US2320802A - Railway braking apparatus - Google Patents

Description

June 1, 1943. c, s. SNAVELY RAILWAY BRAKING APPARATUS 5 Sheets-Sheet 2 Filed Dec. 24, 1941 lll'll N m @QEQ m NAN Mar

June 1, 1943. c s. SNAVELY RAILWAY BRAKING APPARATUS 5 Sheets-Sheet 3 Filed Dec. 24, 1941 5% .Ew .5 EN N MIMQ i wwrwwfwm MM? wk w a 1H ER MNQ. M. N

I I I l I lllllllllllllllll!llllllllllllllllllllllllllIlllll-IIIIIIIIL June 1, 1943- c. s. SNAVELY 2,320,802

RAILWAY BRAKING APPARATUS Filed Dec. 24, 1941 5 Sheets-Sheet 4 @KBRSQK B S $35 am y x W 5 SQN MM. k ww U W? n I Na m km MN L v ENN A n m R 1 R wk N l J L QN QW & mww E k Wm u @QQ MN) m n u u u u n a g g a a Q g a N n H n J m n u g m u a u m Q mk fi mw mkin 4% 5 m Patented June 1, 1943 EAILWAY BRAKING APPARATUS Clarence S. Snavely, Churchill Borough, Pa, as-

signor to The Union Switch & Signal Company, Swissvale, Ia., a corporation of Pennsylvania Application December 24, 1941, Serial No. 424,338

34 Claims.

My invention relates to railway braking apparatus, and particularly to car retarders of the type comprising wheel engaging braking bars located beside a track rail and movable toward and away from the rail into braking and nonbraking positions. More particularly, my invention relates to apparatus of the type described wherein the braking bars are arranged to be moved to their braking positions by means of one or more fluid pressure motors, and to be restored to their non-braking positions by suitable biasing means.

One object of my invention is the provision of improved means for automatically controlling the braking action of a car retarder in accordance with the speed of a car passing therethrough.

Another object of my invention is the provision of improved timing means for measuring the speed of a car passing through a car retarder.

Another object of my invention is the provision of improved means for progressively decreasing the braking force exerted by a car retarder as the speed of a car being retarded by the retarder approaches a selected one of a plurality of predetermined control speeds, and for releasing the retarder when the selected control speed is reached.

A further object of my invention is the provision of means whereby the braking action of r a car retarder may be controlled automatically in accordance with the speed of a car passing through the retarder, or manually at the will of an operator.

A still further object of my invention is the provision of means for providing improved flexibility of operation of a fluid pressure operated car retarder by enabling the pressure which is supplied to the retarder to operate it to be graduated into manually selected levels.

According to my invention the stretch of track with which the retarder is associated is provided with a series of single rail track circuits each of which includes an insulated rail section which is sufficiently short so that two wheels of a car cannot occupy the section at any one time. Each track circuit includes a track relay, and a back contact of all of the track relays in advance, whereby only one track relay will be energized. at a time. sets into operation time measuring means comprising a source of constant frequency alter nating current, and means for counting the cycles of this source.

The means for counting the cycles of the When any track relay is energized, it

source includes a pair of half-step relays which respond to alternate half cycles of the current, whereby each relay operates once during each cycle of the alternating current, and a unit chain of counting relays which pick up successively one each time a selected one of the half-step relays operates. The counting relays are arranged to continue to operate as long as the track relay which initiated their operation remains energized. Assuming that the frequency of the constant frequency source is 60 cycles, and that the unit chain includes 6 relays, it will be seen that successive relays of the unit chain will pick up at intervals of 16 milliseconds, and the chain will complete a full cycle of operation every 100 milliseconds.

The time measuring means also includes a multiple chain of counting relays so arranged that the relays of this latter chain will advance progressively one each time the unit chain completes a round trip of operation.

The time measuring means further includes means for restoring the counting chain to starting position to initiate a new timing period each time a new track relay picks up.

The relays of the unit and multiple chains control other relays for effecting a graduated reduction in the pressure of the fluid applied to the operating cylinder of a fluid pressure operated car retarder in accordance with the setting of a manually operable lever to cause the retarder to release when the speed of a car has been reduced to a selected speed.

The apparatus also includes means whereby the retarder can be controlled manually independently of the manually operable lever.

Other objects and characteristic features of my invention will become apparent as the description proceeds.

I shall describe two forms of railway braking apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1a and lb are views which, when placed one above the other with Fig. 1a on top in such manner that the dotted lines leading to the bottom of Fig. 1a align with the dotted lines leading to the top of Fig. 1b, together constitute a view partly sectioned and partly diagrammatic illustrating one form of apparatus embodying my invention. Figs. 2a and 2b are views similar to Figs. 1a and 1b illustrating another form of apparatus embodying my invention. Fig. 3 is a table showing the method of connecting the front contacts of certain ones of the relays forming part of the apparatus illustrated in Figs. 1a, 1b, 2a and 2b to obtain predetermined control speeds.

Similar reference characters refer to similar parts in all three views.

Referring first to Figs. 1a and 1b, the reference characters I and la designate the track rails of a stretch of railway track over which cars normally move in the direction indicated by the arrow under such conditions that it is desirable to at times control the speed of the cars automatically. For example, the stretch of track here shown might be in a classification yard of the hump type through which cars move under the influence of gravity. It is obvious that in service of this kind the speed of individual cars or strings of cars will vary through wide limits depending among other things on the speed at which they go over the hump, the temperature,

the Weight of the car and its contents, and the condition of the car as to whether it is a free running car or otherwise.

In order to control the speed of the cars, the stretch of track illustrated in the drawings is provided with a car retarder CR which in the form here shown comprises two braking bars 2 and 3 extending parallel with, and located on opposite sides of rail I, and two similar braking bars 2a and 3a extending parallel with and located on opposite sides'of rail Ia.

The braking bars 2, 3, 2a and 3a are operated by a fluid pressure motor M (Fig. lb) comprising a cylinder 4 containing a reciprocable piston 5 attached to one end of a piston rod 6. The braking bars 2, 3, 2a and 3a are operatively connected with the piston rod 6 through a suitable linkwork here shown as comprising a bell crank I and a lever 8 pivotally supported at point 9. When piston 5 occupies its extreme left-hand position, in which it is illustrated in the drawings, the braking bars occupy their non-braking or ineffective positions in which they are out of engagement with the wheels of a car traversing the rails I and Ia. When piston 5 is moved to its right-hand position, however, as when fluid pressure is admitted to the left-hand end of cylinder 4, the braking bars 2, 3, 2a and 3a are moved toward the associated rails to their effective or braking positions in which they will engage the wheels of a car traversing the rails I and Id, to retard the speed of the car.

The braking bars 2, 3, 2a and 3a are constantly biased to their non-braking positions by any suitable means, here shown as a spring III which is interposed in the cylinder 4 between the righthand end of the cylinder and the piston 5.

The motor M is controlled by two magnet valves VI and V2, each comprising a valve stem I2 biased to an upper position by means of a spring I I, and provided with an armature I3 and a winding, I4. When valve VI is energized, as shown in the drawings, valve stem I2 of this valve is moved downwardly against the bias of spring I I, and a pipe I8 which communicates with the left-hand end of motor M is then connected with atmosphere through a port I5. When valve VI is deenergized, however, pipe I8 is disconnected from atmosphere. and is connected with a pipe I6 leading to valve V2. When valve V2 is energized, valve stem I2 of this valve moves downwardly, and connects pipe I6 with pipe I I which is constantly supplied with fluid pressure, usually air, from a suitable source not shown in the drawings, but when valve V2 is deenergized, as shown in the drawings, pipe I6 is then disconnected from pipe I1. It will be apparent, therefore, that when valve VI is energized,

the region of the cylinder 4 of motor M between the piston 5 and the left-hand end of the cylinder is connected with atmosphere, so that the braking bars of the car retarder will then be held in their ineffective or non-braking positions by the spring I0. When, however, valve VI is deenergized and valve V2 is energized, fluid pressure wil1 be supplied to the left-hand end of cylinder 4 of motor M, thus causing the braking bars to move to their effective or braking positions. It will be obvious that when the braking bars are moved to their braking positions, they will exert a braking force which is proportional to the pressure of the fluid which is then supplied to the left-hand end of motor M.

The valves V are controlled in part by a plurality of pressure responsive devices PHI-30 and P45-55, each comprising a Bourdon tube 2I connected to pipe I8 and hence subjected to the pressure of the fluid in the left-hand end of motor M. Each Eourdo-n tube controls two contacts 2222a and 22--22b. The pressure responsive devices P253il and PA E-55 are so constructed and so adjusted that they will operate successively as the pressure in the region of cylinder I between the piston 5 and the left-hand end of the cylinder increases. For example, for all pressures below 20 pounds per square inch, the contact 22-2 2a of each of these devices is closed. If the pressure exceeds 20 pounds per square inch, however, the contact 22-221; of device P20-3IJ opens, and if the pressureexceeds 30 pounds per square inch, contact 2222b of device PHI-30 closes. In similar manner, the pressure responsive device P 3555 is adjusted to open its contact 22-22a at 45 pounds per square inch, and to close its contact 222b at 55 pounds per square inch. Of course, these specific pressures are not essential but are only mentioned for purposes of explanation.

The valves V are also controlled in part by a plurality of relays IPO, 2P0, IPZiI-M, 2P2lI--30, IP45-55 and 2Pl555 which relays, in turn, are controlled by speed responsive apparatus in a manner which will be described in detail hereinafter.

The valves V are further controlled by means of a manually operable lever L which, a here shown, is capable of assuming five positions, indicated by dotted lines in the drawings, and designated by the reference characters P0 to 124, inelusive. Operatively connected. with the lever L are a plurality of contacts 25, 26, 21, 28 and 29. Contacts 25, 26, 21 and 28 are closed, respectively, in the 100, pl, 122 and p3 positions of lever L, while contact 29 is closed in the pl position, the p4 position, or any position intermediate these two positions.

The lever L will usually be located at a point remote from the braking apparatus, as in the control cabin of a classification yard car retarder system, and will be connected with the braking apparatus by means of line wires extending from the control cabin to the braking apparatus.

The previously mentioned speed responsive apparatus for controlling relays IPIJ, 2P5, I P2ii-3Il, 2P253!J, IP4555 and 2P45-55 comprises a series of relatively short insulated control sections IT, 2T, 3T, 4T, 5T and ET, which control sections are formed in the rail I. These control sections will usually be of uniform lengths, .and their lengths may be varied as conditions require, but the lengths of these sections will preferably be such that two wheels of a car cannot occupy the same section at any one time. A preferred length for these sections is 3 ft. 1 /2 in.

Associated with each control section is a track relay designated by the reference character B with a prefix corresponding to the reference character for the associated section. These track relays are sensitive quick acting relays, and each relay is connected in a track circuit which, when all of the track relays are initially deenergized and a pair of wheels moves onto any one of the track sections T, includes a suitable source of current here shown as a battery 30, a back contact 34 of a relay ZSU, a back contact 33! of a relay ISU, a back contact 3! of each of the track relays in advance of the occupied section, the winding of the track relay of the oc cupied section T, the wheels and axle of the pair of wheels on the occupied section T, and the rail Ia.

When a track relay picks up due to the energy supplied over any one of the track circuits just described, if the track relay is an even-numbered relay, relay 2SU will pick up by virtue of a circuit which I shall describe presently and will open its back contact 34, and if the track relay is an oddnumbered relay, relay lSU will pick up by virtue of a circuit which I shall also describe presently and will open its back contact 33L However, when either back contact 34 of relay ZSU or back contact 33| of relay ISU opens, the front contact 32 of the picked-up track relay will then be closed and Will have completed a branch circuit in multiple with the contacts 33l and 34 in series, which branch circuit will maintain energy on the picked-up track relay as long as the pair of wheels which caused the track relay to pick up remain on the associated section. For example, if track relay ITR picks up due to a pair ofcar wheels entering section IT, relay ISU will pick up and will open its front contact 33I, but track relay ITR will be maintained in its energized condition after front contact 33| opens until the pair of wheels leaves section IT, by virtue of a branch circuit including front contact 32 of track relay ITR.

When any one of the track relays is energized, and a pair of wheels W enters any section in rear of the section for the energized relay, the track circuit for such rear section will be held open at the back contact 3! of the picked-up track relay, and the track relay for such rear section will remain deenergized.

When a track relay is energized, and the pair of wheels which caused it to become energized enters the section next in advance, the front contact 32 of the energized track relay will remain closed long enough to complete a track circuit for the advance relay which track circuit will be similar to the circuit described above except that thi circuit will include the front contact 32 of the picked-up relay in place of the back contact 34 of relay 2SU and the back contact 33! of relay ISU in series. The reason why a track relay remains energized until the relay next in advance picks up when the pair of wheels which caused the relay to become energized passes from the associated section to the section next in advance is that the wheels will alway engage the advance section for a brief interval of time before they will break contact with the rear section.

It will be seen, therefore, that when no car is traversing the track circuited territory through the retarder, the track relays T will all be deene1- gized. When, however, a car traverses the track circuited territory, as the forward pair of wheels enters each track section, the track relay for such section will pick up, and the track relay for the section next in rear will release. As soon as the forward pair of wheels passes out of section 6T, relay 6TB will release and will cause relay ISU or ZSU to release. As soon as these relays are both released, the track circuit for each relay whose associated section is then occupied by a pair of wheels will become completed at the back contacts 331 and 34 of these relays. However, only the track relay for the section which is then occupied by the leading pair of wheels in the track circuited territory will complete its pick-up stroke since the opening of the back contact of this relay will interrupt the track circuits for all of the relays in the rear.

The speed responsive apparatus also comprises means for measuring the time during which any of the track relays is energized to thereby provide a measurement of the speed of the car.

In the particular form illustrated, this time measuring means comprises a suitable source of constant frequency alternating current, illustrated in the drawing as an alternator A, and means for counting the cycles of this source. In actual practice, the source of alternating current will generally comprise the usual commercial power source.

The means for counting the cycles of alternating current includes two half-step relays PX and NX of the quick acting two winding polar magnetic stick type and two oppositely poled half wave rectifiers 334 and 35. The one winding 31a of relay PX is connected with alternator A over a front contact 36 of a relay W, the rectifier 334 and a normal contact 38 of relay NX, while the other winding 31b of relay PX is connected with the alternator A over front contact 36 of relay W, rectifier 334, and reverse cont-act 39 of relay NX. In a similar manner, the winding 31!: of relay NX is connected with alternator A over front contact 36 of relay W, rectifier 35, and a normal contact 40 of relay PX, while the other winding 31b of relay NX is connected with alternator A over front contact 36 of relay W, rectifier 35 and reverse contact 4| of relay PX. The rectifier 334 is poled to pass current during positive half cycles only, while the rectifier 35 is poled to permit current to flow during negative half cycles only.

With the relays PX and NX connected with al" ternator A in the manner just described, it will be apparent that when front contact 36 of relay W is open, both relays PX and NX will be deenergized. When, however, front contact 36 of relay W becomes closed, during the first half cycle of current which flows from alternator A winding 31a of relay PX or winding 37a of relay NX Will become energized depending upon whether the half cycle is a positive or a negative half cycle. Assuming for purposes of illustration that the first half cycle is positive, the resultant energization of winding 3M of relay PX will cause this relay to open its normal contact 40 and close its reverse contact 4!. The closing of com tact 4| will complete the circuit for winding 31b of relay NX, and as a result, the first negative half cycle will cause winding 31b of relay NX to become energized, whereupon this relay will open its normal contact 38 and will close its reverse contact 33. The closing of reverse contact 39 will complete the circuit for winding 31b of relay PX, and during the next positive half cycle winding 31b of relay PX will become energized and will cause reverse contact ;4|' of relay PX to open, and normal contact 40 to close. Contact at now being closed, the next negative half cycle will energize winding 31a, of relay NX, with the result that reverse contact 39 will open and normal contact 38 will close. described cycle of operation will then start to repeat itself, and the relays PX and NX will continue to alternately close their normal and reverse contacts as long as the contact 39 re mains closed.

The relay W is controlled by the track relays R in such manner that this relay willbe energized whenever any one of these track relays is energized, by virtue of, circuits which I shall describe shortly.

The relay NX is provided, in addition to the previously mentioned normal and reverse contacts 38 and 39, with a normal contact l24?.a and a reverse contact 42-4227. Assuming for purposes of illustration that the alternator A has a frequency of 60 cycles, it will be apparent that when the relay NX is operating, these contacts will become alternately closed at intervals of of a second or 16 milliseconds. This rate will vary only to the extent that the frequency of the alternator A varies, which variation will be extremely small, particularly if the alternator A comprises a commercial source of power.

The cycle counting means also comprises a unit chain of counting relays III to 6U arranged to pick up successively in response to the alternate operation of the contacts 42- i2a and 4242b of relay NX, and a multiple chain of counting relays GM to 5M arranged to advance progressively one each time the unit chain completes a round trip'of operation. The relays of both chains are of the quick acting neutral type.

Associated with the unit and multiple counting chains is a relay MX of the two winding polar magnetic stick type which serves to make the selection of the circuits for the relays of the multiple group necessary to cause them to pick up in succession in response to each round trip of operation of the unit chain, and a similar relay UX, the function of which will be made clear presently.

The operation of the timing means as a whole is as follows: When the track relays T are all deenergized, as is the case when no car is traversing the stretch of track shown in the drawing, the relays of both timing chains, and the associated relays W, ISU, ZSU, NX, PX, MK and UK are all deenergized. When a car starts to traverse the stretch of track shown in the drawing, relay ITR will pick up first for reasons which will be apparent from the foregoing description, and the picking up of this relay will complete a circuit for relays W, ISU, ill and the winding 4-8 of relay UK in series, which circuit may be traced from the terminal B of a suitable source of direct current not shown in the drawings, through the winding of relay W, a back contact 3333b of each of the track relays ETR, ETR, 4TB, 3TB, and 2TB, front contact 3333a of track relay I'I'R, the winding of relay ISU, a back contact 44 of each of the relays 2U to 6U, inclusive, of the unit counting chain, a back contact 45 of each of the relays BM to 5M of the multiple counting chain, winding 48 of relay UX, wires 4t and 41, and the winding of relay lU to the other terminal C of the source. Relays W, ISU and [U will therefore pick up immediately,

The above aeeasoa and relay UA will reverse its armature to open. its normal contacts and close its reverse contacts.

The picking up of relays Ill and ISU completes a stick or holding circuit for these relays passing from terminal B through the winding of relay W, a back contact. 33-431) of each of the track relays 6TB, 5TB, 4TB, 3TR and 2TB, front contact 3333a of track relay ITR, the winding of relay ISU, front contact 49 of relay ISU,

wires 5% and ti back contact 52 of relay 2U, front contact 53 of relay IU, and the winding of relay ill to terminal C. The function of these stick circuits will be made clear presently.

The picking up of relay W completes at its front contact 35 the previously described operating circuits for the relays PK and NX and these relays therefore start to alternately operate on alternate half cycles of the alternator A in the manner described hereinbefore.

Since relays W and IU are both picked up when the relays NX and PX start to operate, the first time reve se contact 4242b of relay NX becomes closed, it completes a pick-up circuit for relay 2U passing from terminal 13 through front contact 43 of relay W, reverse contact 42-421) of relay NX, wire 55, front contact 54 of relay IU, and the winding of relay EU to terminal C. Relay 2U therefore picks up and interrupts at its back contacts 444 and 52, respectively, the previously described pick-up and stick circuits for relay l U, and completes at its front contact 53 a stick or holding circuit which is similar to the previously traced stick circuit for relays ISU and !U with the exception that this latter circuit includes a back contact 52 of relay 3U, front contact 53 of relay 2U and the winding of relay 2113 in place of a back contact 52 of'relay 2U, front contact 53 of relay H17, and the winding of relay lU. Relay 9U, therefore, now becomes deenergised, while relay 2U remains energized as long as relay 3U remains deenergized.

.W'hen normal contact 42l2a of relay N X again closes, it completes a pick-up circuit for relay 3U which is similar to the corresponding pickup circuit just traced for relay EU, and which ill therefore be apparent from an inspection of the drawing. Relay 3U therefore picks up and interrupts both the pick-up and stick circuits for relay 2U which causes relay EU to release. The picking up of relay 3U also completes a pickup or holding circuit for this relay similar to the previously traced pick-up or holding circuit for relays NJ and 2U.

When relay NX next closes its reverse contact, relay 4U will pick up and relay 3U will release, and when relay NX next closes its normal contact, relay EU'will pick up and relay .U will release and so on, until a complete cycle of operation of the unit chain is completed. When this happens, if section IT is then still occupied, relay IU will again pick up by virtue of circuit connections between the tU and IU relays similar to those between any two succeeding relays of the chain, and will start the operation of the chain over again. It will be seen, therefore, that the relays ill to EU will continue to climb around and around as long as track relay I TR, remains energized. It will also be apparent that if the frequency of the alternator A is 6i) cycles, so that the contacts 42-4211 and 62-421; become alternately closed at intervals of 16 milliseconds, the time spacing between the picking up of successive relays-U will be 16 milliseconds, and the chain will complete a round trip of operation in exactly 100 milliseconds.

The front contact 49 of relay ISU, in addition to being included in the previously described stick circuits for the relays IU to (ill, is also in cluded in a pick-up circuit for the starting relay OM of the multiple chain, which latter circuit may be traced from battery B through the winding of relay W, back contact 33-331) of each of the track relays GTR, 'I'R, 4TH, 3TB. and 2TB, front contact 3333a of track relay ITR, the winding of relay ISU, front contact 49 of relay lSU, wire 59, a back contact 60 of each of the relays 5M, 4M, 3M, 2M and IM of the multiple chain, and the winding of relay OM to terminal C, It will be seen, therefore, that as soon as relay ISU becomes energized following the energization of track relay ITR, relay OM of the multiple chain will pick up.

With relay OM picked up, when relay 3U picks up during the first round trip of operation of the unit chain, it will complete at its front contact 64 a circuit for the one winding 65 of the transfer relay MK, and this relay will thereupon open its normal contact 66-66a and will close its reverse contact 66--6Bb. This circuit includes in addition to front contact 64 of relay 3U, front contact 63 of relay OM, as will be obvious from an inspection of the drawings. The circuit will bei come opened as soon as relay 3U releases, but since relay MX is of the magnetic stick type, contact 66-6622 will remain closed until this relay is again energized in the direction to close its normal contact.

As a result, when relay GU of the unit chain picks up during the first round trip of operation, a pick-up circuit is completed for relay IM passing from terminal B through front contact 43 of relay W, front contact 61 of relay 6U, reverse contact 66-66b of relay MX, front contact 62 of relay OM, and the winding of relay IM to terminal C. Relay IM thereupon picks up, and completes a stick circuit passing from terminal B through the winding of relay W, back contact 33-33b of each of the track relays BTR, 5TB, 4TH, 3TB and 2TB, front contact 33--33a of track relay ITR, the winding of relay ISU, front contact 49 of relay ISU, wire 50, a, back contact 60 of each of the relays 5M, 4M, 3M and 2M, a front contact El of relay IM and the winding of relay IM to terminal C. This stick circuit serves to retain relay IM energized after relay 8U releases as will be obvious.

The picking up of relay [M in addition to con1- pleting its own stick circuit also interrupts at its back contact 63 the pick-up circuit for relay OM, and this latter relay therefore releases.

When relay 30 picks up during the second round trip of operation of the unit chain, the resultant closing of contact 64 completes a circuit for the other winding 68 of relay MX including front contact 63 of relay IM, and relay MX then opens its reverse contact lit-66b and closes its normal contact 6666a.

With normal contact 6666a of relay MX closed, when relay 6U of the unit chain picks up during the second round trip of operation of this chain, the resultant closing of its front contact 61 completes a pick-up circuit for relay 2M including front contact 62 of relay IM. This latter circuit will be apparent from an inspection of the drawing without further detailed description. Relay 2M thereupon picks up and interrupts the previously traced stick circuit for relay 1M and completes a stick circuit for itself similar to the previously traced stick circuit for relay IM.

Onthe third round trip of the unit chain since front contact 63 of relay 2M is now closed, the resulting closing of front contact 64 of relay 3U will complete another circuit for winding 65 of relay MX which will cause this relay to again open its normal contact lit-66a and close its reverse contact 666Eb, and when relay 6U picks up, the closing of its front contact 61 will complete a pick-up circuit for relay 3M. Relay 3M will thereupon pick up and relay 2M will release. In a similar manner if track section IT remains occupied long enough on the fourth and fifth round trips of the unit chain, relays 4M and 5M will pick up and relays 3M and 4M will release.

It will be seen, therefore, that each time the unit chain progresses to and including the EU relay, the multiple chain will advance its action by one relay, Accordingly, assuming that the frequency of the alternator A is 60 cycles so that the unit chain completes a round trip of operation each milliseconds, the picking up of each progressive relay of the multiple chain represents a period of 100 milliseconds. In the particular embodiment of my invention shown provision is made for counting up to 500 milliseconds by the picking up of the M relays, after which, of course, another 100 milliseconds may be counted by permitting another round trip of the unit chain, making a total of 600 milliseconds with the circuits as shown.

It will also be seen that the relay MX merely serves to make the necessary circuit selection of the M group of relays so that each pick-up action of the EU relay of the unit chain will advance the multiple group of relays by one relay.

The function of the hereinbefore referred to stick circuit for relay IU, and of the stick circuits for each of the other U relays of the unit chain is to maintain these relays energized during the interval of time which elapses between the opening, at contact 42-42a or 42-421) of relay NX, of the pick-up circuit for the relay whose stick circuit is then closed and the picking up of the relay next in advance in the chain.

The stick circuits for the relays of the multiple chain similarly serve to maintain the M relay which last became energized in its energized condition during the interval which elapses between the opening of its pick-up circuit at contact 6666a or 66'o6b of relay MK, and the picking up of the relay next in advance. In other words, the stick circuits for both chains function to keep the chains in operation as long as the track relay which started the operation remains energized.

When the car which caused track relay ITR to pick up advances to the point where relay 2TR picks up, the resultant opening of back contact 33-33b of track relay ZTR interrupts any of the stick circuits which then happens to be closed for any of the relays of either the unit and multiple chains, and relays W and lSU therefore immediately become deenergized. As soon as re lay W becomes deenergized, it opens the pick-up circuits for each of the relays of both chains, and since the pick-up and stick circuits for the relays of both chains are then all open, these relays all become deenergized. The deenergization of relay W also momentarily stops the operation of the PX and NX relays.

As soon as the back contacts of all of the U relays and the back contacts of all of the M relays all become closed, thereby checking that these relays are all deenergized, a pick-up circuit for relay EU is completed at front contact 3333a of track relay 2TB and current flows from battery B through the winding of relay W, a back contact 33-431) of each of the track relays 6TH, TB, 4TB and 3TB, front contact 3333a of track relay 2TB, the winding of relay ESU, back contact 10 of each of the relays 2U to EU, inclusive, a back contact H of each of the relays OM to 5M, inclusive, the winding T2 of relay UX, wire 46, and the winding of relay ill to terminal 0. Since relays ISU and W are both included in this circuit, these relays and relay I U all pick up. Furthermore, since the winding 12 of relay UX is included in this circuit, this relay reverses its armature, thereby opening its normal contacts and closing its reverse contacts.

When relay ZSU picks up, it completes a stick circut for relay IU, and a pick-up circuit for relay OM which circuits are similar to the circuits which were completed by relay ISU following the picking up of track relay ITR with the exception that these latter circuits each include a front contact 33-3311 of track relay ZTR, the w nding of relay ZSU, and front contact 13 of relay ZSU in place of front contact 33-331 of track relay ITR, the winding of relay ISU, and front contact 49 of relay ISU.

When relay W picks up, it sets the counting chains into operation, and these chains then function to measure the time required for the pair of wheels of the car to traverse section 2TB in the same manner as these chains functioned to measure the time for the forward pair of wheels of the car to traverse section IT. The circuits for the various relays of the two counting chains Will all be similar to those previously described except for the fact that each stick circuit will now include front contact 33-33a of track relay 2TB. the winding of relay 2SU and front contact 13 of relay 2SU in place of front contact SIB-33a of track relay ITR, the winding of relay ISU and rent contact 49 of relay ISU.

When track relays 3TB and 5TB subsequently pick up, the relay ISU will be picked up and the apparatus will function in the same manner as when relay ITR was picked up. Similarly, when the relays 4TB and 6TB pick up the apparatus will function in the same manner as when relay ZTR is picked up. It Will be seen, therefore, that as a car advances through the track circuited territory, the relays ISU and ZSTJ alternate in their action depending upon whether an odd or an even-numbered track relay is then picked up. Each SU relay checks that all relays of both counting chains have become deenergized before it can pick up after which the IU relay of the unit chain picks up for the beginning of a new timing period.

The back contacts 33! and 34 of the ISU and ZSU relays are included in the pick-up circuits for the track relays for check purposes. As long as the track relays become successively energized, the multiple front contacts of the track relays by-pass the back contacts of the SU relays and accordingly freely permit the relay next in advance to pick up. After the leading car axle leaves section 6T, it will be apparent that the relay 6TB. will have to release before any of the other track relays in the rear can pick up. Accordingly, all other multiple front contacts of the track relays are then opened, and it is then necessary that both SU relays be released in order that their back contacts 33!, and 34 may close and permit another track relay in rear of track relay 6TB to pick up. This check is provided in order to prevent the counting relays from doubling back to another section without first having been reset to the starting point.

The function of the W relay is to provide the necessary separate contacts for supplying operating energy to the NX and PK relays and to the counting chain during the energized periods of the track circuits.

It should be pointed out that while I prefer to provide a source of alternating current controlling the energization of the half-step relays PK and NX to effect the energization of the successive relays of the timing chains, the alternating current source and associated half-step relays may be replaced by any suitable motor means which will alternately close the contacts 42-420, and 42- 322) at a known fixed rate.

It will be obvious that the particular relays 0f the unit and multiple chains which are picked up at any one time are a measure of the time that any section which is then functioning as a measuring section has been occupied. It will also be obvious that since the sections have a known fixed length, the speed of a car passing through the car retarder can be determined from the time during which a section is occupied by a pair of wheels. It follows, therefore, that the relays of the counting chains which are picked up when a pair of wheels vacates a section which is then functioning as a measuring section serve as a measure of the average car speed while the car is traversing a length equal to the lengths of the measuring sections. For example, assuming that the track sections T are all 3 ft. 1 in. long, and that the alternator A has a frequency of cycles per second, if a track section remains occupied for 266 milliseconds, which is the time it will remain occupied with an average car speed of 8 miles per hour, when the section becomes vacated, relays 2M and 6U will be picked up, and it follows that if these relays are picked up when a measuring section becomes vacated, it is an indication that the car which caused themto pick up was traveling at an average speed of 8 miles per hour. Similarly, if a track section which is serving as a measuring section is occupied for 600 milliseconds, which corresponds to a car speed of 3.1 miles per hour, relays EU and 5M will be picked up to indicate that the car speed is 3.1 miles per hour. The car speeds corresponding to various relay combinations are shown in tabular form in Fig. 3, and by reference to this table the car speed for any particular relay combination can be determined.

The previously referred to relays lP lfi-55, iP2ii3-il and IPO constitute one group of relays, and the previously referred to relays EP-iS-ES, 2P2i!3t and 2P0 constitute another group of relays, for so controlling the valves Vi and V2 as to eifect an automatic stepped reduction in the pressure of the fluid supplied to the motor M as the speed of a car passing through the car retarder approaches a predetermined control speed which depends upon the setting of lever L, and for effecting the full release of the retarder when this particular control speed is reached. These two groups of relays are caused to function alternately, according as an odd or an even-numbered track section is acting as a speed measuring section, by means of the UK relay which it will be remembered closes its normal contacts 5l'i55a, 5'l-5'ia, 5;58a and 5859a or it reverse contacts Kit-53b, 5l5'|b, Et -'58?) and 5959b according as an odd-numbered track relay lTR, 3TB or 5TB, or an even-numbered track relay 2TB, 4TB or 6TH. i picked up, and each P relay is provided with a plurality of control circuits controlled by different contact combinations of the relays of the unit and multiple counting chains.

In the particular form of my invention illustrated in the drawings, each P relay is provided with a diiierent control circuit for each of the pl, 112 and p3 positions of the lever L, making three control circuits for each relay. The control circuits for the IP and 2P relays are similar except for the fact that each control circuit for each of the lP relays includes a normal contact of the UK relay, whereas each control circuit for each of the 2P relays includes a corresponding reverse contact of the UX relay. These control circuits may be varied as conditions require, but as shown in the drawing they are so arranged that when lever L occupies its pl position, which position I shall term for convenience its high speed position, relay |P45-55 or 2P45-5'5 will pick up when relays IM and U are simultaneously picked up, the relay |P30 or 2P2530 will pick up when the relays 2M and 2U are simultaneously picked up, and the relay IPO or 2P0 will pick up when the relays 3M and IU are simultaneously picked up. When, however, lever L occupies its p2 position, which I shall term its medium speed position, relay IP55 or 2P45- will pick up when relays 2M and IU are simuL s taneously picked up, relay IP2D30 or 2P2839 will pick up when relay 3M is picked up and relay IPO or 2P9 will pick up when rela AM is picked up. Similarly, when lever L occupies its 133 position, which I shall term its low speed position, relay lP-l55i5 or 21 45-55 will pick up when relays 2M and All are both picked up, relay IP20- 38 or 2P2il3ii will pick up when relays 3M and 4U are simultaneously picked up, and relay IPO or 2P0 will pick up when relays 5M and 2U are simultaneously picked up.

By virtue of circuits which will be described in detail hereinafter, When lever L is first moved to its pl, p2 or p3 position, the fluid pressure motor M will be supplied with fluid at full line pressure, which I shall assume for purposes of explanation to be 100 pounds per square inch. If the relay lP45-5 :3 or 2P i5-5-5 subsequently picks up, the pressure in motor M will be automaticall reduced to a pressure of between 45 and 55 pounds per square inch, if relay lP20-3fl 0r 2P20-30 picks up, the pressure in motor M will be automatically reduced to a pressure or between 20 and 30 pounds per square inch, and if the relay IPO or 2390 picks up, motor M will be vented to atmosphere to effect the automatic release of the.

car retarder.

The p!) position of lever L is its off position and is the position to which the lever is moved when it is desired to manually release the retarder.

The p4 position of lever L is provided to obtain the full braking force available irrespective of the speed of a car which is being retarded, and when the lever occupies this position, the speed control apparatus is ineffective to control the retarder as will appear presently.

Associated with the relays lP45-55, IP20-30 and IF?) is a stick relay ISP which is picked up whenever any one of these pressure control relays is picked up, and associated with the pressure control relays 2P455'5, 2P2030 and 2P0 is a stick relay 281? which is picked up whenever any one of these last mentioned speed control relays is picked up.

Since a time element is involved from the time a pair of car wheels enters a track circuit which is then functioning as a measuring section until a speed determination can be made, it is necessary that any pressure control that is obtained by the picking up of any one of the P relays in response to an immediately preceding speed determination be maintained for a suiiicient length of time to overlap the interval required to make the new speed measurement. Thus, once a given pressure control has been obtained by means of one of the P relays, it should be maintained as long as successive speed measurements indicate the need for that particular pressure. It is for the purpose of obtaining this overlap action that the two groups of pressure control relays are provided, and this overlap is obtained by the use of energy stored in a condenser which is shunted around each pressure control relay P in series with one or more resistances, and which renders the relay slow releasing. A condenser is used because it guarantees a definite time element in a shorter space of time than is possible with schemes utilizing the saturation of the relay to obtain the time element.

The stick relays SP and ZSP are provided to prevent the pressure control relays from starting their timing period at the time of their pickup instead of waiting until the track section the occupancy of which caused them to pick up is vacated. Thus the SP relays on each successive speed measurement will maintain energy on any pressure control relay which is then energized until such time as the next track circuit becomes operated, in which event the reversing of the UK relay will release the SP relay which was previously energized and will thereby permit the condenser associated with the energized pressure control relay to function to delay the release of the pressure control relay until a new speed measurement is completed.

Due to the fact that conditions change from time to time in acar retarder yard due, for ex ample, to weather changes, seasonal difference in the lading of the cars, etc., it is desirable to be able to readily vary the car speeds at which the P relays function, and to this end, I permanently connect each of the contacts of the timing relays of the unit and multiple chains which are provided for controlling the P relays to a different pair of terminal posts mounted on a terminal board TB (Fig. 1b). This terminal board is also provided with a plurality of terminal posts 8|, 82 and 83 which are permanently connected to a wire leading to contact 26 or lever L, with a plurality of terminal posts 84, 85 and 86 which are permanently connected to a Wire 9| leading to contact 21 of lever L, and with a pin rality of terminal posts 81, 88 and 89 which are permanently connected to a wire 92 leading to contact 29 of lever L. This terminal board is further provided with a plurality of terminal posts 93, 94 and 95 which are permanently connected to a wire I02 leading to the movable contact finger 51 of relay UK, with a plurality of terminal posts 96, 91 and 98 which are permanently connected to a wire I03 leading to the movable finger 58 of relay UK, and with a p1urality of terminal posts 99, I00 and IUI which are permanently connected to a wire I04 leading to the movable finger 59 of relay UX.

With the terminal board B arranged in this manner, when it is desired to effect the operation of one of the P relays at any particular car speed for a particular lever setting, reference is first made to the chart shown in Fig. 3 to determine which combination of contacts of the unit and multiple groups come closest to the desired speed, and the contacts of this combination are then connected in series by means of jumpers, between one of the terminal posts which is permanently connected to the lever contact which is closed for the particular lever setting, and one of the terminal posts which is permanently connected to the wire Hi2, I03 or IE4 leading to the contact of the UK relay which is included in the particular control circuit for the desired P relay. For example, if it is desired to cause the IPE] and 2P5) relays to operate at a speed of 4 miles per hour when lever L occupies its 113 or low speed position, it is necessary to connect a contact of the 5M relay and a contact of the 2U relay in the circuit for these relays, and this is accomplished by connecting a jumper IE5 from the terminal post 89 to the one terminal post which is connected with front contact 1? of relay 2U, a jumper I05 from the other terminal post which is permanently connected with front contact ll of relay 2U to the one terminal post which is permanently connected with the contact 89 of relay 5M, and a jumper ID! from the other terminal post which is permanently connected with the terminal post 80 of relay 2U to terminal post IIlI. In actual practice the relay contact which is connected to each terminal post will be indicated by suitable marking means associated with the terminal post and the other terminal posts which are not connected with relay contacts will be properly identified by suitable markings to indicate the proper circuit with which they are associated.

As shown in the drawings, all parts occupy the positions which they normally occupy when no car is passing through the retarder, that is to say, all relays are deenergized, lever L occupies its p!) or off position, and valve V2 is deenergized. Valve VI, however, is energized over a circuit which may be traced from terminal B of the source through contact 25 of lever L, line wire H5, wires H6, H1 and H8, and the winding of valve VI to terminal C. As was pointed out hereinbefore, when valve V2 is deenergized and valve VI is energized, cylinder 4 of motor M is disconnected from the source of fluid pressure and is connected with atmosphere, and the braking bars are held in their inefiective or non-braking positions by the spring Ill. The contact 22--22a of each of the pressure responsive devices 3? is closed, and the contact 22-422?) of each of these devices is open.

In explaining the operation of the apparatus as a whole, I shall assume that a car which is to be retarded is approaching the retarder, and the operator wishing to cause the car to leave the retarder at the highest speed for which the apparatus is designed moves lever L from its pl] or 01? position to its 'pI or high speed position. The movement of the lever L from its ml to its pI position will interrupt at its contact 25 the circuit which was previously closed for valve VI, and will complete at its contact 29 a circuit for valve V2 which may be traced from battery B through contact 29 of lever L, wire I09, back contact IIllI Illa of relay IPIJ, back contact IIII-IIIla of relay 2P6, back contact lit-JIM of relay iP30, back contact IIll-I Hla of relay -2P2B-3il, back contact IlIl-Ilfi of relay IP45-55, back contact Ilfl-i Idea of relay 2P45-55, wires I I I, H2 and I l3, and the winding of valve V2 to terminal C. Valve VI will therefore become deenergized and will disconnect cylinder 4 of motor M from atmosphere, and valve V2 will become energized and will connect cylin-' der 4 with pipe II, thereby admitting fluid to cylinder 4 at full line pressure. The braking bars will therefore immediately move from their ineffective or non-braking positions to their effective or braking positions.

When the first axle of the car enters track section IT, track relay ITR will pick up and will cause the W, ISU and IU relays to immediately pick up. The picking up of track relay ITR will also cause the winding 48 of relay UK to become energized, but since the normal contacts of this relay are already closed, the energization of this relay will not cause any operation of the relay contacts. The picking up of the W relay immediately starts the operation of the half-step relays PX and NX, and since relay ISU is then energized, the counting chain starts to function to measure the speed of the car. If the speed of the car is sufliciently slow to cause the IM and 5U relays to pick up, a circuit will become closed for pressure control relay IP45-55 and stick relay ISP passing from terminal B through contact 26 of lever L, wire 90, terminal post 8|, jumper I 1%, front contact T5 of relay 5U, jumper I29, front contact E8 of relay IM, jumper I2I, terminal post 93, wire 22, normal contact 5l5la of relay UX, wire I2I, resistor I22, the winding of relay IP4555, wire I46, and the winding of relay 5551? to terminal C. This circuit includes a resistor I24 and a condenser I25 in series connected in multiple with the resistor I22 and the winding of relay IP45-55 in series. Relay IP4555 and stick relay ISP will therefore pickup and will complete a stick circuit pass ing from terminal B of the source through front contact I21 of relay ISU, wire I28, normal contact 56-5l3a of relay TJX, wire I23, back contact I39 of relay ISP, wire LEE, back contact I32--I32a of relay IPll, wire I33, back contact !34I34a of relay [1 29-30, wire I35, front contact I36 of relay IPli5--55, the resistor I22, the winding of reiay !P45-55, wire I46, and the Winding of relay ISP to terminal C. This stick circuit also includes the condenser I25 and resistor I24 referred to hereinbefore. It should be noted that since this stick circuit includes front contact I21 of relay ISU, back contact I34l34a of relay iPZii-Sfi and back contact I32-i32a of relay lPfi, when relay IP4555 becomes energized under the conditions just described, it will subsequently remain energized until relay IPZU-ZIB or relay lPli picks up or section iT becomes vacated even though the relays 5U and IM of the counting chain which caused it to become energized subsequently release.

The picking up of relay IP45-55 interrupts at its back contact I IU-I Ilia the circuit which was previously closed for valve V2 and completes at its front contact IIOI lllb a circuit for valve VI passing from battery B through contact 29 of lever L, wire Iliil, back contact IIfl-IIIla of relay lPO, back contact IIIl-I Illa of relay 2P0, back contact IIOI Illa of relay IP2U-3ll, back contact lit-I Illa of relay 2P20-30, front contact Hlll lflb of relay IP45-55, wire I40,-contact 22-222) of pressure responsive device P ES-55, wires II! and H8, and the winding of valve V i to terminal C. Valve V2 therefore becomes deenergized and disconnects motor M from the source of fluid pressure, and valve VI becomes energized and vents motor M to atmosphere. Valve VI will continue to vent motor M to atmosphere until the pressure in the cylinder 4 decreases to 55 pounds per square inch, at which time contact 22-221) of pressure responsive device P4555 will open and will deenergize valve VI. If the pressure in the cylinder 4 decreases below 45 pounds per square inch, the resultant closing of contact 22-221 of pressure responsive device P4555 will complete another circuit for valve V2, and current will flow from battery B through contact 29 of lever L, line wire I09, back contact IIO-IIOa of relay IPO, back contact IIOIIOa of relay 2P0, back contact IIO--I Illa of relay IP20-30, back contact IIO-I Illa. of relay 2P20-30, front contact IIO--IIOb of relay IP4555, wire I40, contact 2222a of pressure responsive device P4555, wires H2 and H3, and the winding of valve V2 to terminal C. Valve V2 will therefore become energized and will connect motor M with the source of fluid pressure until the pressure increases to 45 pounds per square inch at which time contact 22-421) of pressure responsive device P45-55 will open and will deenergize valve V2. It will be seen, therefore, that when relay IP45-55 becomes energized, the fluid in the cylinder 4 of motor M will be reduced to a pressure of between 45 and 55 pounds per square inch, and will be subsequently maintained at this pressure as long as relay [PAS- remains energized.

If the speed of the car is sufficiently slow while the leading pair of wheels is traversing section ITR to cause relays 2M and 2U of the multiple and. unit counting chains to both become picked up, a circuit will then be completed for relay IP2030 passing from terminal 13 of the source through contact 26 of lever L, wire 90, terminal post 82, jumper I4I, front contact 15 of relay 2U, jumper I42, front contact I9'of relay 2M, jumper I43, terminal post 96, wire I03, normal contact BE -58d of relay UX, wire I44, resistor I41, the winding of relay IP2030, wires I45, I56 and I 46, and the winding of relay ISP to terminal C. This latter circuit also includes a condenser I48 and a resistor I49 in series connected in multiple with the resistor I 41 and the winding of the relay IMO-30 in series. Relay |P20-30 will therefore pick up, and relay ISP will remain picked up. 'When relay IP20--30 picks up, it completes a stick circuit passing from. terminal B through front contact I21 of relay ISU, wire I28, normal contact 5656a of relay UX, wire I29, front contact I30 of relay ISP, wire I3I, back contact I32-I32a of relay IPO, wire I33, front contact !34-l34b of relay IP20--30, resistor I41, the winding of relay IP2030, wires I45, I56 and I45, and the winding of relay ISP to terminal C. This stick circuit includes the condenser I48 and resistor I41 referred to hereinbefore. This stick circuit for relay IP2030 will maintain this latter relay energized until relay ISU releases or relay IPD picks up.

The picking up of relay IP2II3!J interrupts at its back contact IIO-I Ilia any circuit which was previously closed for either valve V2 or valve VI, and completes at its front contact IIO-I I 0b another circuit for valve VI passing from. terminal B through contact 29 of lever L, line wire I09, back contact lID-Hlla of relay IPO, back contact IIOlHia of relay 2P0, front contact Nil-JIM) of relay IP2!!35. wire I49, contact 22-222) of pressure responsive device P2030, wire H8, and the winding of valve VI to terminal C. Valve V2 if it is not already deenergized when this circuit becomes closed will become de energized, and valve VI will'become energized to thereby again vent fluid from motor M. When the pressure of the fluid in cylinder 4 of motor M decreases to 30 pounds per square inch, contact 22--22b of pressure responsive device P2030 will open and will deenergize valve VI, and if the pressure in the cylinder of motor M decreases to 20 pounds per square inch, contact 2222a of pressure responsive device P20-30 will close and will complete another circuit for valve V2 which is similar to the circuit just traced for valve .VI with the exception that this latter circuit includes contact 22-22a of pressure responsive device P20-30, wire II 3, and the winding of valve V2 in place of contact 22-222) of pressure responsive device P20-30, wire H8 and the winding of valve VI. It will be seen, therefore, that when relay IP20-30 becomes energized under the conditions just described the pressure responsive device P2030 will function to reduce the pressure of the fluid in cylinder M to a pressure of between 20 and 30 pounds per square inch.

If the car which is traversing the stretch of track shown in the drawing has been slowed down by the car retarder sufficiently to permit relays 3M and IU to pick up while the leading pair of wheels is traversing section ITR, relay IPO will become energized by virtue of a circuit passing from terminal B of the source through contact 26 of lever L, wire 90, terminal post 83, jumper I50, front contact 11 of relay IU, jumper I5I, front contact 80 of relay 3M, jumper I52, terminal-post 99, wire I04, normal contact 59-59:]. of relay UX, resistor I53, the winding of relay IPO, Wires I56 and I46, and the winding of relay I SP to terminal 0. This latter circuit includes a condenser I54 and a resistor I55 in series connected in multiple with the resistor I53 and the windingof relay IPO in series. Relay [P0 will therefore pick up and since this pick-up circuit includes relay ISP, relay I SP will remain energized. When relay IPO becomes energized, it completes a stick circuit passing from terminal B through front contact I21 of relay I SU, wire I28, normal contact 56-56a of relay UX, wire I29, front contact I30 of relay ISP, wire I3I, front contact I32I32b of relay IPIl, resistor I53, the winding of relay IPO, wires I56 and I46, and the winding of vrelay ISP to terminal C. This stick circuit also includes the condenser I54 and the resistor I55 which are included in the pick-up circuit for relay IPD. This stick circuit will maintain relay IPO energized until the leading pair of wheels vacates track section I'I'R.

The opening of back contact IIO--I I 0a of relay IPO interrupts all circuits which were previously closed for ither valve VI orvalve V2, while the closing of front contact I I 0I I05 of this relay completes a circuit for the valve VI passing from terminal B through contact 29 of lever L, line wire, I09, front contact IIO-IIOb of relay IPO, wires I I6, II! and H8, and the winding of relay VI to terminal C. Valve VI therefore becomes energized and vents the fluid in cylinder M to atmosphere to thereby effect the release of the retarder.

I shall now assume that with lever L in its pl position, the leading pair of wheels of a car pass out of section I'I'R and into section 2TB while relay IP45-55 is energized. When this happens relay ISU will release and relay ZSU will pick up to initiate a new timing period in the manner previously described. When relay ISU releases, it will interrupt atits front contact I2I the stick circuit which was previously' closedg'for relay IP4555 and-relays I-Pfi5'-55 and ISP will therefore both become deenergized. Due, --how ever, to the con-denser' I25 and-resistor I24 asthe exceptionthat" this latter circuit includes reverse;o ontact- 5I5'Ib of relay UX -and-the winding of relay 2P45-'-55 together with the-associated condenser IBI and associated resistors IGI and IE2 inplace-"of the-contact 5'I5Ia-of relay UK and' the -w-inding-of relay IP45-55 together with :the-associated condenser I25 and resistors I24 and I22. As soon afterrelay 2P45 55 pick up as relay iP4555r eleases; the -relay 21 45- 55 -will become effective 3 to control the valvesVI and V2 in the same manner that these valves were previously controlled by the relay IP45-155.

If when leverL occupies its pl position; the leading pair of wheels of,a,car -which is being retarded ;.passes*from section-lTR- to 2TB. when either 'theprcssure control relay 'IP2II 3II or IPO is energized, the --pressure control relay 21 -130, orZPO will subsequently be rendered effective to control'the valves VI and Y2 as soon as,a new measurement Ofspeed can, be madeif I i the, speed cfthe car;has.not changed until-the new measurement is completed.

1 t will: beapparent,that a new speed ,measurement will be made eachtime the leadinglpair of wheels-enters anew track section, andif the car peedsuplbetween wo speed measurem n s, when the next speed measurement is ,made, the pressure control relays will automatically ,function to increase the braking pressure. It isbelievedrthat this ,operationxwill'lbe a parent from i an inspectioni of the ,drawings without the necessity for describing vit indetail.

'When lever L. is moved .to its 102 position, the pparatus funct ons n the sam m nner a w e i i moved to, its I po it-ion with th cXc p ion that under these conditions the pressure control relays-are provided-with different control circuits to cause ,thepressure, of .the fluid supplied to ,motorM .tohereduceflin raduated t a the speed of a car approaches the control speed corresponding .to, this lever .nositionand there- .tarder to ,be automatically released when the sp ed "cfnth ar reache this con ro spccdf l control ,circuitfor the I'Pl4 5. 5.5.,rclay,underthese nd t n i esircm t rminaui of thesour thnoughcontact 21 .ofleyer L, wire SI. terminal post .85, v jumper -I63,front;c,onta;t .'I5 of relay ,IU, jumper lfill frontncontact I8 of relay 2M. jumper I,,6,5,,,terminal post fikiwire I112, ,normal I22, the winding of relayIP45,55, wire I46.

and the winding of relay ISP to terminal C. This. circuit includes the condenser I and the resistor I24. 'The circuit'for the relay 2P4 555 is .thecame as that just-traced for the relay IF45 55 except for the difference which will be apparentfrom an inspection of the drawings and from thejoregoingdescription.

The circuit for relay IBM- when leverL occupies its p3-position-passes from terminal -13 1 through front contact 2? of lever L, wire 9I ,ter-

minal post"85,'-jumper 'I65,Tfront cont-act 'lil of relay- 3M, jum per I57, terminal post" 9?,wire I03, normal contact5858a of relay 'UX, wire I44, resistor I41; the Winding of relay IP25-3il, wires I45,- I55 andIMi, and 'the'winding'of relay ISP to terminal *0. This circuit includes thecondenser I48 and resistor MS as will be obvious.

"The circuit for the relay iPO when lever L occupies its 112 position passes from terminal' B throughcontact 21 of lever L, wire 9|, terminal post 55, jumper I53,fr0nt contactfifl of relay 4M,'jumper I59, wire I54, normal contact5$i- 59a of relay UX, resistor and the winding of-relay IPO in series in 'multiple with condenser I54-and resistor I55, Wires I55 and I45, and the winding of relay ISP to terminal C.

When -lever L occupies its'p3 position, theicircuit for relay IP55 passes from terminaLB through contact 28 of lever-L, wire '92,'terminal post--8'I,jumper- I13, front Contact 2'5 oftrelay 2U, jumper I'M, front contacttfi of relay 2M,

jumper I15, terminal-posted wire I02, normal,

contact 5l5la of relay UX,'wire IEI, resistor 4 22- and-the winding of relay IP i555 in'series in multiplewith condenser I25 and resisto I24, wire I46, and the'winding-of relay. ISPto terminalB.

"The circuit for relay IP29-30 when lever L occupies its 113 position passes from'terminal 2B of the source through contact .28 of .lever' L, Wire SZ, terminal post 88, jumper I70, front contact'I'I of relay 4U, jumper I'II, front contact "I9 of relay -3M, wire I12, terminal post 98, wire I93, normal contact '5358a of relay U'X, wire I44, resistor I41 in series-with'the winding of relay IPZEEI3B inlmultiple with condenser I48 and-resistor I49 invseries, wire I45, I and I46 and the winding of relay ISP toterminal C.

"The circuit 'forrelay I'PO when lever L occupies-itspfi position passes'from battery B through contact 28 of lever L,-wire 92, terminal post 89, jumper I05, front contact I! of rela '2U, jumper I05, front contact of relay 5M, jumper I01, terminal post IBI, wire I04, normal-contact59-59a of relay UX, resistance I53 and the winding of relay I PO connected in multiple with the condenser I54 and theresistor I55 in series,

"wire I56, and the-winding of relay ISP to terminalC.

The'circuits for each of the relays'2P45-55, =2P20-30 and 2P0 when lever L occupies its 102 and p3 positions differ from the circuits 'just traced for therelays IP45-55, IP26-35 and IPO inthe same manner that the'circuitsfor the relays-2P4555,'2P2030- and 2P0 difier fromthe circuits for the relays IP45-55, IP2U---30 and I'PO when lever "L occupies its pl position, and willbe apparent from'an inspection of the drawing without further description.

'If the operator moves lever L to its p4 position, the speed responsive apparatus is rendered ineffective to control the retarder and under these conditions the valve V2 becomes energized and remains energized by virtue of a circuit which passes from battery B through contact 29 of lever L, line wire I09, back contact IIfB-I IBa of relay IPQ, back-contact IIO-I Illa of relay 2P0, back contact IIOIIGa of relay IP2530, back contact IIII--I Illa of relay 2P20-3!i, back contact IIll--I IOa of relay IP4555, back contact HIE- IIUaof relay 2P45-55, wires III, H2 and H3, and thewi-nding of valve'Vz to terminal 0. Since valve :VZremains energized under these conditions the braking bars are held in their braking positions by fluid at full line pressure, and the retarder is effective to exert its maximum braking force during the entire time the car is passing through the retarder.

It will be apparent from the foregoing that with railway braking apparatus constructed in the manner shown in Fig. 1 the operator by proper operation of the lever L may cause the braking bars to become automatically released when the speed of a car which is being retarded by the retarder decreases to any one of a plurality of selected speeds, which speeds may be varied as conditions require. It will also be apparent that when the speed of a car is being reduced by the retarder, the pressure of the fluid supplied to the fluid pressure motor of the retarder will be reduced in two stages prior to the actual release of the retarder, thereby providing a more effective control of the car retarder than would otherwise be possible. It should be particularly pointed out that the track circuit lengths as well as the alternating current frequency of the alternator A can be varied depending upon the condition obtaining and the accuracy desired. Ordinarily 60 cycle alternating current would be used since this is the usual commercial frequency available and one that can be accurately controlled in view of its general use for operating electric clocks. If desired an entirely independent source or any desired source of frequency may be used.

It will also be apparent that the counting chain combinations and the number of steps involved in each chain is merely a matter of choice depend-- ing upon the conditions to be served. If desired,

in cases where longer timing is needed it would r-zi be feasible to introduce three groups of multipliers instead of restricting the apparatus to the two groups shown. For such an arrangement the second group would of course rotate in a manner similar to the first group, and the third group would then be used to total the number of revolutions made by the second group. This principle could be carried on as far as is necessary.

It should further be pointed out that the number of speeds that may be selected by the operator from the lever L is purely a matter of design. The attached drawings show a high, medium and low speed. This may be amplified to any desired number of speeds that may be needed. Furthermore. the number of pressure reductions is dependent only on the amount of the equipment which is provided. Moreover there is no necessary or essential relationship between the number of speed controls and the number of pressure reductions that may be provided.

Referring now to Fig. 2, the apparatus here illustrated is generally similar to that shown in Fig. 1. However, the apparatus shown in Fig. 2 includes certain additions that have been made to permit it to perform additional functions, and embodies certain circuit changes which permit a reduction in the number of relays required and the number of contacts which are necessary on other relays, as will be made clear.

As shown in Fig. 2, an additional pressure responsive device Put-80 is provided to provide an additional braking pressure. The device Flois similar to the previously described devices PHI-30 and P55 except for the fact that its contact 22-22a is adjusted to open at pounds per square inch, and its contact AZ-22b is adjusted to close at pounds per square inch.

Furthermore, as shown in Fig. 2, a standard control lever LI similar to the lever L has been provided to permit the car retarder CR to be manually controlled wholly independently of the speed responsive apparatus, together with a manually operable switch MS which functions to shift the control of the car retarder from one lever to the other.

As shown in the drawing, the switch MS occupies the position in which the lever L is effective to control the retarder, and in which its contacts ZOO-400a and 20I2DIa are closed, and its contacts 200200b and 20I20Ib are open. When it is desired to control the retarder by means of the lever LI, this switch is reversed to open its contacts 20E220Da. and 20i20la and to close its contacts 2OEI-20Gb and 2!!I20Ib.

The control of the car retarder by means of lever L! is as follows. When this lever occupies its p0 or off position in which it is shown in the drawings, all contacts of the lever with the exception of the contact 25 are open, and under these conditions valve V2 is deenergized and valve V I is energized over a circuit which passes from terminal B through contact EDI-40H) of switch MS, contact 25 of lever LI, wire 202, Wire 203, and the winding of valve VI to terminal C. Since valve V2 is deenergized, pipe I! is disconnected from pipe I5, and the supply of fluid pressure to cylinder 4 of motor M is therefore cut oil, and since valve VI is energized, cylinder 4 is connected with atmosphere. The braking bars are therefore held in their ineffective or non-braking positions by the spring I0. The contact 22 22a of each of the pressure responsive devices P is closed, and the contact 22-221) of each of these devices is open.

I shall now assume that the operator wishes to make a comparatively light brake application. To do this he moves lever L! from its to its pl position, thereby opening contact 25 and closing contact 26. The opening of contact 25 interrups the circuit which was previously closed for valve VI at this contact, and valve VI therefore now becomes deenergized and disconnects pipe i8 from port I5. The closing of contact 26 completes a circuit for valve V2, and current flows from battery 13 through contact 20I-20Ib of switch MS, contact 25 of lever LI, line wire 204, contact 22-22a of pressure responsive device PHI-30, wire 2G5, and the winding I 4 of valve V2 to terminal C. Valve V2 therefore becomes energized and connects pipe I! with pipe I 6, so that fluid at full line pressure is now supplied to cylinder 4, thus causing the braking bars to move to their effective or braking positions. As soon as the fluid in cylinder 4 reaches 20 pounds per square inch, contact 22-42%. of pressure responsive device P263ll will open and will interrupt the circuit just traced for valve V2. Valve V2 will then become deenergized and will cut off the supply of flu d to cylinder 5 of motor M until the pressure in the motor again decreases below 20 pounds per square inch at which time valve V2 will again become energized and will again admit fluid to the cylinder. If the fluid in the cylinder 4 of motor M increases to a pressure of 30 pounds per square inch for any reason, contact 2 ='-22b of pressure responsive device P20-30 will become closed and will complete a circuit for valve VI which passes from terminal B through contact 20i-20ib of switch MS, contact 23 of lever Li, line Wire 2104, contact 22-22b of pressure responsive device P2 39, an asymmetric unit 206 in its low resistance direction, and the winding I5 of valve VI to terminal C. Valve VI will therefore become energized and will vent fluid from cylinder 4 until the pressure again decreases to 30 pounds per square inch and permits contact. 220--22 b to be open. It will be seen, therefore,

that when lever Ll occupies its pl position, the

braking bars will be held in their braking positions by a pressure of between 20 and 30 pounds per square inch.

If the operator desires to make a more powerful brake application, he will move lever Li to its p2 position in which contact 21 is closed. Under these conditions, valve VI will be deenergized and valve V2 will become energizedover a circuit which passes from battery B through contact 2M2Glb of switch MS, contact 2.! of lever Li, line wire 201, contact 22-2211 of pressure responsive device P45-55, wire 225, and the winding M of valve V2 to terminal C. Fluid pressure will therefore now be admitted to cylinder 4 of motor M until the pressure of the fluid in the cylinder increases to 45 pounds per square inch, at which time control 22--22a of pressure re sponsive device P45-55 will open and will deenergize valve V2. If the pressure in cylinder i now increases to 55 pounds per square inch, contact 22-22b of pressure responsive device-P s5--55 will become closed and will complete another circuit for valve Vi this latter circuit passing from battery B through contact Eel-20H) of switch MS, contact 2'! of lever Ll, line wire 20?, contact 22-22b of pressure responsive device P45--35, asymmetric unit 206 in its low resistance direction, and winding 14 of valve V! to terminal C. Valve Vl will therefore become. energized and will exhaust fluid from cylinder 4 until the pressure decreases to that at which contact 22-221) of pressure responsive device 1 45-55 opens. It will be apparent, therefore, that when lever Ll occupies its p2 position, the braking bars will be held in their braking positions by a pressure of between 45 and 55 pounds per square inch.

If the operator moves lever LI to its 113 position, valve V2 will then become energized over a circuit which passes from battery B through contact 22-i2!3lb of switch MS, contact 28- of lever LI, line wire 298, contact 22-22a of pressure responsive device PIG-43G, wire 265, and the winding M of valve V2 to terminal C. Under these conditions, fluid will be supplied to cylinder 4 of motor M until the pressure in the cylinder reaches '70 pounds per square inch which is the pressure at which contact 22-22:; of pressure responsive device Pit-80 opens. If the pressure in cylinder 4 now increases to 80 pounds per square inch,

contact 22-221) of pressure responsive device- P'I i!8ii will become closed and will complete still another circuit for valve VI. for valve V I may be traced from battery B through contact Mil-201D of switch contact 28 of lever Ll, line wire 20B, contact 2222b of pressure responsive device Pl8l, asymmetric unit 206' in its low resistance direction, and the winding l4 of valve VI to terminal B. Valve V! will therefore become energized until the pressure in cylinder of motor M again decreases to 89;

pounds per square inch. It will be seen, therefore, that when lever L! is moved to its p3 position, cylinder 4 is supplied with fluid at a pressure of between '70 and 80 pounds per square inch, so that the braking bars exert a. corresponding braking force.

If the operator desires to cause the braking bars to exert their maximum braking force, he will move lever Ll to its 104 position. Under these conditions, valve V2 will become energized and will subsequently remain energized by virtue of a circuit which passes from battery B through This latter circuitv contact fill-2M1 of switch MS, contact 29-01 lever LI, line wire209, wire 20.5, and the. windingv of valve V2 to terminal C. It will be apparent, therefore, that under these conditions the braking bars will be held in their braking positions-by fluid at full line pressure.

t should be observed that if the operator moves lever LI from a position corresponding to.

a higher braking force to a position corresponding to a lower braking force, the apparatus immediately and automatically reduces the braking pressure to a value corresponding to the new position of the lever in a manner which will be.

apparent from the drawings without tracing the sequence of operation in detail.

When lever Ll occupies any one of itsp i p2, 12.3-

or p41 positions, so that the braking bars occupy their braking positions and the operator wishes to restore the braking bars to their non-braking result, the supply of fluid pressure to the cylinder 4 of motor M will be cut oil and the fluid which. was previously supplied to the cylinder will be.

vented to atmosphere. The braking bars will therefore move under the influence of the spring H! to their ineffective or non-braking positions. When the braking bars reach their non-braking positions, all parts are restored to the positions in;

which they are shown in the drawings.

Associated with lever L is a relay LP which, provides a means for decreasing the general level.

of the braking pressure at the will of the operator when the car retarder is being controlled by-the. speed responsive apparatus. The relay LP is provided with a control circuit which passes from: terminal B through contact Zfll-Zflla of manu-- ally operable switch MS, contact 29 oflever L, contact 2 of a manually operable switch MSI,

line wire 2m, and the winding of relay LP to terminal C. With relay LP controlled over this.

circuit it will be apparent that when the car retarder is being controlled by lever L, if contact. 2H of switch MSI is then closed, relay LP willv be picked up in all positions of lever L except the pi position. It will also be apparent. thatrelay LP can be released at any time by operating the switch MSI to open the contact 2| I.

In actual practice the switch MSI will usually be a push button of the stick type which is built into lever L, and which is arranged to be retained in either of its two positions by suitable detent means.

Only two pressure control relays IP and IPO.

are provided in Fig. 2. The relay IP has associated therewith a stick relay ISP and is provided with three pick-up circuits one for each of the pl, 322 and p3 positions of lever L.

When lever L occupies its pl position, the pickup circuit for relay ISP passes from battery B.

through contact 2fi02i30a of manually operable switch MS, contact 26 of lever L, wire 90, terminal post 8|, jumper H9, front contact of relay 5U, jumper front contact 18 of relay lM, jumper 12!, terminal post 93, a resistor 2L9.

in series with the winding of relay IP connected in multiple with a condenser 22I in series with resistor 228, and the winding of relay l-SP to. It will be noted that this circuit.

terminal C.

includes front contact I of relay 5U and front contact I8 of relay IM in series, and it will be apparent, therefore, that when lever L occupies its pl position, relay IP will pick up if the speed of a car passing through the retarder becomes less than that at which the relays 5U and IM pick up, namely 11.6 miles per hour.

When lever L occupies its 02 position, the pickup circuit for relay IP then passes from terminal B of the source through contact 200-200a of manually operable switch MS, contact 21 of lever L, wire 9!, terminal post 84, jumper I63, front contact I5 of relay IU, jumper I64, front contact 18 of relay 2M, jumper I65, terminal post 94, resistor 2 I 9 in series with the winding of relay IP connected in multiple with a condenser 22I in series with a resistor 220, and the winding of relay ISP to terminal C. This circuit includes front contact of relay IU in series with front contact I8 of relay 2M, and it follows that when lever L occupies its p2 position, relay ISP will pick up if the speed of a car passing through the retarder becomes less than 9.8 miles per hour.

When lever L occupies its p3 position, the pick-up circuit for relay IP then passes from terminal B through contact 200--200a of manually operable switch MS, contact 28 of lever L, wire 92, terminal post 81, jumper I13, front contact I6 of relay 2U, jumper I14, front contact 80 of relay 2M, jumper I15, terminal post 95, re-

- sistor 2? in series with the winding of relay IP I connected in multiple with the condenser 22I in series with a resistor 220, and the winding of relay ISP to terminal C. This circuit includes front contact I6 of relay 2U in series with front contact 80 of relay 2M, and it will be seen that when lever L occupies its p3 position, relay IP will become picked up if the speed of the car passing through the retarder becomes less than 9.1 miles per hour.

Relay IP is also provided with a plurality of stick circuits each of which includes terminal B of the source, a front contact 2I5 of a different one of the U relays, wire 2H5, back contact 2I'I- 2IIa of relay ISPO, wire 23I, front contact I of relay ISP, front contact 2I8 of relay IP, resistance 2I9 in series with the winding of relay IP connected in multiple with condenser 22! in series with resistor 220, and the winding of relay ISP to terminal C. The front contact 2I5 of at least one of the U relays is always closed when .the unit counting chain is operating and it will be seen, therefore, that when relay IP once picks up it will remain picked up either until the unit chain stops operating, or until relay ISPO picks The relay IPO likewise has associated therewith a stick relay ISPO and is provided with three pick-up circuits one for each of the pl, p2 and p3 positions of lever L. When lever L occupies its pl position, the pick-up circuit for relay IPO passes from terminal B through contact 200200a of manually operable switch MS, contact 26 of lever L, wire 90, terminal post 83,

jumper I59, front contact 11 of relay IU, wire I5I, front contact 80 of relay 3M, jumper I52,

terminal post 99, the resistor 222 in series with the winding of relay IPO connected in multiple with a condenser 224 in series with a resistor 223, and the winding I SP0 to terminal C of the Since relays IU and 3M pick up whensource.

, ever the speed of a car traversing the stretch of track shown in the drawing is less than 6.7 miles per hour, it will be apparent that when 1 lever L occupies its pl position, the relay IPO will pick up if the speed of a car traversing the stretch of track shown in the drawing decreases to a speed of less than 6.7 miles per hour.

When lever L occupies its p2 position, relay IPO will then become energized if the speed of a car traversing the stretch of track in the drawing decreases below a speed of 5.3 miles per hour by virtue of a circuit which passes from terminal B through contact 200200a of manually operable switch MS, contact 21 of lever L, wire 9|, terminal post 86, jumper I68, front contact of relay 4M, jumper I69, terminal post I00, resistor 222 in series with the winding of relay IPO connected in multiple with a condenser 224 in series with a resistor 223, and the winding of relay ISPO to terminal C.

When lever L occupies its p3 position, relay IPO will then become energized if the speed of a car traversing the stretch of track in the drawing decreases below a speed of 4 miles per hour by virtue of a circuit which passes from terminal B through contact ZOO-400d of manually operable switch MS, contact 28 of lever L, wire 92, terminal post 89, jumper I05, front contact ll of relay 2U, wire I06, front contact 80 of relay 5M, jumper I01, terminal post IOI, resistor 222 in series with the winding of relay IPO connected in multiple with a condenser 224 in series with resistor 223, and the winding of relay I SP0 to terminal 0.

Relay IPO is further provided with a plurality of stick circuits each of which passes from terminal B through front contact 2I5 of a different one of the U relays, wire 2I6, front contact 2I'I2I'Ib of relay ISPO, front contact 2|8 of relay IPO, resistor 222 in series with the winding of relay IPO connected in multiple with condenser 224 in series with resistor 223, and the winding of relay ISPO to terminal C.

Referring now particularly to the speed responsive portion of the apparatus shown in Fig. 2, relay W has been eliminated, and the energizing circuits for the half-step relays PX and NX previously described in connection with Fig. 1 have been modified to include a front contact 2I2 of relay ISU or a front contact 2I3 of relay 2SU in place of front contact 36 of relay W. It will be apparent, therefore, that when either relay ISU or relay ZSU picks up, the half-step relays PX and NX will immediately start to operate and will continue to operate as long as the relay which initiated the operation remains energized.

Relay UK has also been eliminated in Fig. and the initial pick-u circuit for the IU relay which becomes closed when the operation of the unit counting chain is initiated by the picking up of any one of the odd-numbered track relays ITR. 3TB or 5TB. has been modified to include a back contact I3'I3a of relay 2SU in place of the winding of the W relay, and a back contact 255 of relay ISPO and a back contact 226 of relay ISP in place of the winding 48 of the relay UX. Tracing this circuit in detail for the condition when track relay 5TB, is picked up, for example, this circuit passes from terminal B through back contact 33-331) of track relay ETR, front contact 33--33a of track relay S'I'R, the winding of relay ISU, back contact 13-13:; of relay ZSU, a back contact 44 of each of the relays 2U to EU, inclusive, a back contact 7 and thewinding of relay IU to terminal C.

'I'heinitial pick-up circuit for the IU relay which becomes closed when the operation of the counting chain is initiated by the picking up of any of the even-numbered track relays ZTR, 4TR-and-6TR in Fig. 2 has been modified in a manner similar to the circuit controlled by the odd-numbered track relays, and will be apparent from the above and from an inspection of the drawing without further detailed description.

It should be pointed out that since the initial I pick-up circuits for relay IU each include a back contact 225 of relay ISPO anda back contact 226 of relay ISP, the relay ISU or 2SU will not pick up in Fig. 2 unless relays ISP and ISPO are both deenergized. This check insures that the SP relays have released between counting operations and permits the elimination of the alternate series of pressure control relays shown in Fig. 1.

It should also be pointed out that this change makes possible the elimination of the UK relay, and reduces the pick-up circuits for the IU relay to a single series of back contacts instead of a double set as shown in Fig. l.

The OM relay has been eliminated in Fig. 2, and the stick circuits for the remaining M relays and fcr'the U relayshave been modified to include in addition to the front contact 4-9-4911 of the ISU relay or a front contact 13-131] of the relay ESU depending upon whether the iSU or 2SU relay is then energized, a back contact of the SU relay which is deenergized. That is to say, when the relay ISU is energized, the stick circuits for each of the M or U relays includes in addition to the front contact 49-492) of relay ISU, back contact 'l3-13a of relay 2SU, and when relay ZSU is energized, the stick circuits for each of the U or M relays includes in addition to the front contact 13-131) of relay ZSU, back contact 49-69:: of relay lSU. Except for the modification 'just noted, and a modification of the stick a circuit for the relay 3U which I shall describe presently, these stick circuits are otherwise identical with the circuits previously described in connection with Fig. 1.

The pick-up circuits for the U and 'M zrelays in Fig. 2, with the exception of the pick-up circuit for relay 3U and the pick-up circuit for the 'IM relay, are identical with the corresponding circuits shownin Fig. 1 exceptffor the fact that front contact 43 of relay W has been ornittedfrom these circuits. This contact has been omitted because the stick circuits for the U relays include the windings of the SU relays which insures proper operation of the U chain.

The pick-up circuit for relay 3U when all of the M relays of the multiple chain are deenergized passes from battery B through a normal contact 42 -'42a. of relay NX, front contact 54 of relay 2U,

the winding of relay 3U, wire 232, back contact (SS-63a of each of the relays 5M, 4M, 3M, 2M and EM, and winding 68 of relay MX to terminal C of the source. When relay IM is picked up, the pick-up circuit for relay 3U on the next round trip of operation of the unit chain will pass from battery B through contact 4242a of relay NX, front contact 54 of relay 2U, the'winding of relay 3U, wire 232, back contact 63-63a of relays 5M, 4M, 3M and 2M, front contact 63-43311 of relay IM, and the winding of relay MX to terminal C. Each time a succeeding one of the M relays of the multiple chain picks up, its front contact will be included in the pick-up circuit which next becomes closed for relay 3U, as will be obvious.

It should be noted that with the pick-up circults for relay 3U arranged in this manner, the windings 6.5 and'68 ofrelayMX will be alternately energized in response tosuccessive energizations :of the relay 3U, whereby the relay 'MX is caused to alternately open and close its polar contacts to effect the successive energization of the relays of the multiple chain in the same manner as in Fig.1.

The pick-up circuit for relay I'M in Fig. 2 is closed by the picking up of relay EU, and when this circuit becomes closed if an odd-numbered track relay is then picked up, this circuit passes from terminal B through back contact 33'3 3b of each of the track relays in advance of the pickedup track relay, front contact '333'3a of the picked-up track relay, the winding of relay ISU,

.back contact IS-43a of relay ZSU, front contact 495.3b-of relay |SU, wire 50, back contact 60 of each of the relays -5-M, lM, 3M and 2M, normal contact 234 of relay MX, front contact 233 of relay EU and the winding of relay IM to terminal-C.

The pick-up circuit for relay IM when any of the even-numbered track relays ZTR, 4TB. or STR .is then picked up passes from terminal B through back contact -3333b of each track relay in advance of the picked-up track relay, front contact 33-43:]. of thepi-cked-up track relay, the

winding of relay 2SU, back'contact 4949a of relay i'SU, front contact 13-131) of relay ZSU, wire a back contact ED of each of the relays 5M, -M, 3M and 2M, normal contact 234 of relay MX, front contact 233 of relay -6U, and the winding of relay IM to -terminalC.

The stick circuits for relay 3U in Fig. 2 differ from the stick circuits for relay 3U in Fig. .l in the same manner that the pick-up circuits for relay SU in Fig. 2 differ from the pick-up circuits for relay 3U in Fig. 1. It is believed, therefore, that these stick circuits will be obvious from an inspection of the drawing without further detailed description.

The operation of the time measuring means as a whole with the apparatus constructed as shown in Fig. 2a is essentially the same as the operation of the apparatus shown in Fig. la, it being noted that with the apparatus shown in Fig. 2a the NX and PX relays are set into operation by'the picking up of the ISU or .ZSU relay in response to the picking up of a track relay and are subsequently maintained in operation until such track relay releases. With the relays NX and PX in operation, the relays of the unit and multiple chains will function to register the time the relays NX and PX remain in operation to thereby measure the speed of a car traversing the track circuited stretch through the retarder. Since the operation of the time measuring apparatus shown in Fig. 2a is essentially the same as that shown in Fig. la, a detailed description of the operation of this portion of the apparatus is believed to be unnecessary.

The operation as a whole of the aparatus shown in Figs. 2 and 2a is as follows: When the manually operable switch MS occupies the position shown, the apparatus is conditioned for the control of the car -retarder by the lever L. Lever L is shown in its position and when the lever occupies this position, all circuits for valve V2 are open and valve VI is energized over a circuit which passes from terminal B through contact 20|-20l a of manually operable switch MS, contact 25 of lever L, line wire H5, wires H6 and 203, and the winding M of valve VI to terminal C. Since valve V2 is deenergized and valve Vi is energized, the braking bars are held in their non-braking positions by the spring Ill.

I shall now assume that with the apparatus conditioned to be controlled by the lever L, the operator moves the lever from its 100 to its pl position to slow down a car which is approaching the retarder to the maximum control speed for which the apparatus is designed. The movement of lever L from its 120 to its pl position interrupts the circuit which was previously closed for valve VI and completes one or the other of two circuits for valve V2 depending upon Whether relay LP is then energized or deenergized. Assuming that relay LP is energized as shown in the drawing, the circuit for valve V2 passes from terminal 38 through contact 29I-2illa of switch MS, contact 29 of lever L, wire 235, back contact 236235a of relay lPil, back contact 231-231a of relay HP, front contact 238-238b of relay LP, wire 239, contact 2222a of pressure responsive device P4555, wire 205, and the Winding H! of valve V2 to terminal C. Valve V2 will therefore become energized and will admit fluid pressure to cylinder 4 of motor M until the pressure in the cy1- inder increases to 45 pounds per square inch, whereupon the pressure responsive device P4555 will function to maintain the pressure in the motor at a pressure of between 45 and 55 pounds per square inch.

If new with lever L in its pi position and with relay LP picked up, relay lP becomes picked up due to the speed of the car passing through the retarder decreasing to the value at which relay lP becomes picked up, the circuit which was previously closed for valve V2 will become interrupted at back contact 2237-4370; of relay IP, and a circuit will become closed for valve V I passing from terminal B through contact 28l20la of manually operable switch MS, contact 29 of lever L, wire 235, back contact 236-43611 of relay lPil, front contact ESL-2375 of relay lP, front contact MEL-24Gb of relay LP, wire 241, contact El lo of pressure responsive device P2El3G, asymmetric unit 265 in its low resistance direction and the winding of valve VI to terminal 0. Valve Vi will therefore become energized and will vent fluid pressure from cylinder 4 of motor M until the pressure decreases to 20 pounds per square inch whereupon pressure responsive device P2ii--3il will then function to maintain the pressure of the fluid in motor M at a pressure of between 2%) and 30 pounds per square inch.

If when lever L was moved to its pl position relay LP had then been deenergized, valve V2 would then have become energized over a circuit which passes from battery B through contact 20 l-2illa of manually operable switch MS, contact 29 of lever L, wire 235, back contact 23-5236 a of relay IPG, back contact 25'!231a of relay IP, back contact 238238c of relay LP, wire 242, and the winding 14 of valve V2 to terminal C. Under these conditions, none of the pressure responsive devices is included in the control of the valve V2, and it will be apparent therefore that the resultant energizaticn of the valve V2 would cause fluid at full line pressure to be sup plied to motor M.

If, with lever L in its pl position and relay LP deenergized, relay IP becomes energized due to the speed of the car decreasing to the proper speed, the circuit previously traced for valve V2 would then become interrupted at back contact 231-23154 of relay IP and acircuit would become closed for valve VI at front contact 231-231b of relay IP which latter circuit may be traced from battery B through contact |2IJI a of manually operable switch MS, contact 29 of lever L, wire 235, back contact 236-236a of relay IPO, front contact 23l231b of relay IP, back contact 240-24011 of relay LP, wire 239, contact 22-22b of pressure responsive device P45-55, asymmetric unit 235 in its low resistance direction, and the winding 14 of valve VI to terminal 0. Valve VI will therefore become energized and will vent fluid from cylinder 4 of motor M until the pressure decreases to 45 pounds per square inch at which time the pressure responsive device P45-55 will function to subsequently maintain the pressure of the fluid in cylinder 4 of motor M at the pressure of between 45 and 55 pounds per square inch.

If, when lever L occupies its 131 position, the speed of the car decreases sufficiently to cause relay IPO to pick up, all circuits previously traced for valve V and VI will become interrupted and a circuit for valve VI will become closed passing from battery B through contact 20l-20 la of manually operable switch MS, contact 29 of lever L, wire 235, front contact 236236b of pressure responsive device [P0, wire H6, and the winding of valve VI to terminal C. Valve V! will therefore become energized and will vent the fluid which was previously supplied to the motor M to atmosphere to thereby permit the spring 16 to move the braking bars to their non-braking or released positions.

It will be seen, therefore, that when lever L is moved to its pl position, cylinder 4 of motor M will be supplied with fluid at full line pressure or at approximately half full line pressure according, as relay LP is then released or is picked up. It will also be apparent that if relay LP is picked up when relay IP becomes deenergized, the pressure will be decreased from a pressure of between 45 and 55 pounds to a pressure of between 20 and 30 pounds, whereas if relay IP becomes picked up when relay LP is released, the pressure of the fluid in motor M will be decreased from full line pressure to a pressure of between and pounds.

It should be noted that relay LP can be picked up or released at the will of the operator by merely operating the switch MSI, and it follows, therefore, that when the lever occupies its pl position, the operator can change the base pressure at which the retarder operates from the full line pressure to half line pressure or vice versa at will. This feature is particularly desirable in yards where some of the cars are heavy cars and other cars are light weight cars, and permits the operator to make the desired selection between the braking force which will be applied to the heavy cars and the braking force which will be applied to the light cars to thereby prevent derailment of the light cars.

The operation of the apparatus when lever L is moved to its 102 or 103 position is similar in all respects to that just described for the operation of the apparatus when lever L is moved to its pi position with the exception that under these latter conditions the speed at which the 1P relay picks up will be different from the speeds which this relay picked up when the lever occupied its pl position. It is believed, therefore, that this operation will be understood from

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