US2110706A

US2110706A - Brake control for high speed trains

Info

Publication number: US2110706A
Application number: US108939A
Authority: US
Inventors: Ellis E Hewitt
Original assignee: Westinghouse Air Brake Co
Current assignee: Westinghouse Air Brake Co
Priority date: 1936-11-03
Filing date: 1936-11-03
Publication date: 1938-03-08
Anticipated expiration: 1955-03-08

Description

March 8, 1938. E. E. HEWITT BRAKE CONTROL FOR HIGH SPEED TRAINS s She ets-Shet 1 File d Nov. s, 1956 2 L qt INVEN'IQR ELLIS E.HEW|TT ATTORNEY March 8, 1938. E. E. HEWITT.

BRAKE CONTROL FOR HIGH SPEED TRAINS Filed Nov. 5, 1936 5 Sheets-Shget 2 T @(W U Q & mm a m3 835 nwzo cou 8 mm mH m 3 W m N w Nw mm m 2: E no 9w & NS 2 u ou 3% m 5. EN o Q E a: Q m N New March 8, 1938. v Ew 2,110,706

BRAKE CONTROL FOR HIGH SPEED TRAINS Filed Nov. 5, 193a a Sheets-Sheet s mi-in! MasTer 5w..

M R P1 P6 n INVENTOR UT ELLIS E-HEWITT ATTORNEY Eerardafion ConT rol ler I Patented Mar. 8, 1938 UNl'iE STARS mars FFiQiEZ PATENT Application November 3, 1936, Serial No. 108,939

63 Claims.

This invention relates to brake control for high speed trains, and more particularly to a method of and apparatus for controlling the brakes on high speed trains with respect to both speed and the rate of retardation of the train.

A problem of the utmost importance in the operation of the new light weight, high speed, passenger trains is that of stopping the trains from high speeds in extremely short distances. Such trains travel in the neighborhood of one hundred miles per hour, or more, and since at one hundred miles per hour a train travels a distance of one hundred and forty-seven feet per second, it will be appreciated that the brakes must be applied with great rapidity and to a high degree if the stopping distance is to be short.

Now it is well known that in the type of brakes now universally employed the coefficient of friction between the brake shoes and the vehicle wheels is relatively low at the high speeds and relatively high at the low speeds, generally increasing gradually at first as the train decreases in speed, and then increasing rapidly beginning at some low speed. If the brakes are applied to a maximum degree at a high speed, the degree must be reduced as the speed of the train diminishes or otherwise sliding of Wheels will result. Wheel sliding is objectionable not only because flat spots are worn on the wheel treads, but also because the retarding effect of a sliding wheel is less than that of a rolling wheel.

In order to stopthe train in a short distance it is, of course, desirable that all wheels be kept rolling and that the maximum braking effect permitted by the adhesion between the wheel and the rail be produced on each wheel. The degree of braking must, therefore, be regulated, as the train decreases in speed, with a view to obtaining both the maximum rate of deceleration and a minimum of wheel sliding.

In the high speed trains now in operation two solutions have been offered to this problem. One solution involves the employment of a device which operates in response to changes in the rate of retardation of the train to so control the degree of application of the brakes as to cause the train to be decelerated at a substantially constant rate of retardation (within tolerable limits), this rate being determined as that safely permissible under predetermined track conditions. This device is commonly known as a retardation controller device, or decelakron.

The other solution to the problem involves the employment of a device which operates in response to the speed of the train to reduce the degree of application of the brakes in steps as the train speed diminishes, in a manner such that the degree of application is at all times, for given track conditions, below that which would produce wheel sliding, but high enough topromptly bring the train to a stop.

Obviously, both of these solutions possess advantages peculiar and characteristic to each. That is to say, the retardation controller device, or decelakron, possesses operating characteristics peculiar only to it, while the speed controlled device possesses advantages or characteristics peculiar only to it. To enumerate some of the principal advantages of each, the retardation controller device permits the maximum degree of application of the brakes for predetermined known track conditions, regardless of the train speed, and automatically corrects for variations in load in thetrain between stops, that is, it permits an increased degree of braking for a heavily loaded train, and correspondingly permits only a lower degree of braking for a lightly loaded train. The speed controlled device operates to -modify or reduce the degree of braking before excessive changes in the rate of retardation of the train take place, and also functions to produce a. smooth stop even in trains having considerable slack. That is to say, whereas the retardation controller device does not operate until a definite change in the rate of retardation has taken place, the speed controlled device functions.

before the increased retardation occurs, and is, 1

therefore, very effective in preventing excessive slack action in trains employing standard type couplers between cars.

In order to secure the shortest possible stopping distances for high speed trains, it is desirable that the advantages of both the retardation controller device and the speed controlled device he incorporated in a brake equipment for such trains. Accordingly, therefore, it is a principal object of the present invention to provide a brake equipment employing both a retardation controller device and a speed controlled device, in an arrangement such that the advantages of each are fully realized without a sacrifice of other desirable operating features.

When in a fluid pressure brake system an application of the brakes is eilected to a maximum degree, it will be obvious that the danger of wheel sliding increases as the brake cylinder pressure approaches a value which produces a degree of braking in excess of that safely permissible by the adhesion between wheels and rails. There is then, for a given train speed, a brake cylinder of Wheel sliding or of excessive rates of retardation. The need for automatic regulation of brake cylinder pressure, therefore, is primarily in the upper range of brake cylinder pressures. In order to utilize to the fullest advantage the combination or" the retardation controller device and the speed controlled device, it is a further object of the present invention to provide a fluid pressure brake system in which the speed controlled device has control of brake cylinder pressures over a range up to what is considered to be a moderately high value for the then existing train speed, and in which the retardation controller device has control of brake cylinder pressures over a range between this moderate value and the maximum value, for the then existing train speed.

If the train is provided with ordinary couplers between the cars, it is likely that considerable slack must be run in when an application of the brakes is initiated. Whether or not the slack is large or small, it is desirable that the train slack be closed up gradually so as to minimize the danger of damaging shocks. To accomplish this, the brakes should be first applied to a moderately high value and then more gradually increased to the maximum value. It is a further object of this invention to .provide a brake equipment in which the brakes are first applied rapidly up to a predetermined degree, and then the degree increased slowly up to a maximum degree, the first or rapid portion of the application being principally under the control of the speed controlled device and the second or slow portion of the application being principally under the control of the retardation controller device.

From the standpoint of safety, brake equipments for high speed trains should provide for effecting applications by more than one mode of operation, as, for example, by straight air operation or by automatic operation. Moreover, provision should be made for operating the brakes from a. towing vehicle in the event that the train has to be towed in; or in the event that an ordinary type of locomotive has to be substituted for the special type usually employed in connection with high speed trains, then from it by operation of the usual brake valve. Accordingly, therefore, it is a yet further object of the invention to provide a brake equipment embodying the features heretofore referred to, in which til service applications of the brakes are normally effected by straight air operation and emergency applications by automatic operation, with provision for effecting service applications also by automatic operation, either from the special high speed locomotive provided, or from a standard steam locomotive substituted for the high speed locomotive.

In connection with the preceding object, it is a yet further object to subject both straight air applications and automatic emergency applications of the brakes to the joint control of the retardation controller device and the speed controlled device, and to subject automatic service applications to the control of the speed controlled device only.

Yet further and more specific objects of the invention, dealing with the provision of specially developed mechanisms, and particular arrangements of these and other mechanisms, will be more apparent from the following description, which is taken in connection with the attached drawings, wherein,

pressure below which there is little or no danger line 22 of Fig. l-B, illustrating a portion of the speed controlled device shown in that figure.

Fig. 3 illustrates a modification which may be made to the equipment shown in Figs. 1A and 1B.

Description 0 j embodiment of Figs. 1A and, 1B

Considering briefly at first the embodiment shown in these two figures, I have indicated a brake cylinder at H], which is to be understood as the usual type brake cylinder for operating a conventional type of friction brake (not shown), and While only one brake cylinder has been shown it is contemplated that in practice as many will be employed as is found desirable. A relay valve is indicated at l l for controlling the supply of fluid under pressure to and its release from the brake cylinder ill. A speed controlled device 42 controls the supply of fluid under pressure to and its release from the relay valve H. The speed controlled device i 2 is in turn in part controlled by a speed controlled switch it, which controls a plurality of circuits closable only when a pneumatic switch device 54 operates.

The brake equipment also includes an application and release magnet valve device l5, a master switch device It, a retardation controller device, or decelakron, ii, an automatic valve device l8, and a brake valve device 19. A source of fluid under pressure is represented by a main reservoir 2i), which is intended to be maintained charged from the usual compressor (not shown).

The various control pipes include a straight air pipe 22 and a brake pipe 2%. A. main reservoir pipe is indicated at 25 while a so-called feed valve pipe is indicated at 2%, this latter pipe being connected to the main reservoir 26 by way of a feed valve device 2'5 of conventional design and provided for the usual purpose of such a valve device.

While the equipment illustrated is intended primarily for the head end or control car of the train, it will be hereinafter pointed out the manher in which duplicates of some of the devices and parts illustrated may be distributed throughout a train, so as to provide a complete train brake equipment.

Considering now more in detail the devices above referred to, it will be noted that a number of these have been illustrated in outline form r only. In such instances the devices are to be considered as being of conventional design, or of a particular design described and claimed in pending applications, as Will be hereinafter referred to.

The more important devices shown in outline form only will be considered first. The relay valve device I l is preferably of the type described and claimed in my pending application Serial No. 740,202, filed August 17, 1934. The relay valve device ii operates upon supply of fluid under pressure to pipe 38 to efiect a supply of fluid under pressure from the main reservoir pipe 25 to the brake cylinder ill, to a degree dependent upon the degree of pressure in the pipe 36. Upon a reduction of the pressure in the pipe 36, the relay valve device ii correspondingly reduces the pressure in the brake cylinder Ill.

The automatic valve device it? is preferably of the familiar type having a service valve portion 3| and an emergency valve portion 32. As is illustrated, the automatic valve device is connected to the brake pipe 24. Upon a reduction of pressure in the brake pipe 2% at a service rate the service valve portion 35 only responds to supply fluid. under pressure from an auxiliary reservoir 33 to a pipe t l, to a degree dependent upon the degree of brake pipe reduction. During a service reduction in brake pipe pressure, the emergency valve portion 32 does not respond.

However, upon an emergency rate of reduction in brake pipe pressure not only does the service valve portion 3|! respond to supply fluid. under pressure from the auxiliary reservoir 33 to the pipe B l, but the emergency valve portion 32 also responds to supply fluid under pressure from an emergency reservoir 23 to a pipe 35, the supply in each instance continuing until equalization takes place between each reservoir and the pipe supplied therefrom.

When the brake pipe 2t is recharged following a service application of the brakes, the service valve portion 3i operates to release fluid under pressure from the pipe 3-4, and to recharge the auxiliary reservoir 33, in the manner well known to those skilled in the art. Upon a restoration of brake pipe pressure following an emergency reduction therein, both the service valve portion 3i and the emergency valve portion 32 move to release position, to release fluid under pressure from the pipes il and s5, respectively, and to respectively recharge the

reservoirs

33 and 28.

In practice, I prefer to make the auxiliary reservoir 33 considerably smaller than the emergency reservoir 28, so that, upon an emergency rate of reduction inbrake pipe pressure, the service valve portion 55! can produce a moderately high pressure only in the pipe 34, whereas the emergency valve portion 32 may produce a much higher pressure in the pipe 35. The purpose of this will be more apparent later.

The brake valve device is is preferably of the general type described and claimed in my pending application, Serial No. 105,659, flled October 15, 1936. In adapting this type of brake valve device to the brake system disclosed in the present application, I have intentionally omitted some of the pipe connections to the brake valve device. The feature of the brake valve device of importance insofar as the present brake system is concerned, is that both straight air and automatic applications of the brakes may be controlled by movement of a handle ill in a single service application zone. This is made possible by providing a selector mechanism operable by a selector lever 33. When the selector lever 38 is in a straight air position, the brake valve is conditioned to supply fluid under pressure from the feed valve pipe 25 to a control pipe 40, to a degree dependent upon the degree or extent of movement of the handle 37 from its release position into the service application zone. Fluid under pressure may, therefore, be supplied to the control pipe iii to any desired degree and may be released therefrom by moving the handle 31 back to the release position. During this operation of the handle, with the selector lever 38 in the straight air position, the brake pipe 24 is maintained charged.

When the selector lever 38 is turned to the automatic position, the handle 37 may then be moved to a service position in the same application. zone as before to reduce brake pipe pressure at a service rate, in the manner characteristic of the usual type brake valve. During this manipulation of the handle, fluid under pressure is not supplied to the control pipe All, and it remains connected to the atmosphere.

Regardless of whether the selector 38 is in the straight air or the automatic position, when the handle 3'! is turned to an emergency position, beyond the aforesaid service application zone, the pressure in the brake pipe is reduced at an emergency rate.

Considering now the speed controlled device I 2, this device is essentially the same as that described and claimed in my pending application, Serial No. 88,098, filed June 30, 1986, and comprises a valve section er, a diaphragm section it, a magnet valve section A, and a compensating section. it.

Considering first the valve section 32, this section comprises a supply valve 46, a release valve Al and a mechanism for operating the two valves. The supply valve it is urged toward seated position by a spring as and is adapted to be unseated by movement of a lever A9 pivotally carried on a pin 58 supported in a sliding member 5|. The

sliding member Si is urged to the right by a spring 52, and slides in a bore 53 in the casing.

The lower end of the lever t9 engages a slide or plunger 5 which in turn engages a fluted stem 55 associated with the supply valve 456. The upper end of the lever s9 is bifurcated to receive a reduced portion 56 of a stem 5'! associated with the release valve ll. The stem 5'? is moved backward and forward by movement of the upper end of the lever lil.

When the sliding member Si is moved to the left, and carries with it the pin lit, the lever 49 will first fulcrum about its lower end to actuate the released valve 4? to seated position, to close communication between chamber 5&3 and an exhaust port 59, and when the release valve has been thus seated, the lever ld will fulcrum about its upper end and shift the slide or plunger 54 to the left to unseat the supply valve &6 against the bias of its spring till. Unseating of the supply valve Mi opens communication between the main reservoir pipe 25 and the chamber 58. The chamber 58 is in open. communication with the relay valve H by way of the aforementioned pipe 30, so that fluid under pressure supplied to the chamber 53 flows to the relay valve to effect the operation thereof.

When the sliding member iii is actuated to the right following the aforedescribed operation, it will first move to a point where spring 43 seats the supply valve -15. If no further movement takes place, the supply of fluid under pressure to the chamber 58 will be lapped. However, if the sliding member 5i continues to move to the right, the upper end of the lever 59 will draw the stem 5?, and consequently the release valve 4'7, to the right, and thereby release fluid. under pressure from the chamber 58 to the atmosphere, by way of the exhaust port 59.

The diaphragm section 25,; is provided to effect movement of the sliding member 55 to the left. The diaphragm section comprises a series of diaphragms S59, 65, 62 and spaced apart and disposed in axial relation, the eliective pressure areas of the diaphragms decreasing in the order named. The diaphragms form with the casing of the mechanism a chamber 66 between the two diaphragms 68 and a chamber between the diaphragms til t2, and a chamber 66 between the diaphragms 32 and The diaphragm 68 is provided with follower plates disposed on either side thereof and indicated at 6?. The diaphragm 6| is provided with a single follower plate 68, to which the diaphragm is secured, the follower plate having an annular fiange 69 and a spacing lug III centrally thereof. The diaphragms 62 and 53 are provided with similar follower plates indicated at H and It will be noted that the follower plates maintain the diaphragms in spaced relation, and that the diaphragms are not connected one to the other. The diaphragm 63 is provided with a second follower plate 14, which is provided with a recess I5 for a purpose which will be set forth later.

The magnet valve section M comprises three electromagnets I6, '57 and i8, designated respectively as high speed magnet valve, intermediate speed magnet valve, and low speed magnet valve. The high speed electromagnet I6 controls the operation of a double beat valve III. The double beat valve It is urged toward an upper seated position by a spring 8i), and to a lower seated position upon energization of the electromagnet I6. In its upper seated position the double beat valve '59 opens communication between a passage 8|, leading to the chamber 64 between the diaphragms Bi l and GI, and the atmosphere by way of a passage containing a restriction or choke 82. In its lower seated position, the double beat valve '59 closes off this communication to the atmosphere, and opens communication between a pipe and passage 83 and the aforementioned passage 8I leading to the chamber 64.

The intermediate speed electromagnet TE controls a similar double beat valve 85. This double beat valve is urged toward upper seated position also by a spring 86, and to lower seated position by the eiectromagnet I? when energized. In its upper seated position the double beat valve 85 opens communication between a passage 8?, leading to the diaphragm chamber 65, and the atmosphere by way of a passage containing a restriction or choke 88, and a port 89. In its lower seated position, the double beat valve 85 closes this communication to the atmosphere and opens communication between the aforementioned pipe and passage 83 and the passage 81 leading to the chamber 65.

The low speed electromagnet I8 controls the operation of a double beat valve 99 of slightly different construction from the two formerly described double beat valves. This double beat valve is urged toward upper seated position by a spring 96 and to lower seated position by the electromagnet it when energized. In its lower seated position, the double beat valve 95 opens communication between a passage 92, leading to the diaphragm chamber 66, and the atmosphere by way of a passage containing a restriction or choke 93. In its upper seated position, the dou- Tole beat valve closes off this communication to the atmosphere and opens communication between the aforementioned passage 83 and the passage leading to the chamber 66.

It will be thus observed that the three electromagnets it, I? and I8 control, respectively, the supply of fluid under pressure to and its release from the three diaphragm chambers 64, 65 and 95.

It will also be observed that three spring loaded check valves 95, 96 and 9? provide, respectively, a one-way communication between each of the passages BI, 8'! and 92 and each of the chambers 6Q, 65 and 66, respectively. Each of the check valves is biased to a seated position by a light spring 99, and is unseated upon a preponderance of fluid pressure acting on the valve within the seated area.

Suitably secured in the casing enclosing the compensating section is a diaphragm iilil, subject on its left hand side to the pressure of fluid in the chamber 98 and on its right hand side to atmospheric pressure in a chamber IIii, which latter chamber is at all times open to the atmosphere by Way of port I82. The diaphragm itiii is provided with follower plates I53 and IM on either side thereof, the former follower plate H33 being provided with a stud portion projecting through the diaphragm and the other follower plate H34 and having disposed on the threaded end thereof a securing nut I05.

Projecting to the left of the follower plate I03 are two sets of lugs I06. Each set of lugs has secured thereto, as by a pin I81, an end of one of two levers I68. Each of the levers I08 is pivotally mounted intermediate its ends on a second pin IfiQ supported by one of two sets of lugs Iii projecting from a rigid portion of the casing. The extreme lower end of each of the levers I08 is connected by a common pin H3 to the lower end of an arm III. The arm III is provided intermediate its ends with a pin I I2 which is adapteo to fit inth the recess 15 of the follower plate I4 attached to the scall diaphragm 63.

The upper end of the arm III is cup shaped, as indicated at I, so as to receive the end of a stem H5. The stem I I5 is provided with an enlarged portion, as illustrated, which engages a spring washer H6 bearing upon a spring II'I suitably disposed in a spring housing H8. It will thus be apparent that, as the stem H5 is actuated to the right, the spring II! will be compressed, movement of the stem being guided by the sliding of a rounded end portion N9 of the stem in a bore I20 in the casing. The cupped end I Id of the arm III is maintained in alignment with the pin H5 by lugs I22 on either side of the arm.

Considering now the speed controlled switch device I3, this device comprises essentially three sets of stationary contacts I25, I26 and I21, which are adapted to be engaged, respectively, by movable bridging contacts I 28, I29 and I30, the three bridging contacts being disposed on a common supporting stem I3I, preferably formed of insulating material as indicated.

The movable contact I28 is rigidly secured to the stem n31, while the two movable contacts I29 and I38 are loosely disposed on the stem and are movable between pairs of shoulders I32 on the stem against the bias respectively of springs I33 and I34, in a manner to be more fully described presently.

The stem I3! has secured thereto a disc I35 and between this disc and a portion I36 of a housing enclosing the speed controlled switch device is a spring I31, which reacts against the disc I35 to urge the stem I 3! downwardly. Upward movement of the stem is caused by the outward movement of fly ball weights I38 due to centrifugal force. The fiy ball weights I38 are pivotally mounted to a rotatable member 453 on pins I 4!. The rotatable member I 48 is driven according to the speed of the vehicle or train by an attached shaft I42, which rotates in a stationary portion Hi3. It is to be understood that the speed controlled switch device has been shown in diagram matic form only, for the purpose of simplification, and that, when employed in practice, a device having the usual construction characteristic of centrifuge devices of this type will be employed.

Considering now the pneumatic switch device I l, this device is embodied in a casing containing therein a piston I55, subject on its lowermost side to the pressure of fluid in a chamber I46 and subject on its uppermost side to pressure of a spring M1. ihe piston M5 is provided with a stem I88 having secured thereto and insulated therefrom a contact M9, adapted to bridge and engage two stationary contacts I58. Upon supply of fluid at a low pressure to the chamber I48, the piston 5 5 moves upwardly to cause contact M9 to bridge the contacts I5Il, and upon release of fluid below this low pressure from the chamber I86 the spring I41 actuatesthe piston I45 downwardly to disengage contact I 49 from the contacts I5Ei. As is illustrated, the chamber I48 is connected to the straight air pipe 22, and operation of the switch device is, therefore, controlled by straight air pipe pressure.

Considering now the application and release magnet valve device I5, this valve device is embodied in a casing having a supply valve I5I and a release valve I52. The supply valve I5I is urged toward seated position by a spring I53, and toward unseated position by an application electromagnet I5 when energized. The release valve I52 is urged toward unseated position by a spring E55 and toward seated position by a release electromagnet I58 when energized.

When the supply valve I5I is seated and the release valve I52 is unseated, the straight air pipe 22 is in communication with the atmosphere by way of an exhaust port I51. When the release valve i52 is seated and the supply valve I5! is unseated, the communication between the straight air pipe and the atmosphere is closed and the straight air pipe is placed in communication with the feed valve pipe 28.

The master switch device I8 is embodied in a casing having suitably arranged therein in spaced relation three diaphragms indicated at I68, I5I and I82. These three diaphragms are all secured together by means of a stem I83. The stem I83 carries an electric contact I64 insulated therefrom, which is adapted to engage, upon movement of the stem I83 to the left, first a resilient stationary contact I65, and then a similar contact 88.

The diaphragm I80 has, at one side thereof, a chamber I81, which is in open communication with the straight air pipe 22. The diaphragms IBI and I82 have therebetween a chamber I68, which is in open communication with a pipe I89 leading to the retardation controller device I1. The diaphragm I52 has a chamber I18 to the other side thereof which is in open communication with a pipe I1 I. The chamber between the two diaphragms Itiil and I8 is, at all times, open to the atmosphere, and is, therefore, at atmospheric pressure.

The diaphragms I85 and I55 are of equivalent effective pressure areas, while the diaphragm I82 has a smaller effective pressure area than either of the other two diaphragms.

Disposed in the left end of the switch device casing is a small plunger I13 urged to the right by a spring I14. When the stem I55 moves to the left, the end I15 will engage the plunger I13, whereupon the spring I14 will tend to arrest further movement of the stem to the left. At the time the stem engages the plunger, the movable contact I84 will have engaged the stationary con tact I85 but will not have yet engaged the stationary contact I68. The stem will then have to compress the spring I14 to effect engagement of contact I84 with the contact I 68. The purpose of this arrangement will appear more clearly later.

The retardation controller device, or decelakron, shown at I1 is embodied in a casing containing a slidable weight or body I18 movable back and forth in a right line in the direction of travel of the vehicle or train. At one end of the bodyis positioned a lever I19, pivotally mounted to the casing intermediate its ends at I8, and carrying at one end a roller I8! and at the other end a roller I812. The roller I8I bears against the body I18, While the roller I82 bears against the end of a slide valve I83, this slide valve controlling communication between the aforementioned pipe I89 and another pipe I8 3, as well as between the pipe I69 and an exhaust port I85.

A spring I85 acts upon the opposite end of the slide valve I83, and, therefore, urges the slide valve toward the left. While it has not been so illustrated, the tension on the spring I88 may be varied to suit the occasion.

The retardation controller device is disposed on the head end car in a train in a manner such that, when the train is decelerating, the resulting force of inertia acts to shift the body I18 to the left, this movement of the body being opposed by the spring I86. The spring I88 is a calibrated spring so that the degree of movement of the body I18 is proportional to the rate of deceleration of the train. At a particular rate of deceleration, the slide valve I83 will be shifted to a position where it blanks communication between pipes I69 and I84, and at a particular higher rate of deceleration to the position where the pipe I88 is connected to the exhaust port I85.

The operation of this embodiment of my invention will now be described.

Running condition When the vehicle is running under power, or is coasting, the brake valve handle 31 is maintained in the release position. With the main reservoir 20 fully charged, fluid under pressure will be delivered at feed valve pressure to the feed valve pipe 28, from whence it will flow to the brake valve device I9, and to the chamber below the supply valve IBI in the application and release valve device I5. Fluid at main reservoir pressure will be delivered to the main reservoir pipe 25, from whence it will flow to the relay valve device II, and to the chamber to the left of the supply valve 46 in the speed controlled device I2.

Within the brake valve device III, a communication is established, in the release position of the handle 31, between the feed valve pipe 28 and the brake pipe 24, and the brake pipe will be thus charged to feed valve pressure. From the brake pipe 24, fluid under pressure will flow to the automatic valve device I8, and therein to the service and emergency valve portions, and from these two valve portions, respectively, to the auxiliary reservoir 33 and the emergency reservoir 28. The entire brake system will thus be charged and become ready for operation.

As has been previously indicated, applications of the brakes may be effected by either straight air operation, or by automatic operation. In addition, the maximum degree to which the brakes may be initially applied at any given time depends upon the speed of thevehicle at that time, so that, in describing the operation of the brake system illustrated, it is necessary to take into account the speed of the vehicle. For the purpose of illustration, it will be assumed that the vehicle has a maximum speed of one hundred miles per hour, and in describing the operation of the brake system illustrated other speed values will be assumed to facilitate the understanding of the operation of certain of the apparatus employed.

Further, it will be assumed that the main reservoir 25 is maintained charged to a pressure value in excess of one hundred pounds (per square inch), as, for example, one hundred and twenty or one hundred and twenty-five pounds; and that the feed valve device '21, which is to be understood as being of conventional design, will deliver fluid to the feed valve pipe 26 at a pressure of one hundred and ten pounds.

Straight air service applications above sixty miles per hour When the vehicle is traveling at a speed in excess of some chosen high speed, as, for example, sixty miles per hour, the parts of the speed controlled switch device I3 will be in the positions illustrated in Fig. lB. That is to say, the fly-ball weights l38'will have been moved outwardly far enough, for any speed between sixty and one hundred miles per hour, to have caused the contact I28 to engage and bridge the two contacts I25, and the contact I29 to similarly bridge and engage the contacts I26. It will be noted that contact I35 is out of engagement with the contacts I21. 7

Now if it is desired to eiiect a straight air service application of the brakes, the operator first makes certain that the selector lever 38 is in the straight air position, and then moves the brake valve handle 3i into the service application zone to a degree according to the desired degree of application of the brakes. It will be assumed that the handle 31 is moved to the extreme end of the service application Zone, corresponding to a full service application, in which event fluid under pressure will be supplied to the control pipe 46 until the pressure in this pipe attains the maximum value of say one hundred pounds.

Fluid under pressure in the control pipe MI flows to one side of a conventional type double check valve device I98, where the valve therein is shifted to lower position, and fluid under pressure then flows to the pipe III. From the pipe I'iI, fluid flows directly to the chamber I10 in the master switch device it. This flow takes place at a rapid rate so that the small diaphragm I62 responds immediately and moves the stem I63 to the left, far enough to compress the stop spring I'M. The contact I54 then engages both of the stationary contacts I55 and I65. This connects a battery IQI to each of two'train wires I92 and I83, energizing both the release electromagnet I56 and the application electromagnet I54. The release valve I52 is thus seated and the supply valve I5! is unseated. Fluid under pressure then flows from the feed valve pipe 25 to the straight air pipe 22. From the straight air pipe 22, fluid under pressure flows to the chamber I46 in the pneumatic switch device I4.

In the switch device I4, the piston I45 is immediately actuated upwardly at a low pressure to cause contact M8 to bridge the contacts I50. The closing of these contacts immediately energizes both the high speed electromagnet I6 and the intermediate speed electromagnet "IT, by completion of two circuits from a battery I94, one of which includes the contacts I49 and I 53, conductor I95, contacts 525 and I28, and conductor I86 leading to the high speed electromagnet "I6, and the other of which includes contacts I26 and I29, and conductor I 9? leading to the intermediate speed electromagnet ll. The electromagnet Iii actuates the double beat valve I9 to lower seated position, and the intermediate speed electromagnet ll actuates its double beat valve 85 also to lower seated position.

Fluid under pressure in the straight air pipe 22 may then flow through a branch pipe W3 to a conventional type double check valve device I99, where it shifts the valve therein to upper position, and flows to the aforementioned pipe 83. From the pipe 33 flow continues through the passage 33 in the speed controlled device I2, and from thence past the now opened lower seat of the double beat valve It to the passage 8| and diaphragm chamber 64. Fluid under pressure also flows past the open lower seat of the double beat valve 85 to the passage 8? and the diaphragm chamber 65. Similarly, fluid under pressure also flows from the passage 83 past the open lower seat of the double beat valve 9i! (although the low speed electromagnet I8 is deenergized at this time) to the passage 92 and the diaphragm chamber 56. It will be observed that the passage 83 extends into the chamber 98, so that fluid under pressure is also supplied to this chamber to the right of the small diaphragm 63.

Thus upon initiating an application of the brakes when the Vehicle is traveling at a speed in excess of sixty miles per hour, fluid under pressure is supplied to all of the diphragm chambers as well as to the chamber 98 to the right of the small diaphragm $53. It has been assumed that fluid under pressure is supplied to the straight air pipe to a high degree, so that it is not necessary to consider at this time the functioning of the compensating section 45 of the speed controlled device, as this portion of the device is useful primarily in connection with low straight air pipe pressures.

Fluid pressure acting to the right and also to the left of each of diaphragms El, 62 and 63 will render these three diaphragms ineifective, but fluid pressure acting to the right of the diaphragm B8 flexes this diaphragm to the left, and thereby shifts the sliding member 5i so as to first seat the release valve 4'! and to then unseat the supply valve iii. Fluid under pressure will then flow from the main reservoir pipe 25 to the chamber 58, from whence it will flow through pipe 30 to the relay valve device II. The relay valve device will respond to the pressure of this fluid to produce a corresponding pressure in the brake cylinder Ifl.

Fluid under pressure in the straight air pipe 22 also flows to the chamber it? of the master switch I6, and acts upon the diaphragm I60 in opposition to the fluid pressure acting on the small diaphragm I52, and when the degree of pressure in the chamber I81 reaches a value which is in the same relation to the pressure in the chamber Eli? as the area of the small diaphragm E62 is to the area of the diaphragm I68, the spring PM will shift the stem I63 to the right so that contact IEi l disengages from the contact I66, but holds engagement with the contact I65. The application electromagnet I54 will then be deenergized, so that the supply of fluid under pressure to the straight air pipe will be lapped. As the pressure in chamber 58 of the speed controlled device IZ attains a value equal to that in the straight air pipe 22 and in chamber 64, diaphragm 60 will be flexed to the right far enough for supply valve 46 to be seated. The relay valve l i will then lap brake cylinder pressure at a corresponding value.

There will thus be quickly established a moderately high degree of application of the brakes, which is not equivalent to the degree of pressure supplied to the control pipe All, but which is proportional thereto.

Fluid under pressure supplied to the pipe lll flows also to the pipe Hi l, and through the retardation controller device W to the pipe I69 and the chamber I58 between the diaphragms It! and E52. But the pipe I8 3 contains a restriction or choke 2% which greatly retards this flow, and in addition, the pipe 59 has connected thereto a timing reservoir 2M, of sufiicient volume to very appreciably delay the build up of pressure in the chamber I63. Eventually and after a predetermined interval of time the pressure in the chamber I68 will attain a value equal to that in the chamber I'll).

, As the pressure in the chamber the acts upon the larger diaphragm lfil, it will, at some particular value, again shift the stem H63 to the left, compressing the spring Ht, to again energize the application electromagnet I55. This will result in increasing straight air pipe, pressure, and correspondingly increasing brake cylinder pressure to a value which is substantially equivalent to that in the control pipe M], since the two switch diaphragms let and it! are of equal areas. It will be apparent, of course, that this increase in straight air pipe pressure will take place slowly because the pressure in chamber I68 increases slowly.

One of the reasons for quickly effecting an application of the brakes to a moderately high degree is to permit a more gradual run-in oi any slack which may exist in a train to which the system has been adapted. Another reason, having to do with the functioning of the retardation controller device, will be more clear later.

It will, however, be-apparent at this point that by the arrangement provided a moderately high degree of application of the brakes is quickly effected, followed immediately by a slow increase in the degree of application to a value substantially equivalent to the pressure established in the control pipe it.

Now as the brakes are app-lied to the maximum degree possible for a service application, the vehicle will begin to decelerate at an increasing rate of retardation. The resulting force of inertia acts upon the retardation controller body H8 and urges it to the, left. If, before the speed of the vehicle has diminished to sixty miles per hour, the rate of retardation should increase to a value such that slide valve I83 is shifted to the position where the pipe E69 is connected to the atmospheric or exhaust port 555 (which is a relatively large port), fluid under pressure will be released rapidly to the atmosphere from the chamber H58. This will, of course, result in a reduction in brake cylinder pressure, tending to arrest the increase in rate of retardation, and to possibly also diminish it. It should be noted, however, that even should the retardation controller device completely exhaust the chamber 158, it cannot reduce the degree of application of the brakes below the value corresponding to that produced by supply of fluid under pressure to the chamber Ht only. That is to say, the retardation controller device can modify the degree of application of the brakes only over a limited range of brake cylinder pressures.

When the rate of retardation has decreased sufiiciently, the slide valve l83 may open communication between pipes I69 and lu l, so that the pressure in chamber lSB will increase, but the choke 2M and timing reservoir 2st permit only a slow increase in pressure in this chamber, so that brake cylinder pressure is increased very slowly and the liability of producing an excessive and undesirable rate of retardation is minimized.

Now as the speed of the vehicle diminishes, the speed controlled switch device it will act at substantially sixty miles per hour to cause the contact lit to disengage from the contacts 52", while holding the contacts M9 in engagement with the contacts I25. The high speed electromagnet it will be then deenergized, and double beat valve i9 will move to its upper seated. position, where it will connect the diaphragm chamber (i l to the atmosphere by way of the restriction or choke 82. Fluid under pressure will then be very slowly released from the chamber b t to the atmosphere.

This Will result in the pressure in the chamber 58 overbalancing that in the chamber 6%, Whereupon the release valve l'i will unseat just enough to gradually release fluid under pressure from the chamber 58 to the atmosphere until such time as the pressure remaining in the chamber 58 is balanced by the steady pressure in the chamber 65 acting on diaphragm El, which occurs when the pressure in chamber 6 3 has been finally exhausted. That is to say, when the chamber M has been exhausted the pressure in chamber 58 Will have been reduced to a value which bears to the original value the same relation as the area of the diaphragm Bl bears to the area of the diaphragm 6d, assuming, of course, that there has not, in the meanwhile, occurred any change in straight air pipe pressure.

The relay valve ll responds to the reduction of pressure in the chamber 58 to correspondingly reduce brake cylinder pressure. Due to the action of the choke or restriction 82 in permitting the pressure in chamber EM to reduce at a sloW rate only, the change in brake cylinder pressure occurs slowly so that there is no great change in the rate of retardation of the vehicle due to this change in pressure. Where the brake system is adapted to a train, this gradual change or" pressure may be made to take place in close approximation to the tendency of the rate of retardation to increase due to the increasing coeflicient of friction between the brake shoes and the wheels, although this may not be practicable in all instances. At any rate, the change in pressure can be readily made slow enough to keep the cars in the train bunched.

When the speed of the vehicle has diminished to a chosen intermediate speed, as, for example, thirty-five miles per hour, the speed controlled switch device it will operate to cause contacts 529 to disengage from the contacts 9%, while holding contacts let and 121 disengaged, and this will deenergize the intermediate speed electromagnet a l. The double beat valve 85 will then move to upper seated position, to release fluid under pressure from the diaphragm chamber 65 to the atmosphere by way of the choke or restriction 88. In a manner similar to that described before, the pressure in the chamber 65 will be gradually reduced, whereupon the valve section 32 will operate to similarly reduce the pressure in chamber 58 since the area of diaphragm 62 is less than that of diaphragm 8!, and consequently efiect a like reduction brake cylinder pressure.

When the speed or" the v a chosen low speed, as, for e nple, fifteen miles per hour, the contact 53% of the speed controlled switch device will engage the contacts l2l', and thus energize by way ofconductor the low speed electromagnet 38. Double beat valve 99 will be then shifted to lower seated position, and thus release fluid under pressure from the chamber 63 to the atmosphere past the choke or restriction 93. This will result in a further reduction in brake cylinder pressure, in the manner previously described, so that, when the chamber 66 has been finally exhausted, the pressure in the brake cylinder it) will have attained a value which is in relation to the pressure in chamber 98 as the area of the small diaphragm 63 bears to the area of the large diaphragm 59.

Now if at any time during the deceleration of the vehicle the rate of retardation should increase above that for which the retardation controller spring I85 has been designed, or adjusted, the retardation controller device will operate to reduce the pressure in the switch chamber N58, to further reduce straight air pipe pressure. The pressure in the diaphragm chambers of the speed controlled device l2 varies as the pressure in the straight air pipe varies, because upon decrease of pressure in the'passage 83 and chamber 93, the check valves 95, 96 and ill will unseat to permit release of fluid under pressure from each of the diaphragm chambers t l, 65 and 66.

It will be seen then that a reduction in straight air pipe pressure, efiected as a result of operation of the retardation controller device, will result in a similar reduction in brake cylinder pressure, the retardation controller device in any case being ineifective to reduce brake cylinder pressure below a value which corresponds to the degree of pressure in chamber We of the master switch device, but which value bears a different relation thereto for each speed range considered.

As the vehicle comes to a stop, the body H8 of the retardation controller device will assume the position illustrated, since the force of inertia acting theron is now absent, so that, if the retardaion controller device has previously reduced the pressure in the switch chamber ltd, pressure will now be restored in a very short time. This will, of course, result in the maximum possible brake cylinder pressure for speeds below fifteen miles per hour.

If now it is desired to effect a release of the brakes, the brake valve handle Si is turned to the release position, whereupon fluid under pressure will be released from the control pipe st! to the atmosphere. This will resuit in a release of fluid under pressure from the two switch chambers I68 and lit, it being noted that a one-way check-valve device 2533 is provided to insure a prompt release of fluid under pressure from the chamber H58. Release of fluid under pressure from the two chambers I88 and Nb eflfects deenergization of both the" application electromagnet iti and the release electromagnet I 5%, whereupon straight air pipe pressure will be correspondingly reduced, and thereby effecting a corresponding reduction in brake cylinder pressure.

As will be obvious from the description thus far, a graduated application and a graduated reicle has reduced to lease of the brakes may be effected by proper manipulation of the brake Valve handle 37.

Straight air service application between speeds of thirty-five and sixty miles per hour If at the time of initiating the application of the brakes thevehicle is traveling above thirtyfive miles per hour but below sixty miles per hour, the high speed electrcmagnet it will be deenergized, due to contact E23 having pr viously disengaged from the contacts iZo. Therefore, when fluid under pressure is supplied to the straight air pipe 22 by operation of the application and release magnet valve device [5, it can flow only to the diaphragm chambers 6E and 9B. The degree of brake cylinder pressure which results, therefore, will be in proportion to straight air pipe pressure in the same relation as the area of diaphragm Si is to the area of diaphragm 6B, and will thus not be as great as that attainable above sixty miles per hour.

This degree, however, may be suficient to cause operation of the retardation controller device 11, in which event it will, as before described, vary the pressure in the switch chamber Hit only to reduce the degree of application suiiiciently to prevent the rate of retardation from exceeding the desired limiting value.

Now as the speed of the vehicle diminishes to thirty-five miles per hour, the intermediate speed electromagnet ll will be deenergized, whereupon the brake cylinder pressure will be reduced in the manner already described. Asthe speed of the vehicle diminishes to fifteen miles per hour, a further decrease in brake cylinder pressure will be effected.

The retardation controller device may, of course, operate at any time that the rate of retardation exceeds the limiting value, to reduce the pressure in the chamber to in turn reduce brake cylinder pressure, but it is, of course, operable to vary brake cylinder pressure over a very limited range only, regardless of the speed range considered.

Straight air service application between speeds of fifteen and thirty-five miles per hour If, at the time the brake application is initiated, the vehicle is traveling above fifteen miles per hour but less than thirty-five miles per hour, not only will the contact lit be out of engagement with the contacts 525, but the contact 129 will also be out of engagement with the contacts iZfi. Thus both the high speed electromagnet l6 and the intermediate speed electromagnet T! will be deenergized. Fluid under pressure can then only be supplied to the diaphragm chambers 66 and 98, and the degree of brake cylinder pressure produced bears to straight air pipe pressure the same relation that the area of the diaphragm 82 bears to the area of the diaphragm 66. In all other respects, the functioning of the parts of the brake system will be substantially as in the-manner heretofore described.

It should, therefore, be apparent from the foregoing that the initial degree of application of the brakes is determined according to the speed range in which the vehicle is operating at the time of initiating an application of the brakes. For the higher speeds, that is, from sixty miles per hour to one hundred miles per hour, the maximum brake cylinder pressure may be produced. In an intermediate speed range, that is, from thirty-five to sixty miles per hour, only moderately high brake cylinder pressures can be produced.

in the lower speed range, that is, from fifteen to thirty-five miles per hour, only low brake cylinder pressures can be produced, and under fifteen miles per hour only very low brake cylinder pressures can be produced.

Since the brake cylinder pressures which can be produced below fifteen miles per hour are low, it is possible that the brake cylinder pressure would be insufhcient in some instances to cause the brake shoes to be pulled up against the wheels. To prevent this, and to insure that at least the brake shoes will be pulled up snugly against the wheels, the compensating portion 45 has been provided.

Assuming now that fluid has been supplied to the chamber 99 to five pounds pressure only, this pressure will act upon the right side of the small diaphragm 63, and also on the left side of the diaphragm I00. If the pressure acted upon the diaphragm B3'only, it could at most produce only one or two pounds pressure in the chamber 58, which would produce a like brake cylinder pressure. This pressure is too low to pull the brake shoes up tight against the wheels. But with pressure acting upon the diaphragm I00, this diaphragm flexes to the right, thus rocking the two levers I08 about their pivot pins I09, and this moves the lower end of the arm III to the left, as viewed in Fig. 1B.

The arm III presses its pin II2 against the follower plate I4, assisting the fluid pressure acting upon the diaphragm 03 in shifting the sliding member 5| to the left. The parts are so designed that for pressures up to five pounds in the chamber 98 the compensating mechanism acts to cause a like pressure to be produced in the chamber 58, and thus in the brake cylinder I0 also. But as the pressure in the chamber 98 exceeds five pounds, the follower plate I04 attached to the diaphragm I00 will strike lugs 204 and thereby be ineifective to produce an increase in force acting to swing the lower end of the arm III to the left. Moreover, the spring II! is so designed that as the pressure in chamber 58 becomes equal to the five pounds acting on the diaphragm I00, the parts of the valve section 42 will move to lap position. The compensating mechanism, therefore, is effective only for pressures around five pounds and below.

Emergency application ,When it is desired to effect an emergency application of the brakes, the brake valve handle TI is turned to the emergency position, whereupon the pressure in the brake pipe 24 is released to the. atmosphere at an emergency rate. At the same time, fluid under pressure is supplied to the control pipe 40 to the maximum possible degree, which will be one hundred pounds for the case assumed.

Upon an emergency reduction in brake pipe pressure, both the emergency valve portion 32 and the service valve portion. 3| in the automatic Valve device respond, the emergency valve portion supplying fluid under pressure to the pipe 35 leading to the double check valve device I90, and the service valve portion supplying fluid under pressure to the pipe 34 leading to the double check valve device I99.

With fluid under pressure supplied to both sides of the double check valve device I90, the valve therein will move upwardly or downwardly depending upon on which side the pressure is the greater. In practice I prefer to make emergency reservoir 28 largeenough so that the pressure supplied to the pipe 35 will be greater than that supplied to the pipe 40, as, for example, one hundred and ten pounds. Fluid under pressure in the pipe 35 may then flow through the double check valve device 199 to the pipe Ill and the chamber I10. From this point on the operation of the brake system is substantially the same as described for the full service application, brake cylinder pressure being a maximum for speeds above sixty miles per hour, and being reduced as the speed of the vehicle diminishes, and also being subject to limited control by the retardation controller II.

Fluid under pressure supplied to the pipe 34 by the service valve 3| is of no avail at this time due to the fact that the pressure of fluid in the straight air pipe 22 and the branch pipe 598 will greatly exceed the pressure in the pipe 3 3, as in practice I prefer to make the auxiliary reservoir 33 comparatively small so that the ultimate pres sures delivered by it can never exceed a moder ately high pressure in the straight air pipe. The application will, therefore, be entirely dependent upon the pressures delivered to the pipe 35 by the emergency valve section 32.

During an emergency application, the retardation controller device Il may function as before described for a full service application. In practice, it has been usual to have the retardation controller device adjusted to permit a certain.

maximum rate of retardation during service applications of the brakes, and a higher rate of retardation during emergency appllcations.- This is accomplished by providing an adjusting mechanism which operates upon initiating an emer gency application of the brakes to change the setting of the retardation controller device, such for example, as is illustrated and claimed in my pending application Serial No. 741,063, filed August 23, 1934. ing feature in the presentv disclosure, because it forms no part of the present invention.

To effect a release of the brakes following an emergency application, the brake valve handle 3? is returned to the release position, whereupon the brake pipe is again recharged to its normal pressure. Both the emergency valve section 32 and the service valve section 3 I, of the automatic valve device, return to release position, where fluid under pressure is released from both the pipes 35 and M. This, of course, results in a. reduction of pressure in both switch chambers I68 and iii] to effect a full release of the brakes as heretofore described.

Automatic service application of the brakes Automatic service applications of the brakes are intended to be eifected only when it is impossible to effect applications by straight air operation, or

when the vehicle is beingtowed by a standard steam locomotive or the like.

When it is desired to effect an automatic service application of the brakes, the selector lever 30 is turned to the automatic position, and the brake valve handle 37 is then turned to service position where it is left long enough to reduce brake pipe pressure to the desired degree. The reduction in brake pipe pressure which results takes place at a service rate, so that the service valve portion 38 only of the automatic valve device responds. This valve portion then supplies fluid under pressure from the auxiliary reservoir 33 to the pipe 34, the pressure of this fluid shifting the valve in double check device I9I downwardly, and fluid under pressure then flowing to the pipe 03.

I have not included this adjust- If the speed of the vehicle is at this time above sixty miles per hour, fluid under pressure flows from the pipe 83 to all of the diaphragm chambers 6t, 65, 6'5 and 98, but if the speed is lower than sixty miles per hour, the flow will be to only such chambers as are in communication with the passage 83 at that time.

It will be noted that the service valve 31 supplies fluid under pressure directly to the pipe 83, and that this supply is not under the control of the retardation controller device 1?. As before indicated, the auxiliary reservoir 33 is made sufficiently small so that the pressure delivered to the pipe 35 is considerably lower than that which is usually established in the straight air pipe 22 during either a straight air service application or an emergency application. As a consequence, the need for retardation control is not of as great importance.

The speed controlled device 12 is, however, operative to control brake cylinder pressure during this type of application with relation to the speed of the vehicle, and functions in the manner already described.

When it is desired to effect a release of the brakes following this type of application, the brake valve handle 37 is returned to release position to restore brake pipe pressure. The service valve 3! then returns to release position to release fluid under pressure from the pipe 34.

Modification shown in Fig. 3

The modification shown in Fig. 3 deals with the substitution of a novel type of pilot relay valve device 219 and a standard master switch device 215 for the master switch device 16 shown in Fig. 1-A.

The master switch device 21 1 is preferably identical with the master switch device of Fig. 1A, except that the two diaphragms i8! and it?! of that switch device are now replaced by a single diaphragm 2H2, which is of the same effective pressure area as the diaphragm at the opposite end of the switch device subject to straight air pipe pressure.

The diaphragm 212 may be considered as mechanically arranged similar to the diaphragm H51 in the master switch device 16, that is, it is connected to a stem 213 similar to the stem 163, and is subject on one side to fluid pressure in a chamber 214. The chamber 214 is in open communication with a pipe 255 leading to the pilot relay valve device 218.

The pilot relay valve device comprises two sections, a valve section 216, and a diaphragm section 211. The valve section 216 may be identical with the valve section 42 of the speed controlled device 12 of Fig. 1-3, and the corresponding parts of the two valve devices are indicated by like numerals, the description heretofore given for the valve section 42 applying to the valve section 216.

The diaphragm section 21?, of the pilot relay valve device 210, comprises two flexible diaphragms 218 and 219 of different effective pressure areas, disposed in spaced relation, the former diaphragm being provided with follower plates 220 and the latter diaphragm being provided with follower plates 221. The left hand follower plate 221 is provided with an annularfiange 222 and a spacing lug 223, which maintain the two diaphragms in spaced relation. It is to be noted, however, that neither the diaphragms nor their follower plates are in any way connected together, that is to say, each diaphragm is independently movable.

The two diaphragms 218 and 219 coact with the casing of the valve device to form a chamber 225 between the two diaphragms, and a chamber 226 to the right of the diaphragm 219. .A light spring 221 in the chamber 226 holds the two diaphragms in contact.

The diaphragm chamber 225 is connected to the aforementioned pipe E69, while the chamber 226 is connected to the aforementioned pipe 111. The chamber 58 of the valve section 216 is connected to the chamber 214 of the master switch device 21!, by way of the aforementioned pipe 2w. The chamber to the left of the supply valve 46 is connected to the main reservoir pipe 25.

In the operation of the modification shown in Fig. 3, when fluid under pressure is supplied to the control pipe 40 or pipe 35, it will first flow rapidly by way of pipe 111 to chamber 226. The pressure of this fluid will act upon the smaller diaphragm 219 to operate the valve portion 216 to supply fluid under pressure from the main reservoir pipe 25 to pipe 2i5 and switch chamber 2M, this flow taking place at a rapid rate, so that a moderately high pressure is established in the chamber 214 very quickly; The master switch device 211 will then operate the application and release magnet valve device 15, as heretofore described, to effect rapidly a brake cylinder pressure, the value of which is in proportion to the pressure in. the chamber 226, of the pilot relay valve device, in the same relation that the area of the smaller diaphragm 219 bears to the larger diaphragm 218, assuming a vehicle speed above sixty miles per hour.

Fluid under pressure supplied to the control pipe 58 and pipe ill will also flow to the diaphragm chamber 225, by Way of choke 290, pipe I84, the retardation controller device 1'1, and pipe 169. This flow will, as previously described, take place at slow rate, and will cause the pressure in the switch chamber 214 to be gradually increased to a value substantially equivalent to the pressure in the control pipe 40. This will in turn cause the brake cylinder pressure to be increased to a corresponding degree.

It will, therefore, be observed that the arrangement shown performs the same functions as are performed by the switch device id of Fig. 1--A, that is, first quickly effecting a moderately high degree of application of the brakes, followed by a slow increase in the degree of application until the degree of application is equivalent to the control pipe pressure.

The retardation controller device 1! is thereafter operable to control the pressure in the chamber 225, just as it was operable to control the pressure in the chamber 168 of the master switch device 16.

Adaptation of brake system to a train While the brake system embodying the invention has been illustrated as being adapted to a single vehicle only, it may be readily adapted to a train comprising a plurality of cars by merely duplicating certain of the parts shown. Each car will, of course, be equipped with one or more brake cylinders, for which one relay valve device IE only is required. Each vehicle is preferably equipped with one speed controlled device 12, although it may in some instances be found more desirable to provide one speed controlled device for two or more cars. Each speed controlled device may have itsown speed controlled switch l3, or one such switch may be provided for all of the speed controlled devices.

Each car in the train is preferablyprovided with an application and release magnet valve device l5, while one master switch device IE only need be provided, preferably located on the head end or control car. The same applies for the retardation controller device ll.

With respect to the automatic valve device l8, since the brake pipe 24 extends throughout the train, it is preferable that one of these devices, together with the two

reservoirs

28 and 33, should be provided on each car of the train. Thus it will be seen that by mere duplication of certain of the parts on succeeding cars in a train, a complete brake system results.

Experience and preference will, of course, dictate modifications and arrangements other than those disclosed and described, so that it is not my intention to be limited to the particular illustrations given, nor otherwise than by the spirit and scope of the appended claims.

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

1. The method of controlling vehicle brakes, which comprises, eifecting an application of the brakes, and controlling the degree of the application jointly with respect to both speed and the rate of retardation of the vehicle in a manner such that during the application the minimum degree of the application is controlled with respect to the speed and the maximum degree of the application is, controlled with respect to the rate of retardation.

2. The method of controlling vehicle or train brakes, which comprises, eifecting quickly an application of the brakes to a predetermined degree, increasing the degree of the application more slowly up to a maximum degree, controlling the degree of the application between the said predetermined degree and the said maximum degree with respect to the rate of retardation of the vehicle or train, and controlling the degree of the application below the said predetermined degree with respect to the speed of the vehicle or train.

3. In a vehicle or train brake system, in combination, means for effecting an application of the brakes, speed controlled means, means operated according to the rate of retardation of the vehicle or train, and means so constructed and arranged that said speed controlled means controls the degree of application of the brakes over a predetermined range and said retardation controlled means controls the degree of application over a different range.

4. In a vehicle brake system, in combination, means for eflecting an application of the brakes to a predetermined degree, means for increasing the degree of application of the brakes to a maxi mum degree which is above said predetermined degree, speed controlled means for controlling the degree of application of the brakes below said predetermined degree, and means operated according to the rate of retardation of the vehicle for controlling the degree of application of the brakes above said predetermined degree.

5. In a vehicle brake system, in combination, means for effecting an application of the brakes, means operated according to the rate of retardation of the vehicle for controlling the degree of application of the brakes, and means operated according to the speed of the vehicle for varying the range over which said retardation controlled means may vary the degree of application of the brakes.

6. In a vehicle brake system, in combination, a brake cylinder, means for effecting a supply of fluid under pressure to said brake cylinder rapidly up to a chosen value, means for increasing brake cylinder pressure slowly to a degree above said chosen value, means operated according to the rate of retardation of the vehicle for controlling brake cylinder pressures above said chosen value, and speed controlling means for controlling brake cylinder pressures below. said chosen value.

'7. In a vehicle brake system, in combination, a brake cylinder, means for effecting a supply of fluid under pressure to said brake cylinder, means operated according to the rate of retardation of the vehicle for varying brake cylinder pressure to maintain a substantially constant rate of retardation of the vehicle, and speed controlled means for controlling the range over which said retardation controlled means may vary brake cylinder pressure.

8. In a vehicle brake system, in combination, a brake cylinder, means for establishing a communication through which fluid under pressure is supplied rapidly to efiect a rapid supply of fluid under pressure to said brake cylinder, means for establishing a different communication through which fluid under pressure is supplied slowly to slowly increase the degree of the brake cylinder pressure, means operated according to the rate of retardation of the vehicle for controlling the supply of fluid under pressure through said second communication, and speed controlled means for controlling brake cylinder pressure regardless of through which communication fluid under pressure is supplied to establish brake cylinder pressure.

9. In a vehicle brake system, in combination, speed controlled means for controlling a communication through which fluid under pressure is supplied to effect an application of the brakes, fluid pressure operated brake control means for controlling the supply of fluid under pressure to said'comrnunication, and means operated according to the rate of retardation of the vehicle for controlling at least in part the operation of said brake control means.

10. In a vehicle brake system, in combination, speed controlled means for controlling the degree of application of the brakes, means including a fluid pressure operated device for controlling the operation of said speed controlled means, and means operated according to the rate of retardation of the vehicle for controlling in part the supply of fluid under pressure to said fluid pressure operated device.

11. In a vehicle brake system, in combination, a fluid pressure operated switch device operated upon supply of fluid under pressure thereto to effect an application of the brakes, means establishing a communication through which fluid under pressure is supplied at an unrestricted rate to operate said switch device, means establishing a second and separate communication through which fluid under pressure is supplied at a restricted rate to additionally effect the operation of said switch device, and means operated according to the rate of retardation of the vehicle for controlling said second communication.

12. In a vehicle brake system, in combination, a brake control device having two chambers and operable upon supply of fluid under pressure to either or both of said chambers to effect an application of the brakes, means for efiecting a supply of fluid under pressure to both of said chambers, and means operated according to the rate of retardation of the vehicle for controlling the pressure in one of said chambers.

13. In a vehicle brake system, in combination, a fluid pressure operated device having two chambers and operable upon supply of fluid under pressure to one of said chambers to eifect an application of the brakes to one degree and upon supply of fluid under pressure to both of said chambers to efiect an application of the brakes to a different degree, means for effecting a supply of fluid under pressure to both of said chambers, and means operated according to the rate of retardation of the vehicle for varying the pressure in one of said chambers without affecting the pressure in the other chamber.

14. In a vehicle brake system, in combination, a fluid pressure operated switch device having two chambers and operable upon supply of fluid under pressure to one or both of said chambers to effect an application of the brakes, means for establishing a communication through which fluid under pressure may be supplied at an unrestricted rate to one of said chambers, means for establishing a separate communication through which fluid under pressure may be supplied at a restricted rate to the other of said chambers, and means operated according to the rate of retardation of the vehicle for controlling one of said two communications.

15. In a vehicle brake system, in combination, a fluid pressure operated switch device having a plurality of chambers and operable upon supply of fluid under pressure to one or more of said chambers to effect an application of the brakes, and operable upon the variation of pressure in one of said chambers to modify the degree of application of the brakes, means for effecting a supply of fluid under pressure to one or more of said chambers, and a retardation controller device for controlling the variation of pressure in one of said chambers.

16. In a vehicle brake system, in combination, a brake controlling device having two chambers and operable upon supply of fluid under pressure to one of said chambers to effect an application of the brakes to one degree and operable upon supply of fluid under pressure to both of said chambers to effect an application of the brakes to a different degree, manually operated means for effecting a supply of fluid under pressure to both of said chambers, and means operated according to the rate of retardation of the vehicle for controlling the pressure of fluid in one of said two chambers.

17. In a vehicle brake system, in combination, electro-responsive means for efiecting and controlling the degree of application of the brakes, a fluid pressure operated brake control device having a plurality of chambers and operable upon supply of fluid under pressure to one or more of said chambers to control the operation of said electroresponsive means, means for effecting a. supply of fluid under pressure to all of said chambars to eflect the operation of said electroresponsive means to apply the brakes, a retardation controller device operated according to the rate of retardation of the vehicle, and means responsive to operation of said retardation controller device for varying the pressure in one of said chambers.

18. In a vehicle brake system, in combination,

a brake controlling device having two chambers and operable upon supply of fluid under pressure to one or both of said chambers to effect an application of the brakes, manually operated means for efifecting a supply of fluid under pressure to both of said chambers, means operated according to the rate of retardation of the vehicle for controlling the pressure in one of said chambers and operable at a chosen rate of retardation to close communication between said one chamber and said manually operated means, and means operable to permit release of fluid under pressure from both of said chambers by manipulation of said manually operated means regardless of the operation of said retardation controlled means.

19. In a vehicle brake system, in combination, electrically controlled valve means for controlling the application and the release of the brakes, a fluid pressure operated switch device having two chambers and operable upon supply of fluid under pressure to one of said chambers to effect an application of the brakes to a chosen degree corresponding to the pressure in said chamber, and operable upon supply of fluid under pressure to the other of said chambers to effect an increase in the degree of application of the brakes above that corresponding to the pressure in said first chamber, means for effecting a supply of fluid under pressure to both of said chambers to initiate an application of the brakes, and means operated according to the rate of retardation of the vehicle for varying the pressure of fluid in said other chamber, the variation of pressure in said other chamber being ineffective to reduce the degree of application of the brakes below said chosen degree.

20. In a vehicle brake system, in combination, a brake controlling device having two chambers and operable upon supply of fluid under pressure to both of said chambers to effect an application of the brakes and operable upon variation of pressure in either of said chambers to vary the degree of application of the brakes, means for forming a communication to one of said chambers through which fluid under pressure may be supplied at an unrestricted rate, and means for forming a communication to the other of said chambers through which fluid under pressure may be supplied at a restricted rate, and means operated according to the rate of retardation of the vehicle for controlling said second communication and operable at a chosen rate of retardation to rapidly reduce the pressure of fluid in said second chamber.

21. In a vehicle brake system, in combina'ton,

valve means for controlling the application and the release of the brakes, means including a control device having a plurality of chambers to which fluid under pressure is supplied for controlling the operation of said valve means, means for effecting a supply of fluid under pressure to said chambers to effect the operation of said valve means to apply the brakes, a retardation controller device for controlling the pressure of fluid in one of said chambers, and means controlled with respect to the speed of the vehicle for independently controlling the operation of said valve means.

22. In a vehicle or train brake system, in combination, valve means for controlling the application and the release of the vehicle or train d brakes, electroresponsive means including a fluid pressure operated switch device having a plurality of chambers and operable upon supply of fluid pressure to said chambers to effect the operation of said valve means to apply the brakes, manually operated means for effecting a supply of fluid under pressure to one of said chambers rapidly and a supply of fluid under pressure to another of said chambers more slowly, to effect an application of the brakes, inertia operated means for controlling the pressure of fluid in said last mentioned chamber, to vary the degree of application of the brakes, and means controlled by the speed of the vehicle for also varying the degree of application of the brakes.

23. In a vehicle brake system, in combination, magnet valve devices for controlling the application and the release of the brakes, a fluid pressure operated switch device having a plurality of chambers and operable upon variation of pressure in one or more of said chambers to control the operation of said magnet valve devices, manually operated means for controlling the supply of fluid under pressure to and its release from said plurality of chambers, means operated according to the rate of retardation of the vehicle for controlling the pressure of fluid in one of said chambers, and means controlled by the speed of the vehicle for varying the degree of application of the brakes independently of variation of pressure in any of said chambers.

24. In a vehicle brake system, in combination, valve means for controlling the application and the release of the brakes, means including a fluid pressure operated switch device for controlling the operation of said valve means, means operated according to the rate of retardation of the vehicle for controlling the operation of said switch device, and means controlled by the speed of the vehicle for also controlling the operation of said valve means.

25. In a vehicle brake system, in combination, valve means for controlling the application and the release of the brakes, means including a fluid pressure operated switch device for controlling the operation of said valve means, means operated according to the rate of retardation of the vehicle for controlling the operation of said switch means, and means controlled by the speed of the vehicle for also controlling the operation of said valve means and operable as the speed of the vehicle diminishes due to application of the brakes to cause said valve means to reduce the degree of application of the brakes.

26. In a vehicle brake system, in combination, fluid pressure operated valve means for controlling the application and the release of the brakes, means for forming a communication through which fluid under pressure is supplied to effect the operation of said valve means, means including a fluid pressure operated switch device for controlling the supply of fluid under pressure to and its release from said communication, means operated according to the rate of retardation of the vehicle for exercising a limited control over the operation of said switch device, and means operated by and in response to the speed of the vehicle for controlling the manner in which the pressure of fluid supplied to said communication acts upon said valve means.

27. In a vehicle brake system, in combination, a fluid pressure operated switch device for controlling the application and the release of the brakes, said switch device having two movable abutments of different eifective pressure areas, one of said abutments being subject to fluid pressure in a first chamber and the other of said abutments being subject on one side to fluid pressure in said first chamber and on the other side to fluid pressure in a second chamber, means for forming a communication to said second chamber through which fluid under pressure may be supplied at an unrestricted rate, means for forming a communication to said first chamber through which fluid under pressure may be supplied at a restricted rate, and a retardation controller device for controlling said second communication.

28. In a vehicle brake system, in combination, a fluid pressure operated switch device for controlling the application and the release of the brakes, said switch device having two diaphragms of different effective pressure areas, said two diaphragms being so constructed and arranged as to form therebetween a first chamber and to one side of the smaller of said two diaphragms a second chamber, means for forming a communication through which fluid under pressure may be supplied at an unrestricted rate to said second chamber, means for forming a communication to said first chamber including a choke and a timingreservoir associated therewith, and a retardation controller device for controlling the pressure of fluid in said first chamber only.

29. A control device for a fluid pressure brake comprising, in combination, a plurality of contacts, a plurality of movable abutments, means cooperating with said abutments to form three pressure chambers, one of said chambers being between two of said abutments, another of said chambers being to one side of one of said two abutments, and the third of said chambers being to one side of a still different abutment, and means for operating said contacts in response to movement of said abutments upon variation of pressure in one or more of said chambers.

30. A control device for fluid pressure brakes comprising, in combination, a casing, three diaphragms coacting with said casing to form three pressure chambers, two of said diaphragms being of equal pressure area and the third of said diaphragms being of lesser eifective pressure area than the other two, a first of said chambers being between one of the large diaphragms and the small diaphragm, the second of said chambers being to one side of the small diaphragm, and the third of said chambers being to one side of the third diaphragm, a plurality of normally opened contacts, and means associated with said three diaphragms and so constructed and arranged that upon supply of fluid under pressure to one or both of said first and second chambers said contacts are closed and upon supply of fluid under pressure to said third chamber at least some of said contacts are opened.

31. In a vehicle brake system, a combination, a control device having a plurality of chambers to which fluid under pressure is supplied to effect an application of the brakes, means for manually effecting a supply of fluid under pressure to both of said chambers, automatic means operated upon a decrease of fluid pressure therein for efiecting a supply of fluid under pressure to both of said chambers, and means operated according to the rate of retardation of the vehicle for controlling the pressure of fluid in one of said chambers regardless of whether supplied by said manually operated means or said automatic means.

' 32. In a vehicle brake system, in combination, electroresponsive means for controlling the application and the release of the brakes, means including a fluid pressure operated switch device having two chambers, for controlling the operation of said electroresponsive means, manually operated means for effecting a supply of fluid under pressure to both of said chambers, a normally charged pipe, an automatic valve device operated upon a predetermined reduction of pressure in said normally charged pipe for effecting a supply of fluid under pressure to both of said chambers, and a retardation controller device for controlling the pressure of fluid in one of said chambers regardless of whether supplied by said manually operated means or said automatic valve device.

33. In a vehicle brake system, in combination, a control device for controlling the application and the release of the brakes, said control device having two chambers and being operable upon supply of fluid under pressure to one of said chambers to effect an application of the brakes to one degree and operable upon supply of fluid under pressure to both of said chambers to effect an application of the brakes to an increased degree, manually operated means potentially effective to effect a supply of fluid under pressure to both of said chambers, automatic means operable upon a reduction of pressure therein to potentially effect a supply of fluid under pressure to both of said chambers, valve means for selecting between said potential sources of supply, and means for restricting the rate of supply to one of said chambers regardless of from which source the supply is effected.

34. In a vehicle brake system, in combination, a fluid pressure operated switch device for controlling the application and the release of the brakes, said switch device having two chambers and operable upon the supply of fluid under pressure to one of said chambers to effect an application of the brakes to one degree and operable upon the supply of fluid under pressure to both of said chambers to effect an application of the brakes to an increased degree, manually operable means for eifecting a supply of fluid under pressure to both of said chambers, automatic valve means for effecting a supply of fluid under pressure to both of said chambers, valve means for selecting between said two supplies, means for delaying the supply of fluid under pressure to one of said chambers, and a retardation controller device for controlling the degree of pressure in one of said chambers according to the rate of retardation of the. vehicle.

35. In a vehicle brake system, in combination, valve means for controlling the application and the release of the brakes, speed controlled means operated according to the speed of the vehicle, retardation control means operated according to the rate of retardation of the vehicle, means operative during normal service or emergency applications of the brakes to cause the degree of application to be under the joint control of said speed control means and said retardation control means, and means operative upon effecting an auxiliary service application of the brakes for causing said speed controlled means only to control the degree of the application.

36. In a vehicle brake system, in combination, speed controlled means operated by and in response to the speed of the vehicle, retardation controlled means operated by and in response to the rate of retardation of the vehicle, means for efiecting an application of the brakes by straight air operation or by automatic operation, and means for causing all straight air applications and automatic emergency applications of the brakes to be under the joint control of said speed controlled means and said retardation controlled means, and for causing automatic service applications of the brakes to be under the control of said speed controlled means only,

3'7. In a vehicle brake system, in combination, valve means for controlling the application and the release of the brakes, means for forming a communication through which fluid under pressure is supplied to effect the operation of said valve means, speed controlled means for controlling the action of the pressure in said communication upon said valve means, means including a fluid pressure operated switch device for controlling the supply of fluid under pressure to said communication, a retardation controller device for controlling operation of said switch means, a normally charged pipe, and a valve device operated upon a reduction of'pressure in said pipe for eifecting a supply of fluid under pressure to said communication at a time. when said switch device is not operated or is ineffective to operate.

38. In a fluid pressure brake system, in combi chambers to which fluid under pressure is supplied to effect the application of the brakes and in which the pressure of fluid is varied to vary the degree of application of the brakes, manually operable means for effecting a supply of fluid under pressure to said chambers, automatic valve means for also effecting a supply of fluid under pressure to said chambers, and retardation control means for controlling the pressure of fluid in one of said chambers, said retardation control means being ineffective to reduce brake cylinder pressure below a value permissible according to the operation of said speed controlled said last mentioned means.-

39. In a vehicle brake system, in combination, a first valve means for controlling the application and the release of' the brakes, speed controlled means operated by and in response to the speed of the vehicle for controlling said first valve means, a second valve means for also controlling the operation of said first valve means, and means including a retardation controller device for controlling the operation of said second valve means.

40. In a vehicle brake system, in combination, a valve device for controlling the application and the release of the brakes, said valve device having a plurality of chambers to which fluid under pressure is supplied to effect an application of the brakes, means for effecting a supply of fluid under pressure to said chambers, and a retardation controller device for varying the pressure of fluid in one of said chambers.

41. In a vehicle brake system, in combination, valve means for controlling the application and the release of the brakes, said valve means having a first chamber to which fluid under pressure is supplied to effect an application of the brakes to one degree, and having a second chamber to which fluid under pressure is also supplied to effect an application of the brakes to an increased degree, means for eifecting a supply of fluid under pressure to both of said chambers, and a retardation controller device for varying the pressure of fluid in one of said chambers, said retardation controller device being ineffective to reduce the degree of application of the brakes below that corresponding to the effect of the pressure of fluid in said other chamber.

42. In a vehicle brake system, in combination, a valve device for controlling the application and the release of the brakes, said valve device having a first chamber to which fluid under pressure is supplied to effect an application of the brakes to a chosen degree, and having a second chamber to which fluid under pressure is supplied to increase the degree of application of the brakes above said chosen degree, means forming a first communication to said first chamber through which fluid under pressure is supplied at an unrestricted rate, means forming a second communication to said second chamber through which fluid under pressure is supplied at a restricted rate, and a retardation controller device for controlling said second communication.

43. In a vehicle brake system, in combination, a valve device for controlling the application and the release of the brakes, said valve device having two movable abutments of difierent effective pressure areas, one of said'abutments being responsive to fluid pressure in a first chamber, and the other of said abutments being responsive to fluid pressure in a second chamber, means forming an unrestricted communication leading to said first chamber, means forming a restricted communication leading to said second chamber, and a retardation controller device for controlling one of said two communications.

44. In a vehicle brake system, in combination, a first valve means for controlling the application and the release of the brakes, a second valve means for also controlling the application and the release of the brakes, speed controlled means, retardation controlled means operated according to the rate of retardation of the vehicle, and means whereby said first valve means is controlled only by said speed controlled means, and whereby both said first valve means and said second valve means are controlled by said retardation controlled means.

45. In a vehicle brake system, in combination, a valve means for controlling the application and the release of the brakes, said valve means having two unconnected movable abutments each of which has a chamber to one side thereof, means forming an unrestricted communication to one of said chambers, means forming a difierent communication to another of said chambers, means associated with said second communication for delaying flow of fluid under pressure therethrough, and a retardation controller device for controlling the flow of fluid through and the release of fluid from one of said communications.

46. In a vehicle brake system, in combination, a valve means for controlling the application and the release of the brakes, said valve means having a plurality of movable abutments with a chamber to one side of each, and being operable to control the operation of said valve means according to which of said chambers has fluid under pressure supplied thereto, manually operable means for supplying fluid under pressure to said chambers, automatic valve means operable upon a reduction of pressure therein for supply ing fluid under pressure to said chambers, and a retardation controller device for controlling the pressure of fluid supplied to one of said chambers regardless of whether supplied by said manually operated means or said automatic valve means.

47. In a vehicle brake system, in combination, a valve device for controlling the application and the release of the brakes, said valve device having two diaphragms of difierent effective pressure areas, the larger of said diaphragms having a first chamber to one side thereof, and the smaller of said diaphragms having a second chamber to one side thereof, means for effecting a supply of fluid under pressure to said second chamber to effect an application of the brakes to a chosen degree, means for also efiecting a supply of fluid under pressure to said first chamber to increase the degree of application of the brakes to a maximum value above said chosen degree, and a retardation controller device operable to vary the pressure in said first chamber whereby to vary the application of the brakes between said maximum value and said chosen degree.

48. The method of controlling the brakes for vehicles or trains, which comprises, initiating an application of the brakes, establishing the initial v braking force according to the speed of the vehicle or train, and then varying the braking force jointly according to both the speed and the rate of retardation of the vehicle or train.

49. The method of controlling the brakes for a vehicle or train, which comprises, initiating an application of the brakes, establishing the initial braking force according to the speed of the vehicle or train, reducing the initial braking force in steps as the speed of the vehicle or train diminishes, and varying the degree of braking force between each of said steps as required to prevent the rate of retardation from substantially exceeding a chosen value.

50. The method of controlling the brakes for vehicles and trains, which comprises, initiating an application of the brakes, and varying the degree of the application jointly with respect to both the speed and the rate of retardation of the vehicle such that the degree of the application is variable over a fixed range above a predetermined vehicle speed, and variable over a fixed but difierent range below said predetermined speed.

51. The method of controlling the brakes for vehicles or trains, which comprises, initiating an application of the brakes, and controlling the degree of the application partly in response to vehicle speed and partly in response to the rate of retardation of the vehicle such that there is established for each of a plurality of speed ranges a difierent but fixed set of upper and lower limits between which the degree of the application is varied.

52. The method of controlling the brakes for vehicles or trains, which comprises, initiating an application of the brakes, establishing the initial degree of the application according to the speed of the vehicle or train, and thereafter controlling the degree of the application jointly in response to both the vehicle speed and the rate of retardation of the vehicle or train such that there is established for each of a plurality of speed ranges a different upper and lower limit between which the degree of the application may be varied.

53. In a vehicle or brake system, in combination, means operable to effect an application of the brakes to each of plurality of certain different uniformdegrees of braking force, means responsive to the speed of the train for so controlling said brake application means as to cause it to establish diflerent ones of said certain degrees of braking force for different train speeds, and retardation control means for so controlling said brake control means as to cause it to establish for a given rate of retardation difierent degrees of braln'ng force for different train speeds.

54. In a vehicle or train brake system, in combination, means for eifecting an application of the brakes, speed controlled means, means operated according to the rate of retardation of the vehicle or train, and means so constructed and arranged that said speed controlled means establishes the initial degree of application of the brakes, while said retardation controlled means is thereafter operable to modify said initial degree of application, and both said speed controlled means and said retardation controlled means subsequently cooperate to jointly modify the degree of the application as the speed of the vehicle or train diminishes.

55. In a vehicle or train brake system, in combination, means for effecting an application of the brakes, speed controlled means, inertia means, and means so constructed and arranged that either or both of said speed controlled means and inertia means may be effective at any time during an application to control the degree of the application.

56. In a vehicle brake system, in combination, means for effecting an application of the brakes, means operated according to the rate of retardation of the vehicle for controlling the degree of application of the brakes, and means operated according to the speed of the vehicle for decreasing the range over which said retardation controlled means may vary the degree of application of the brakes.

57. In a vehicle brake system, in combination, a brake cylinder, means for establishing a communication through which fluid under pressure is supplied rapidly to effect a rapid supply of fluid under pressure to said brake cylinder, means for.

establishing a diiierent communication through which fluid under pressure is supplied slowly to slowly increase the degree of the brake cylinder pressure, inertia operated means for controlling the supply of fluid under pressure through one of said communications, and speed controlled means for controlling brake cylinder pressure regardless of through which communication fluid under pressure is supplied to establish brake cylinder pressure.

58. In a vehicle brake system, in combination, a brake control device having two chambers and operable upon supply of fluid under pressure to either or both of said chambers to efiect an applicaticn of the brakes, means for effecting a supply of fluid under pressure to both of said chambers, and inertia operated means for controlling the pressure in one of said chambers.

59. In a vehicle brake system, in combination, a brake cylinder, a valve device for controlling the supply of fluid under pressure to and its release from said brake cylinder, said valve device having a plurality of chambers to and from which fluid under pressure is supplied and released to effect the supply to and release from said brake cylinder, means for effecting a supply of fluid under pressure to said plurality of chambers, and an inertia operated device for controlling the pressure of fluid in at least one of said chambers.

60. In a vehicle or train brake system, in combination, means for effecting an application of the brakes, speed controlled means, inertia operated means, means controlled by said speed controlled means for establishing the initial degree of application of the brakes according to which of a plurality of speed ranges the vehicle or train is traveling in at the time of initiating the application, and means controlled by said inertia operated means for varying the degree of the application over a range which bears a substantially constant relation to the initial degree of the application as established by said speed controlled means.

61. In a vehicle brake system, in combination, a brake cylinder, a control pipe to which fluid under pressure is supplied to effect an application of the brakes, inertia operated means for controlling the degree of straight air pipe pressure, means responsive to straight air pipe pressure for controlling the supply of fluid under pressure to and its rel-ease from said brake cylinder, and speed controlled means for controlling said last mentioned means.

62. In a vehicle brake system, in combination, a brake cylinder, a straight air pipe, means for effecting a supply of fluid under pressure to said straight air pipe to effect an application of the brakes, a retardation controller device for controlling straight air pipe pressure, valve means responsive to straight air pipe pressure for controlling the supply of fluid under pressure to and its release from said brake cylinder, and speed controlled means operated according to the speed of the vehicle for controlling the operation of said valve means.

63. In a vehicle or train brake system, in combination, means for establishing a control pressure to eflect an application of the brakes, speed controlled means, means operated according to the rate of retardation of the vehicle or train, means so constructed and arranged that said speed controlled means and said retardation controlled means cooperate to jointly control the degree of application or" the brakes, and a switch device operated by said control pressure for rendering said speed controlled means effective.

- ELLIS E. HEWI'I'I.

CERTlFICATE OF CORRECTION.

Patent No. 2,110,706. March 8, v.19

ELLIS E. HEWITT.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 11, second column, line 11, ,claim 6, for the word "controlling" read controlled; page 12, second column, line 75, claim 22, after "fluid" insert under; page 1h, second column, line L5, claim 58, strike out the words "said last mentioned; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 27th day of September, A. D. 19586 Henry Van Arsdale (Seal) Acting Commissioner of Patents.