US382032A - dixon - Google Patents

Description

(No Model 2 sheets-sheet 1.

- T. S. E. DIXON.

AIR BRAKE POR RAILROAD GARS.

No. 382,032.` Patented May 1, `1888.

humuihnxmpher, wahingmu. D4 Q (No Model.) l l 2 Sheets-Sheet 2. T. S. HIDIXON.

AIR BRAKE FOR RAILROAD GARS.

Patentedlmay 1,- 1888.

UNITED STATES PATENT OFFICE THERON S. E. DIXON, OF CHICAGO, ILLINOIS, ASSIGNOR OF` ONE-HALF TO LYSANDER HILL, OF SAME PLACE.

AIR-.BRAKE FOR RAILROAD-CARS.

SPECIFICATION forming part of Letters Patent No. 382,032, dated May 1,1888. l l I Application filed December 16, 1887. Serial No. 253,112. (No model.)

To all whom it may concern:

- Beit known that I, THERON S. E. Dixon, a citizen of the United Statesof America, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Air-Brakes for Railroad- Cars, of which the followingis a specification.

Figure 1 is a sectional view of a form of my improvement, and Fig. 2 is a sectional View of a modication of my improvement.

My invention relates to the so-called automatic air-brake system, in which the engineer, by charging and venting a train-pipe at the locomotive, operates a valve-controlling piston on each car to admit compressed air from a separate storage-reservoir to the brakecylinder and discharge it therefrom at Will, for the purpose of setting and releasing the brakes. In consequence of the air having to travel from the neighborhood of each lvalvecontrolling piston along the train to the ventcock at the locomotive, in order to reduce the train-pipe pressure sufficiently to operate such' piston, it follows that the brakes are not applied simultaneously on the several cars, but consecutively, beginning at the front and ending at the rear of the train.

the setting of the brakes on any two contiguons cars is sufficient to enable the rear car of the two to run forward and strike the next car ahead, after the brakes have been set on the latter and before they are set on the former, thereby causing more or 'less shock lbetween the two cars, and that the amount of this shock increases toward the rear end of the train, and in long trains becomes very damaging at the rear cars when the emergency-stop is applied to bring the train to a sudden halt. It has also been demonstrated bythe electrical air-brake that if the brakes be simultaneously applied on all the cars the train, however long, will come to a quick and easy stop withoutshock. Efforts have been made, with more off less success, to cause the venting of the train-'pipe at the locomotive for emergencystopsto effect a substantially instantaneous reduction of airpressure throughout the entire length of the train=pipe by producing a local discharge from the train-pipe .at each It has been found in practice that the interval of time between 'To that end the pistons and ports have been so constructed that when the emergencystop is applied they rstcause the brake-cylinders vto be partially charged with compressed air from the car-reservoirs, and then open a vent from the train-pipe to the brake-cylinder under each car to effect a series of local dis charges from the train-pipe to the several brake-cylinders, a valve arranged-in an airpassage from the train-pipe to the brake-cylinder and subject on the one side to the pressure of the train-pipe and on the other side to the pressure of the brake-cylinder, aided by a spring,serving to close the local discharge when the pressures of the train-pipe and brake-cylinder become nearly eqnalized. In a structure having such mode of operation, however, several obstacles intervene tending to hinder the perfect accomplishment of the purpose desired. First, the air endeavoring to pass from the train-pipe into the brake-cylinder encounters initially the resistance of the compressed air already vented from the car-reservoir into said cylinder; secondly, as fast as it enters the brake-cylinder it increases this initial resistance and contributes to its own further retardation; thirdly, the amount which can be thus vented into a partially-filled brake-cylinder is quit/e limited; fourthly, to whatever extent thetrain-pipe air enters the brake-cylinder it contributes to hasten the closing of the local discharge, thus allowing the latter only an instant to operate and materially limiting its capacity; tifthly, the quick charging of the brakecylinder, which results from admitting air into it simultaneously from the train-pipe and rcs ervcir,applies the brakes almostinstantly with full force on the car Where it occurs before the sudden local reduction of pressurein the trainpipe has had time to fully reach and affect the valve on the next ca r in rear, and thereby tends to counteract the very effect desired-to Wit, the prevention of shockJ with the old brake systems long in use on passenger-cars has shown that so abrupt an application of brake-pressure is not in any way Experience advantageous, and it is especially undesirable the setting of the brakes on any car should not be fully completed before it begins on the next car in rear. Even with an apparatus having so imperfect a mode of operation, however, the reduction of train-pipe pressure along the train has proved sufticiently quick, under favorable conditions, to demonstrate the fact that variations of air-pressure produced by the manipulation of a cock on the locomotive are inherently capable of controlling the application of the brakes by reservoir-pressure on long trains without substantially injurious shock, and that there is thereforeno necessity for resorting to uncertain, expensive, and easily-deranged electrical appliances to govern the admission of air to the brake-cylinder.

The obiect of myinvention is to so improve the construction and mode ot' operation of automatic air brakes as to avoid the disadvantages hereinabove set forth by producing sudden, unobstructed, and ample local discharges from the train-pipe, and giving them time to reach and affect the brakes on each car during the setting of the brakes on the next car ahead and before such setting is fully completed.

To this end the first and main part of my invention consists, essentially, in cutting off and dispensing with the passage from the trainpipe to the brakecylinder and locally venting the train pipe directly to the atmosphere through a passage or port,which is opened by preliminarily lowering the pressure in the train-pipe and closed by a sufiicient increase of pressure in the brake-cylinder.

Anotherand independent improvement consists in so constructing and applying the springvalve, which closes the local discharge, that said valve shall not close and cut oli' the discharge until after the train-pipe pressure has fallen below that of the brake-cylinder, thereby lengthening the period and increasing the amount of the local discharge.

Another andindependent improvement consists in combining in one and the same valve the functions of opening and closing the local .discharge-passage.

Other improvements will be suiiiciently indicated by the several claims hereto appended.

My improvements are severally capable of embodiment in many different structural forms and arrangements, and with one or more than one valve for controlling each local discharge-passage.

In order to partially illustrate the variety of structure that may be employed, I have on Sheet 1 of the drawings represented a form of apparatus in which one valve eliects the opening and another the closing of said passage; and on Sheet 2 another form of apparatus, in which a single valve performs both functions, it being understood that these are only some of the many ways in which my improvements may be carried into practice.

I will now describe the structures shown in manner in which they eHect the more important advantages resulting from such new mode of operation.

For convenience of description, and because the Westinghouse automatic air brake is well-known in the art and will be understood without minute explanation, I prefer to illustrate my improvements as applied to that system, although they are equally applicable in connection with other automatic systems.

In the drawings, Fig. 1, A represents the well-known piston-valve of the Westinghouse automatic air-brake, B being its controllingpiston arranged in a valve casing, B; C, its su pplementary spring-stem; D, the passage from the car-reservoir to the brake-cylinder; E, the exhaustfrom thebrake-cylinder to the openair; F, thetrain-pipe; a, the port which puts the carreservoir into communication with the brakecylinder for service-stops or grading; a', the port which effects the same communication for emergency-stops, and G the valve which, when opened by the movement of the piston to apply the emergency-stop, permits the local discharge to take place from the trainpi pe. In the different constructions of the Westinghouse apparatus the valve G-that is to say, the valve which opens to allow said local discharge from the train-pipe when the emergency-stopisapplied-assumesdiierentforms, and is in some instances operated directly and in others indirectly by the movement of the main piston B. For the purposes of illustration I have selected one of these forms as typical of all valves that normally hold the local discharge closed and only open it when the emergency-stop is applied. In this form the valve G is a slide-valve supported by the supplementary stem C, which is struck and moved only when the main piston is in the act of applying the emergency-stop.

My improvements are as follows: First, I cut off and dispense with all communication between the train-pipe and brake-cylinder, and in lieu thereof provide an open air-port, H, through which, when the local discharge is taking place, the air will vent from the trainpipe directly to the atmosphere without encountering any resistance from the airpress ure in the brake-cylinder,and without tending to force the brakes too abruptly against the car-wheels, using the reservoirairalone to set the brakes, as in the old passenger system. The local discharge having been thus estab lished may be closed by a separate valve, I, through the action of a small piston or diaphragm, J, which is subject on one side to the increasing pressure of the brake-cylinder air and on the other side to the decreasing pressure of the train-pipe air, whereby the local discharge when once opened will be held open so long as the train-pipe pressure exceeds that of the brakefcylinder, and will thereafter be automatically closed by the latter. At the option of the constructor,a spring may or may not be applied to aid in opening or closing the valve I; or,in lieu of a spring,the air-surfaces acted upon by the brake-cylinder air and the ICO train-pipe air, respectively, may be made differential, so that an excess of pressure on the one side or the other will be requisite to seat or unseat the valve. This feature (the spring or its equivalent) is, however, independent of my main invention, which is fully operative with or withoutit. As the result of the general construction above described, and from the fact that the brake-cylinder fills from the reservoir alone, the local discharge-port will be held open longer and the venting of the train-pipe will consequently be more ample and complete than when,as heretofore,said cylinder is filled from both the reservoir and ltrain-pipe. As compared with the old method of'venting the train-pipe into the brake-cylinder, my new mode of operation therefore pro'- `duees the triple effect of venting without resistance into an unlimited space and for a longer period, and the practical effectiveness of the local discharge is thereby greatly increased. The time required to fill the brakecylinder from the reservoir will depend entirely upon the size ofthe emergency-port,and hence can be adjusted as experience-shall determine to be best.

Secondly, as my next improvement, I connect with said valve I or piston Ja spring, K, arranged to `act with the train-pipepressure and against the brake cylinder pressure to hold said valve open for a limited time after .the brake-cylinder pressure equals or exceeds that of the train-pipe, thereby allowing a still longer time for the latter to ,vent to the atmosphere and producing a correspondingly more effective reduction of its pressure by the local discharge. The force of this spring when thus applied should be so proportioned as to allow asufcientincrease of brake-cylinder pressure to overcome it and close the local discharge, and should also be so limited as not to equal (in terms of air-pressure per square inch of piston-surface) that of the springmarked L, (or other spring'employed in returning the main piston B from its emergency-stop position,) in order that the local discharge may not interfere with the movements ofthe main piston. Differential surfaces may also be employed as the equivalent of the spring K, care 4being taken to adjust the difference of area, so as to proportion and limit its action, as above indicated. In the form shown in Fig. l the spring K is a rubber sleeve, serving not only as a spring, but also as an air-tight packing for the piston J when the brakecylinder is iilled. Heretofore a spring has been used `to aid the brake-cylinder pressure to Vclose the local discharge into the brake-cylinder by acting with the brake cylinder air against the train-pipe air, and has accordingly diminished .rather than increased vthe extentandeffectiveness of the local discharge, such arrangement being, however, an absolute necessity where .thetrain-pipe andcar-reservoir both vent into the brakecylinder at the same moment-,and thus enable the reservoir-air to pass around into the train-pipe unless the communication be closed'before the pressurein the brake-cylinder exceeds that in the train-pipe.

My third improvement consists in combin- 7c ing in a single valve the functions of the two valves G Ithat is to say, the functions of opening and closing the local discharge. Any valve performing these two functions must be capable of two independent movementsto wit, one movement resulting from the traverse of the main piston to apply the emergency-s'top, and another movement resulting from the increasingpressure in the brake-cylinder. Of the various constructions that may be devised for this purpose I prefer the one shown in Fig. 2. In this figure M represents a small cylinder secured in the outer or lower end of the casing B' and closed at its exposed end by a plug, M', having a circumferential recess, m, which communicates on the one hand with a central bore, m', extending from the line of the recess to the inner end of the plug, and on the other hand with a passage, m2, leading from the brake-cylinder or from the passage through which said cylinder is filled bythe action Aof the triple valve. In the small cylinder M a piston, N, (the general equivalent of the piston J, above described,) is arranged, packed airtight and subject on one side to the airpressure of the brake-cylinder derived through-the passages m2 m m, and Qn the other side to the air-pressure of the train-pipe, which freely enters the small cylinder through an opening, f, in its inner end. Attached to the main piston B is a tubular stem, b, terminating at its lower end in a ange, b', which performs the double function of guiding the lower end of stem b and supporting a thimble, O, and which either tits so loosely in casing B as to allow the air from train-pipe F to pass freely around it to cylinder M, or `else is provided with holes for that purpose. A stem, N, attached to piston N, extends up into the tubular stern b. The office of the thimble O is to support and control the valve Gr, which governs the local discharge-port. (Shown in dotted lines.) To this end the thimble is normally held seated on the ange b by the force of a light spring, P, but is able to slide on the stem and is provided with a bar orkey, o, which passes through a slot, b2, in stem b. Below the flange b is a sliding ring, Q, pressed upward by a spring, Q', against the lowerend ofthe bushing B2 of the casing B, and projecting slightly inside of the line or" said bushing. The ordinary dripplug is shown at B3. The operation is as follows: The normal position of the several parts is asshown in Fig. 2. When the train-pipe air-pressureis reduced sufcientl y to apply the emergency-stop, the main piston B descends, .carrying down with it the iiange' b', which in turn strikes and moves down the ring Q against the resistance of spring Q' until the upper end of valve G comes belowthe local dischargeport and the pin o reaches or nearly reaches the upper end of stem N', whereupon the air from the train-pipe vents through said port to IOO IIO

the atmosphere. At or near the time when the local discharge is thus opened the valve A also opens the emergency-port a', which puts the car-reservoir in communication with the brake-cylinder and lls the latter with reservoirair. Vhen the incrcasingpressure in the brake-cylinder sufiiciently exceeds the decreasing prcssure in the train-pipe, it lifts the piston N, causing the stem N', which slides freely in the tubular stem b, to strike the key or pin o and push the thimble up against the resistance ofspring P, thereby closing the local discharge. 'Vith respect to lthe resistance thus offered to the movement of the small piston N the spring P, it `will be observed, is the general equivalent of the spring K, above described. The readmission of air -pressure through the traiirpipe will now release the brakes and rescat the piston N at the lower c nd of the cylinder M, thus bringing all the parts to their normal position.

With the construction last above described important advantages are gained by arranging a packing ring or seat, r, of rubber, leather, or other suitable material, at the inner end of the plug M', and another, r', at the upper side ofthe piston N, and so proportioning the parts that whenthe piston N is at the lower extremity of its movement it will seat on the packing-ring r, and when -at the upper eX- tremity of its movement it will seat the packing-ringrl against the annular surface ri at the upper end of cylinderM, thusclosing the joint air-tight in either instance and holding it closed by the force of the air-pressure upon said piston, so that the air can neither leak from the trainpipe to the brake-cylinder when thelatter is empty nor from the brake-cylinder to the train-pipe when the conditions are reversed. I deem it best that the tension of the light spring P should be sufficient to overcome the friction of the slide-valve G, but with the construction here shown that the force of the spring P per square inch upon the piston N should not exceed the combined force of the springs P Q per square inch upon the main piston B, in order that when the train-pipe begins to be refilled from the locomotive the piston N may not yield before the main piston commences its return movement. In the coustruction illustrated in Fig. 2 the piston N, by reason of its relation tov the packing-rings, r r', has a very peculiar action, being,when seated thereon, a differential piston and While in traverse non-differential. The result is that when the local discharge is opened the piston N remains seated on the ring r until the brakecylinder pressure acting on the small under surface inside of the ring overbalances the train-pipe pressure acting ou the much larger upper surface, and hence the local venting of the train-pipe does not cease until its pressure is reduced considerably below that of the brake-cylinder. On thc other-hand, when the train-pipe commences to be refilled, the packing-ring r' being seated against the annular upper end of the cylinder M and the trainpipe pressure acting only on the area of the openingwhile the brakecylinder pressure acts upon the entire lower side of the piston, the latter will necessarily remain immovable until the main piston B, returning to its normal position, releases the brakes and discharges the pressure from the under side of the piston N. The piston N ,therefore, cannot move in either direction until the moment arrives when such movement is necessary, and the instant it commences such movement its differential character disappears and au in creased force is brought to bear upon it to ren der its movement positive and certain, thus affording exactly the conditions for its most advantageous operation. Instead of rubber, leather, or other soft surfaces at r r', the pis ton and its seats may be ground to an air-tight joint. A dust shield or guard, t, (shown in dotted lines) is preferably applied to the open end ofthe local discharge-passage to prevent dust from entering and tending to interfere with the action of the valves. U is a cock arranged in the local branch of the train-pipe, by which the pneumatic apparatus of any ear may be cut ofi' from the train-pipe in case the brakes of such car should become disabled, or for any other reason.

The effect of my several improvements is to insure a local discharge so free, quick, and ample and a consequent reduction ofthe trainpipe pressure so sudden and decided that a positive and powerful actionwill be produced almost instantly upon the piston-valve of the next car, and so on throughout the train, at the same time setting the brakes more slowly, so as to bring them all, as nearly as possible, into simultaneous action and cause the train to come to a quick and easy stop without shock. The time involved in setting the brakes will depend entirely upon the size of the emergency-port, which may be adapted to any requirement.

Having thusdescribcd my invention, Iclaiin as newl. The combination of the brake-cylinder, the train-pipe, the car-reservoir, and the main valve-operating piston with a passage leading from the trainpipe to the open air for locally venting the train-pipe to the atmos phcre, and with means whereby said passage is opened by preliminarily lowering the pressure in the train-pipe in applying the emergency-stop, and closed by a sufficient increase of pressure in the brake-cylinder, substantially as described.

2. The combination of the brake-cylinder, the train-pipe, the car-reservoir, and the main valve-operating piston with a passage lead.

the train-pipe, the car-reservoir, and the main valve-operatingV piston with a passage leading from the train-pipe to the open air for locally venting the train-pipe tothe atmosphere, anda valve which opens said passage when the main valve-operating piston opens the emergency-port, and which. is controlled by the movement of that piston, substantially as described.

4. The combination ofthe brake-cylinder, the train-pipe, the car-reservoir, and the main Valve-operating piston with a passage leading from the train pipe to the open air for locally venting the train-pipe to the atmosphere in applying the emergency-stop, and a valve which closes said passage by the pressnre of the air in the brake-cylinder, substantially as described.

5. The combination, in a fluid-brake mechanism, of a train-pipe, brake-cylinder, air-reservoir, and a main valve-operating piston, B, with a discharge-passage lleading from the train-pipe to the open air, provided with a valve, which is operated by the final movement of the piston B in applying the brakes for emergency-stops, thereby venting the trainpipe to the atmosphere, substantially as described.

6. The combination" of the brake cylinder, the train-pipe, the car reservoir, the main valve-operating piston, the passage leading from the train-pipe to the open air for locally lventing the train-pipe directly to the atmosphere in applying the emergency-stop, and the valve for closing said passage by an increase of pressure in the brake-cylinder, with a spring or its equivalent to aid in holding said passage open' against the increasing pressure of the brake-cylinder, substantially as described.

7. In a duid-brake mechanism, the combination of the main piston B with a supplemeutary piston N, and a single valve operated by said pistons whose movement opens and closes the local discharge-passage leading from the train-pipe to the atmosphere, substantially as described.

8. In a fluid-brake mechanism, the combination of the main piston B with a valve operated thereby to open the local dischargepassage leading from the train-pipe to the atmosphere, and a supplementary piston for operating said valve to close said discharge, substantially as described.

9. In a duid-brake mechanism, the combination of the main piston B with a valve operated thereby to open the local dischargepassage leading from the train-pipe tothe atmosphere, and a supplementary piston, which under the influence of the brake cylinder pressure operates saidvalve to close said discharge, substantially as described.

10, In a duid-brake mechanism in which the movement of air to and from the brakecylinder is controlled by a main valve-piston, the combination of an auxiliary piston actuating a valve which vents the train-pipe to the atmosphere, with a packing-ring or seat for the purpose of preventing the movement of the piston until a substantial difference of pressure upon its opposite sides has been attained without impairing by a continuance of the differential surface the force of the movement of the piston when once it is initiated, substantially as described.

11. In a Huid-brake mechanism, the coinbination of the seat 1' with the auxiliary piston N, which operates to close the local discharge, whereby said4 discharge is held open after the pressure in the brake-cylinder equals that in the train-pipe, but is eiiectually closed when the train-pipe pressure becomes further reduced, substantially as described.

l2. In a fluid-brake mechanism, the combination of the seat r2 with the auxiliary piston N, which operates to close the local discharge, whereby said discharge when closed is held closed during the readmission of air to the train-pipe, even under a greater pressure in the train-pipe than in the brake-cylinder, and until the pressure in the brake-cylinder is reduced, substantially as described.

13. In a Huid-brake mechanism, the combination of the yseats r r2 with the auxiliary piston N, which operates to close the local discharge, whereby said discharge is held open until the pressure in the train-pipe is less than that in the brake-cylinder, is then eii'ectually closed through the further decrease of pressure in the train-pipe, and remains closed until by the discharge of the brake-cylinder the pressure therein becomes less than that in the train-pipe, substantially as described.

14. In a fluid-brake mechanism, the combination of the valve-carrying thimble O With a stem, b, and spring I, substantially as described.

15. In a iiuid-brake mechanism, the cornbination of the piston B and valve G and the valve-carrying thimble O with the stem b and spring P, and with the ring Q and its spring Q', substantially as described.

16. In a fluid-brake mechanism, the combination of the piston B and valve G and. the valve-carrying thimble O and its pin o with the piston N and its stem N', substantially as described.

17. In a fluid-brake mechanism, the combination of the piston B and valve G and the piston-rod N with the hollow stem b, the thimble O, the pin o, and the spring P, substantially as described.

THERON S. E. DIXON.

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