US1076664A - Fluid-pressure brake. - Google Patents

Description

J. W. CLOUD.

FLUID PRESSURE BRAKE.

APPLICATION FILED JULY 18, 1911.

1,076,664.. Patented Oct. 28, 1913.

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JOHN W. CLQ'UIJ, OF LUNDON, ENGLAND, .ASSIGNOR TO THE WESTINGHOUSE AIIEt BRAKE COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENN SYLVANIA.

FLUID-PRESSURE BRAKE.

Specification of Letters Patent.

Application filed July 18, 1911.

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Patented (lot, 28, 1913. Serial No. 639,115.

To all whom it may concern Be it known that I, dorm W. CLOUD, a citizen of the United States, and a resident of London, England, have invented a certain new and useful Improvement in Fluid- Pressure Brakes, of which the following is a specification.

This invention relates to fluid pressure brakes, and more particularly to an apparatus adapted for the measurement of the volume of the train pipe of a fluid pressure braking apparatus for the purpose of indicating to the engineer the approximate length of such train pipe which is properly coupled and freely open so as to be available for effecting the usual braking operations.

The volume indicator of the present invcntion operates in accordance with the following general principle: If fluid under pressure be permitted to escape from a re ceptable which is maintained at a pressure different from that of the atmosphere until a predetermined change in the pressure in the receptacle is effected, the pressure of the volume of fluid thus transferred from the receptacle, provided said volume is fixed, will be a measure of the volume of the receptacle practically regardless of the initial pressure therein.

lit has previously be proposed to utilize the above principle for measuring the volumetric capacity of the train pipe of a fluid pressure braking apparatus by providing an automatic valve arranged to permit the passage of fluid under pressure from or into the train pipe until a predetermined change in the pressure therein has occurred, the fluid passing through the said valve during this operation being estimated by a measuring chamber or other suitable device. In one such apparatus the valve is arranged to be operated by a diaphragm, one side of which is subject to fluid at the initial pressure of the train pipe, and the other side of the dia r phragm being in open communication with the train pipe, and the fluid under pressure bein allowed to enter or escape through the valve. As soon as a predetermined change of pressure in the train pipe has occurred the diaphragm is arranged to be operated by means of a spring so as to close the valve and thereby cut off communication between the train pipe and the atmosphere, the amount of fluid under pressure which has passed through the valve being measured in any convenient way. It has been found 111 practice that with this arrangement the closing of the valve when the desired change of pressure in the train pipe has occurred is not sufiiciently effective or determmate, since as soon as the train pipe pressure has altered sutliciently to permit the closure of the valve, 110 further change in the train pipe pressure occurs and the pressure tending to keep the valve closed is thus extremely small, with the result that gradual leakage through the valve may take place, thus interfering with the accuracy of the measurement.

The present invention has for its object to provide an improved valve mechanism for effecting a positive and definite closure of the train pipe as soon as the desired change in pressure in the latter has taken place and comprises essentially a valve (preferably a slide valve) the operation of which is controlled by means of an auxiliary valve operated by a diaphragm subject on one side to the initial pressure in the train pipe and on the other side to the gradually varying pressure in the latter, as fluid is with drawn therefrom during the measuring operation.

In the accompanying drawing, Figure 1 is a sectional view on the line C-G of Fig. 3 of a preferred form of valve mechanism constructed in accordance with my invention and showing the parts in normal position, the passages 18, 14:, 20, 21, and 26 therein, While shown in dotted lines, being in front of the plane of section and the slide valve t being sectioned on the line (Z--(Z of Fig. 5; Fig. 2 a sectional view of the valve mechanism on the same plane as Fig. 1, showing the parts in position for measuring the volume of the train pipe; Fig. 3 a section on the line ca -a of Fig. 1, looking in the direction of the arrow; Fig. 4 a sectional view of the valve mechanism, taken substantially on the line b-b of Fig. 1 and looking in the direction of the arrow; and 5 a face view of the main slide valve and a plan view of the valve seat therefor.

Referring now to the figures of the drawing, the valve mechanism comprises a loose- 1y fitting piston 1 located in the chamber 2 and subject on one side to the pressure of a light spring 3 and controlling the movement of a slide valve 4 in a valve chamber 5. The valve chamber 5 is permanently connected to the train pipe 31 through passages 6 and 7 leading thereto.

In the valve casing, a controlling chamber 8 is provided, which is separated from the passage 7 leading to the train pipe by means or a diaphragm 9 adapted to control the operation of an auxiliary valve 10 which is normally held in its open position by means of a spring 11. The diaphragm 9 is provided with the usual guide stem 9 slidably mounted in the usual guide bearing 9. The valve 10 controls communication from a space 12 connected by means of a passage 13 with the piston chamber 2, to a passage 1 1 terminating in a port- 15 in the seat of the slide valve l, said valve being provided \Vlbh a cavity 16 adapted to connect the port 15 with the passage 17 when the slide valve is in its operative position.

it manually controlled plug cock 18 is provided which is capa 20 ole of being set in one or other of two positions by means of a handle 19. The cook 18 is formed with a number of passages in its body portion, a passage 20 in the cock serving in one position of the handle to connect the valve chamber 5 with the controlling chamber 8 by means of passages 21, as shown in Fig. 3. In the same position of the handle 19 a passage 22 in the cook 18 serves to connect a passage leading to a measuring chamber 32, with the atmosphere through an exhaust port 24. The passage 20 is also adapted, when the handle 19 is operated, to establish communication from a passage 26 in the valve casing leading to the passage 13 to an exhaust passage 25, a cavity 28 and a passage 29 in the cock being arranged in the measuring position of the handle 19 to establish communication from a passage 30, leading to the underside of the slide valve i, to the passage 23 leading to the measuring chamber and also from the passage 30 to the passage 17, before referred to, as shown in Fig. 2.

The operation of this form of the apparatus is as follows: When the plug cook 18 is in the normal position, shown in Fig. 1, the measuring chamber 32 is connected to the atmosphere through the passage 23,

the passage 22 in the plug cock, and the exhaust port 2% in the valve casing, and the controlling chamber 8 is connected through the passages 20 and 21 with the valve chamber 5, and as passages 6 and 7 connect valve chamber 5 with the train pi e 31, both sides of the diaphragm 9 are now exposed to train pipe pressure and the valve 10 is held in its open position by the action of the spring 11. When it is desired to eltect a measurement cat the volume or" the train pipe, the plug cock 18 is moved by means of the handle 19 from the position shown in Fig. 1 to the position indicated in Fig. 2 6-5 of the drawing, and during this movement the passage 20 in plug cook 18 registers with the passage 26, leading to the passage 13 and exhaust passage 25, so that a small quantity of fluid under pressure passes from the chamber 2 to the atmosphere through the exhaust passage 25. The chamber 2 being thus momentarily connected to atmosphere, the fluid under pressure on the opposite side of the piston 1 moves the piston and slide valve 4 into such a position that the passage 30 leading to the underside of the slide valve is uncovered. The movement of the plug cock from its normal position cuts off communication from the chamber 5 to the controlling chamber 8 so that the latter is entirely isolated and contains fluid the initial train pipe pressure. The plug cock having reached its measuring position, communication from the measuring chamber 32 to the exhaust outlet 12% is cut off and communication is established from the valve chamber 5, through passage 30, passages 22 and 29 in the plug cock to passage 23 and the measuring chamber 32. Fluid under pressure from the train pipe thereupon flows into the measuring chamber by way of the passages (i and 7, valve chamber 5, and the passage 30, and the flow of fluid from the train pipe continues until the train pipe pressure on the right hand side of the diaphragm 9 is sufiiciently less than the pressure in the controlling chamber 8 to permit the diaphragm 9 to move toward the right and close the valve 10 against the action of the spring. It will be noted that so long as the valve 10 is open, the fluid leaking past the loosely fitting piston 1 into the chamber 2 is conducted into the measuring chamber through the passage 13, past the valve 10, through passage 1%, the cavity 16, passage 17 and cavity 28 in the plug cock, so that the piston 1 is maintained in its extreme right hand position, against the action of the spring 3, by the pressure in the valve chamber 5. As soon as the valve 10 is closed the escape of fluid from the chamber 2 to the measuring chamber is prevented and the piston 1 moves back to its original position by equalization of pressure past the piston, and under the action of the spring 3, so as to close the passage 30 and cut oil the flow of fluid under pressure from the train pipe. The controlling spring 11 is adjustable so that the flow of fluid under pressure from the train pipe is stopped as soon as a predetermined reduction in pressure therein has occurred, for example, say five pounds per square inch, and the pressure of fluid which has en'- tered the measuring chamber is indicated in any suitable way, thereby affording a measurement of the voliune of the, train pipe. The initial movement of the slide valve 4t back to its original position, as soon as the valve 10 closes, causes the passages I l and 17 to be disconnected so that the leakage of fluid from the chamber 2 is entirely prevented, thus efi'ectually insuring the complete return of the piston under the action of the spring 8. It is es scntial that during the measuring operation the controlling chamber be absolutely hermetically sealed by the plug cock 18 since a small leakage from this chamber Will very seriously affect the accuracy of the measurement, and it is therefore desirable that a pressure gage be provided for the train pipe so as to indicate independently that the predetermined reduction of pressure has been effected. .ln carrying out the measurement, it is of course necessary that the train pipe should be cut oil as far as it is possible from any external source of pressure and for this purpose it is desirable to close the feed grooves to the auxiliary reservoir of the brake system by effecting a small reduction in the train pipe pressure before moving the plug cock to the measuring position as is usual for the purpose of testing the brakes. After having eiiected a reduction of the train pipe pressure for this purpose a short interval of time should be allowed to elapse before moving the plug cock to its measuring position, in order to allow an surges of air in the train pipe to completely subside so that the pressure in the controlling chamber can become entircly equalized With the uniform pressure in. the train pipe before proceeding With the measurement.

The construction of the various elements of which the improved valve mechanism is composed is immaterial and various modifications in this respect may be made Without departing from the spirit and scope oi the invention.

Having now described my invention, What it claim as new and desire to secure by Lettors Patent, is:

l. in a fluid pressure brake, the combination With a train pipe, of a receptacle, means for establishing communication from the train pipe to the receptacle, an automatic valve mechanism for controlling communication from the train pipe to said receptacle, a chamber, means for isolating the chamber from communication With the train pipe, and a valve device subject to the oppoi-iing pressures of the train pipe and said chamber whereby the decrease of pressure on one side of said valve device will close com munication from the train pipe to said receptacle.

2. In a fluid pressure brake, the combination with a train pipe, of a receptacle, a valve mechanism for controlling communication from the train pipe to said receptacle, manually operated means for varying the pressure on one side of said valve mech anism for operating same to open communication for venting air from the train pipe to said receptacle, a chamber, communication from the train pipe to said chamber being closed by said manually operated means, and a valve device subject to the opposing pressures of said chamber and the train pipe for also controlling the pressure on said valve mechanism for operating same to close said communication to said receptacle.

In a fluid pressure brake, the combination with a train pipe, of a receptacle, a valve for controlling communication from the train pipe to said receptacle, a cylinder, a piston therein for operating said valve, manually operated means for venting fluid from one side of said piston to actuate the same to open communication from the train pipe to said receptacle, a chamber, communication from the train pipe to said chamber being closed by said manually operated means, and a valve device subject to the opposing pressures of the train pipe and said chamber for controlling the release of fluid from said piston to effect the movement of said piston and valve to close said communication to said receptacle.

l. In a fluid pressure brake, the combination with a train pipe, of a receptacle, a chamber, a valve for controlling communication from the train pipe to said receptacle, a cylinder, a piston therein for operating said valve, manually operated means for closing communication from the train pipe to the chamber and for venting air from one side of said piston to actuate the same, a valve for stopping the venting of fluid from such side of said. piston, and a movable abutment subject to the opposing pressures of the train pipe and said chamber for operating said last named valve.

5. In a fluid pressure brake, the combina tion With a train pipe, of a receptacle, a valve for controlling communication from the train pipe to said receptacle, a cylinder, a piston therein for operating said valve, manually operated meals for venting air from one side of said piston to actuate the same, a valve for controlling communication from one side of said piston to said recep tacle, a chamber containing fluid at original train pipe pressure and a movable abutment subject to the opposing pressures of the train pipe and said chamber for closing the last nan'ied valve upon a predetermined re duction in train pipe pressure.

6. In a fluid pressure brake, the combination vvith a train pipe, of a receptacle, a valve for controlling communication from the train pipe to said receptacle, a cylinder, a piston therein for operating said valve, manually operated means for venting air from one side of said piston to actuate the same, a valve for controlling commiiinication from one side of said piston to said receptacle, a chamber containing fluid at original train pipe pressure and a movable abutment subject in one direction to train pipe pres sure and the pressure of a spring and in the opposite direction to the pressure in said chamber for closing said last named communication upon a predetermined reduction in train pipe pressure.

7. In a fluid pressure brake, the combination with a train pipe, of a closed receptacle, a main valve mechanism for controlling a communication from the train pipe to said receptacle, manually operated means for varying the pressure on one side of said valve mechanism to operate the same to open said communication, an auxiliary valve mechanism and means whereby the same is operated upon a predetermined reduction in train pipe pressure for varying the pressure on one side of said valve mechanism to thereby operate same to close said communication.

8. In a fluid pressure brake, the combination with a train pipe, of a closed receptacle adapted to receive fluid vented from the train pipe, a main valve for controlling communication from the train pipe to said receptacle, a cylinder, a piston therein normally subject on opposite sides to fluid under pressure for actuating said valve, a diaphragm subject on pressure, and means whereby the same is subjected on the opposite side to a controllable fixed pressure, there being a passage leading from one side of said piston, an auxiliary valve operated by said venting fluid through said passage corresponding with a predetermined reduction in train pipe pressure, and a manually operated cock having an operating position for connecting the train pipe with said closed 40 receptacle, and having means for venting fluid from said cylinder in the movement of the cock to said operating position.

In testimony whereof I have hereunto set mv hand.

JOHN W. CLOUD.

\Vitnesses A. A. BERGIN, O. P. LnDDoN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C.

one side to train pipe 30 diaphragm for 35

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