USRE891E - Improvement in slide-vavles for steam-engines - Google Patents

Description

l 0n the line S S in Fig. 1.

`increase in thelength of the steam-chest.

RICHARD C. BRISTOL, OF CHICAGO, ILLINOIS.

IMPROVEMENT IN SLIDE-VAVLES FOR ySTEAM-ENGINES. I

Specification forming part of Letters Patent No. 24,439, dated June 21, 1859; Reissue No. S91. dated February 7, 1860. i

T0 all whom, it may concern:

Be it known that I, RICHARD C. BRISTOL, ot'Chic-ago, in the county of Cook and State of Illinois, have invented a new and useful Improvementin Slide-Valves for Steam and Gas Engines; and I do hereby declare 'that the following is a full and exact description of the construction and operation of the same, reference being had to the accompanying drawings, forming a part ot' this specication, in whichp Figure l is a side elevation, reckoning' relatively to its motion. Fig. 2 is an end elevation. Fig. 3 is a vertical section on the line '1 T in Fig. 2, and Fig. 4 is a vertical section Similarletters oi' ret'erenceindicate like parts in all the drawings.

It is well known that the pressure of steam upon a slide-valve tends ,to produce a great amount ot' friction, and various devices have been made known with a view to diminish this injurious eti'ect. One of these has been to construct upon the back ofthe valve a short cylbeing suspended by a link attached to the' cover ot' an elevated steanrchcst, relieves the valve from much of the pressure ot' the steam.

inder with a piston working therein, which,

these partial rollers may be placed much nearer together and a much larger effective diameter thereof may be adopted, as also a shortersteainchest, than with wheels. These partial rollers .are also guided and kept in position at or near their bearing-points, so that they are not, like ordinary rollers, liable to any possibility otdisported part, and so -arran ging suitable passages through the parts ofthe valve, that the steam is conveyed to thecylinder-ports through I such passages alone, with 'the usual eii'ect due to expansive working, while the two parts ot' the valve may be allowed to work to alimited extent relatively t0 each other without in volv- Another way has been to mount the piston of such a valve upon wheels running1 in vways parallel to the i'ace ot' the valve. These and other previously-known devices have either been expensive -in construction or have but imperfectly accomplished the object, orboth,

while they have necessitated an unusually vcapacious steam-chest, thus rendering the eX- pansion ot' the steam, when an independent cut-off is used, less ei'ectual; and in no case,

when the pressurevhas been supported from l otf the valve, has the very common and desirable plan been practicable of working a cut'- oif valve on the back of the main slide-valve.

The nature ot' my invention consists in employing in lieu of wheels four or more partial rollers which areA not subject to any friction upon their axes, neither do they compel any My rollers are circular or cylindrical so large portions of their periphery partial through asto allow the valve' to travel thereon to the iullextent of its motion. The remainder of the periphery is reduced in diameter, so that in g a leakage ot' steam at the joints. Asbalan ced slide-valves have been constructed, such a result has been impossible.

The nature of my invention likewise also consists ina process of adjustingthe twoy parts of the valve before working it, or after workin g it for a period with the two partsiu, free rela.- tion to each other. p Y g The adjustment ot similar valves has beenA heretofore produced by the pressure ot' the steam upon a certain portion not balanced` or As the friction ot' one part within p relieved. the other is liable to be very considerable, it has, in order to secure a proper adjustment,

been necessary to leave a large portion of the' face-piece uncovered by the back piece or piston, and consequently unrelieved from pressure, which, yuponthe portion thus situated, has produced a continuous friction between the valve-face and cylinder-face. My inventionv overcomes this diiculty by causing a rigid union, or nearly so, of the two parts ot' the valve after the face-piece has assumed the proper position for a tight Contact with the cylinder-face.

ToV enable others skilled iu the artto mak and use my invention, I will proceed to describe, bythe aid ofthe drawings, theinanner in which I construct and operateit.

The valve proper is constructed in two portions, A and B, the latter being iitted steamiight into the former, so that it is adapted to slide vertically therein to a certain extent, as represented, without allowing steam to pass through the joint. Set-screws C C are provided, by which the portions A and B may be made to hold their relative places very iirml y, itl required. The cut-ofi' valve D is fitted to slide steam-tight on the upper face of B, and y is guided thereon by ledges or lips. The top ot' B overhangs A at each side, as represented by B2 B, and the partial rollers which are introduced b'etwcen these overhanging portions and the cylinder face M support B on the circular portions ot' their several peri'pheries and 1compel it to travel in a plane parallel to the face M.- The form which I prefer for these partialV rollers is shown in Figs.`l and 2, a part being shown by strong and a part by dotted lilies in each tigure. The overhan ging portions of B are made to inelose and confine the upper sides or circular ends of these partial rollers, as shown by B2, B3, and B, and the lower sides, or lower circular ends thereof, are inclosed or conlined by analogous means, M2, M3, and M4, on or near the cylinder-face. I also make suitable apertures, E', through the partial rollers E, near their extremities, and insert pins B B', which extend through these slots into the metal ofthe back piece, B, and simila-r pins, M', which extend into the metal ot' the cylinder-tace M. These apertures or slots are ot' such length and such form as to allow the partial rollers ioplay to the proper extent without touching the pins so long as the partial rollers are. in their correct positions; but the moment one ot' these partial rollers becomes in any considerable degree displaced at either the top or the bottom it presses the sides of the corresponding slot against the pin, and thus prevents itself from becoming more displaced.

" Any sensible displacement of either of the or partial rollers also causesit to meet the other to meet a stop to aid in preventing it from becoming any iu ri fther displaced. The red `outlines show the condition ot' these partial rollers at the end otl each movement of the valve.

, B, at each vibration, and thus ot' cutoff device w i i l l The steam is admitted to the ports in the cylinder through the passages a a and c v in the respective parts `A B. These passages Yare arranged as represented, sothat the part A may slide vertically upon, B, and vice versa, without closing the passages a b,and without lscrews C C are'slackened, an

producing any leak at the joint or dividing line.

In commencing to operate my valve the set thus allowed to be pressed downv into steamtight contact with the cylinder-face M by the pressure ot' thersteam on that part of A which s not vprotected therefrom byrB. It is usuv d thepart A is y herein set forth.

ally worked for several days in this condition, so that it is free to rise and sink without at'- t'eeting B, and is then (either at a single operation or by gradually increasing the tightness at several operations) set firmly in relation to B, by turning the set screws U C, in which case it continues to fit tightly upon the cylinder-face M, by reason tha parallel thereto.

It will readily be seen that my invention is capable of being constructed in various forms and proportions other than those which I have here represented. For example,

hich is suitable to work on the back or within the body of other slidevalves may be employed in my invention as the valve D, instead of the precise t'orm and proportion which I have represented. Broad heads may also be forged on the pins B and M,'which pins may be threaded and tapped into the respective parts so as to become bolts, and thus a lateral play of the partial rollers E may be prevented by the heads of these bolts in lieu of by the lips B9 and M3,as represented. Many other modifications may readily be adopted without varying substantially from the principal features of my invention.

YI do not claim sustaining a portion on the whole of the pressure upon a slide-valve by the use of wheels or of ordinary rollers; but,

Having now fully described my invention, what I claim as new therein, and desire to secure by Letters Patent, is-

1.` The construction and arrangement of the partial rollers E, when sustained in their respective positions substantially in the manner and for the purposes herein set forth.

2. Providing a slide-valve with lips B2 and stops B4, substantially as herein shown and described, for the purpose of sustaining the pressure of the steam thereon. upon the rolling supports E, or their equivalents, and ot' continin g the rolling supports to prevent their becoming displaced.

3. I do not claim the employment of a cnt-ofi" valve, D, sliding ou' the back of a valve having passages through which the steam is admitted to the ports in rthe cylinder under the control of both valves; but Iclaim the withindescribed arrangement ofthe supported back piece, B,loose tace-piece A, cutting-oit means D, and the united passages, a b, in the respective parts A B, whereby the parts A B are allowed 'to work to a limited extent relatively toeach other without affecting the action ot the steam, nor allowing any'escape of'the same through the joint.

4.' Bigidly connecting the parts A and B, after they have been properly adjusted, by means of the set-screws G C, or their vequivalents, substantially as and for the purposes l R. C. BRISTOL. Witnesses: e

J. L. FARGO,

Y A. G. WARNER.

t the motion of B is any variety-

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