may be increased to produce a higher average tractive power without lowering the true factor of adhesion of thev locomotive; means for obtaining a like effect by a similarly altered cut-off in reverse operation; and means for rendering said alteration of cutoff ineffective during the higher range of operating speeds of the locomotive.

8. A reversible steam engine having a pair of cylinders one of which is a leading cylinder and the other a following cylinder in one direction of motion and vice versa in the opposite direction of motion, steam admission valve means for said cylinders having means for setting the same to produce a predetermined normal maximum cutoff the same for both ends of both cylinders,`

mechanism adapted to shorten the cut-off on the crank end and lengthen the cut-off on the head end of either cylinder as compared with the cutoff on the two ends of the other, and control means adapted to select, as between said cylinders, which shall have the modified cut-offs.

9. A reversible steam engine having a pair of cylinders one of which is a leading cylinder and the other a following cylinder in one direction of motion and vice versa in the opposite direction of motion, steam admission valve means for said cylinders having means for setting the same to produce a predetermined normal maximum cutoff the same for both ends of both cylinders, mechanism adapted to shorten the cut-off on the crank end and lengthen the cut-off on the head end of either cylinder as compared with the cutoff on the two ends of the other, and automatic control means actuated under the influence of the direction of motion of the engine to select the following cylinder and effect said altered cut-off on that cylinder only.

10. A reversible steam engine having a pair of cylinders one of which is a leading cylinder and the other a following cylinder in one direction of motion and vice Versa in the opposite direction of motion, steam admission valve means for said cylinders having means for setting the same to produce a predetermined normal maximum cutoff the same for both ends of both cylinders, mechanism adapted to shorten the cut-off on the crank end and lengthen the cut-off on the head end of either cylinder as compared with the cutoff on the two ends of the other, control means adapted to select, as between said cylinders, which shall have the modified cut-ofs, and means operative under the influence of shortening of the normal cut-oif of the locomotive to render said mechanism inoperative.

l1. A reversible steam engine having a pair of cylinders one of which is a leading cylinder and the other a following cylinder in one direction of motion and vice versa in the opposite direction of motion, steam admission valve means for said cylinders having means for setting the same to produce a predetermined normal maximum cutoff the same for both ends of both cylinders, mechanism adapted to` shorten the cut-off on the crank end and lengthen the cut-off on the head end of either cylinder as compared with the cutoff on the two ends of the other, automatic control means actuated under the influence of the direction of motion of the engine to select the following cylinder and effect said altered cut-ofi on that cylinder only, and means operative under the influence of shortening of the normal cutoff of the locomotive to render said mechanism inoperative.

12. A simple multiple cylinder engine having admission valves for the cylinders, means automatically acting to effect a substantial differing power distribution to one cylinder as compared with another during a complete cycle when operating at late valve cut-off, and means automatically acting to effect equal and regular power distribution as to, each cylinder at a reduced valve cut-off.

13, In a multiple cylinder locomotive, the combination of cylinders, valve chests, valves, main steam passages, valve gear, a reverse gear controlling the valve gear in synchronous movement and including a reverse lever, means associated with the valves for effecting a difference in the cut-oi as between cylinders and means associated with the reverse gear to determine which cylinder shall have the greatest cut-off, said last mentioned means automatically operating the rst mentioned means upon movement of the reverse lever.

14. In a locomotive, the combination of cylinders, valve chests, valve mechanism, main steam passages at the ends of the cylinders, valve gear, reverse mechanism for the valves, means associated with the valve mechanism for effecting an earlier cut-ofi on the steam passage at the crank end of either of the cylinders, and control means for determining which cylinder shall have the early cut-off on the crank end.

15. In a locomotive, the combination of cylinders, valve chests, valve mechanism, main steam passages at the ends of the cylinders, valve gear, reverse mechanism for the valves, means associated with the valve mechanism for effecting an earlier cut-off on the steam passage at the crank end of either of the cylinders, and control means for determining which cylinder shall have the early cut-off on the crank end, such control means being under the iniiuenoe of the reverse mechanism.

16. In a locomotive, the combination of cylinders, valve chests, main valve mechanism, main steam passages at the ends of the cylinders, valve gear, reverse mechanism, the valve mechanism being set to give approximately equal cut-off at both ends of the cylinders when the valve is in full travel, means controlling the valve mechanism to effect an earlier cut-off of the valve at one end of a cylinder than at the other and control means for determining which cylinder shall have such earlier cut-olf.

1'?. In a locomotive, the combination of cylinders, valve chests, main valve mechanism, main steam passages at the ends of the cylinders, valve gear, reverse mechanism, the valve mechanism being set to give approximately equal cut-off at both ends of the cylinders when the valve is in full travel, means controlling the valve mechanism to eiect an earlier cut-off for theV valve at one end of a cylinder and a later cut-off for the valve at the opposite end than the nominal cutoff for full travel, together with means for determining which cylinder shall have such altered cut-01T.

18. In a locomotive, the combination with the cylinders, main valves, valve chests, valve gear, and reversing apparatus operating all valves simultaneously and providing a full gear travel of the valves of a predetermined normal maximum cut-off, of mechanism for increasing that normal cut-off at one end of a cylinder and reducing that normal cut-off at the other end of the cylinder, means for simultaneously retaining the full gear cut-off on the other cylinder, control means for said mechanism and means associated with the reversing apparatus for initiating and discontinuing the action of said control means.

19. In a locomotive having cylinders, main inlet valves, valve chests, and valve gear and reversing apparatus for operating the valves and providing a predetermined normal maximum operating cut-off; a movable cam actuated by said valve gear for operating a main inlet valve, said cam having a high and transition surface for holding the valve from the seat and a low surface for closure or seating of the valve and an intermediate surface to hold the valve from its seat beyond the normal point of closure.

20. In a locomotive having cylinders, main inlet valves, Valve chests, and valve gear and reversing apparatus for operating the valves and providing a predetermined normal maximum operating cut-off; a movable cam means for operating a main inlet valve, said cam means having a high surface and a low surface respectively operating for opening and closure of said valve, a cam follower connected to said valve and positioned to ride on the cam surface, and a shiftable cam element providing for the cam follower to ride on the higher or lower cam surfaces for a greater distance at starting than for normal operation.

21. In a locomotive having cylinders, main inlet valves, valve chests, and valve gear and reversing apparatus for operating the valves and providing a predetermined normal maximum operating cut-oir; a movable cam means for operating a main inlet valve, said cam means having a high surface and a low surface respectively operating for opening and closure of said valve, a cam follower connected to said valve and positioned to ride on the cam surfaces, a shiftable cam element providing for the cam follower to ride on the higher or lower cam surfaces for a greater distance at starting than for normal operation, means for shifting the cam element for starting into or out of the path of the cam follower and means resisting the placing of the shiftable cam element in position other than for normal running operation of the locomotive.

22. In a locomotive having cylinders, main inlet valves and valve gear with reversing apparatus, movable cams actuated by the valve gear for operating the main inlet valves, the leading cylinder having approximately equal cut-offs at both ends of the cylinder, means associated with the following cylinder to effect an earlier cut-off on the crank end and a later cut-ofi on the head end with relation to the cut-off on the leading cylinder, and control means automatically operative upon reversal of the reversing apparatus for determining which cylinder shall have the altered cut-offs.

23. In a limited cut-off steam engine having cylinders, main inlet valves, valve chests and valve gear for operating the valves and providing a predetermined normal maximum operating cutoff; a movable cam actuated by said valve gear for operating a main inlet valve, said cam having a high and transition surface for holding the valve from its seat up to the point of normal cut-01T and a low surface for closure or seating of the valve and an intermediate surface to hold the valve from its seat beyond the normal point of closure, said intermediate surface operating to prevent the lifting of the valve from its seat before the normal point of admission.

HUBERT J. TI'IUS. JOHN S. WALLIS.

Images