US2486271A - Train control system - Google Patents

Description

Oct. 25,1949. H. P. FOLKER 2,486,271

TRAIN CONTROL SYSTEM Filed March 10, 1947 I Sheets-Sheet l lNl/EN TOR B yerber/ Fo/A er ATTORNEY Oct. 25, 1949. H. P. FOLKER TRAIN CONTROL SYSTEM 3 Sheefts-Sheet 2 Filed March 10, 1947 mi k e 5 WP A 5 l wk 1 5 gay 444 /M% AW aa w Oct. 25, 1949. H. P. FOLKER v TRAIN CONTROL SYSTEM- 3 Sheets-Sheet 3 Filed March 10, 1947 I N VE N TOR Herbs/f l? Fb/ker- Y Patented Oct. 25, 1949 TRAIN CONTROL SYSTEM Herbert P. Folker, Oakland, Calif., assignor to National Safety Appliance 00., Ltd., San Francisco, Calif., a corporation of California Application March 10, 1947, Serial No. 733,476

Claims. 1.

This invention relates generally to train control systems of the type adapted to efiect automatic brake applications and to enable a manual forestalling operation to prevent brake application under certain conditions.

In the past train control systems have been known which incorporate means on the locomotive adapted under certain conditions to receive a track impulse which serves to vent the main brake pipe of the pneumatic brakin system of the train to thereby efiect an automatic application of the brakes. Forestalling devices such as are used with such systems incorporate a time delay mechanism having an automatic cycle which is put in operation when the engineer actuates a forestalling lever. In the event a track impulse is received by the system during the time delay afiorded by the forestalling mechanism, a brake applicationdoes not occur. Should the engineer fail to make timely operation of the forestalling lever, an automatic brake application occurs in response to a track impulse, and the train is then stopped, thus requiring the engineer to thereafter carry out a release or restoring operation. the type described in Folker et a1. 1,439,081 and 1,690,816 a magnetic track impulse is utilized which directly operates one of a pair of valves incorporated in a duplex control valve, whereby a line leading to an automatic stop valve is vented to secure a brake application. The forestalling unit as previously utilized with a system of the Folker type (see Patent 1,592,930) serves to automatically shut off the line leading from the automatic stop valve to the duplex control valve, and to vent the line leading to the duplex control valve to thereby prevent operation of the same in response to a track impulse for a given period of time.

Forestalling units of the type disclosed in Folker 1,592,930, or as modified to include a forestalling unit of the hydraulic type, have not been well adapted to operation of the forestalling unit from a position remote from the time delay means employed. This is a disadvantage in making installations on modern passenger trains, such as trains of the streamlined Diesel type, because it is frequently desirable in such installations to provide a small manually operated device at a position at a considerable distance from the time delay means of the forestalling unit, for initiating the iorestalling operation.

An additional disadvantage of the prior Folker train control system, as described above is that when the iorestalling unit is located a In train control systems of l 2 considerable distance from the automatic stop valve and from the duplex control valve, the length of the connectin pipes is such that pressure cannot be quickly built up in the pipe leading to the duplex train control valve, with the result that at the end of the forestalling period when the shut-01f valve previously described is automatically opened, pressure from the automatic stop valve may be lowered to such a point that an automatic brake application occurs.

It is an object of the present invention to improve the Folker. type of train control system whereby the forestalling means is simplified and made adaptable to a wide variety of installations, including'installations where the member which is manually actuated for a forestalling operation is located aconsiderable distance from the forestalling time delay means.

A further object of the invention is to improve upon systems of the above character whereby the pipe leading from the forestalling unit to the duplex train control valve may be extended to any length desired, without causing an undesired brake application at the end of a forestalling period.

Another objectoi the invention is to provide a novel and automatic means for quickly recharging the line leading from the forestalling unit to the duplex train control valve with air under pressure from a secondary source, at the end of a forestalling period.

Additional objects and features of the inven-. tion will appear from the following description in which the preferred embodiments of the invention have been set forth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

Figure 1 is a diagrammatic view, partly in section, illustrating a train control system incorporating the present invention.

Figure 2 is a diagrammatic view, partly in section, illustrating the forestalling unit and associated parts incorporated in Figure 1.

Figure 3 is a diagrammatic View illustrating a modification of Figure 1 to incorporate line charging means.

Figure 4 diagrammatically illustrates a control system similar to Figure 3 but with direct manual rather than remote operated forestalling means.

Figure 5 is a diagrammatic view in section illustrating the construction of the direct manual forestalling unit illustrated in Figure 4.

The train control system as illustrated in Figure 1 consists of a duplex train control valve l0 of the type adapted to be operated by a magnetic track impulse and as disclosed for example generally in Letters Patent 1,439,081, 1,439,082, 1,592,930 and 1,690,816. As presently explained in detail the duplex control valve I is used in conjunction with the release or restoring valve II, the automatic stop valve l2 (see 1,529,058) and the forestalling unit l3. Located at a point remote from the forestalling unit l3 there is a manually operated forestalling valve l4. In addition to the parts just mentioned the system may include an air strainer l6, 3. double heading interlocking valve l1, and a double heading outout cock 3.

The release or restoring valve H, and valves l1 and H3, can be substantially as shown and described in Folker 1,690,816.

The piping for the various parts mentioned above is as follows: A control pipe 20 extends from the duplex control valve II] to the restoring valve H, and an extension 2| of the same extends from the restoring valve to the forestalling unit. Line 22 which connects to the automatic stop valve I2 is the brake application pipe of a conventional pneumatic train braking system. Pipe line 23 leads iromthe stop valve l2 to the engineers brake valve, and is equipped with a double heading cock l8. Line 24 represents a connection to the main air supply reservoir of the braking system. Line 26 is an extension of line 24 beyond the filter I6 and connects with the time delay means of the forestalling unit as will be presently explained. Pipe line 21 connects from the stop valve |2 to certain parts of the forestalling unit as indicated and in effect is an extension of the control line 2|. Another pipe 28 connects stop valve |2 with the air supply pipe 26. Pipe 29 connects the restoring or release valve II with the interlocking device l1, and line 3| connects this device to the double heading cock l8.

For a normal position of the various parts, that is a position in which the system is in condition to be responsive to a track impulse to effect an automatic brake application, brake pipe 22 is maintained closed against venting to the atmosphere by the stop valve l2, while air pressure is maintained in control pipes 20 and 2|, and cock |8 is open to permit control of the braking system from the engineers cab. Pipe 28 leads to the main air reservoir and is in restricted communication with the control pipes 20 and 2|. Each of the two valves in the duplex control valve H! are retained closed magnetically, and when the control valve passes over a track magnet, the field of which has not been neutralized by a signal current, one of the two duplex control valves (normally held closed magnetically) is open to vent the control pipe, the particular valve operated dependent upon the direction of movement of the train. Venting of control pipe 20 to the atmosphere resulting from opening of one of the two control valves, reduces holding pressure upon the operating diaphragm of the stop valve l2, and as a result the valve member of the stop valve moves to a position to cause venting of the brake pipe 22 to the atmosphere, and the non-release valve incorporated in the same closes communication between pipes 23 and 22.

The forestalling unit incorporated in Figure 1, together with the remote forestalling valve I4, is illustrated in greater detail in Figure 2. The forestalling means illustrated consists of time delay means of the hydraulic type, including a Ill reservoir 33 adapted to contain a quantity of suitable liquid such as oil. Restricted orifice 34 establishes communication between the lower portion of reservoir 33 and the lower portion of a vertically extending cylinder 36. A piston 31 is slidably fitted in cylinder 36 and is attached to the lower end of a rod 38. The upper end of rod 38 is attached to a member 39 which can be termed a piston valve, and which is slidably fitted in a second cylinder 4|. Piston 31 is provided with suitable sealing means such as the cup leather 42, and like means such as a cup leather 43 is provided for piston 39. A compression spring 44 is shown positioned at the lower end of cylinder 36 and is adapted to be compressed when the piston 39 completes its final downward movement. The lower portion of the cylinder 4| is provided with ports 46 and 41 which are closed by the piston valve 39 for the lowermost, position of the same as illustrated in Figure 2, but which are exposed for communication with the upper portion of cylinder 36 when the piston valve moves up- Wardly.

As will be presently explained during a forestalling period piston 31 together with piston valve 39 is caused to move upwardly at a regulated rate by application of line pressure to the reservoir 33, and after reaching the upper limit of their travel, these members move downwardly to their initial position. The space above piston 31 is in continuous communication with the main reservoir supply pipe 26.

In conjunction with timing means I provide a shut-oil valv 5| together with a valve actuator 52. The shut-off valve is double seated and consists of a movable valve member 53 carried by the fluted stem 54. The valve member in its one limiting position closes upon a stationary seat 56 and in its other limiting position on seat 51 surrounding the stem 54. The orifice 56 connects with the pipe line 21 as illustrated, and a space between seats 56 and 51 connected with the control line 2|. In the normal position of the shutoff valve as illustrated in Figure 2, lines, 2| and 21 are placed in free communication. However when stem 54 is actuated to close valve member 53 upon seat 56, line 2| is vented to the atmosphere past stem 54 and line 21 is closed.

The actuator 52 consists of a body forming a cylinder 58 and fitted with the piston 59. The space on one side of piston 59 connects with the signal whistle 6|, and with line 62 which connects with the port 41 of the timing means. Thus when air pressure is applied to pipe or duct 62 piston 59 is urged in a direction to move stem 54 and thereby close valve member 53 upon seat 56. While such pressure is applied to pipe 62 the signal whistle 6| is operated.

In addition to the foregoing the forestalling unit includes the pneumatic actuator 63, and a combination vent and closure valve 64. Actuator 63 consists of a body 66 fitted with the cylinder 61. A piston 68 is fitted in cylinder 61 and is attached to the rod 69. A tube II is also attached to red 69 and extends to the exterior of the device. A plunger 12 provided with a projecting stud 13 is slidably fitted within tube H and is yieldably urged toward projected position by the compression spring 14. Another compression spring 16 urges the piston together with the tubular member toward retracted position. Duct 11 communicating with one side of piston 68 is connected by pipe 18 to the port 46 of the timing means, and also by pipe 19 to the remote valve l4.

"Valve 64 consists of a valve member 8| adapted to-close upon the stationary seat 82 and carried by the stem 83. The valve stem is provided with a duct 84 which communicates with the orifice 86 formed on the outer end of the stem. The outer end of the stem loosely carries a cup 81 provided with'vent openings 88, and with a seating disc 89. One side of the seat 82 is connected by pipe 9| with the line 21 leading to the automatic stop valve. connected by line 92 to a duct 93 in the timing means whereby this pipe is in communication with the space in the upper part of the liquid reservoir 33.

Y The timing means, the pneumatic actuator 63 and the valve 64 are correlated by latching means which can be constructed as follows: A latch lever 94 as diagrammatically illustrated has a stationary' pivotal mounting 95 and has a portion of the same interposed in the path of movement of the piston valve 39. The free end of lever 94 carries what can be termed a latch bolt 96, the lower end of which for purposes of schematic illustration is normally interposed between the aligned stud 13 and the cap 81. The arrangement of parts in this connection can be similar to that illustrated in Patent 1,592,930 (see Figures 5 and 6 of same) assuming that the plunger stem 74 corresponds to the plunger stud 13 in the present instance. The latching means just described can be similar to that disclosed and. claimed in said Patent N 0. 1,592,930, and functions as follows: When no pressure is being applied to the piston 68 of the pneumatic actuator 63 the parts occupy substantially the operating positions illustrated in Figure 2. Valve member 8| is closed upon its seat 82 and line 92 is vented to the atmosphere through ducts 84, 86, and 88. When pneumatic pressure is applied to piston 68 by way of duct 11, movement of this piston transmits motion to the stud I3 and such motion is transmitted through the lower end of latch bolt 96, to close cap 81 upon orifice 86, and to move the valve member 8| to open position with respect to seat 82. after when piston valve 39 strikes latch lever 94 and swings the same upwardly a limited distance, latch bolt 96 is retracted from its normal position between stud 13 and cap 81, whereby valve member 8| is permitted to close and cap 81 permitted to move to open the venting orifice 86. As willpresently be explained in greater detail this initiates a downward movement of the piston valve 39 and after piston 3! has completed its downward movement, pneumatic pressure upon piston 88 is relieved whereby this piston is permitted to return to its initial position under the urge of compression spring 16, thereby enabling the latch bolt 96 to again drop down into its former position illustrated in Figure 2.

The remote valve l4 may be located a considerable distance from the mainparts of the forestalling unit. It consists of a body l8| provided with a valve member |82 normally urged by spring I83 against stationary seat I84. A fluted stem 58? is attached to the valve member and is adapted to be engaged by the lower end of an operating rod I87. The operating rod extends to the exterior of the valve body where it is provided with an operating button I88. Within the body the operating rod is attached to a, piston I89 fitted in the cylinder One side of the piston I89 is vented to the atmosphere through the space about rod I81, and the other side is normallyin communication with the outflow pas- The other side of seat 82 is Theresage H2. The inlet passage I I3 of the valve is connected to the main reservoir supply pipe l I4, while the outflow passage 2 connects with the line 19, which connects with the pneumatic actuator 63 and with the timing means.

Operation of the system as described above with reference to Figures 1 and 2, can be reviewed as follows: Assuming that the system is in normal condition ready to receive a track im-- pulse, and that the double heading cock I8 is turned to open position to permit control from the engineers cab as desired, the two valves of the duplex control valve I8 are in closed position and retained closed against the pressure of air in control pipe 28, by the magnetic field of supermanent magnet as described in aforesaid Patent No. 1,548,593. The paths of the forestalling unit are substantially in the position as illustrated in Figure 2, and the double seated shut-01f valve 5-l is in the position illustrated whereby pipes 2 I and 2| are in free communication. By virtue of pressure maintainedin pipe 21 the valve member of the automatic stop valve I2 is maintained in such a position that the valve means of the same maintains pipe 22 in nonventing condition. At the same time however pipes 28, 2| and 21 are in'restricted communication with the mainjsource'of air supply through the stop valve.

Assuming that a track impulse is received by the duplex control valve without operation of the forestalling unit, line 28 is vented to theatmosphere by the opening of one of the valve members of the duplex control valve, and it serves to vent line 21 from the stop valve l2, whereby the stop valve automatically operates to vent'the brake pipe 22 to the atmosphere. This serves to efiect an automatic brake application. In order to restore the system to normal operation the engineer must then move the handle of the restoring valve H to restoring position, whereby pipe 28 is vented to the atmosphere and temporarily disconnected from pipe 2|, and pipe 2| is connected to pipe 29 and thereby vented to the atmosphere through the interlocking valve IT. This retains the brakes applied and permits the pressure in pipe 28 to drop to atmospheric, whereby the valve member of the duplex control valve which'has been actuated to open position, is permitted to return to closed position. Thereafter when the handle of the restoring valve II is returned to normal position, pipe 28 is reconnected with pipe 2 I. v Assuming now that the engineer is alert and carries out a forestalling operation to prevent a brake application by a track impulse, button 188 of the remote forestalling valve I4 is depr'essed whereby valve I82 is unseated to permit application of air pressure from the main supply through pipe 19 to the pneumatic actuator 63. Operation of actuator 63 serves to close the venting orifice 86 and unseat the valve member 8|, whereby pressure from line 2'! through line 9| is applied through pipe or duct 92 and duct 93 of thetiming means to the space above the liquid in reservoir 33. Liquid from reservoir 33 now commences to flow through the restricted orifice 34 to the space beneath the piston 31. The initial movement of thispiston is aided by the compression spring 44. Piston valve 39 moves upwardly with piston 31, and when port 46 is exposed this port together with line 18 is placed in free communication with the space above the piston 31. In connection with the upward movement of the piston 31 it will be noted that the full pressure of the main reservoir supply is applied at all times to thespaceabo've piston =33. However the supper :area lOf piston 3.1 minus (the :upper area of piston .39 is less than :bottom area to which :the liquid -pressure applied. fillhereiore a 'difierential :force acts to urge the piston zupwardly. Exposure .of port 46 droxthe space above the piston applies the :full lmain reservoir pressure to the pipe 18, to the pipe 19 and the pneumatic actuator .63. The pressure thus supplied to the actuator .can'be termed the molding pressure, and thereafter the-operatormay melease the button 108, without interfering with automatic continuation of the forestalling cycle. :Release of button 1-118 permits this button to raise {to the position illustrated in dotted lines :in Figme 2, due to the :fact that piston I09 is urged upwardly by pressure applied .to passage I I2.

Simultaneously with exposure of port 46 port 45 :is likewise exposed .to the .line pressure exist-- ing .the upper portion of cylinder 36. Therezfore reservoir pressure is applied through 6.2 to the pneumaticoperator-52 whereby the piston .59 of this operator operates the shut-.ofi .valve .5l to close the valve member 53 upon seat 56.. Thus shortly after the commencement of the iorestalling period the control line 2| is :shut iofi item communication with the remainder of the control line .2], and .likewise that .portion .of the control line leading to the duplex control valve by way .of pipe v2| is vented to the atmosphere. Thus a track impulse will not .operate either one of .the two control valves.

The piston 31.moves upwardly at a predetermined speed and when .it reaches substantially the 24 1 81 limit of its travel, piston valve 3.9

.strikes the latch lever 94 with the result that the liquid in reservoir 33 to atmospheric pressure results in downward movement of the piston '31 under the urge of air pressure from the main reservoir supply. During the last portion of the downward travel of piston '31 ports 16 and '41 are again exposed to the atmosphere about the upper ,part of piston valve '39, whereby an is no longer supplied to the pneumatic actuator '52. Thus the shut-off valve 51 is permitted to open and .reestablish .communication'between pipes '21 and 2 1.. discharging .from port 46 to the atmosphere reduces the pressure in pipes 18 and I9 to atmospheric whereby button .lll8 is permitted to drop .down -.to its normal position by gravity. This serves to indicate to the operator that the forestalling-period has ended. The forestallingperiod and its termination can also .be indicated by .a small signal whistle connected :to line 19..

.A particular -feature of the system .as described above is the simplicity of the novel :means .em-' alloyed ior maintainingholding pressure upon the pneumatic :actuator 63. As previously described this :is accomplished by the line 18 which :makes a ciinect connection :fromlthe actuator to the port 4'6. :Piston .valve :39 serves to automatically contrdl the application of the main reservoir supply through the port 46 and the pneumatic :actuator whercbythe-holding pressure isautomatically applied shortly after the .-f,or.estalling period (commemes and :is automatically :removed at the end of themestallmg operation. simple means eliminates the mecessity (of using more compli- :cated devices :for this purpo e. :as for :example or supplemental diaphragm or pistomoperated valve. A ifiurther teat-are of the apparatus is the :use of .a booster :spring M below :the piston .31. This sprin speeds :up the initial movement of the piston 6.1., thus reducing the period of time are uired for the operator toihold the button zl 08 depressed.

in certain installations-of the system .described :above :it is desirable to locate the forestalling unit :at a considerable distance from the duplex control valve. This introduces-{the problem of uickly recharging the extended pipe line leading from the duplex control valve, at the-.ondoi "a iorestalling operation. Where the control line .is of (considerable -length it .is impossible to charge the :same with :air .at the end of the ionsstalling operation by .air supplied from the auto- ;matic .stop valve, without causing undesired operationlof the latter with false .momentary application of the train brakes. In the system of Figure ,3 this difficulty is overcome by the .uselof a line charger -l 1.6. This line 'charger has one duct LI 1 connected with theline 21 leading to .the .stop valve, another duct .8 which-is connected to the control line .24 andaduct .l 1.9 which connects with the line 26 leading from the .main reservoir supply, or some equivalent supplemental source {of air. .In general this .line .charger serves to supply charging air from the main reservoir sup- .ply or equivalent.supplementalsource to the control .line at the .end .of the Iorestall'ing operation, .to quickly build .up the pressure in the same, after which the connection .to the supplemental source is automatically discontinued Ior .normal operation of the system.

The particular line charger illustrated consists .ofaloody .i,2l within wfhichare the two .valvernomhers A22. Each of these valve members is -.carried .by .a guided and .fiuted stem 1.23,, and is adapted :to close under the urge of spring .125 upon azs'ta- .tiona-ry .seat .124. .A second stationary .seat 1211a .can be provided about each .stem. The lower portions of the stems 423 have central passages 12.6 which open through the lower ends of the stems into the space .1121. This space 'is vented to the atmosphere .as illustrated. Below the .stems .123 there is .a yoke .bar .123 which is provided with valve seat inserts I29. The yoke bar J28 is interposed between two opposed pistons [31 and 132. A retention stud 13.3 is carried by the :lower side of the yoke 428 and is fitted within :a central opening provided in piston .132. Space 434 above the piston .13.! .isin restricted communication through orifice ll36 with the duct 1.118. and is in unrestricted communication with aclosed air chamber 1-13]. This chamber may .be a cavity iormed within the bodyof the device, or it may be .a separate chamber connected .to the device by suitableextcnsionpipes. Space I33 below the .smal1er.piston.l.32 is conneoted by duct 139 with .a space -l4=l .aboue .theleft hand .valve member 112. and which spacelikewise communicates with duct H1. Space M2 .above :the right hand valve member L22 is in direct communication with duct .1 fl 9. Intermediate space I43 surrounds the inter- ,mediate portions of the-stems 1 23 and communicates with the upper portions of -ducts or passages 12.6. Thus when .both of the valve members .122 are closed as illustrated in Figure 3,.space 1 43.315 vented to the atmosphere through the .ducts 1.25 and caw'ty L21.

Operation of the line charger described above .is as lfQllOWSI For a normal condition of the system with line pressure inoontrol lines 24 and 9 21, valves I 22 are closed as illustrated. At the beginning of a forestalling operation double seated shut-01f valve is operated in amanner previously described to shut off communication between pipes 2| and 21, and to vent pipe 2I to the atmosphere. This serves to vent air through the orifice I36 from both spaces I34 and the cavity or chamber I31. This in turn results in such a reduction of pressure in space I34 as to cause the lower (and smaller) piston I32 to force the yoke bar I28 together with piston I3I upwardly to cause the seat inserts I29 to engage and lift the valve stems I23. This operation serves to move the valve members I22 to full open position and at the same time ducts I26 are closed to interrupt communication between spaces I21 and I43. Seals are also established about the stems I23 because of engagement of inserts I29 with seats I24a. When in open position spaces MI and I42 are in communication with space I43 through th flutes of the valve stems I23. Thus pressure from the main reservoir supply line 26 is supplied through space I42 and space I43 to the space I4I above the left hand valve member I22 where it assumes the same value as the pressure in pipe 21. From space I4I pressure is transmitted through duct I39 to the space I38 below the smaller piston I32. Application of pressure to space MI in effect forms a direct connection between the main reservoir supply line 26 and the line 21 leading from the automatic stop valve.

At the end of the forestalling operation the double seated shut-off valve 5| is moved to open position in the manner previously described, to re-establish communication between lines 2I and 21. Simultaneously air pressure from line 21 is supplied through the shut-off valve ill to lines 2I to 20 to quickly build up pressure in the latter to normal value. This charging operation does not substantially reduce the pressure in line 21 because during that interval this line is also directly connected with the main reservoir supply line 26 or equivalent supplemental source, through spaces I4I, the flutes of the left hand valve stem, space I43, the flutes of the right hand valve stem, and space I42.

When the pressure in line 2| has been built up to substantially normal value, pressure in the chamber or cavity I31 has likewise increased to such a value that piston I3I is now urged downwardly with suificient force to overcome the upper force of the piston I32. Therefore the yoke bar I28 is moved downwardly to cause all of the parts to return to normal position as illustrated in Figure 3.

Restriction I36 serves the useful purpose of retarding building up of pressure in the cavity I31 toward the end of the charging interval. Cavity I31 provides an increased capacity for space I34 and thus together with restriction I36 provides a proper interval" before cut out, that is before the pressure in space I34 builds up to a sufiicient value to move pistons I3I and I 32 in a direction to cause valve members I 22 to close and interrupt further supply of air from the main reservoir' supply or other supplemental source of air.

It will be apparent from the foregoing that the line charger as described serves to automatically recharge the control lines connected from the forestalling unit to the duplex control valve, without occasioning a drop in pressure in the pipe line leading from the automatic train stop valve.

Thus the lines connected from the forestalling unit to .the duplex control valve may be any length desired without in any way interfering with proper operation of the system. It will be appreciated that for connecting lines of different lengths leading from the duplex control valve to the forestalling unit, the cavity or chamber I31 should be adusted accordingly as to volumetric capacity and likewise restriction I36 can be adjusted. A larger cavity and/or a smaller restriction serves to increase the time period of the charging operation to adapt the system to longer connecting lines.

In the event a track impulse is received by the duplex control valve to cause actuation of the same, while the line charger is supplying air to the line 21, the venting of air from line 2I will be insuflicient to prevent building up of pressure in the same, because of the relatively high available rate of air supply from the charger.. There fore after the normal charging period valve members I22 of the line charger close, and thereafter continued venting by the duplex control valve causes a brake application.

The system illustrated in Figure 4 likewise uses a line charger I-I6 but the forestalling unit in this instance is directly operated manually, rather than from a remote point. Thus the valve I4 in this instance is omitted, and in place of the pneumatic actuator 63 there is a hand lever I46 mounted upon the rotatable shaft I41. As diagrammatically illustrated the shaft carries a spring pressed lug I48 adapted to engage and transmit force to the lower end of the latch bolt I49. Thus when the hand lever is turned clockwise 270 as viewed in Figure 5, the cap 81 ofthe valve 64 is operated whereby the valve member BI is unseated. This operation is the same as when the pneumatic actuator 63 of Figure 2 is operated by air pressure, and it effect-s commencement of a forestalling cycle. Latch bolt I49 is pivotally attached to the latch bolt I5I, corresponding to the latch arm 94 of Figure 2. When the piston 31 reaches the upper end of its travel latch lever I5I is operated to retract the bolt I49, with a result that valve 64 is permitted to return to its normal initial position, and the forestalling lever I46 permitted to return to its initial position as illustrated. In actual practice the parts just described can be similar to corresponding parts disclosed in Patent 1,592,930.

The direct manual forestalling means of Figure 5 cooperates with the line charger II6'in the same manner as the remote operated forestalling means of Figure 3. Here again the line charger serves to supply air to the control line 2| at the end of the forestalling period to avoid an improper application of the brakes.

I claim:

1. In a pneumatic train braking system of the type including a control valve adapted to'vent a control pipe of the system in response to a track impulse to thereby efiect automatic application of the train brakes, a valve adapted to be manually opened and having its inlet side connected to the main air supply reservoir of the system, and a forestalling unit set in cyclic operation by opening of said valve and serving to efiect shut off of said control pipe for a predetermined time tion towardthe said other end of the cylinder,

a= shut-offval've interposedin said: control pipe; another pneumatic actuator serving to operate saidshut-off' valve; another valve means serving" to apply pneumatic pressure to said last named:

actuator duringthe travelaof said piston fromits' normal position, and: means: actuatedhy the" piston at the end of its: travel fromv said initial.

normal position for rendering the first. named: actuator inefi'ective= to" maintain its associated valve means closed.

2; A. system. as; inv claim. 1 in which the valve means: servingv to connect. the chamberof the first named pneumatic actuator with, said cylinder' consists oi: a second pi'stom attached to thefirst: piston; a second: cylinder in which the sec-- ond piston operates;. and. a port exposed by the: second piston after initial movement of the same: and. connected to said first named actuator.

3:- In a: pneumatic'trainbraking system includ' ing a; control: valve adapted to. be'opened in response to a track impulse. tovent'a' control line and an automatic: stop valve connected to the COIlflI'Oll line wherebywhen the; control line is vented said automatic-stop valveventsthemain brake pipe" to thereby effect a brakeapplication, a iorestalling' unit. including; timedelay: means and ashut-offi valve operated during? the time delay'period tointerrupt the'controlline' and to vent that? portion of said lineleading from the cone trol valve tothe shut-off valve.- andoperated atthe' end of the? forestal'lin gi period to reconnect saidporitiomot the control. line tothe automatic:

stopvalve, and automaticpneumatic line charg ing-means connected tot-he control line and. serving to-supply air under pressure to the same-onlyfor a, short interval: at the. endLof. theiforestalling period;

4.. Ina. pneumatic train braking systemincludling. a. control valve. adapted to be. opened in. re.- sponse to a track impulse to vent a control line and. an automatic. stop valve connected to the control line whereby. when. the control line is vented said automatic stop valve vents the. main rorake pipe of the. train braking, system, a torestalling unit associated with the controlline;. said unit including time delay meanshaving an automatic cycle of operation adapted tote initiated.

by an operator, and a shut-ofi'valve insaid control'line andadaptediatthe beginning of the fore.-

stalling cycle to close that portionof the control.

rupt such, supply ofi. supplementalair: at; the: each offsaidlchargingiinterval.

5;. In". a. pneumatic train braking: system as; in: claim: 4' which said line chargingmeans. has pneumatic: connections with. both thatvportioni of-T the control .lineleading from the automatic: stop valve and that portion: leading from the control. valve,-. and incorporates valve means for automaticallv supplying that portion or the control line: leadingfrom the stop'valve: with air under." pressurefrom a: supplementali source ofi ain sup ply;, to recharge that portion ofthe.- control. line. leading fromthe-control valve, at the endoi. the forestalling'. cyola.

6; In: a. pneumatic-train braking; system as in. claim 4; in which. said line-charger. comprisessa' body having a pneumatic connection. with the mainreservoir supply of. they trainv braking sys.-- tem, a connection. to that. portion. of. the: control:

; linetleading from. the. automatic. stopvalve, and.

a connection. to that portion of the controlline leading .from said. control valve. a pair 05, valve. devices. in said. body, and. fluid. pressureoperated means in the body. for effecting. operation of. said. valve devices,. said valves fluid. operated. means serving to admit air from. the main.r.eser-- voir supp y to that. portion of. the control. line. leading. from the stop valve at the end of. the forestalling. cycle: and until: the. pneumatic pressure. in that portion of. the. control line leading. from. the. control. valve has been. built up to sub.- stantially normal value...

7.. In. a line. charger, a body having a. passage. for oonnectionwith a source of. air under pressure, a. second. passage. having connectionwith a.

line: to. be. charged with. airand. a third. passage. for connection. with a. line. which. is. adapted. for communication.- withsaid first. named. line,.a pair. oi'valve meanswithin.saidhody,.each valve means: including avalve member. movablein opposite directions between openand closed.positi0n,,a.stationary seatformed. withmthevalve body andhooperating withsaidl valve member, a valve. stem attachedto eachvalvemember, and a. valve orifice formed in. one end or said stem, said valve body being provided withtwo spaces'on that side oi each. of. the, stationary valve seats whi'chthe' corresponding, valve member engages. the first. space. being in communication. with. the first named passage,, the second space. being in communication with the third namedv passage}. 2. vented space within the body in communication. with the endsofsaid valvestems and also in coma-- munication with the atmosphere, an intermediate space in the valve body located intermediate" the valve. seats. and saidlast. named vented space,.sald intermediate. space serving to interconnect both. the. first andsecond spaces, when saidlvalve mem;-- bers are. in open -position,.aligned cylinders formed; in the; valve.- bod'v,. a pair. of. aligned. pistons di'sposed within said cylinders, a. yoke bar interposed. between. said pistons. and having, seating, surfaces. formed. on their. end portionsadapted. to engage theadiiacent ends of; the=valvestems,,meansform-- ing. a. pneumatic. connection. between the. space on one. side of. one ofithe pistons .andsaid third. line,! aflow restricting. orifice interconnectingthaspace on one sideot. the other onemf. saidlpistons. with said second line, and. a cavity or chamber likewisein communication. with said. last: named. space,- said pistons functioning, in response to. pneumatic. pressure applied to the. same to move. saidyoke. bar in. opposite directions between limiting. posl-- tions, the. valve members. in one. limiting. position. being, both. open and having the. orifices. in.

- 13 their stems closed, and in the other limiting positions the valve members being both closed and said yoke bar being free with respect to the ends of the stems whereby said intermediate space is vented to the atmosphere through said stem orifices.

8. In a line charger, a body having a passage for connection with a source of air under pressure, a second passage having connection with a line to be charged with air, and a third passage for connection with a line which is adapted for communication with said first named line, a pair of valve means within said body, each valve means including a, valve member movable in opposite directions between open and closed position, a stationary seat formed within the valve body and cooperating with said valve member, a I

valve stem attached to each valve member, and a valve orifice formed in one end of said stem, said valve body being provided with two spaces on that side of each .of the stationary valve seats which the corresponding valve member engages, the first space being in communication with the first named passage, the second space being in communication with the third named passage, :a vented space within the body in communication with the ends of said valve stems and also in communication with the atmosphere, an intermediate space in the valve body located intermediate the valve seats and said last named vented space, said intermediate space serving to interconnect both the first and second spaces when said valve members are in open position, aligned cylinders formed in the valve body, a pair of aligned pistons disposed within said cylinders, a yoke bar interposed between said pistons and having seating surfaces formed on their end portions adapted to engage the adjacent ends of the valve stems, means forming a pneumatic connection between the space on one side of one of the pistons and said third line, a flow restricting orifice interconnecting the space on one side of the other one of said pistons with said second line, and a cavity or chamber likewise in communication with said last named space, said pistons functioning in response to pneumatic pressure applied to the same to move said yoke bar in opposite directions between limiting positions, the valve members in one limiting position being both open and having the orfic'es in their stems closed, and in the other lim-- iting positions the valve members being both closed and said yoke bar being free with respect to the ends of the stems whereby said intermediate space is vented to the atmosphere through said stem orifices. I

9. In a pneumatic train braking system as in claim 4 in which said line charging means incorporates means serving to automatically interrupt supply of supplemental charging air to the control line .at the end of a short charging period irrespective :of operation of the control valve during such interval.

10. In a pneumatic train braking system including a control valve adapted to be opened in response to a track impulse to vent a control line and an automatic stop valve connected to the control line whereby when the control line is vented said automatic stop valve vents the main brake pipe of the train braking system, a shut-off valve in the control line and adapted in one position of the same to close that portion of the control line leading to the automatic stop valve and to Vent that portion of the control line leading to said control valve, said shut-off valve in the other position of the same serving to re-establish communication between both portions of the control line, and line charging meansconnected to that portion of the control line leading from the automatic stop valve and serving for a short charging interval to automatically supply said portion :of the control line with supplemental air under pressure to recharge the entire contro1 line when said shut-ofi valve is moved to said other position to re-establish communication between both portions of the control line, said line charging means also serving to automatically interrupt such supply of supplemental air at the end of said charging interval.

HERBERT P. FOLKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Farmer Oct. 2, 1928

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