US2243242A - Sander - Google Patents

Description

May 27, 1941.

c. A CAMPBELL S ANDER Filed Jan. i6, 194 .s sheets-sheet 1 Zinnen or @Vw/@ QL. @nulidad/ t Cttomegs mv. @m mv bm Q m,

May 27, 1941- c. A. CAMPBELL 2,243,242

Srwentor Gttornegs May 27, 1941.

5 SheetsrSheet 3 TO SANDER,

' EOEd R.H.WHEEL c. A. CAMPBELL Patented May 27, 1941 SANDER Charles A. Campbell, Watertown,11S-T. Y.,-, ua,ssignor to The New York Air Brake Company, a corporation of New Jersey Application January 16, 1940, Serial No. 314,172

Claims.

This invention relates to sanding apparatus and is particularly advantageous in connection with high speed trains on Which sanding should occur throughout the train, that is, simultaneously ahead of every braked Wheel or at least ahead of every truck. The reason for this is that high braking ratios must be used to secure safe stopping distances and these ratios are such that wheel sliding is likely to occur, particularly in emergency applications, unless the condition of the rail is good.

Since the condition of the rail is affected by uncontrolled factors such as the Weather, the only manner known at present to ensure a uniformly satisfactory condition is to sand as an incident to brake application and in such a way that the sanding will become elective at least as soon as the brake application. It must occur simultaneously throughout the train because if sanding were caused only at the head of the train, the brakes at the rear of the train would apply before their respective Wheels reached the sanded portion of the rail.

While it is desirable to sand initially in front of every braked Wheel, and it is desirable that sanding continue throughout the brake application, it is not necessary that sanding atall Wheels continue throughout the brake application. Consequently, according to the preferred embodiment of the present invention, sanding 'occurs initially in iront of every truck, continues throughout the brake application for trucks at intervals throughout the length of the train, say every third truck, and terminates after a short time interval ahead of the intervening trucks. The timed activity interval for locally timed sanding is sucient to permit those Wheels on which locally timedsanding is used to reach rail which has been sanded by continuous sanding, before the temporary sanding ends. In this Way Waste of sand and of sanding air are each minimized.

This system oi limiting the duration of sanding locally at points throughout the train can be used with a master controller which gives -timed sanding in emergency or timed sanding after manual actuation or sanding at will. With the local timing, those sanders Which are aiected by the local timing can not remain in operation longer than a certain limited period. Sanders not so locally timed are controlled as to the duration of sanding from the head of the train.

The term locally timed sanding is intended to indicate sanding which is timed at certain locations in the train. While` the timing mechanism would conveniently be near such sander, the term locally timed sanding is not intended to imply any specialV location for the timing means which aiiectslocal timing, because obviously, various Ways of imposing a'short operating time limit on selected units can be worked out and some of them rnighthave the timing means not strictly local to the Sanders. 1

In a sanding system in which all the Sanders start to operate throughout the train and then certain selected Sanders cut out after a denite time'interval, sanding is eiective throughout the train 'from v'the `start of sanding and remains effective Vto allintents and purposes throughout the stop, because those Sanders which remain in operation throughout the stop will suiciently sand the rails for the entire train. While it is believed that the rail Will be sufciently sanded by the use of locally timed sanding for at least the second and third'V trucks following a truck in front `of which sand is continuously delivered, the arrangement of continuous and timed units may be modified according to particular conditions or the preferences of the designer.

To some extent the requirements will be affected by the character and speed of the train and the character of the track over which it is operated. While reference has been made to sanding ahead of every truck, this represents the extreme condition where the very best possible action is to be had regardless of expense. Where Wheels are closelyispaced, as they are in trucks, a single sander ahead of the truck is ordinarily suiicient, and that arrangement Will be indicated as to the trailing vehicles in certain of the figures. Where two trucks are very close together, as they are in certain types of coupled cars, a sander ahead of the leading truck might suffice for both. Where a number of Wheels are .closely spaced as is the case with drivers on a locomotiva. Sanders for alternate drivers mightbe sufficient in certain cases, although individual sanding for all drivers is desirable in starting.

The purpose of this comment is to indicate that the requirements arefexible ,and may be met by the use of ordinary foresight and the suggestions of sanding every driver or every truck are general rather `than limiting in their significance as used in the presentV specification.

AFor purposes of illustration, I show in the present application, a controllingrelay valve mechanism with electrically actuated pilot valve and a sand trap with intercepting valve and clean-out features which.` form the subject matter of an applicationv iiled January 16, 1940, Serial No. 314,173,` and hence are not claimed herein. However, claims will be presented in the present application to a timing scheme applied to the relay valve of said other application and designed to afford the local timing function required by and characteristic of the present invention. Although a particular timing mechanism will be claimed in the present application, it will be apparent to those skilled in the art that equivalent local timing schemes might be substituted.

The present application is a continuation in part of my application Serial No. 274,295 led May 17, 1939.

In the drawings:

Figure 1, which is drawn in two parts intended to be joined on the line a-a, is a side-elevation of a train indicating proper locations of Sanders operating on the continuous principle and on the timed principle.

Figure 2 is a plan View illustrating the relationship of the sander relay valve to two sandery heads, one for each Wheel of a pair.

Figure 3 shows the sanding control valve and its related sanding switch, the sanding relay valve, and one of the two sander heads controlled thereby at the head of the train. The sanding relay valve of Figure 3 is of the continuous acting type. The sanding relay valve is shown in running (inactive) position.

Figure 4 shows the sander relay valve and connected sander head arranged to operate on the timed sanding principle. The sanding relay valve is shown in running (inactive) position.

Nota-Figs. 3 and 4 when assembled from left to right in the order stated, form a diagram of a two truck installation in which the rst truck has continuous and the second has timed sanding.

Figure 5 is a fragmentary section, the section being taken on the line 5-5 of Figure 3.

Figure 6 is a fragmentary section on a larger scale than Figures 3 and 4, showing the slide valve mechanism of the sander relay valve in preliminary impulse position, in which the clean out blast is delivered.

Figure 7 is a similar view showing sanding position.

Figure 8 is a similar View showing the nal cleanout position assumed as the sander relay valve moves toward its running position.

Refer iirst to Figure 1. In this figure a conventional streamlined train is represented. The train comprisestwo propelling units indicated by the reference letters A and B, and five cars drawn thereby indicated by the letter D. The train is shown as composed of two two-car artic-A ulated units and an independent end car, but the wheel arrangement is not important.

Sanders are indicated in advance of all trucks and are differentiated by the letters C and T, the Sanders indicated by the letter C being of the continuous sanding type shown in Fig. 3 and those indicated by the letter T being of the locally timed sanding type, shown in Figure 4.

These two types will be described in detail hereinafter, but it may be said that the Sanders C operate continuously as long as the sanding control device on the locomotive cab calls for sanding. They are all put into action by a single sanding switch controlling a single sanding circuit. The continuous Sanders operate so long as the switch remains closed. The locally timed Sanders, however, go out of action after a definite time interval -determined by the volume of a timing reservoir hereinafter described, and so chosen that the wheels served by the timedY Sanders,v will reach rails sanded by the continuous sander next ahead of them before the timed sanders go out of operation.

While each such locally timed sander could be given an individual and appropriate timing period, it is simpler to adopt a single time period for all locally timed Sanders suited to the longest time reuired throughout the train. In this way the apparatus can be standardized.

A sanding circuit comprising the wires I2 and I3 extends throughout the length of the train. The sanding magnets hereinafter described are connected in parallel between the wires I2 and I3. A source of current is conventionally illustrated ras a battery I4, and the circuit is controlled by a normally open switch, identied by the numeral i5, applied to its shiftable contactor. When forced up by a piston I6 against the resistance of the coil spring I 1, the contactor I5 engages contacts I8 and closes the circuit.

The piston IB may be urged to close the sanding circuit by air under pressure derived from the main reservoir I9 under the control of a sanding control valve generally indicated at 2l. This valve may be of any suitable type, but is illustrated as comprising the valve described and claimed in the patent to Campbell No. 2,035,533, issued March 31, 1936. Since its construction is not a feature of the invention its ultimate functions alone will be here described.

When the sanding at will button 22 is pressed, the switch I5 will be held closed so long as the button is pressed in. If the valve 23 is forced downward either by depressing the button 24 or by admission of air under pressure through the pipe 25 to act against the piston 25, air under pressure will be admitted against the piston I6 for a time period determined by the volume of timing reservoir 21 and the capacity of an exhaust choke 28. At the end of such period the valve 23 resets and the switch I5 opens.

The -pipe 25 is connected to a valve 29 which is operated in emergency to admit air to pipe 25. could be either the engineers brake valve or K the control valve on the leading unit, for example (bothI schemes being Well known in the art) The desired eifect is that upon the occurrence of an emergency application the valve 23 is actuated. The time period for closure of switch I5 after actuation o f valve 23 is so chosen that lt remains active for a period of time at least as long as the maximum stopping period during an emergency application. Thus, continuous sanding will cease shortly after the stop is completed, and` is in reality timed by the control mechanism at the head of the train.

So far as the present invention is concerned, all that is necessary is some means to energize the circuit I2, I3, preferably for a definite period in emergency applications, or to energize it at will for other purposes, as the case may be.

The type of sander; here under consideration is operated by air under pressure. The particular source is not a feature of the invention. On the leading unit the main reservoir I3 (Fig. 3.), of the air brake system is a convenient source. On other units, for example, trailers, a local reservoir 3| (Fig. 4) may be used. vThis may be charged in any way, but in Figure 4 a connection 32 leads tlrnjough a flow restrictingA choke 33 and check valve 34 from some charged portion of `the air brake system to local reservoir 3l. The choke limits the demand for air irn. posed upon the air brake. system and thus inhibits disturbing effects..

Parts which are identical in Figures 3 and 4 will rst be described.

For each sanding unit there is a pipe bracket 35 to which an air supply line 36 leads from the air source. Bolted to the bracket 35 is the body 31 of the sander relay. The body is bushed to afford a slide valve chamber 38 and a communicating cylinder 35. A cap 4l closes the end of the cylinder and is sealed thereto by a gasket 42 which extends inward to serve as a seat for rim 43 on the piston 44.

This piston 44 has a packing ring as shown and is formed integrally with a stem 45 having guiding lugs at its end remote from the piston. It is urged to the right by a coil compression spring assembly 46. The spring seats, plunger and key associated with the spring form an assembly familiar in the air 'brake art and are used to facilitate assembly with the spring under initial stress. 'Ihe stem 45 is notched to receive and closely confine a graduating valve 41 which rides on the back of a slide valve Y48. The valve 48 coacts with a seat in the bushing of slide valve chamber 38 and works between shoulders on stem 45 so as to have lost motion relatively to stem 45 less than the total ltr-avel of piston 44.

A port 49 leads to the cylinder space at the outer side of (to the left of) piston 44, `and the piston is caused to shift at controlled rates by equalizing ythe pressure between port 49 and chamber 33, and by isolating the port from the chamber and venting the port. It is in the means for performing these functions that Figures 3 and 4 differ, and such means will be discussed later.

The slide valve seat has three ports of which l and 52 are connected -to the impulse pipe 53, and 54 is connected to the sanding jet pipe 55.

The slide valve has three through ports 55, 51 and 58, each enlarged at its lower end in the direction of shift of the valve. The graduating valve 41 has a through port 59, which at one limit of lost motion between the valves 41, 48, registers with the upper end of port 51 (see Figures 3, 4 and 8) and at the other limit registers with port 55 (see Figures 6 and 7).

In running position (Figures 3 and 4), seat ports 52 and 54 are blanked by the slide valve 48, while seat port 5l registers with port 58, which, however, is blanked by graduating valve 41.

As the piston 44 starts outwardv (tothe left); the slide valve 48 remains at rest and port 59 in the graduating valve opens to port 56 near and at the limit of lost motion. This is preliminary impulse position, Figure 6, in which air is supplied to impulse pipe 53, only. l

When the piston 44 completes its outward excursion and seats on the gasket 42, port 5|' is blanked by the slide valve 48, port '52 connects with port 51 which is blanked by graduating valve 41 and port 54 is fed by port 58 which is always exposed at its upper end. This is Sanding position, Figure 7, in which air is fed to sanding jet pipe 55, but not to the impulse pipe 53. f

As piston 44 starts inward (to the right) from its outermost position, slide valve 48 remains at rest and near and at the limit of lost motion between the graduating valve 41 and slide valve 48, port 59 opens into port 51. This is Final cleanout position (Figure 8) in which air is supplied to ports 52 and 54 and hence to both the sanding jet pipe 55 and impulse pipe 53.

The enlargement at. the lowerendof port-.56

provides for sustained flow to the impulse pipe as the parts move from Preliminary impulse position (Figure 6) toward Sanding position (Figure 7). The enlargements atthe lower ends of ports 51, 58, permit sustained flow to both the sanding jet pipe '55 and impulse pipe 53 as the par-ts move from Final cleanout position (Figure 8) to Running position (Figures 3 and 4). Thus flows for the necessary short periods can be had by delaying motion of the piston by the use of chokes which control ows to and from the space to the left of piston 44,

The pipes 53 and 55 for -every sanding unit have each two branches, one leading to a sanding head for the left wheels (shown in Figures 3 and 4) and the other leading to a duplicate sanding head for the right wheel (omitted from Figures 3 and 4 since it would ycomplicate the drawings and involves mere duplication.) In fact, one rel-ay valve can control any reasonable number of sander heads.

The magnet valve control for continuous sanders will now be described by reference to Figure 3. The winding El is connected between wires I2 and I3, and when energized, forces down armature 62, stem 53 and double beat poppet Valve 64 lagainst the opposition of spring 85. The Valve closes selectively against an exhaust seat 88 (its norm-a1 position) and a supply seat 81 (when the winding 5l is energized).

The chamber 38 between these seats is connected with port 49. A chamber 69 beneath supply seat 51 is supplied with air under pressure by pipe 35. A choke 1i controls the rate of eX- haust and a choke 12 controls the rate of supply, thus determining the rates at which piston 44 shifts to the left and to the right, respectively.

Obviously, energization of winding 6| causes theY piston 44 to shift to the left where it stays until the winding 5l is cle-energized. This causes its return excursion.

The magnet valve control for timed Sanders will now be described by reference to Figure 4. The winding 13, like the winding 5l, is connected between the wires l2 and i3. When energized, it forces down the armature 14 which is connected through the stem 15 with the duplex poppet valve having an exhaust head 15 coacting with an exhaust seat 11 and an inlet head 18 coacting with an inlet seat 19. It will be observed that the :seats 11 and 18 are arranged reversely as corn-pared to the seats 83 and 61. The space between the seats 11 and 19 is connected by a passage 8l and pipe 82 with a timing reservoir 83.

AA coiled compression spring 84 urges the valve in the direction to close the valve head 13 against the supply seat 18 and hold the exhaust valve 16 away from the exhaust seat 11. Thus, the timing reservoir is normally vented to atmosphere.

A filler piece 85 is interposedy between the.

pipe bracket 35 and the body of the magnetically actuated valve. The air supply pipe 35 is connected through the choke 12 with a chamber 86 in the filler piece 85, and this space is in free communication with the port 49, already described. It is also in restricted communication through a choke 81 of somewhat larger capacity than the choke 12, with the supply chamber 88 from which the supply valve 18 controls the ow.

Under running conditions as indicated in Figure 4, the reservoir 3l is charged, the exhaust valve 16 is open, the inlet valve 18 is closed. Consequently, the reservoir 83 is at atmospheric pressureggPressures on oppositesides of thepistonf44 are equalized, and the slide valve structure is the right-hand position underthe urge of the spring 4G. It follows that the impulse pipe 53 and the sanding jet pipe 55 are at atmospheric pressure, since the supply of. air under pressure to each is cut off and since both are vented through the sand trap, as will later be described. When the winding 13 is energized, the exhaust valve 16 closes and the supply valve 1B opens.

The effect is to close the exhaust from the timing chamber 33, and connect the timing chamber through the relatively large choke 81 with the chamber 85 and by a port 49 with the space to the left of the piston 44.

It should be observed, however, that the chamber S6 is also connected by the relatively small choke 12 with the supply reservoir 3|. Consequently, the iirst effect of energization of the winding 13 is to reduce the pressure to the left of the piston 44 at a rate which is determined by the capacity of the choke 81. The piston therefore makes its outward travel at a gradual rate, say, in about one-half second. It remains in this position until the pressure in the reservoir 83 rises so nearly to equalization with pressure in the reservoir 3| that the spring 46 is enabled to return the piston to the right.

It follows from the construction just described that in the timed sanding relay of Figure 4, energization of the winding 13 produce-d by energization of the circuit |2|3 causes the piston 44 to move out, remain in its outer position for a d'eilnite period, and then return to the right to its normal or running position, even though the winding 13 be still energized. When the. winding is linally de-energized, the only eiiect is to disconnect the 'timing reservoir 83 and vent the same quickly to atmosphere, thus conditioning the apparatus for the next timed sanding operation.

Comparison of the operation of the continuous sanding unit described with reference to Figure 3 and the locally timed sanding unit described with reference to Figure 4 will indicate that the only difference between their operative characteristics is that in the locally timed unit the piston 44 moves outward, remains in its outermost position a denite period, and then returns to its normal position irrespective of the state of energization of the circuit through the wires I2 and I3, whereas in the sander of Figure 3 the piston 44 moves outward in response to energization of the circuit, remains outward as long as the circuit is energized and returns inward or to the right when the circuit is de-energized. Except for this diierence in timing, the valve functions are the same, that is, air is first supplied to the impulse line 53, then for a short period to both lines 53 and 55, then to the sanding line 55 only. This is the sanding position of Figure 7. On its return excursion, air to the impulse line 53 is supplied while air is still being supplied from the sanding line 55 and then both ows will cut oli at about the same time. This scheme of control can be used with any type of sander making use o an impulse connection and a sanding air connection, but it attains its greatest utility with that type of. sander developed by the present applicant in which the supply of air to the impulse line tends to cut off the sanding hose from the sand retaining chamber of the sand trap and then develops pressure in the sanding hose for cleanout purposes.

Best results with this type of opera-tion are secured with a dilating, rubber, self-clearing nozzle,v becausev the development of pressure dilates the nozzle and breaks away any ice or mud which may tend to clog it. If the line is unclogged, the intercepting valve which cuts oi the hose from the sand chamber opens immediately after the termination of the impulse liow, but if the line is clogged, the intercepting valve remains closed until the nozzle clears and it may remain closed after air is being delivered to the sanding line 55, in which event, the air so delivered will maintain the pressure in the sanding hose until clearing occurs and will retain the intercepting valve closed so that no sand can be delivered to the clogged hose.

While various types of traps responding to the above description can be devised, there has been chosen for illustration a preferred form which is the subject matter of the copending application above-identied. The structure of this trap is shown in suflicient detail in Figures 3, 4 and l5 to permit a ready understanding of its operative characteristics.

The sand trap structure is supported as a unit by a bracket member 9| which is mounted either on the car body or on the truck by means not illustrated in the drawings, the mode of support not being a feature of the present invention. Member 9| has an impulse air passage 92, a sanding air passage 93, a sand hopper 94, and a large atmospheric air passage which is designed to furnish air to the stirring jet, as will be explained.

The passage 35 is cored in a side boss 96 which projects into the sand hopper 94 at one side, and which carries a hub 91 with a vertical guideway formed therein. The hopper is somewhat contracted toward its lower end, and the discharge passage is encircled by a bushing 93. To supply air to the passage 95, an atmospheric intake pipe 99 is threaded into the upper end of the boss 96 and affords a large capacity ow passage from atmosphere.

Overlying the boss 96 and hub 91 and encircling the pipe 99 is a horizontal screen |0| through Which sand enters the hopper from an overlying sand box |04. The clean-out or impulse line 53 is connected to the clean-out air passage 92 by way of a union fitting |06 containing a check valve |01 urged closed by a spring |08 and arranged to prevent back flow to the line 53. 'Ihe sanding line 55 connects with the sanding air passage 93 by way of another union tting i|| enclosing a strainer H3.

The body of the sand trap is bolted against the bottom of member 9| and sealed thereto by gaskets. (The connecting bolts do not appear in the drawings.)

Body H4 includes continuations of the passages 92 and 93 which are given the same reference numerals. There is also in the body ||4 a sand passage ||5 to which the hopper 94 delivers. In this passage there is an upstanding boss H6 upon which rests the lower end of a stem H1 whose upper end is slidably guided for vertical movement in the hub 91. The stem I1 carries an umbrella H8 which, when the parts are assembled, acts as a sand deflector and which, when the body ||4 is removed, descends and serves as a valve to prevent the escape of sand.

Formed in the body ||4 and slightly t0 one side of the port through the bushing 98 is a sand retaining chamber ||9 which is generally cylindrical in form and around which the sand passage ||5 curves so as to enter the sand retaining chamber from beneath. This produces a sort of snail shell housing.

On the opposite side of the chamber H9 from the approach passage H is an atmospheric air chamber |2|. 'Ihis is closed by a removable cap |22 and communicates at its top freely with the atmospheric chamber 95. An auxiliary atmospheric port |23 connects the chamber |2|. with the sand retaining chamber H9. This port has a regulatory function which determines its size. The port can on occasion be omitted. A stirring nozzle |24 receives air from chamber |2| and discharges below the normal sand level indicated in Figure 5 by the legend SL. This line represents the normal angle of repose of sand when the trap is not in action. The upper face of the nozzle |24 has a slot |26 which is blinded more or less when the sand level is high. The slot thus performs a compensating function, regulating the rate of sand discharge of the trap by modifying the stirring effect.

The discharge connection from chamber H9 comprises a horizontal passage approximately concentric with the axis of the chamber H9 and above the level of sand (SL). In this passage are mounted a wear resisting insert |21 and a rubber bushing |28 which together produce a 'Venturi throat or contraction. This throat leads to the sanding hose |29 and the hose terminates in a distensible nozzle |3|. This is directed to the angle between the rail indicated diagrammatically at |32 and the wheel similarly indicated at |33.

Projecting through the chamber H9 and axially aligned with the throat above described is a nozzle structure which during sanding is retracted so that when the nozzle directs a jet of air into the throat, air and suspended sand are drawn from the chamber i9 and discharged into the throat. During clean-out operations, however, the nozzle moves toward the throat and an elastic member which serves also as a protecting sleeve seals with the throat to prevent discharge of sand during the clean-out operation, Bolted to the Ibody H4 is a cap |34 in which are formed. extensions of the ports 92 and 93. The cap overlies a chamber |35 formed -in the body ||4 and clamps at its periphery a flexible diaphragm |35. This is of rubber-like material and has annular corrugations to permit an ladequate range of free motion. It is backed up by a suitably formed diaphragm plate |38 which is formed integrally with the tubular stem |39. The center of the diaphragm is clamped to the hub of the plate |38 by a ring or washer I4! held by a nut |42. This nut is radially slotted, the slots leading to an annular groove whichv surrounds the threads on the stem and communicates with drilled ports |43 leading to the interior of the hollow stern |39. The ring |4| ene circles and hence docs not blind these ports.

The tubular stem |39 is guided in a bushing |44 pressed into an opening suitably located in the cap |34 and is guided at its' inner end or forward end in a sleeve-like bushing |45. This seats in a cavity formed to receive itin the inner face of the chamber |35 and is channeled to confine the bead or flange at the margin of a thimble-like sleeve |46.

Sleeve |45 is formed of rubber-like material.

It protects the guide-way from sandand *terminates in a conical valve surface |47 which is attached to the end of the tubular member |39 and seals against the bushing |21 when the diaphragm |39` forces the' stem to the right-. At such time, it isolates the sand chamber from the sanding hose but does not close the end of the tubular member |39.

nipulation of the valve 2|.

The valve portion |41 encircles and is attached to a nipple |48 screwed into the end of the stem |39. A spring |49 is conned between the member |45 and the diaphragm plate |38 and thus serves to urge the diaphragm outward (i. e. to the left) and also to retain the member |45 in position.

Pressed into the lbore of the tubular stem |39 is a nozzle structure |5| whose form is clearly shown in the drawings. This receives air through the bore of the stem from the sanding passage 93 and discharges it in the form of a jet directly toward the throat ITI-|28. Clearance within the tubular stem |39 and around nozzle |5| is aiorded so that ports |43 provide restricted com.- munication to the extreme inner (right-hand) end of tubular member |39. A ball check valve |52 closes against back iiow through the nozzle but is so contrived as not to resist outward flow through the nozzle.

The space to the right of the diaphragm |33 is in communication with the chamber ||9 by Way of an equalizing port |53 in which is mounted a sand excluding iilter |54.

Any sanding operation initiated by operation of the valve 2| will affect the continuous sanding traps and the locally timed sanding traps in a manner not modified by the nature of the ma- Sanding may be caused by pressing the sanding at will button 22 or by pressing the timed sanding button 24 or by admission of air to depress the piston 25. Either of the latter two contingencies implies timed sanding. Since that is the most important, it will be discussed.

Assume, therefore, that the valve 23 is moved downward in some Way and is allowed to go through its timing cycle under the control of the reservoir 2 and the choke 28. The contactor I5 will bridge the contacts I8 and energize the windings 'I3 of the continuous sanders, and the windings 6| of the locally timed Sanders. The timing operation of the valve 23 is such that the circuit throimh the wires |2 and I3 will remainenergized for a period longer than the stopping time for an emergency stop. The rst eiect of energization is to cause all the pistons 44 to move to their outermost position, passing through preliminary impulse position and arriving at sanding position. The relays for continuous sanding will remain in this position as long as the circuit is energized. The locally timed relays will remain in this position for the local timing period and then return to the running position of Figure 3. The sanding functions on all cars will be the same except that the duration of sanding on the locally timed units will be relatively short, preferably only long enough to permit the sanded Wheels to reach tracks which have been sanded by units further ahead in the train.

Each trap operates in `response to the preliminary impulse to disconnect the chamber H9 from the sanding hose |29 and develop air pressure in the sanding hose. This pressure is dissipated as soon as the relays reach sanding po` sition (Figure 7) unless the corresponding nozzle |3| is closed. If it is clogged, then pressure will continue until it is clear and will be maintained by i'low through the sanding line 55 and sanding nozzle |5.

After the preliminary impulse has been delivered through the line 5.3 and terminated, and as soon thereafter as the nozzle |3| is clear, the diaphragm |35 will retreat and active sanding will commence. When the relay valve 31 of either type of sander moves back toward running position, there Will be a momentary blast through the impulse line 53 which will cause the diaphragm i to move to the right and intercept the connection between the corresponding chamber IIS and the corresponding hose |29. Thus, the last air discharged through the sander will clear out the last remaining traces of sand. The purpose of this is to diminish the tendency of the nozzle i3! to clog.

The present application is limited to the local timing features and to the system aspect involving local timing and local timing in combination with over-all timing. By over-al1 timing" is meant that produced by the timing of the master valve 23.

Obviously, the broad inventive concept is susceptible to many embodiments and While the one here described is preferred and has demonstrated utility, the possibility of modifications is recognized. Consequently, the detailed disclosure herein made is to be taken as illustrative and not limiting.

What is claimed is:

1. 'Ihe method of sanding rails under high speed trains composed of a plurality of b-raked units, which comprises initiating sanding ahead of all braked units as an incident to the commencement of a brake application; continuing such sanding ahead of at least the leading unit; and suspending sanding ahead of succeeding units after an interval at least sufficient to assure that each thereof has reached rails sanded ahead of the unit next preceding it.

2. The method of sanding rails under high speed trains composed of a plurality of braked units, which comprises initiating sanding ahead of all braked units as an incident to the commencement of a brake application; continuing such sanding ahead of the leading unit and certain only of the succeeding units at intervals throughout the length of the train; and suspending sanding ahead of the other units after an interval at least sufhcient to assure that each thereof has reached rails sanded ahead of the unit next preceding it.

3. The combination of a sand trap having a chamber; means for supplying sand thereto; an ejector nozzle and associated throat operable by the supply of air under pressure to the nozzle to propel sand from said chamber; a sanding pipe to which said throat delivers; a pressure operated intercepting valve for preventing discharge of sand from said chamber; a sanding air connection for supplying air under pressure to said ejector nozzle; an impulse air connection for supplying air under pressure to close said intercepting valve; means eiective at least when the intercepting valve is closed for delivering air from the last named connection to said sanding pipe while retaining actuating pressure on said intercepting valve; a controlling valve shiftable from an inactive position, in which the supply of air is out oil", through a series of three functional positions to said inactive position, in the rst of which functional positions it serves to deliver air under pressure to the impulse connection, the second to deliver air to the sanding air connection alone, and in the third to deliver air at least to said impulse connection, and electro-pneumatic means responsive to 'a change of energization and serving in response thereto to cause said valve to move through said series of functional positions and resume inactive position, said electro-pneumatic means being responsive to a reverse change of energization to reset Without actuating said valve.

4. The combination of two pneumatically operated sanding units, the rst for a leading Wheeled unit and the second for a succeeding wheeled unit, two pneumatically actuated relay valves each associated with a corresponding one of said sanding units and each operable to put such unit into 'and out of operation; two electrically controlled pilot Valve mechanisms, one for each relay Valve, each pilot valve mechanism having a normal position in which it conditions its relay valve to suspend sanding, andan abnormal position in which it conditions its relay valve to initiate sanding; timing means associated with the pilot valve and relay valve of the second unit arranged to cause such relay valve to move to non-sanding position from sanding position after a definite time interval independently of action of the pilot valve; acircuit including the electrical portions of both said pilot valve mechanisms; and means for energizing and deenergizing said circuit to cause said pilot valve mechanisms to assume their normal positions simultaneously and their abnormal positions simultaneously.

5. In a train sanding system the combination of a plurality of sanding mechanisms located at intervals throughout the train; a single controller serving to condition said system alternatively to operate or suspend operation; and timing means associated with certain only of said sanders and rendered effective by initiation of sanding to terminate operation of such Sanders after a definite time interval.

6. In a train sanding system, the combination of a plurality of Sanders locate-d at intervals throughout the train; a master control mechanism for said system having a running position in which it renders the entire system inactive and a sanding position in which it serves to render the entire system active; timing means to retain said master control mechanism in the second-named position for a denite time interval and then restore it to running position; and local timing means arranged to affect certain only of said Sanders and serving to render such Sanders inactive irrespective of the master control mechanism after a time interval shorter than that imposed by said master control mechanism.

'7. In a train sanding system, the combination of a plurality of sander units for corresponding wheeled units throughout the train; an electric circuit extending throughout the train; a plurality of electro-responsive units connected with said circuit and corresponding with said sander units; controlling means interposed between each electro-responsive unit and the corresponding sander units, 'said controlling means being of two types interspersed throughout the length of the train, one type serving to cause and suspend sanding according to the state of energization ofthe circuit, and the otherv type serving to initiate sanding in response to a definite change of energization of the circuit and then after a time interval suspend sanding; and switching means controlling the energization of said circuit.

8. In a train sanding system, the combination of a plurality of sander units for corresponding Wheeled units throughout the train; an electric circuit extending throughout the train; a plurality of electro-responsive units connected with said circuit and corresponding with said sander units; controlling means interposed between each electro-responsive unit and the corresponding sander units, said controlling means being of two types interspersed throughout the length of the train, one type serving to cause sanding when the circuit is energized and suspend it when the circuit is deenergized, and the other type serving to cause sanding in response to energization of the circuit and then suspend it after a relatively short time interval regardless of continued ene"- gization of the circuit; and switching means controlling said circuit.

9. In a train sanding system, the combination of a plurality of sander units for corresponding wheeled units throughout the train; an electric circuit extending throughout the train; a pluralvity of eiectro-responsive units connected with said circuit and corresponding with said sander units; controlling means interposed between each electro-responsive unit and the corresponding sander units, said contrclling means being of two types interspersed throughout the length of the train, one type serving to cause sanding when of said switch closing means, to cause opening of said switch after a time interval longer than said relatively short time interval.

10. In a train sanding system the combination of a plurality of normally inactive Sanders located at intervals throughout a train; means for putting said Sanders into operation; and two distinct timing means each rendered active as an incident to putting the system into operation, one such means arranged to terminate sanding by at least one sander after a relatively short time interval, and the other arranged to terminate sanding by all other Sanders after a longer time interval.

CHARLES A. CAMPBELL.

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