US2817013A - Safety track switch control system - Google Patents

Description

Dec. 17, 1957 R. F. WELLS SAFETY TRACK SWITCH CONTROL SYSTEM Filed Nov. 18, 1954 4 Sheets-Sheet l FIGQIA INVENTOR. R.F.WELLS HIS ATTORNEY Dec. 17, 1957 R. F. WELLS SAFETY TRACK SWITCH CONTROL SYSTEM Filed Nov. 18, 1954 4 Sheets-Sheet 2 FIG. 18.

3A 3B 5 66- 5T 2-7T D Mi N A S n W w W 6 3 T v m a B EW 6 A R mT T FR B OE Hm E S mm LP INVENTOR. RFWELLS HIS ATTORNEY United States Patent Ofi 2,837,913 Patented Dec. 17, 1957 ice SAFETY TRACK SWITCH CONTROL SYSTEM Robert F. Wells, Rochester, N. Y., assignor to General Railway Signal Company, Rochester, N.

Application November 18, 1954, Serial No. 469,752

6 Claims. 01. 246-161) This invention relates to safety track switch control systems for railroads, and it more particularly pertains to the automatic control of a railway track switch in accordance with the speed and/ or class of an approaching train.

When a railway grade is such as to be dangerous in case the brakes of a train proceeding down the grade should fail to keep the train under control, a derail or safety track is often provided having sand on the trackway in which a train with insuflicient brake control may be brought to a stop with a minimum amount of damage. General practice is that a switchman is required at the safety track to operate a track switch connecting the safety track to the main track in accordance with whether or not an approaching train is under safe braking control. The normal position of such a track switch is in alignment for traflic into the safety track.

The system according to the present invention eliminates the need of a switchman stationed at the safety track, and provides automatic means for governing the safety track switch in accordance with the speed of an approaching train. It is further provided that by the use of track circuits in approach of the safety switch, it can be determined as to Whether the approaching train is a passenger or a freight train. If it is a freight train that is approaching the safety track, the safety track switch is reversed only if the speed of the train is below a given limit as determined by a timer. If it is a passenger train that is approaching the safety track, the safety track switch is reversed only if the speed of the train is below a higher given speed limit as determined by another timer. The safety switch is automatically operated back to its normal position after passage of a train upgrade, even though there has been no action taken on the part of the operator of a centralized traffic control machine providing supervisory control of the track switch. This is to provide derail protection in case the rear end of the train proceeding upgrade should become uncoupled and out of control.

An object of the present invention is to automatically operate a track switch in accordance with the speed of an approaching train.

Another object of the present invention is to automatically detect the class of a train and to select a timer for operation in accordance with the class of train detected.

Another object of the present invention is to automatically operate a track switch in accordance with the speed and class of an approaching train.

Another object of the present invention is to operate a track switch in accordance with the completion of operation of one of a plurality of timers selected in accordance with the class of an approaching train.

Another object of the present invention is to detect by track circuits the class of a train approaching a track switch, detect the speed range of the train and operate the track switch in accordance with whether or not the speed of the train exceeds a predetermined maximum speed for the particular class of train detected.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference is made to the accompanying drawings in which similar reference characters are used to designate corresponding parts and in which:

Figs. 1A and 1B when placed side by side illustrate one embodiment of the present invention as applied to the control of a safety track switch between two passing sidings;

Figs. 2A to 26 are track diagrams illustrating diiferent stages in the progress of an eastbound train; and

Figs. 3A to 36 are diagrams illustrating the sequence of operation of relays and control devices for traffic conditions as illustrated in the respective diagrams of Figs. 2A to 2G.

Conventional schematic diagrams have been used for disclosure of the system organization in the drawings, the drawings being prepared more particularly to facilitate an understanding of the mode of operation and the principles involved, rather than to show the details in construction and the specific arrangement of components that may be provided by those skilled in the art in accordance with the requirements of practice. The symbols and have been used to indicate connections to the respective positive and negative terminals of suitable batteries or other sources of direct current, and the symbols (B+) and (B) have been used to indicate connections to the respective positive and negative terminals of a split battery having a center tap (CN) The track layout for one embodiment of the present invention is illustrated in Fig. 1B as being a stretch of single track 10 having traflic in both directions. It is assumed that traffic to the right is down grade and eastbound trafiic. Passing sidings A and B are associated with the stretch of main track 10 and are spaced by a block including track sections 2T, 5T, 2-7T, A4T, B4T and 3T. Adjoining the track section 3T at the east end is a track section 6T. These track sections are used in the conventional manner for the control of the signals, and in addition the track sections A4T and B4T are used to govern the operation of timers associated with the operation of a track switch 3W. The track section A4T is used to determine by its length as to whether short or long trains, generally passenger or freight trains respectively, are approaching the track switch 3W. Thus, the track section A4T is made of a length such that the longest passenger train to be expected can just be in cluded within the limits of the track section. A track relay TR is provided for each of the track sections and is controlled by a conventional track circuit (not shown). Thus, track relays 2-7TR, A4TR, B4TR, 3TR and 6TR are provided for the associated track sections 27T, A4T, B4T, ST and 6T respectively. Passing siding A is connected at its right hand end to the main track 10 by the track switch 2W, and passing siding B is connected at its left hand end to the main track 10 by a track switch 4W.

A sand track is provided for stopping trains which cannot be controlled in going down the grade, and this track is connected normally to the main stretch of track 10 by a track switch 3W at a point just west of the west end of the passing siding B. The sand track is constructed with sand on the trackway so as to stop any train with the minimum amount of damage. It is to be understood that other means for stopping trains on this track could be used in accordance with the requirements of practice, such, for example, as car retarders, derails and the like. The track switches are power operated by conventional power switch machines SM, the switch machine 35M being provided for the power operation of track switch 3W.

Signals of any suitable type are provided for governing traflic in both directions through the main stretch of track and into the passing sidings. The signals illustrated are assumed to be of the searchlight type, signals 2A, 2B, 4, 6A and 6B being provided for governing eastbound traffic and signals 7A, 7B, 5, 3A and 3B being provided for governing westbound traffic.

It is assumed that the signals at the ends of the passing sidings are controlled by a suitable centralized traffic con trol system such, for example, as the code communication system disclosed in the patent to W. D. Hailes et al., No. 2,399,734, granted May 7, 1946. Respective switch and signal control relays 3WZ, 6RGZ and 7LGZ'are assumed to be subject to control by the operator of a centralized trafiic control system such as that of the Hailes et al. patent, for example, but for simplicity, the relay 3WZ is illustrated as being energized directly from a switch control lever SML that is assumed'to be provided on the centralized trafiic control machine. The relay 3WZ is of the magnetic-stick type and itis provided for governing the operation of track switch 3W. Relays 6RGZ and 7LGZ are provided for governing signals 6 and 7.

Timing devices PTE, FTE and TE are provided in association with a repeater relay TEP for the purpose of determining when the speed of an approaching train is such that the train is under control and may proceed safely down the grade over the track switch 3W in its reverse position. These timing'devices can be of the .type disclosed, for example, in the patent to O. 8. Field, No. 2,378,293 granted June 12, 1945.

Stick relays 7ASPS, BPS and BTS are providedfor the control of relay TEP, particularly for governingithe operation of the track switch SW for westbound traflic and switching operations.

Lock relays 3L and 3LSare provided for insuring safe operation of the track switch SW, and a:relay 3WPP is provided to restore track switch 3W to its former position in case of an obstruction which prevents full operation of the track switch 3W. The operation .of the track switch 3W is normally governed by a relay SWPP.

Switch repeater relays 3NWP and 3RWP are provided for repeating the respective normal and reverse locked positions of the track switch 3W, these relays are controlled according to conventional practice by a suitable switch circuit controller that is-assumed to be included in the switch machine M.

Relays 7H and 4H are relays used for the control of signals 7 and 4 respectively in accordance with the condition of occupancy of the trackway in advance of the associated signals.

Time locking relays 6A8 and 7A5 are for providing a predetermined time delay before a track switch can be operated after signal 6 or-signal 7 has been ut to stop. These relays have thermal time element devices 6TH and 7TH respectively associated therewith. Relays 6RP and 7RP are provided for repeating the stop positions of the mechanisms of signals 6 and 7 respectively.

Having thus considered the organization of the apparatus in general, a more detailed consideration will be given to the circuit organization upon consideration of typical operating conditions of the system.

Operation The normal conditions of the system are assumed to be those conditions where there are no trains present inthe track layout, the signals subject to centralized traffic control are at stop in correspondence with their associated levers on the centralized 'tralfic control machine (not shown), and the track switches are in their normal positions in correspondence with associated levers SML on the control machine. In accordance with there being no trains present, the track relays TR are in their energized positions, and in accordance with the signals being at stop, the associated stop repeater relays, such as the relays 6RP and 7RP for the signals 6 and 7 respectively are in their energized positions. The relays 6A5 and 7A5 which are associated with signals 6 and 7 respectively are normally maintained in their picked up positions by the energization of their stick circuits. Thus relay 6AS is normally energized by a circuit extending from including front contact 11 of relay 6RP, front contact 12 of relay 3TR, winding of thermal relay 6TH, front contact 13 of relay 6A8 and winding of relay GAS, to The resistance of the winding of relay 6AS is such as to prevent the operation of the thermal relay 6TH because of there being insufficient current passing through the winding of that relay to cause any appreciable heating eifect. Similarly, the relay 7AS is normally held up by a stick circuit extending from including front contact 14 of relay 7RP, front contact 15 of relay 3TR, winding of thermal relay 7TH, front contact 1.6 of relay 7A5 and winding of relay 7A5, to

Inasmuch as the signal 4 is an automatic signal, the home relay 4H for governing that signal is normally energized by a circuit extending from including front contact 17 of relay B4TR (see Fig. 1A), front contact 18 of relay A4TR, wire 19, back contact 20 of timer PTE, back contact 21 of timer PTE, back contact 22 of timer TE, back contact 23 of relay TEP, front contact 24 of relay 3TR, front contact 25 of relay 3NWP, front contact 26 of relay 7AS, front contact 27 of relay 3WPP, and winding of relay 4H, to This relay when picked up checks that the timers are properly restored and energizes signal 4 through its front contact 28 to cause signal 4 to display a caution indication. Signal 4 is a two position signal operable to display yellow or red aspects when the signal mechanism is energized or deenergized respectively.

The lock relay 3L is normally energized by a circuit extending from including back contact 29 of relay 7LGZ, back contact 30 of'relay 6RGZ, front contact 31 of relay 3TR, front contact 32 ofrelay 6A8, front contact 33 of relay 7A8 and winding of relay 3L, to Relay 3LS is also normally energized by its pick up circuit which is closed at front contact 34 of relay 3L. A stick circuit is provided for relay 3LS which is closed, when the switch machine 3SM is in midstroke, through back contact 35 of relay 3NWP, back contact 36 of relay SRWP, and front contact 37 of relay 31.5.

The relay 7H, which is provided for the control of the clearing of signal 7 does not have its control/circuit illustrated, but it is to be understood that this relay is energized in accordance with the entire block between the passing sidings A and B being unoccupied by a westbound train and in accordance with there being no signal clearing control set up from the control ofiice for the clearing of the opposing signal 2. The circuit for the control of relay 7H can be provided, for example, as is fully disclosed for the control of relay 71-1 in the patent to S. N. Wight No. 2,082,436, granted June 1, 1937.

The stick relay 7ASPS is normally energized by a circuit extending from including front contact 38 of relay 7AS, front contact 39 of relay 3TR, wire 40, front contact 41 of relay 2-7TR, front contact 42 of relay A4TR, front contact 43 of relay B4TR, and winding of relay 7ASPS, to A stick circuit is also normally closed for this relay including front contact 38 0f relay 7AS, wire 44, and front contact 45 of relay 7ASPS.

The switch circuit pole changing relay 3WPP is normally energized through back contact 46 of relay SWRP.

To consider the mode of operation of the system upon passage of a train downgrade, it will be assumed that an eastbound train is approaching signal 2A. As has been heretofore pointed out, the clearing of the signal 2A causes the dropping away of relay 7H, and thus relay 7H is dropped away upon the transmission of a control from the control ofiice for clearing signal 2A.

Upon the approach. of the train, the operator of the centralized trafi'ic control machine controls the track switch 4W to a position in accordance with whether or not it is desired that the train shall enter the passing siding B, and the signal control lever associated with signal 6 is actuated to a signal clearing position. The operator of the control machine also operates the lever SML (see Fig. 1B) for actuation of the magnetic stick relay 3WZ to its dropped away position for the reversal of the track switch 3W. The controls designated by the operator of the control machine are sent out to the field, and in accordance therewith the relay 6RGZ is picked up, and the relay 3WZ is driven to its dropped away position. The lock relay 3L which is associated with track switch 3W is not dropped away upon the picking up of relay 6RGZ for clearing signal 6 because of energy being supplied to relay 3L through front contact 61 of relay 3NWP. Thus relay 3L is maintained picked up until the operation of track switch 3W is initiated.

It will now be assumed that the eastbound train enters the block between the passing sidings A and B and proceeds to a point to cause the dropping away of the track relay 2-7TR. The dropping away of this relay causes the picking up of relay BPS by the energization of a circuit extending from including back contact 47 of relay 2-7TR, front contact 48 of relay A4TR, front contact 49 of relay B4TR, front contact 50 of relay 7ASPS, and winding of relay BPS, to Upon the picking up of this relay, a stick circuit is closed through front contact 51 of relay BPS shunting contacts 48, 49 and 50 out of the circuit just described. Energy may also be applied to this stick circuit upon the closure of back contact 48 of relay A4TR and upon the closure of back contact 52 of relay B4TR.

As the train progresses further so as to enter the track section A4T, upon accepting the caution indication of the automatic signal 4, the timers PTE and FTE become initiated simultaneously. These timers become energized at this time through back contact 53 of relay 3WZ, wire 54, front contact 55 of relay BPS, front contact 56 of relay 7ASPS, front contact 57 of relay B4TR, back contact 58 of relay A4TR, wire 59, and back contact 60 of relay TEP.

The timers PTE and FTE have their times of operation set for the minimum times respective passenger and freight trains may consume in the front ends of the trains passing from the point of entrance to the track section A4T to the point of entrance to the track section B4T, and yet be under safe speed control. For a typical condition, this time may be comparable to a speed of 22 miles per hour for passenger trains and a speed of 8 miles per hour for freight trains. Thus, it will be seen that in view of the fact that both timers PTE and FTE are initiated at the same time, the timer PTE will complete its operation a substantial time before the. completion of operation of the timer FTE.

If the passage of a passenger train is considered, when the train is advanced to a point as illustrated in the diagram of Fig. 2D, the track relay 2-7TR becomes picked up before the track relay B4TR has been dropped away. If at this time the timer PTE has completed its operation, the system follows a sequence of relay operations as is illustrated by the sequence chart of Fig. 3D. This sequence of operations follows irrespective of whether or not the timer FTE has had time to complete its operation.

Upon completion of operation of the timer PTE, the relay TEP becomes picked up by the energization of a circuit extending from including back contact 53 of relay 3WZ, wire 54, front contact 55 of relay BPS, front contact 56 of relay 7ASPS, front contact 57 of relay B4TR, back contact 58 of relay A4TR, front contact 62 of relay 27TR, wire 63, front contact 64 of relay PTE, and winding of relay TEP, to 'lh is relay when picked up is maintained energized by a stick 'circuitextending from including back contact 53 of relay 3WZ, wire 54, front contact 55 of relay BPS, front contact 56 of relay 7ASPS, wire 65, front contact 66 of relay TEP and winding of relay TEP, to It will be noted that in order that the relay TEP may be picked up by the circuit that has been described, the front contact 62 of relay 2-7TR must be closed. It is this circuit selection that determines that the train approaching is short enough to be entirely contained within the track section A4T, and thus should be safely under control if proceeding at a rate up to 22 miles per hour.

The picking up of relay TEP causes the picking up of the relay 3WRP for application of energy to the switch machine 38M. Relay 3WRP is energized by a circuit extending from including back contact 53 of relay 3WZ, front contact 67 of relay TEP and winding of relay 2WRP, to This relay when picked up connects the positive terminal of a suitable source of direct current to the control wire 68 for the switch machine 3SM through back contact 69 of relay 3WZ, front contact 70 of relay 3WPP, front contact 71 of relay 3WRP, and front contact 72 of relay 3LS. The negative terminal of the source of direct current for operation of the switch machine is connected to the control wire 73 for switch machine 3SM through back contact 74 of relay 3WZ, front contact 75 of relay 3WPP, front contact 76 of relay SWRP, and front contact 77 of relay 3LS.

The circuit by which the relay 3L has been energized through front contact 61 of relay SNWP is opened when the switch machine 3SM starts its operation, and thus the relay 3L is dropped away because it is assumed that the relay 6RGZ has been picked up for the clearing of signal 6' and thus the back contact 30 of. relay 6RGZ in the circuit for relay 3L is open at this time. The dropping away of relay 3L, however, does not immediately cause .the release of relay 3LS upon the opening of front contact 34 of relay 3L because the relay 3LS is held by its stick circuit when the switch 3W is in mid stroke. This stick circuit is closed from including back contact 35 of relay 3NWP, back contact 36 of relay SRWP, front contact 37' of relay 3L5, and winding of relay 3LS, to

Upon completion of the operation of the track switch 3W to its reverse position, the reverse switch repeater relay 3RWP becomes picked up and relay 3LS is dropped away. Relay 3LS shunts the control wires 68 and 73 for switch machine 3SM through back contacts 72 and 77.

A circuit is then closed for clearing signal 6A or 6B as selected in accordance with the position to which the track switch 4W has been operated. The energization of either of these mechanisms 6A or 6B is through front contact 78 of relay 6RGZ, front contact 79 of relay 3RWP, and such other selections as are generally required as indicated by xxx and by the dotted line extending to the signal mechanism 6A and 6B. I

The slow release relay SWPP is deenergized upon the picking up of the switch control relay SWRP for initiating operation of the track switch 3W, but if there is no obstruction to complete operation of the track switch,

the track switch 3W completes its operation to its reverse position and picks up relay 3RWP in time to maintain relay 3WPP picked up by applying energization through front contact 80 of relay 3RWP. If the track switch 3W should be obstructed, the relay 3RWP would not be picked up, and thus the relay 3WPP would become dropped away. In other words, the relay 3WPP is made sufficiently slow in dropping away to hold over for the ordinary operating time of the track switch 3W so that this relay is dropped away on switch operation only provided the track switch 3W fails to complete its operation.

The dropping away of relay 3WPP when the track switch. 3W is in mid-stroke pole changes the control wires 73 and 68 by the shift ng of c n a ts 70 and' S, a

hus est s he. pera io f t e t ac s it h W1to i f rmer p siti nt len t of a tr i is. s h tha th a k ec o B4T-must be entered before the track section '2-7T is a te th m r pea e e y TE ca notibe Pic p p n compl i o t per tion f he timer-PI as ha be n desc ibed becau e th pick-up circui for r lay E i udin the time YEH requires the-closur 015 fr nt onta 6. of e ay -3 .l the l sur of ont contac 7 o r ay B4 R- i t e rain s o g i s ne essary t a h speed of t e train e c nid a y less a o a short t ain. so hat t e timer hich h s a l n time et ing hanth t me FIE has me t complet i operat on befo e e t of th trac s ct nn 134T. When he i erFTEc Pl te t ope a io wi t ac r ay 2- i i deenersiz t p s i n and thetra k re1ayB4TR pi k up a ci c t is l sed for t e pick n up of relay T P v tending from including back contact 53 of relay 3 Z W r front n act 55 f reI Y PS, f ont contact 56 of relay 7ASPS, front contact 57 of relay ,B4TR, back contact 58 of relay A4TR, back contact 62 ofrelay R., wire 1, front on ac 82 of relay FTE, a wind ng o l y E to The p k g up f r y TEP under these conditions establish s astick circuit for relay TEP that has been described for maintaining, this relay picked up irrespective of the condition of occupancy of the respective track sections 2-7T, A4T and B4T.

Upon the picking up of relay TEP as has been described in accordance with the completion of operation of the timer FTE, the track switch 3W is operated to its reverse position and the signal 6 is cleared in the same manner that has been described when it was assumed that the relay TEP was picked up by the completion of operation of the timer PTE.

It is further provided that if a train occupies the track section B4T for a predetermined length of time as measured by the timer TE, the relay TEP can be picked up and the track switch 3W can be operated to its reverse position. This timer is used particularly for switching moves, but it can also be effective for the normal progress of an eastbound train (as is illustrated in the diagram of Fig. 2G) if the train should not reduce its speed sufficiently within the track section A4T to have permitted either the timer PTE or the timer FTE to complete its operation, but should reduce its speed materially in the track section B4T before entering the detector track section 3T.

The circuit by which the timer TE is energized upon the dropping away of the track relay B4TR extends from (l) including back contact 53 of relay 3WZ, Wire 54, front contact 55 of relay BPS, front contact 56 of relay 7ASPS, back contact 57 of relay B4TR, Wire 83, back contact 84 of relay TEP, front contact 85 of relay STR and winding of relay TE, to Upon the picking up of relay TEP, the relay 3WRP is picked up by the energization of a circuit that has been described, and the picking up of this relay causes the power operation of the track switch 3W to its reverse position in the same manner as has been specifically described when consider-' ing the picking up of relay TEP in accordance with the completion of operation of the timer PTE.

To consider restoration to normal conditions of the apparatus after passage of an eastbound train, it will be -energiz ed according to the usual practicein centralized traflic control systems, but the closureof its back contact 30 in the circuit for the lock relay 3L cannot cause the picking up of this relay-because the circuit for relay 3L is open at this time at front contact'31 of relaySTR. The stick relay 6A5 becomes restored 'to its normally energized condition after the train has entered track sectionoT. The circuit by which the relay 6A5 is picked up extendsfrom (+),inc1u ding front'contact 11 of relay 6RP, back-contact 12 of relay 3TR, back contact'86 of relay 6TR;andiwinding of relay 6AS, to

'When the eastbound train leaves the track section B4T, the picking up of relay 'B4TR removes energy from relay BPS at back contact 52 and causes the relay BPS to be restored to its normally, deenergized position. The dropping away of relay BPS removes energy from relay TEP by the opening of front contact; 55 because relay BTS is in its deenerg ized position at this time as this relay is picked up only for a switching move for westbound traflic.

Relay TEP in dropping away causes the dropping away of relay SWRP by opening it circuit at front contact 67, the front contact 87 of relay 7H which is connected in multiple with front contact 67 of relay TEP being open at this time because of the presence of the train in the block between passing sidings A and B. The dropping away of relay SWRP pole changes the control wires 73 and 68 except that energy cannot be applied to these control wires until the picking up of the lock stick relay 3LS to close front contacts 72 'a nd'77 in the circuit for the control of the switch machine 35M. Relay 3L5 cannot'be picked up untilthepicking up of the lock relay 3L which in turn cannot be picked up until the track section 3T becomes unoccupiedin the rear of the train so as to close front ,contactfilofrelaylsTR.

When'the track section'ST becomes unoccupied in the rear of the eastbound train, the relay 7H is picked up, provided-there is no'following train in the block between the passing sidings A and B; The picking up of relay 7H causes the picking up of relay SWRP upon the closure of its front contact 87, assuming that the back contact 53 of relay SWZ is still closed. Also, when the track section 3T becomes unoccupied ,in the rear of the train, the closureof'front contact 31' of relay '3TR in the circuit for the lock relay 3L causes the picking up of that relay, which in turn, by the closure of its front contact 34, causes the picking up of the relay 3L8 to apply energy to the switch machine 33M of a polarity to maintain that switch machine in its reverse position until the operator at the control ofiice operates his lever SML back to its normal position. When this is done, the picking up of relay 3WZ reverses the polarity of energization of the switch machine 33M to cause the operation of the track switch 3W to its normal position. Under these conditions the control wires 68 and 73 for the switch machineSSM are energized through circuit selections that have been described when considering the normal conditions of the system.

For the particular embodiment of the present invention under consideration, the distance between the passing sidings A and B is such that it is not proposed to clear the signal 2A or the signal 213 for a following eastbound train movement until the first train has left the detector track section 3T. In order for the operator of the control machine to clear a signal 2A or 2B for a following train, it is necessary that he first operate his lever SML to its normal position for the operation of the track switch 3W to its normal position. When the switch 3W has b en, operated to its normalposition, an indication of its position is transmitted to the control ofiice. This indication ofthe normal position of the track switch 3W switch 3W to its reverse position in setting up a route for a westbound train is such that no timing is required,

provided that the block between the passing sidings A and B is clear of eastbound trains and that the signals 2A and 2B are at stop as is indicated by the energized condition of the relay 7H. With the relay 7H picked up, the closure of front contact 87 provides that the relay SWRP is energized whenever the operator at the control ofiice operates his lever SML to its reverse position as as to drive the magnetic stick relay 3WZ to its dropped away position. As has been pointed out, the picking up of relay 3WRP pole changes the control Wires 68 and 73 to energize the switch machine 3SM with a polarity for operation of the track switch 3W to its reverse'position.

It is desirable for safety purposes that the track switch 3W be restored to its normal position in the rear of a westbound train as soon as that train has passed out of the detector track section 3T. This gives derail protection in the rear of the train in case part of the train should become uncoupled and roll uncontrolled down the grade. Operation of the track switch 3W to its normal position under these conditions is accomplished be cause the relay 7H is in its dropped away position at that time and thus the relay 3WRP has been dropped away to pole change the control wires 68 and 73 for the switch machine 38M. Even though the back contacts 74 and 69 of relay 3WZ are closed because the operator of the control machine has not yet restored his switch lever SML to its normal position, the switch machine 3SM becomes energized with proper polarity tooperate the track switch 3W to its normal position upon the picking up of relay 3LS when the track section 3T becomes unoccupied in the rear of the westbound train. Under these conditions energy is applied to the switch machine control wire 73 from the positive terminal of a suitable source of energy through back contact 69 of relay 3WZ, front contact 70 of relay SWPP, back contact 88 of relay 3WRP, and front contact 77 of relay 3LS. The negative terminal of this source of energy is connected to the switch machine control wire 68 through back contact 74 of relay 3WZ, front contact 75 of relay 3WPP, back contact 89 of relay SWRP and from contact 72 of relay 3LS. 5 There will be an indication transmitted to the control oflice that the track switch 3W has been operated to its normal position, and the reception of the indication at the control oflice that the track switch 3W has been operated to its normal position sets up an out-ofcorrespondence indication that informs the operator of the control machine that he should operate his switch control lever SML to its normal position in correspondence with the position to which the track switch 3W has been operated. This operation provides for the picking up of the magnetic stick relay 3WZ which completes the restoration to normal conditions of the organization for energization of the switch machine 3SM.

The timers PTE, FTE and TE are not operated for normal westbound trafiic because the normally energized relay 7ASPS is dropped away upon the clearing of a signal 7A or 7B for governing westbound traffic. This is accomplished by the opening of front contact 38 of relay 7AS upon the clearing of signal 7A or 7B. Although relay 7AS is restored when the westbound train enters the track section B4T, relay 7ASPS cannot pick up because its pick-up circuit includes front contacts 41, 4-2 and 43 of relays 27TR, A4TR and B4TR re spectively in series. The circuit by which the relay 7AS is picked up when a westbound train enters the track section B4T extends from including front contact 14 of relay 7RP, back contact 15 of relay 3TR,

wire 90, back contact 91 of relay B4TR, wire 92, and

'winding of relay 7AS, to Thus, the relay 7ASPS remains in its dropped away position as the westbound train progresses, and the opening of its front contact "56 prevents energization of the timers.

Provision has been made for switching moves at the left-hand end of the passing siding B, and one condition under which switching is desirable at this location is where a long train coming up grade is required to divide and leave part of the train on the passing siding B because of being unable to take such a long train up the steep grade ahead.

A train to divide under these conditions proceeds with its front end extending into the block between the passing sidings A and B and leaves the rear portion of the train in the track section GT and proceeds to a clearance point behind the signals 6A and 6B for a switching operation into the passing siding B. As soon as the track section 3T becomes unoccupied in the rear of the train as it proceeds into the track section B4T, the track switch 3W is restored automatically to its normal position as has been described. To'reverse the track switch 3W and permit the train to back into the passing siding B it is necessary to wait for the timer TE to operate.

As a means of permitting the operation of the timer TE for causing reverse operation of the track switch 3W for a switchingmovement, it is provided that the relay BTS is picked up when a route is called for for a westbound train by the clearing of signal 7A or signal 7B. The pick-up circuit for relay BTS extends from including front contact 93 of relay 7H, front contact 94 of relay 3TR, front contact 95 of relay 7LGZ, wire 96, and winding of relay BTS, to This relay is maintained picked up as long as the track section 6T is occupied by a stick circuit extending from including back contact 97 of relay 6TR, wire 98, front contact 99 of relay BTS, and winding of relay BTS, to With relay BTS picked up, track section B4T occupied, and track section 3T unoccupied, a distinctive condition is indicated wherein a switching move is called for in that the train has been divided, part of the train beeing left in the track section 6T, and the first part of the train being in position for a switching operation into the passing siding B.

Thus, tthe timer TE becomes energized when the track relay 3TR is picked up to close front contact 85, the circuit for the energization of the relay TE extending from including back contact 53 of relay 3WZ, wire 54, front contact 100 of relay BTS, back contact 101 of relay B4TR, back contact 57 of relay B4TR, wire 83, back contact 84 of relay TEP, front contact 85 of relay 3TR, and winding of relay TE, to After the timer TE has completed its operation, the relay TEP becomes picked up by the energization of a circuit extending from including back contact 53 of relay 3WZ, wire 54, front contact 100 of relay BTS, back contact 101 of relay B4TR, back contact 57 of relay B4TR, wire 83, front contact 102 of relay TE, and winding of relay TEP, to The picking up of this relay closes a stick circuit through front contact 66 for shunting the contacts 57 and 102, out of the circuit just described. Relay TEP when picked up restores the timer TE by opening its circuit at back contact 84.

Upon the picking up of relay TEP as has been de scribed, the relay 3WRP becomes energized through back contact 53 of relay 3WZ and front contact 67 of relay TEP, and the picking upof this relay causes the operation of the track switch 3W to its reverse position by a mode of operation that has been described. This conditions the system so that the signal 6B can be cleared through front contact 79 of relay 3RWP, and the first part of the train can be backed into the passing siding B to leavethe cars as required. When this train is fully in the rear of signal 73, the relay 7H picks up, and the picking up of this relay maintains the relay SWRP in its energized position and thus maintains the track switch 3W reverse so that it is unnecessary to wait for timer operation before the locomotive initiates another switching move out of the passing siding B to couple up to the 11 rear end of the train which has been left in the track section 6T.

Thus, the operator at the controloffice sends out the proper centralized trafiic control for the clearing of signal 73 to move the locomotive out onto the main track, and after'the locomotive has passed through the detector track section 31', the track switch '3W-is automaticallyoperated back to its normal position according to a mode of operation that'has'been 'heretofore described, but the timer TE is initiated so that the relay TEPis picked up after operation of the timer TE to operate the track switch 3W to itsreverse position andthus permit passage of the locomotive through track switch- 3W to couple up with the rear endof its train in thetrack section 6T and thus be-in condition to proceed according to'normaloperation for westbound trains through the block betweenpassingsidings A and B.

Having thus described one embodiment of a safety track switch control 'systemas provided by thepresent invention, it is desired to be understood that this form has beenused principally .to disclose the general organization and principles of operation rather than to disclose thespecific organization that would be employed in practice, and it is desired to be understood that various adaptations, alterations, andmodifications may be made to the specific form shown according to the requirements of practice without in any manner departing from the spirittor scope ,ofthe. present invention exceptas limited by the appended claims.

What I claim is:

1. A safety track switch control systemcomprising in combination, a stretch of railway track having a safety track switch connected thereto, said stretch of track being divided into a plurality of adjoining track sections, a particular one of said track sections being of a length to contain completely only a short train, manually operable means for designating respective normal and reverse positions for operation of said track switch, timing means including certain of said track sections operable to indicate the speed of an approaching train as being at or below a predetermined medium speed and at or below a predetermined low speed, a switch control relay for governing operation of said track switch, circuit means operable whenrendered effective to energize said switch control relay subsequent to the operation of said manually operable means for designating the reverse position for said 'trackswitch, said circuit means being renderedefiective when atrain is approaching said track switch only provided said timing means indicates the train is approaching at or below saidpredetermined low speed as long as .the train continues to occupy simultaneously a plurality of. said tracksections including said particular tracksection, and said circuit means being rendered effective when atrain is approaching said'track switch if .said timing means indicates the train is approaching at or below saidpredetermined medium speed provided that the train is indicated as being short by being fully contained within said particular one of said track sections, andmeans for operating said track switch to respective reverse and normal positions in accordance with the respective energized and deenergized positions of said-switch control relay.

2. A safety track switch control system for railroads comprising in combination, a stretch of'railway track having a safety track connected thereto by a power operable track switch, said stretch of track having three adjoining track sections in approach of said track switch, the length of the intermediate of the three track sections being just slightly greater than the length of a long passenger train, a switch control relay, means including said switch control relay for operating said track switch, two timing devices having respective short and long time settings, means for initiating both of said timing devices simultaneously upon the approach of a train to said track switch, and circuit means for operating said switch control relay when only said intermediate track section is occupied provided said timer having a short setting has completed its operation, saidcircuit means being effective to operate said switch control relay when said intermediate track section and the preceding adjoining track section but not the other adjoining track section are occupied by a train approaching said track switch provided that said timing device having a long time setting has completed its operation.

3. A safety track switch control system for railroads comprising in combination, a stretch of railway track having a safety track connected thereto by a power operable track switch, said stretch of track being divided into three adjoining track sections in approach of said track switch, a switch control relay, means for operating said track switch in response to the operation of said relay, two timing devices having respective short and long time settings, means for initiating both of said timing devices simultaneously when a train approaches said track switch, and circuit means for operating said switch control relay in accordance with the completion of operation of either of said timing devices, said circuit means being effective subsequent to completion of operation of said timer having a short time setting provided that only the intermediate one of said track sections is occupied by a train, and said circuit means being eflective subsequent to completion of operation of said timer having a long time setting provided that said intermediate track section and the next preceding track approaching said track switch section are occupied by a train and the other track section adjoining said intermediate track section is unoccupied.

4. A safety track switch control system for railroads comprising in combination, a stretch of railway track having a safety track connected thereto by a power track switch, said stretch of railway track having three adjoining track sections in approach of the safety track switch, manually operable means for designating the respective normal and reverse positions for operation of said track switch, two timing devices having respective short and long time settings, means for initiating both of said timing devices simultaneously when a train approaches said track switch, and circuit means effective subsequent to the actuation of said manually operable means for designating the reverse position for said track switch for operating said track switch to its reverse position only subsequent to completion of operation of said timing device having a short time setting provided only the intermediate one of said track sections is occupied by a train or only subsequent to completion of operation of said timing device having a long time setting provided a train is occupying the first two of said track sections in approaching the track switch but the third of said track sections is unoccupied.

5. A safety switch control system for railroads comprising in combination, a stretch of track including a power operable safety switch, said stretch of track being divided into at least three adjoining track sections in approach of said switch, a track circuit including a track relay for each of the track sections, a switch control relay for governing the operation of said track switch, two timers having different times of operation, means for initiating both of said timers upon the approach of a train to said track switch as detected by occupancy of one of said track sections, circuit means for operating said switch control relay to a position for the operation of said track switch to its reverse position subsequent to completion of operation of a selected one of said timers but prior to the dropping away of said track relay for the last of said adjoining track sections to be occupied in approaching said track switch, and means including contacts of certain ones of said track relays for selecting one of said timers to govern said circuit means only provided the approaching train occupies the intermediate one of said three track sections but not its adjoining track sections, said circuit means being operable to select 6. A safety switch control system for railroads comprising in combination, a stretch of railway track including a power operable safety track switch, said stretch of track being divided into at least three adjoining track sections in approach of said track switch, a track circuit including a track relay for each of the track sections, a switch control relay for governing the operation of said track switch, manually operable means including said switch control relay for governing the power operation of said track switch, two timing devices having different time settings, means for initiating said timing devices at substantially the same time upon the approach of a train to said track switch, and circuit means effective to prevent the operation of said track switch to a particular position in response to the operation of said manually operable means until the timing device having the longest time setting has completed its operation except that said circuit means is effective to permit operation of said track switch to said particular position when said timer having the shorter time setting has completed its operation provided that the approaching train is occupying an intermediate one of said track sections but not the adjoining track sections.

References Cited in the file of this patent UNITED STATES PATENTS 1,763,011 Shaver June 10, 1930 1,827,829 Thompson Oct. 30, 1931 1,913,729 Shaver June 13, 1933 2,061,756 Crago Nov. 24, 1936 2,208,436 Synder July 16, 1940 2,307,476 Vanhorn J an. 5, 1943 2,385,179 Allen Sept. 18, 1945 2,651,711 Iohanek et a1. Sept. 8, 1953 U. S. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,817,013 December 17, 1957 Robert F. Wells It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Let ters Patent should read as corrected below.

9 and 30, strike out ("approaching said track switch! Column 12, lines 2 ix-aim" in line 31, same column,

and insert the same after Signed and sealed this 25th day of March 1958.

(SEAL) Attest:

KARL Ho AXLINE Attesting Officer Comnissioner of Patents

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