US1766539A - Car-retarder system for railroads - Google Patents

Description

June 24, 1939. c w. PRESCOTT 319755539 cm RETARDER SYSTEM FOR RAILROADS Filed Dec. 14, 1.927 3 Sheecs-Sheet 1 FIGJ.

J1me 1930. c. w. PREsccTT CAR RETARDER SYSTEM FOR RAILROADS Filed Dec. 14, 1927 3 Sheets-Sheet 2 June 24, 1930. c w PRESCQTT 1,766,539

CAR RET'ARDER SYSTEM FOR RAILROADS Filed Dec. 14, 1927 5 Sheets-Sheet 3 FIG. 5.

{w ATTORNEY Patented June 24, 1930 UNITED STATES PATENT OFFICE CHARLIE-S W.,PRESCOTT, 0F MILL HILL, ENGLAND, ASSIGNOB '10 GENERAL RAILWAY SIGNAL COMPANY, 01 ROCHESTER, NEW YORK CAB-RETABDER SYSTEM FOR RAILBOADS Application filed December 14, 1927. Serial No. 289,949.

This invention relates to car retarders of the, track brake type used in classification or hump yards of railroads, and more particularly to means for automatically controlling the braking action of such retarders in accordance with the speed at which the cars to be retarded are moving.

Although the present invention may be applied'to retarders of various construction and to retarders either located on the main lead where the cars are accelerated, to retarders located on the main classification yard or switch portion of the classification yard, or may be applied to retarders located on the ladder tracks from which diverge a plurality of classification tracks, the invention has been shown applied to retarders in which the passing car wheels are engaged by adjustable brake shoes, and also the invention has only been shown applied to a retarder located on the ladder track from which numerous classification tracks diverge. In accordance with the present invention it is proposed to vary the degree of braking efiected by a particular retarder in accordance with the speed at which the car is approaching such retarder or passing through the same, the speed of the car being preferably determined by the time required for a car to travel a redetermined distance, that is, by the timeistance interval principle.

Other objects, of the present invention reside in the provision of means 'for automatically determining the degree of pressure to be exerted upon the brake shoe acting on a particular car depending on the weight of such car.

Other objects, purposes and characteristic features of the present invention will appear from the description thereof, when considered in connection with the accompanying drawings.

In describing the invention in detail, reference may be made to theaccompanying drawings in which V Fig. 1 is a layout view of a ladder track with a plurality of classification tracks branching therefrbm having an automatically controlled car retarder embodying the present invention applied thereto, of which the various mechanisms have been shown conventionally Fig. 2 shows on an enlarged scale and in detail one of the five control treadles shown in Fig. 1 of the drawings;

Fig. 3 shows a modihed'form of treadle and associated mechanism more particularly applicable to a railway system where some of the cars to be classified have four wheel trucks and others have six wheel trucks, which ii. used in the circuit combination shown in Fig. 1 constitutes automatic retarding mechanism in which the degree of braking of each of a plurality of cars coupled together is determined by the speed of such cars; .7

Fig. 4 shows how a large number of treadles such as shown in Fig. 3 may be connected in the system shown in Fig. 1 so as to have different treadles act upon the same time controlled mechanism; and,

Fig. 5 shows the apparatus and circuits contained within the mechanism casing CRM shown in Fig. 1.

In a car classification system the cars of numerous long freight trains are detached one or a few at a time, are accelerated in any suitable manner as by running them off of a hill or hump, which cars are then switched into the proper track after which they are retarded by suitable means so as to avoid detrimental impact with cars already standing on such track. In this connection reference may be had to my prior Patent No. 1,681,131 granted August 14, 1928, in which Fig. 1 shows such a classification system in a general way. It is however desired to be understood that classification systems may take many various forms, the one to which reference has been made being merely a typical illustration of such a system, and that the cars may be accelerated by other means than the hump shown in this prior application. If cars have been classified in this-away new freight trains may be made up by the various cars which have reached the same destination, namely the same classification track.

In order to illustrate how the present invention may be applied, the invention has been shown, applied to a car retarder system of the track brake type, such as shown in the rior application to Howe Ser. No. 70,599 led November 21, 1925. This car retarder comprises shoe beams 33 dis osed on opposite sides of the rail 1 of a railway track, the particular railway track illus trated being a ladder track from which diverge the classification tracks 2, 3 and 4. These shoe beams 33 are at times, through the medium of springs,yieldingly urged toward the track rails by suitable car retarder mechanism contained in the casing CRM, the degree of pressure exerted by the shoe beams 33 depending upon which one of the live control wires leading to the contacts L", L, L L or L of the lever L, or leading to the control relays R", R, R R or R, is energized. The energization of any one of these wires, except the ofi wire VV will cause the shoe beam 33 to apply pressure to the car Wheels through the medium of the car retarder mechanism as determined by the position of this car retarder mechanism, and the particular circuit so energized will, after the mechanism has been moved to the corresponding position, be opened in the car retarder mechanism casing (JRM in a man-' ner as clearly described in the prior application to Howe. It should be noted that a selecting lever SL has been provided for connecting the five control wires of the car retarder mechanism to either the hand operated lever L or to the automatic-control mechanism including the relays R, R, R, R and R. This lever SL has been shown in the normal automatic position, that is, with the lever SL in the position shown the car retarder is controlled automatically. If this lever SL is moved to the dotted position the car retarder mechanism CRM may be controlled by the manuall operable lever L, which lever is preferab y housed in a suitable tower so located that the car retarder is clearly visible.

The control relays R", R, R, R, and R, each contain an upper high resistance winding 5 and a bottom low resistance winding 6. It readily appears that if the upper winding of any one particular relay is energized for any reason its armature 7 will be attracted so as to connect the positive terminal B of a suitable source of energy to the car retarder mechanism CRM through the winding 6 and by reason of the flow of current in this latter circuit the armature 7 will be maintained closed in spite of the removal of ener from the upper winding 5.

Referring to ig. 5 which shows the complete wiring arrangement for a retarder and its control mechanism CRM embodying the present invention, the motor 90, which if rotated in one direction increases the braking action of the brake shoes 33 and if rotated in the reverse direction decreases this braking action, is preferably one of the compound wound type, havin a shunt field winding 210 and a series fie d w1nd1ng 211, the latter being connected in series with a brake magnet windin 212, the armature 216 and the commutating field winding 213 of the motor. As indicated, the shunt winding 210 is always energized, whereas the series winding 211 and the commutating winding 213 are energized only while the motor armature is energized either because current is applied thereto or because of current flow due to regenerative braking. The brake magnet coil 212 acts magnetically on the brake 214 to release the brake while current is being applied to the motor. For the purpose of controlling the motor by the manually operable lever L or the automatically controlled stick relays R, R, R, R and R", the automatic cutout circuit controlleis comprising the cams C", C, C, C and C", operating contacts 142, 142, 142, 142 and 142, cooperating with stationary contacts 138 -139", 138139, 138 -139, 138 -439 and 138--139, are provided. These cutout circuit controllers also serve to drop out the stick relays R, R, R, R and R. Further, the double throw electromagneticall operated contactors R and F and a relay ii are required for reasons ap arent from the drawings. These cams C, 8 C, C and C will rotate in the direction of the arrows shown thereon as the braking of the car retarder is increased. The forward operating contactor F is in its abnormal active position when the retarde is .o be moved to a closed or increased braking position, and the reverse contactor R is energized to its abnormal position when the car retarder is to be moved toward the open or reduced braking position. The forward contactor F is operated to its abnormal osition as represented by the dotted lines 1f the coil F is energized, at which time the contact 217 is opened and the contacts 218 and 219 are c osed, whereas if the coil R is energized, contactor R is operated to its abnormal dotted position and the contact 220 is opened, and the contacts 221 and 222 are closed. The magnet windings R and F 2 are connected in multiple and directl across the armature of the motor 90, and t e energization of these coils aids the springs 223 or 224 in returning the particular contactor to its normal position after the winding R or F as the case may be, is again deenergized, after having been energized. In other words, while either the contactor R or the contactor F is moved to its abnormal dotted position, its corresponding coil R or F is not energized and therefore the magnetic attraction due to energization of R or F need only be sufiicient to operate the contacts in opposition to the force of the springs 223 or 224; whreas upon the deenergization of sire one or the other of the coils R or F after having been energized causes the springs 224 or 223, together with the magnetic force due to the energization of the coils R or F to return the contactor to its normal position.

In other words, the armature 216 of the motor 90 is presumably not energized at the time the retarder is to have its adjusted position changed, so that the coils R and F are both dead, so to speak, when one or the other of coils R and F are energized and the energization of coil R or F need only overcome the force of its corresponding spring 224 or 223. On the other hand, the application of current to the motor 90 causes a counter electro-motive force to be generated therein which applies current to coils R and F so that the deenergization of the coil R or F whichever was energized at the time, causes both the energized coil It or F together with its corresponding spring 224 or 223 to return the contacts to normal, thus causing a very quick break of the circuit, blowout coils being preferably used to aid in disrupting the are upon opening of these contacts.

In order to permit the operator to accelerate the motor or increase its torque he may shunt certain resistance units connected in series therewith, the arrangement being such however that these resistance units can not be shunted until an interval of time after current has been applied to the motor through such resistance units. In other words, current is applied to the motor in two steps, the time spacing between these steps bein controllable by the operator or if dethese resistance units need not be shunted at all. In the particular construction shown, the relay H is used for this purpose, and this relay may be energized to shunt such resistance units if both the push button 152 is depressed and one or the other of the contactors R or F is in its active position. In other words, if a particular stick control relay is picked up the car retarder will be operated to a position corresponding to the relay which was operated and if this car retarder has reached such position the control circuit is opened within the mechanism casing CHM and the stick relay is again dro ped.

It shou d be noted that a selecting relay SR has been provided. This selecting relay SR is one of the mechanical stick type and comprises coils and 11 containing armatures 12 and 13 therein, respectii'ely, these armatures being connected by non-magnetic insulating material as shown, which insulating material carries contacts 14 and 15. From this construction it readily appears that the energization of one or the other of the windings 10 and 11 will, if the relay is not already in that position, cause the armatures 12 and-13 to be shifted toward the energized winding, and that the armatures 12 and 13 and the contacts 14 and 15 will remain in such position until the other of the coils is energized. In this connection it should be noted that when the selecting relay SR is in its normal position the wires W, W and W are all connected to the wire X and that with the selecting relay SR in its left hand abnormal position the wire W is connected to the wire X and the wire W is connected to the wire X.

This selecting relay SR is used to limit the pressure which the brake beams 33 may exert against the wheels of a moving car; the wires X and X if disconnected, as they will be when the relay SR is operated as the result of a light car having entered the retarder, will not permit the car retarder mechanism CRM to be operated to either the third or fourth position, it being understood that wire X? corresponds to the wire connected to contact L and wire X corresponds to wire 232 of Fig. 19 of the above referred to Howe application. This selecting relay SR is automatically controlled by weighing mechanism W'M which may take any suitable form. For instance, in practice this weighing mechanism WM may be a weigh bridge or scale for indicating the Weight of the car and which will have contacts associated therewith which are closed during the passage of a car providing such car weighs more than a predetermined amount. Also, this weighing mechanism WM may comprise a rail deflection contact which closes a circuit in response to deflection of the rail or rails so long as a car exceeding a predetermined weight passes over such rails. This weighing mechanism WM has .been shown conventionallv, and in this conventional showing a movable contact 20 is held in. its normal position by spring 21, this spring 21 and contact 20 being so associated with the rail of the railway track that the contact 20 bridges the stationary contacts 22 and closes a circuit beginning at one terminal B and ending at another terminal C of a suitable battery including the coil 10 of the selector relay SR if a heavy car passes over such rails. In other words, the coil 10 of the selector relay SR is energized it a car weighing more than a certain amount passes by the location of the weighing mechanism IVM. When the car in question has passed entirely through the car rctarder it engages a trcadle which treadlc through the medium of contact 23 momentarily energizes the coil 11 of the selecting relay SR and thereby returns the selecting relay SE- to its normal position.

In order to determine the speed of a car approaching or passing through the car retarder several time element relays T3 and Tilt and TR have been provided. Each of these time element relays includes a coil 24 having a movable armature or core therein fastened to, but insulated from, a movable contact 26, which contact is adapted to engaging stationary contacts K", K, K K, and la. The movable contact 26 is free to move upward very quickly upon energization of the coil 24, but if this coil 24 is deenergized the movable contact 26 will very radually gravitate to a lower position. his gradual return of the contact 26 is due to the retarding effect of the dash pot 27, having a valve t pe piston 28 therein, and although this va ve type piston 28 permits free upward movement, downward movement of the iston 28 is retarded by the restricted openlng 29 in the dash pot 27.

In the particular form of the invention illustrated there are provided treadles T, T, T, and T having contacts 41, 42, 43, and 44 associated therewith, which contacts are preferably closed during the passage of the first wheel of the car running on that rail but not during the passage of the second, third and fourth wheel of such car. One form of mechanism for accomplishing this desired function is shown in Fig. 2 of the drawings.

Referring to Fig. 2, the treadle T in the conventional form shown consists of a vertically disposed plunger extending through a hole contained in the rail 1 of the railway track, which plunger T is pivotally fastened to the arm 30, which arm 30 is pivoted on a pin 31 and has a spring dog 32 connected to the end thereof. This dog 32 cooperates with a ratchet wheel 34 having the same number of teeth therein as the number of wheels on one side of a car, which in the particular arrangement shown is four because the freight car F which is intended to represent freight cars of the usual construction, have only four wheels on each side thereof. The parts are so proportioned that the passage of a car over the treadle T wil cause the ratchet wheel 34 to be moved through an angle of 90 and if this treadle T is released the spring 36 will return the treadle T as well as the dog 32 back to its normal position so that the passage of the second wheel of the car over this treadle T will cause another 90 rotation of the ratchet wheel 34. The ratchet wheel 34 is fastened to the rotatably supported shaft 37 by suitable means, such as a key, and to this shaft is secured a cam 38 which through the medium of the roller will depress the contact 41 against the tension of the spring 42 during the passage of the first wheel of the car, but will not cause such depression of the contact 41 during the passage of the second, third and fourth wheel of the car. In other words the treadles T T etc. are of such construction that their corresponding contacts are operated once for every four wheels which depress the treadle thereof.

Operation In order to get a clear understanding of the operating characteristics of the system illustrating an embodiment of the present invention, let us consider the passage of a car along the track rails 1 and through the car retarder conventionally shown. Let us assume that the car F has been accelerated by suitable means not shown in the drawings in the direction of the arrow and that this car F is so light that it will not cause closure of the contacts 20-22. When the first wheel of the car F passes over the treadle T it causes closure of the contacts 4145, thereb energizin the coil 24 of the timing relay R throng i a circuit leadin from the terminal B of a suitable source 0 energy, through the contacts 41-45, wire 46, winding 24 of the timing relay TR, to the common return wire C connected to the other terminal of said source of energy. The closure of this circuit causes the timing relay TR to quickly move its movable core and in turn contact 26, to the extreme upper dotted position in engagement with the stop and in contact with the stationary contact K. As the next three wheels of the car pass over the treadle T the contacts 4l-4 are not closed because there is merely idle movement of the ratchet wheel 34 (see Fig. during these three depressions of the treadle T. Let us assume that the car F is moving at such a high rate of speed that the movable contact 26 of the timing relay TB is still in engagement of the stationary contact K when the first wheel of the car F strikes the second treadle namely the treadle T As the first wheel of this car F depresses the treadle T the contacts 42-47 will momentarily close, thereby energizin the coil 24 of the timing relay TR throug the following circuit 2- beginning at the terminal B of a source of ener y, contacts 42-47, wires 49 and 50, win ing 24 of the timing relay TR to the common return wire C connected to the other side of said source. This momentary energization of this winding causes the movable contact 26 of the timing relay TR to assume the extreme upper dotted position. Also this momentary closure of contacts 42-47 causes energization of the high resistance winding 5 of the stick relay B, it being remembered that the speed of the car F was so high that the contact 26 of the timing relay TR would not allow sufii cient time for this contact to leave the stationary contact K by the time the first wheel of the car reached the treadle T; it should also be remembered that the car in uestion is so light that its passage over the weighin machine WM did not cans? o eration o the selecting relay SR. This circuit for the high resistance winding 5 of the stick relay B may be traced as follows :beginni ng at terminal B, contact til-e7, wires 49 and 51, contact 26 of the timing relay Til contact li oi this same timing relay TR, wire Z the high resistance winding 5 of the stick relay it", wire W, contact 14 of the selecting relay SR, wire X through the mechanism GEM of the car retarder more specifically disclosed in the application of Howe heretofore mentioned, to the common return wire C connected to the other side of said source of energy. The completion of this circuit causes the armature '2 of the stick relay to be attracted thereby closing a series stick circuit for operating the car retarding mechanism and maintaining the relay R' energized, which may be traced as follows :--beginning at the terminal B. contact 'Z of the stick relay Fi the low resistance winding 6 of this relay, wire W contact- 14, wire X contact n2 contact 139 wire 24:5, contactor E to the common return wire C. The closure of this low resistance stick circuit applies sufficient current to the car retarder mechanism to cause the mecha nism to be operated from the 05 position, or zero position, to the position 2 to which the retarder is moved upon energizing wire X in which position sufiicient braking will he efiected for light cars it being understood that a light car should. not be retarded as effectively as a heavy car reason of the tendency of the car wheels to rise up be tween the brake shoes of the retarder if the braking pressure exerted by these brake shoes is excessive. It should be noted that if in the meantime the contact 26 of the tining relay 'lR has moved ofi of the stationar contact K this will not in any way ailect the condition of the stick relay it", because this stick relay is energized through the stick circuit including the low resistance winding 6 assuming that the armature or contact 7 of this relay is still attracted. As soon as the car retarder mechanism has oper ated the car retarder to the second braking position the stick circuit for the relay R is broken at the contact 142 (see l i 5) within the mechanism casing Gilli/l an the relay R is ale-energized, for reasons heretofore explained.

in exactl the same man oi the car rom the tread T will cause one of the R", or R to be energized distance of movement I" the contact 26 of the timing relay Til? during the time interval required for the car to move from the treadle T to the treadle T In other words, if the car in moving from the treadle T? to the treadle T had consumed so much time that the contact 26 of the timing relay TR would have been permitted to move all the way back to its normal position in contact with the stationary contact K", the sticlr relay would have been picked up and through its stick circuit including the wire W" and the contact 142 (see Fl 5) would have operated the car retarder RM to the 0d or zero position. in the same manner as just described the timing relays TR, TR and T3 are energized to control the retarder depending on the speed of the car when moving from one treadle to the next succeeding treadle.

Let us now assume that a heavy car is moving from left to right and that its passage over the weighing mechanism WM causes closure of the contacts 2022. The closure of these contacts 2022 completes the circuit for energizing the coil 10 of the selecting relay SR, which circuit may readily be traced in the drawings. The completion of this latter circuit causes the selecting relay SE to shift its contacts 14: and 15 to the left so as to connect the wire W with the wire X and connect the wire V f to the wire X When the first wheel of the heavy car strikes the treadle T it closes an energizing circuit for the coil 24 of the timing relay TR thereby causing the contact 26 thereof to be moved to the dotted position. The passage of the next three wheels of this car will not effect closure of the contacts 4il45 for reasons heretofore given.

Let us assume that the contact 26 has moved to engage the stationary contact K during the time that this heavy car moved from the treadle T to the treadle 'l. It will be noted that the closure of contacts 42%? upon the arrival of the car at trcadle T applies energy to the stick relay R throu h the following circuit B, contacts 12.2%? wires El-51, contact 26 of the timing relay 'llit stationary contact K wire Z high resistance winding 5 of the stick relay R wire V7 contact 15 (which has now been shifted to the left) wire K through the contact 142 which now assumes its right hand position through the relay F in the car retarder mechanism (see Fig. 19 of said Howe application) to the common return wire C. The resistance of the circuit just traced is so high that insufiicient current flows to cause operation of the car retarder mechanism CHM and therefore the car retarder brake shoe beams 33 will not yet be operated. The closure oil this pick-up circuit for the stick relay E effects closure or the following stick circuit by reason of the attraction of the armature '7 :--beginning the terminal B, contact or armature 'Z' of the relay R the low resistance windingof this relay wire W contact 15 wire X contact a 142 (see Fig. 5), relay F through the mechanism oi the car retarder, to the comlltl IllS

mon return wire C. The completion of this circuit causes the car retarder mechanism to be moved to the third braking position which will effect a hi her degree of braking than does the secon braking position to which the car retarder was operated when the light car passed therethrough, for reasons heretofore explained. It should especiall be noted that even though the heavy car ust considered moved at a lower speed from the treadle T to the treadle T than did the light car, this heavy car was retarded more severely than was the li ht car. The reason for the need of this ad itional braking is that the amount of retardation necessary to retard a car depends lar ely on the weight of such car, because the inetic energy stored in such moving car is directly proportional to the weight thereof. In this connection it should be noted that the car retarder may assume the position zero, position 1 or position 2, when a light car passes therethrough, but may assume any of the five positions when a heavy car passes therethrou h. In other words, the present invention oes not only automatically fix the re tardation in accordance with the speed at which the car to be retarded travels but also fixes the amount of retardation in accordance with the weight of such car.

Mada d construction-Although freight cars 0 the usual type have four wheel trucks, that is have two such trucks thus resulting in four wheels on each side of the car, the tendency of car construction is directed toward six wheel trucks, and in order to apply the present invention to a system where the cars to be classified may have either four or six wheels on each side thereof an arrangement has been shown in Fig. 3 of the drawings whereby the treadle if once depressed will remain depressed until the car has moved a full car length after such depression, after which the treadle will be released. In Fig. 3 of the drawings has been shown a track rail which has treadles T and T etc., associated therewith. Each of these treadles is fastened to a sector 60 by suitable means, such as a pin 61, which seetor is ivoted about the pin 62. This sector is held in its normal position against the stop 63 by the spring 64. This sector has a contact 65 fastened thereto but insulated therefrom which is adapted when moved from its normal to its dotted position to momentarilv engage the contact 66, but cannot engage the contact 66 when it is moved from its dotted to its normal position. This by reason of the provision of the insulation 67 on one side of the contact 66, this contact 66 being ivoted on pin 69 and bein held in its nonna position by spring 68. The sector 60 is not only urged to its normal position by the spring 64, but is held in such position by t e brake shoe 70 held against the circumferential edge of the sector 60 by the spring 71. This spring 71 is guided by the pin 72 passing through the stationary lug 73 and having its other end connected to the core 71 I contained in the coil 75. From this construction it readily appears that if the treadle T is forced down the sector 60 is moved in spite of the brake 70 due to the tremendous force acting on this treadle. Ii now the wheel passes off of the treadle T" the spring 64 Wlll not be sufficiently strong to return the sector 60 so long as it is engaged by the brake shoe 70.

In accordance with one form of the present invention the treadles shown in Fig. 3 of the drawings are connected in the circuit arrangement shown in Fig. 1 of the drawings as conventionally shown in Fig. 4 of the drawings.

Operation 0 the modified constructions- Referring to igs. 3 and 4 and bearing in mind the construction shown in Fig. 1 to which the apparatus shown in Fig. 3 is applied in a manner as indicated in Fig. 4, let us assume that a car is moving from left to right over the track rails 1 in Fig. 4 of the drawings, and that it passes over the treadle T which is of a construction as shown in Fig. 3. The passage of the first wheel of the car over the treadle T causes it to be depressed and held by the brake shoe 7 O. During this movement of the treadle T from its normal to its dotted position there is a momentary engagement of the contact 65 with the contact 66, during which engagement energy is applied through wire 46 to the winding 24 of the timing relay TR (see Fig. 4) and is also applied through the wire 59 to the contact 26 of the timing relay TR. The application of current to the contact 26 of the timing relay TR will cause the car retarder to be moved to the zero or ofi position through the medium of W for reasons heretofore described in connection with Fig. 1 of the drawings if it did not already assume this position. The momentary application of current to the winding of the timin relay TR causes the contact 26 to be li ted to the extreme upper position against the stop (see Fig. 1). Let us assume that the car in question continues its movement from left to right and after an interval of time strikes the treadle T. Operation of the treadle T by the first car wheel of this car causes energy to be applied to the contact 26 of the timing relay TB. through wires 49 and 51, the application of which ener will pick up one of the relays R", R R, fi or R depending on the extent that the contact 26 of this relay has moved during the time the car has travelled from the treadle T to the treadle T and in turn will cause the car retarder to assume the proper braking position in accordance with the weight and the speed of the car in question; also, the depression of the treadle T causes current to be momentarily applied to the coil 75 associated with the treadle T parativel messes which energization of this coil releases the brake and permits the spring 6% to return the treadle T to its normal position. During the return of the treadle T to normal although the contact 66 will be moved no electric circuit is completed by reason of the insulated portion 67 heretofore mentioned. Also, the depression of the treadle T by the first car wheel of the car inquestion causes energy to be applied to the wind ing 2 of the timing relay TR through wires 49 and 50, so that this timing relay may determine the speed of the car while moving from the treadle T to the treadle T In the same we as described in connection with the treadle the passage of the car over the various other treadles will cause the retarder to assume a braking position tending to bring the car speed down to a predetermined value and hold it there. In the schematic arrangement shown in Fig. 4: 1t is assumed that the retarder used extends over the entire distance of the treadles T T either as a single retarder oras a series of separate retarders. Referring to Fig. 4 it will be noted that the nine treadles shown T to T inclusive, are so connected that every third treadle is connected to the same timing relay TR. This construction is a very economical arrangement by reason of the few timing relays and control relays required for a comlong stretch of track over which the spec of the cars is repeatedly checked at recurring space intervals.

In order to illustrate applicants invention it has for convenience been shown applied to a ladder track of a car classification slylstem although it is equally applicable to t e main lead either on the slope of the accelerating hump or at the bottom thereof, is applicable when the main lead diverges into the ladder tracks and is applicable to the classification track itself. Also although only one arrangement for braking a car in accordance with both its weight and its speed has been shown it should be understood that other arrangements may be used within the scope of the present invention; for instance, instead of determining the speed of the car by the time-distance interval principle it may be determined by a speed responsive device driven by the moving car. In other words, the particular arrangement shown has been illustrated to show typical application of the present invention rather than to the exact construction preferably used in practicing the invention or the scope of the same; and it is desired to be understood that various changes, modifications and additions may be made to adapt the invention to the particular classification system and the pan ticular type of retarder to which the invention is to be ap lied without departing from the scope oft e present invention or the idea of means underlying the same except as demanded by the appended claims.

What I claim is 1. In a combined manual and automatic car retarding system, the combination with a car retarder of the type in which suitable electrically controlled power operated mechanism is employed for determining the degree of retardation to be effected, manually operable means for controlling the power operated mechanism of such car retarder, automatic means for controlling the power operated mechanism of such retarder, and selecting means whereby either said manually operable means or said automatic means may be selected and rendered capable of controlling the power operated mechanism.

2. In a combined manual and automatic car retarding system, the combination with a car retarder of the type in which suitable electrically controlled power operated mechanism is employed for determining the degree of retardation to be effected, manually operable means for controlling the power operated mechanism of such car retarder, automatic means for controlling the power operated mechanism of such car retarder, and manually operable selecting means which if in one condition permits said power operated mechanism to be controlled by said manually operable means and which if in another condition permits said power operated mechanism to be controlled by said automatic means.

3. An automatically controlled car retarder of the track brake type comprising, brake shoes disposed alon the side of the track for engaging the si es of the wheels of passing cars, power operated means for adjusting the pressure at which said shoes are urged against the wheels of a passing car, and automatic means for repeatedly checking up the s eed of a car as it moves through the retar er and for operating said power operated means to adjust the pressure exerted by said brake shoes in accordance with actual speedpf the car at the time.

4. An automatic car retarder .system -for retarding cars in accordance with their actual eed' comprising, a car retarder or the traih brake type in which brake shoes along the track engage the wheel sides of a railway car, power operated means for adjusting the pressure exerted by said brake shoes, treadles along the track for manifesting when a car passes a particular point, a timing device for each successive pair of treadles for determining the speed of the car while traveling from one treadle to the next treadle, and means for controlling said power operated means to cause-said brake shoes to be applied to an extent depending on the speed of the car.

5. An automatic car retarder system according to claim t in which there are fewer timing devices than there are spaces between successive treadles.

(3. An automatic car retarder syst cording to claim 4, in which the vari. d: vices are so correlated that each of the timing devices is capable of determining the speed of a car moving through any one of several different sections of t :l:.

T. An automatically controiled car retarder. of the track brake type comprising, brake shoes disposed along he side of the track for engaging the sides 01' the wheels of passing cars, power operated means for adjusting the pressure at which said shoes are urged against the wheels of a passing car, and automatically controlled means for controlling said )ower o crated means in accordance with t e spec atwhich a'car is moving through said retarder and in accordance with the weight of said car.

8. An automatically controlled car retarder of the track brake type comprising, brake shoes disposed along the side of the track for engaging the side of the wheels of passing cars power operated means for adusting the pressure at which said shoes are urged against the wheels of a passii car, and automatic means for partly releac i the braking action or increasing the braking action of said retarder as a car asses through said retarder depending on tie rate of retardation of said car.

9. An automatically controlled car retardei' of the traclr. brake type comprising, brake shoes disposed along the side of the track for the sides the wheels of passing cars, power operated means for adjusting the pressure at which said shoes are urged against the wheels of a passing car, and automatic means having its operation dependent upon the speed at which a car is moving through the retarder for increasing or decreasing the hr "ng action of said rttarder as conditions rec .re to obtain the proper braking action.

10. An automatically controlled car retarder of the track brake type comprising, brake shoes disposed along the side of the track for engaging the sides of the wheels of passing ears, power operated means for adjusting the ressure at which said shoes are urged against the wheels of a passing car, and automatic means or" the time-distance interval type functioning in accordance with the speed at which a car is movin throu h said retarder for controlling said retarder to either increase or decrease the braking action of said retarder depending upon the speed of said car.

11. An automatically controlled car retarder of the track brake type comprising, brake shoes disposed along the side of the track for engaging the sides of the wheels of passing cars, power operated means for adjusting the pressure at which said shoes are urged againstthe wheels or a passing car, and plurality of slow-acting devices each a sociated with a diilerent stretch of track and e ch assuming a condition depending upon the speed of the car when moving through the associated stretch of track and each controllin said retarder in accordance with the speed of said car when passing throw such stretch. of track.

12. An automatically controlled car retardcr of the track brake type comprising, brake shoes disposed along the side of the track for engaging the sides of the wheels of passing cars, power operated means for adjusting the pressure at which said shoes are urged against the wheels of a passing car, and automatically controlled means for controlling said power operated means in accordance with the speed at which a car is moving while it is being braked by said retarder and also in accordance with the weight of said car In testimony whereof T atlix my si mature.

CHARLES w. PRES ()TT.

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