US2255902A - Auxiliary valve gear for locomotives - Google Patents

Description

Sept. 16, -1941.- H. JSHERRILL 2,255,902

AUXILIARY VALVE GEARIFORI' LOCOMOTIVES Filed Jan. 2, 940' BY MW Patented Sept. 16, 1941 UNITED STATES PATENT OFFICE AUXILIARY VALVE GEAR FOR LOCO- MOTIVES r 7 Harry J. Sherrill, Youngstown, Ohio Application January 2, 1940, Serial No. 311,974

Claims. (Cl. 121-163) port opening before reaching the cut-off position and also during movement of the valve from the point of release to the end of the stroke.

A still further object of the invention is the provision of an auxiliary valve gear mechanism of simple sturdy construction comprising a relatively few easily assembled parts.

A still further object of the invention is the provision of an auxiliary valve gear mechanism providing definite adjustability between two of its several parts so that the cut-off position of the steam valve may be varied thereby in order to adapt it for freight work wherein a slow cutolf is desirable or for passenger work wherein a fast cut-off is desirable. With the foregoing and other objects in view which will appear as the description proceeds;

the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it-

being understood that changes in the precise embodiment of the invention herein disclosed, can be made within the scope of what is claimed without departing from the spirit of the invention. 7

' The invention is illustrated in the accompanying drawing, wherein:

Figure 1 is a side elevation of a valvegear showing the auxiliary valve gear connected therewith, the various parts of the complete gear represented by their center points. a

Figure 2 is an enlarged detail view of the auxiliary valve gear in Figure 1 and shows in detail the mechanism employed in effecting action of the steam valve.

Figure 3 is an end elevation of Figure 2. I

Figure 4 is an enlarged schematic illustration of a portion of the invention shown in Figure 2 and is provided with broken lines indicating approximate quarters of revolution of the pinion gear therein shown. I

By referring to the drawing it will be seen that the 'variable 1 the illustrated embodiment of the invention shows a valve gear for imparting reciprocatory movements to the steam admission and exhaust valve of an engine and only sufficient illustration is given to enable those skilled in this art to readily understand the invention. The valve gear mechanism shown herein can be used in conjunction with any well known valve gear, and is shown in use with the Baker valve gear wherein a bell crank l0 provided with a horizontal arm I l which derives its movement through a system of links and levers from an eccentric pin l2 of a driven wheel l3 of a locomotive. To the lower end 'of the vertical arm of the bell crank I0 is pivoted a bell rod M which inclines forwardly and upwardly, the forward end being split and pivotally mounted on a pin [5. Pivo-ted to the forward end of the bell rod on the pin I5 is the upper end of a vertically disposed combination lever 16. Pivotally connected to the lower end of the combination lever l6 there is an adjustable union link ll, the opposite end of which is adjust-ably pivoted to a crank arm I8 of a crank shaft 19 which is rotatably mounted in an approximately vertically positioned pivot rod 20, the upper end of the pivot rod 20 being pivotally mounted on a stationary pivot 2| which is positaken 'on lihes 33 tioned on a portion of the locomotive frame. The lower end of the pivot rod 20 has pivotally connected thereto a secondary union link 22 which is-connected in the usual manner to the main cross head pivot 23 of the engine. The main cross head is connected to the driven wheel [-3 of the locomotive by the usual connecting rod 24.

By again referring to the crank shaft l9 and to Figures 2 and 3 of the drawing in particular, it will be seen that the crank arm I8 is provided with a pair of openings therein to either of which the adjustable union link I! may be pivotally affixed. It will also be seen that the crank shaft [9 extends through the pivot rod 20 and carries a pinion gear 25. A suitable bracket 26 is all-fixed to the pivot rod 2!] and serves to support the innermost end of the crank shaft [9. Still ring to Figures 2 and 3 of the drawing it will be seen that a stationary rack 21 has been provided on which a'plurality of gear teethadapted to mesh with-the teeth of the pinion gear 25 are formed. The rack 21 is mounted on the locomotive frame by any suitable means. It will thus be seen that as the locomotive wheel l3 revolves in the direction indicated the system.

of links and levers connecting the eccentric pin l2 and the pin l5 of the combination lever'lli,

refertrated. It will also be seen that the principal advantage of the mechanism shown and de-' dwell followed by a quick cut-off of the valve is scribed herein is the ability of varying the move ment of the steam valve 28 which is connected,

through a suitable valve stem cross head rod 29 to a pivot on the combination lever l6 thus movement of the combination lever 16 actuates the steam valve 28 in a desirable manner.

By referring to Figure 4 of the drawing it will be seen that an enlarged view of a portion of thejinvention including the pinion gear 25-has been shown,.-and that broken lines divide the pinion gear 25 into approximate quarters with I the crank l8 positioned almost vertically as also shown in Figure 2 of the drawing and it willbe seen that clockwise revolving motion of the pinion gear resulting from its engagement with the rack 21 will result in the crank 18 traveling 'through the first quarter, as indicated in Figure 4, during which it will speed up the motion of 'thelever I! in relation to thatoi the lever 20.

When the crank is in horizontal position as shown in dotted lines A in Figure 4, the motion imparted the lever I! will .momentarily'be the same'as that of the leveriil as the crank l8 swings downwardly through the second quarter of revolution as indicated to assume an approximately perpendicularposition. It will be observed that the motion is greatly retarded as the crank I8 is traveling in an opposite direction 'tgi advantage in the movement of the steam valve 28. Theoretically there is no retardation or acceleration of the steam valve 28 as it now effects an even travel rather than an uneven travel as in the mechanism formerly used the revolving of the main pivot around the wheel of the locomotive alternately imparted fast and slow motion to the combination lever. The mechanism herein disclosed smoothes out this movement through the use :of the pinion gear and rack and crank arm and effects the desirable operation of the a r .steam valve. According to this invention a long e'flected. This enables the valve to be opened "fully quickly and also to close quickly so that the supplyand exhaust of steam are not wiredrawn during the period of revolution. In other iwordsthis invention provides an alternate accelerated and retarded movement of the valve during its stroke so as to accomplish a quick and complete opening of the admission port and maintain it up to a point very near the cut-ofi;

What I claim is:

1. A valve gear mechanism for steam-engines having a driven rotatable member, a driven reciprocable member, and a steam admission and exhaust valve, comprising a combination lever, deriving motion at its lower end portion from said reciprocable member and at its upper end that, of the lever 20 and that when the crank 18 reaches the lowermost position and corresponds in alignment with the lever 2% the relative movement of the lever I! will have almost'ceased vrithrespect to the, lever 20. As the crank l8 subsequently swings, upwardly into 1 the thirdquarter as indicated, the motion is still greatly retarded butincreases gradually until the point indicated by the dotted lines designated by {the 7 letter, -B;wher ein the motion is again the same as that of 'the'lever 20. Passing. this point the crank it rises vertically through the iourth quarter as indicatedduringwhich time the motion is again accelerated as the crank I8 is now overtaking the lever 20 'and thus causing acceleration. 'The reverse occurs when the move.-

mentis reversed by the movement of the pinion gear, 25in the opposite direction along the rack.v

2 as the leverZ-il returns to the position indicatedin Figure 2 of the drawing." It will thus' be, obvious that when various component parts of the device are of correct size and spaced in correct; positions with respect to one another the result obtained is a rapid movement of the'val-ve, 28' in the beginning and endof its-stroke and I prising the utilization of a rod pivoted-at its to greatly retard this movement during the mid sults in the same motion atbothfiends ofyits V traveh This movement alternates as the pivot,

rod. zll swings back and forthaand the resulting V variation of, movement imparted. to theloweriend;

oiithe combination lever; it results in fa direct J dle fportion of the stroke. The acceleration causes the valveto open, quickly andclosequiizkly asgobviou'sly, motion imparted the valve .28 re-Q- portion from said rotatable member, and means including a pivot rod, a pinion gear engaging a.

rack providing a connection betweenthe said lower end of the combination lever and the said reciprocable member, said means adapted to impart a modified movement to the said combination lever so as to reduce the effective movement of the combination lever. during a portion of its travel and to increase the effective movement thereof during another portion of its travel.

2. An auxiliary ,valve gear mechanism for steam engines having .a driven rotatable member, a driven reciprocable member, and a steamadmission and exhaust valve, comprising a combinationlever deriving motion at its lower end portion from said reciprocable member and at its upper-end'portion from said rotatable ;mem-- ber, a reciprocable cross head for said'valve and a rod providing an operative connection between said cross head and the upper end-portion 'of said combination-lever, together with means formodifying the movement imparted" to the-lower end of the combination lever, said means-comupper' end, a pinion gear carried on said rod adapted to engage a stationary-rack, the bottom of the said pivot rod deriving motion from the said driven reciprocable member and the. lower end of the said combination lever deriving mo- 2 tion from the said pinion gear, to modify-the-- effective -movement of the said steam" valve at predetermined points during the movement thereof.

3. A valve gear reciprocable member, and-a steam admission reciprocable; member, a. rod connecting the com bination lever'and the steam valve so that modi.

; fi'ed "movement of j the tombinationleizer as inn mechanism for steam engines 7. having a driven rotatable memb'er, adriv'pn' and exhaust valve, comprising a. combination lever deriving motion at;i-ts 'upperl' end portion.

from said rotatable member and at itslew'er'fend portion from a pinion gearcarried on a pivntrod. and: engaging a stationary rack, .thes'aidpivot. rod pivoted one; stationar-y pivot. atits upper endiand receiving movement at itslower end from the said parted thereto by the said pinion gear and pivot rods will vary the elfective movement of the steam valve so as to increase the same during a portion of its travel and decrease the same during another portion of its travel.

4. A valve gear mechanism for steam engines having a driven rotatable member, a driven reciprocable member, and a steam admission and exhaust valve, comprising a combination lever deriving motion at its upper end portion from 1 said rotatable member and at its lower end portion from said reciprocable member by way of and through a pivot rod pivoted to a stationary pivot at its upper end and receiving movement from the said reciprocable member at its lower 1 end and carrying in rotatable manner a pinion gear engaging a stationary rack positioned adjacent thereto, a crank shaft positioned in said pinion gear and providing means for effecting a connection between a crank arm thereof and the lower end of the said combination lever, together with a rod connecting the said steam valve and the said combination lever so that movement of the said combination lever results in a desirable movement of the said steam valve. 25

5. A valve gear mechanism for steam engines having a driven rotatable member,; a driven reciprocable member, and a steam admission and exhaust valve, comprising a combination lever deriving motion at its upper end portion from said rotatable member and at its lower end portion from said reciprocable member by way of and through a pivot rod pivoted to a stationary pivot at its upper end and receiving movement from the said reciprocable member at its lower end and carrying in rotatable manner a pinion gear engaging a stationary rack positioned adjacent thereto, a crank shaft positioned in said pinion gear and providing means for eifecting a connection between a crank arm thereof and the lower end of the said combination lever, the said crank arm and the said combination lever provided with two or more pivot locations so that a connecting rod may be adjustably positioned in between them, together with a secondary rod connecting the said steam valve and the said combination lever so that movement of the said combination lever results in a desirable movement of the said steam valve.

HARRY J. SHERRILL.

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