US2718588A - Highway crossing signal control system - Google Patents

Description

Sept. 20, 1955 G, w. BAUGHMAN HIGHWAY CROSSING SIGNAL CONTROL SYSTEM Filed July 28, 1951 ME/ X12 AT M J.

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m Rm 2, mu a 3 GY B HIS ATTORNEY United States Patent HIGHWAY CROSSING SIGNAL c'oNrn'or SYSTEM George W. Baughman, Swissvale, Pa., assignor to Westinghouse Air Brake Company, Wilmer-ding, Pa., a corporation of Pennsylvania Application July 28, 1051, Serial No. 239,129

20 Claims. (Cl. 246-430) My invention relates to highway crossing signal control systems, and particularly to a system adapted to initiate operation of a highway crossing signal when a train approaching the intersection of a railway and a highway is at a distance from the crossing determined by the speed of the train.

In systems for controlling highway crossing signals, adequate warning periods are provided before the arrival of a train at the intersection of the railway and a highway so that motorists and other users of the highway will stop short of the railway crossing. In systems for controlling highway crossing signals employing track circuits, a warning period of at least twenty seconds is provided before the train arrives at the intersection by locating the entrance point of a control section of track a distance from the intersection equal to the distance a train travelling at the highest authorized speed \m'll travel in the twenty seconds. While such systems provide an adequate warning period for trains approaching the highway crossing at speeds approximating the highest authorized speed, a slower moving train entering the control section in approaching the intersection will initiate the operation of the highway crossing signal long before the arrival of the train at the intersection. The prolonged operation of the highway crossing signals will cause delays and blocking of the trafiic moving over the highway. The continued long delays at any given highway crossing also gives rise to a habitual disregard for the warning signals at the crossing by those motorists making daily use of the highway.

It is therefore an object of my invention to provide a novel highway crossing signal control system for initiating the operation of the crossing signals in accordance with the speed of the approaching train so that the crossing signals are operated at all times for substantially uniform periods of time prior to the arrival of the train at the crossing.

To this end I have devised a system for initiating the operation of a highway crossing signal by measuring the time required for any given train to travel over a timing section of the railway in its approach toward the highway crossing. The principle involved in my novel systemvis the use of two capacitors preferably of the electrolytic type, one capacitor being larger than the other, the smaller capacitor being alternately charged from a low voltage source and the energy transferred to the larger capacitor, the discharge of the larger capacitor in steps through the smaller capacitor in turn controlling the operation of the highway crossing signals. The larger of the two capacitors is connected in multiple with a control relay having predetermined pickup and release values of energy. The energy transferred to the larger capacitor is gradually built up over a predetermined time interval to a point when the energy stored by the capacitor equals the pickup value of the control relay. The discharge of the larger capacitor in steps by the smaller capacitor in the manner hereinafter described reverses the process 2,718,588 Patented Sept. 20, 1955 and gradually lowers the. energy level to a point when the control relay is released.

In the highway crossing signal control system devised. by me, two adjacent approach sections are required, one adjacent to the highway crossing and the other more remote from the highway. The section nearest the highway I shall term the operating section, while the other section I shall term the timing section. The operating section is of such length that a train entering the section and traveling at the highest authorized speed will provide an adequate periodv of signal operation at the crossing during the approach of a train traveling at the maximum permissible speed. The circuits. of my system are so arranged that upon entry of a train: into the timing section of the approach sections, a. code transmitter will be operated for alternately connecting the smaller capacitor to a direct current source and disconnecting the small capacitor from the voltage supply and connecting the charged capacitor to the larger capacitor for transferring the stored energy thereto. The greater the number of operations of the code transmitter, the more nearly will the charge of the large capacitor approach the voltage of the direct current supply. After a predetermined time interval while the train is occupying the timing section, the energy level of the larger capacitor will equal the pickup value of the control relay to energize the control relay. A third capacitor of the same capacity as the smaller capacitor is connected in multiple with the smaller capacitor to increase the charging rate of the larger capacitor. Thus the longer atrain requires to travel over the timing section of the track, the greater will be the energy stored in the larger capacitor. When the train enters the operating section of the track other circuits of my system are established, either for operating the highway crossing signal immediately upon the entry of the train into the operating section, or after a time delay measured by the removal of the charge from the larger capacitor in steps by the smaller capacitor upon the continued operation of the code transmitter.

Other objects and characteristic features of my invention will become apparent from the following description.

I shall describe one form of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view illustrating a preferred form of my invention.

Referring to the drawing, the reference characters AT and BT designate adjacent sections of a stretch of railroad track intersected at grade by a highway H, the highway crossing being protected by a highway crossing signal XS which may take any suitable form, such as a flashing light signal, an oscillating semaphore arm or a guard rail, but which for the sake of simplicity is herein illustrated as a signal bell controlled by a crossing relay XR over an obvious circuit. The track sections AT and BT are provided with conventional track circuits including the track relays ATR and BTR, respectively. The track section AT will hereinafter be referred to as the timing section AT, while the track sec tion BT will be referred to as the operating section ET. The operating section BT should be long enough to provide at least a twenty-second warning at the crossing upon entry of a train into the section from the timing sec tion AT when the train is traveling at the maximum permissive speed. In the detailed description which follows, the length of the operating section will be considered as being 6000 feet long while the timing section AT will be considered as being one-quarter the length of operating section BT or 1500 feet long. For the purposes of clarifying the description which is to follow, I will assume that a train approaching the highway H in the direction of the arrow and traveling at the maximum permissive speed will pass over the timing section AT in ten seconds or less. It will be understood that the length of the sections and the time interval required by a train to traverse the timing section AT given herein are for the purposes of description; but in actual practice other track section lengths and other time intervals may be employed to meet the particular requirements of a given intersection and/or a particular operating rule of a railroad.

The track relay BTR of the operating section BT when energized holds the crossing relay XR energized to prevent the energization of the crossing signal XS, the controlling circuit for relay XR being from the positive terminal B of a battery LB over the closed front contact 1 of the track relay BTR through the operating winding of the relay XR to the negative terminal N of the battery. The shunting of the track circuit of the operating section BT will deenergize the track relay BTR releasing the crossing relay XR to operate the highway crossing signal XS over the now closed back contact 2 of the relay XR.

Associated with the timing section AT is a code transmitter CT which may, for example, be of the type described in Letters Patent of the United States No. 1,913,826 issued to Herman G. Blosser on June 13, 1933, for Oscillating Motor, and which has a contact 3 that alternately engages the upper and lower contact points when the operating winding is energized. The B terminal of the battery LB is connected over a back contact 4 of the track relay ATR and over a front contact 5 of the track relay BTR to the upper contact point of the code transmitter, while the operating winding of the code transmitter is connected over a back contact 6 across the terminals of the battery LB. The shunting of the track circuit for the timing section AT upon entry of a train into the section will release the track relay ATR to close the back contacts 4 and 6, the closed back contact 6 energizing the code transmitter CT to alternately close the upper and lower contacts 3. The code transmitter CT will continue to operate as long as the timing section AT is occupied, and positive terminal B of the battery will be connected to the upper contact point of the code transmitter as long as the timing section AT is occupied by the train approaching the highway H and the operating section ET is unoccupied.

The operation of the code transmitter CT upon occupancy of the timing section AT by a train approaching the highway H charges and discharges a capacitor Q1 over the code transmitter contacts 3. The capacitor Q1 is charged when the upper contact 3 of the code transmitter is closed and discharged when the lower contact is closed by connecting the capacitor Q1 in multiple with a capacitor Q2 over an obvious circuit which includes the primary winding of a transformer T1. The capacitor Q1 is the smaller of the two capacitors and the two capacitors are so proportioned that each time a charge is delivered from the capacitor Q1 to the capacitor Q2 a code following relay CR connected across the secondary winding of the transformer T1 will be energized to operate its contacts 7. The alternate closings of the code following relay contacts hold a control relay HR energized through a decoding circuit which includes a decoding transformer T2 having a center tapped primary winding connected to the code following relay contacts 7, and a secondary winding. The secondary winding of the transformer T2 is connected to a series resonant circuit including a capacitor Q3 and an inductor L1 tuned to the code frequency of the code transmitter CT, and a full wave rectifier W1 connected across a portion of the inductor L1, said decoding circuit being more fully described in Letters Patent of the United States No. 1,773,472 issued to Paul N. Bossart on August 19, 1930, for Railway Traffic Controlling Apparatus.

The alternate charging and discharging of the c a pacitor Q1 by the continued operation of the code trans mitter CT while the timing section AT is occupied will gradually step up the energy stored in the capacitor Q2. The capacitor Q2 is connected in multiple with the operating winding of a control relay QHR through a resistor R1. Relays in general are considered to have a pickup current value at which the relay picks up or operates its contacts and a release current value at which the relay releases its contacts. The charging of a capacitor is usually referred to in terms of potential or voltage, and since in the present case, the impedance of the energizing circuit for the control relay QHR may be considered as a constant, the control relay QHR will be considered as having predetermined or known pickup and release values of voltage or energy at which the contacts of the relay will be picked up or released.

As previously indicated, the length of the timing section AT is such that a train traveling at the maximum permissive speed will traverse this section in less than ten seconds. The capacity of the smaller capacitor Q1 and that of the larger capacitor Q2 are so proportioned that the energy level of the larger capacitor will be built up in steps by the discharge of the smaller capacitor, to the pickup energy value of the control relay QHR after the ten seconds allotted to the occupancy of the timing section AT by a train traveling slower than the maximum permissive speed. The control relay QHR will be picked up after the initial ten seconds to complete a holding circuit for the core transmitter CT over its front contact 8 which by-passes the back contact 6 of the track relay ATR, and will connect a capacitor Q4 in multiple with the capacitor Q1 over its front contact 9 and over a front contact 10 of the track relay BTR, and will also complete a holding circuit for the crossing control relay XR which by-passes the front contact 1 of the relay BTR. The holding circuit for relay XR may be traced from the B terminal of the battery LB over a front contact 11 of the control relay HR, over a front contact 12 of the control relay QHR through the operating winding of the relay XR to terminal N.

The capacitor Q4 is of the same capacity as the capacitor Q1. By connecting the capacitor Q4 in multiple with the capacitor Q1, the two capacitors will be simultaneously charged by the operation of the code transmitter CT and discharged into the capacitor Q2 in the manner described to increase the charging rate of the capacitor Q2. Thus the longer a train remains in the timing section AT, the greater will be the charge on the capacitor Q2. The delay in operating the highway crossing signal XS is proportional to the time required by the train to pass through the timing section AT. This delay time is measured by removing the charge on the capacitor Q2 in steps by the continued operation of the code transmitter CT, as will hereinafter appear.

I will now assume that a train traveling at the maximum permissive speed enters the timing section AT in its approach toward the highway H. The train in the timing section AT will release the track relay ATR to operate the code transmitter CT to charge and discharge the capacitor Q1. Since the train will pass through section AT in less than ten seconds, the control relay QHR will remain released. Upon entry of the train into the operating section ET, the track relay BTR will release to open its front contact 1, thereby deenergizing the crossing relay XR to operate the crossing signal XS. Any charge which may have accumulated on the plates of the capacitor Q2 during train occupancy of section AT will be dissipated in the resistor R1 and the coils of the relay QHR.

I will now assume that a train traveling at less than maximum permissive speed enters the timing section AT, in which event the train will remain in section AT longer than ten seconds. The track relay AT R upon releasing starts the code transmitter CT operating to charge the capacitor Q1 over the back contact 4 of relay ATR, the front contact 5 of relay BTR and the upper contact 3 of the code transmitter and to discharge the capacitor Q1 over the lower contact 3 of the code transmitter into the capacitor Q2. The control relay HR will be picked up to close its front contact 11, while control relay QHR will be picked up after ten seconds of operation of the code transmitter in the manner hereinbefore described. The pickup of the relay QHR establishes the holding circuits for the crossing relay XR and the code transmitter over its front contacts 12 and 8, respectively, while the front contact 9 connects the capacitors Q4 and Q1 in multiple over the front contact of the track relay BTR to increase the charging rate of the capacitor Q2.

When the slow moving train enters the operating section ET, the track relay BTR releases and closes its back contact 10 to discharge the capacitor Q4 through a resistor R2, the front contact 9 of the control relay QHR being closed. The releasing of the track relay BTR also opens the circuit for the crossing relay XR but this relay is still held up by the circuit over the front contact 12 of the relay QHR and the front contact 11 of the relay HR. The charging circuit for the capacitor Q1 is also opened by the releasing of the track relay BTR and a discharging circuit over the back contact 5 of the track relay BTR through a resistor R3 is substituted therefor. The charged capacitor Q2 will maintain the control relay QHR energized, thereby maintaining the code transmitter energized over the front contact 8.

With the code transmitter operating, the capacitor Q2 will be discharged in steps, the transmitter contacts a1- ternately connecting the capacitor Q1 to the capacitor Q2 for charging the former and then discharging the capacitor Q1 through the circuit established over the back contact 5 of the track relay BTR. The discharge of the capacitor Q2 is at a slower rate than that at which this capacitor was charged following the initial ten second interval after which the control relay QHR was picked up to connect the capacitors Q4 and Q1 in multiple. With the proportions given hereinabove by way of example, the rate of discharge of the capacitor Q2 should be approximately one-fourth the rate at which the capacitor was charged following the initial ten second period the train Was in the timing section AT.

it may now be assumed that the slow moving train is wholly within the operating section BT and the timing section AT is unoccupied. The pickup of the track relay ATR will open its back contacts 4 and 6 but the opening of these contacts will in no way affect the circuits established by the released track relay BTR and the pickedup control relays QHR and HR.

The discharge of capacitor Q2 will continue until the energy level of the capacitor is reduced to the release value of the control relay QHR. The release of the relay QHR will open the holding circuit of the code transmitter CT, thereby stopping the operation of the code following relay CR. The control relay HR will release to open its front contact 11, thereby opening the operating circuit for the crossing relay XR to operate the crossing signal XS. The release of the control relay QHR also opens its front contact 112 in the holding circuit of the crossing relay XR. The signal XS will thus be operated and continue to operate as long as the train is in the operating section ET. The circuits as illustrated will again be reestablished when the operating section ET is unoccupied.

A characteristic feature of the highway crossing signal control system herein described is a circuit check on the charging and discharging circuits of the capacitors Q1, Q2 and Q4. As long as the charges and discharges of the capacitors give rise to currents in the primary winding of the transformer T1, code following relay CR will continue to operate. or discharging circuits occur, as for example a short circuit or an open line, the code following relay CR will stop operating, thereby releasing the control relay HR. The release of the relay HR will open its front contact 11 to open the holding circuit of the crossing relay XR. The speed of the train under such circumstances in trav- Should any defect in the charging eling through the timing section AT will not provide any time delay in initiating the operation of the crossing signal XS when the train finally enters the operating section BT.

Although I have herein shown and described only one form of a highway crossing signal control system embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In speed measuring apparatus for a train traveling over a track section of predetermined length, the combination comprising, a capacitor, a second capacitor of larger capacity than said first capacitor, an energy source, a relay having a predetermined pickup value of energy at which said relay closes its front contacts and a predetermined release value of energy at which said relay opens its front contacts; means controlled by train occupancy of said track section for alternately charging the smaller capacitor from said energy source and transferring the charges of the smaller capacitor to the larger capacitor, said relay being picked up when the charge on said larger capacitor is equal to the pickup value of said relay, said charging and transferring means alternately charging the smaller capacitor from the larger capacitor and discharging the smaller capacitor when a train leaves saidtrack section to discharge the larger capacitor in steps until the charge on said larger capacitor is equal to the release value of said relay, the time interval for the stepped discharge of the larger capacitor to the release value of said relay being in accordance with the time re quired by the train to travel over said track section of predetermined length.

2. In timing apparatus for a vehicle traversing a path of predetermined length, the combination comprising, an energy source, an energy storage means, a second energy storage means capable of storing greater amounts of en ergy than the first energy storage means, oscillatory means operative at a predetermined frequency during vehicle occupancy of the path for alternately transferring energy from said energy source to the first energy storage means and transferring the energy from the first energy storage means to said second energy storage means, means operative when the vehicle leaves the path to operate said oscillatory means at the predetermined frequency to alternately transfer the energy of said second energy storage means in steps to the first energy storage means and dissipate the energy of the first storage means, the time required to dissipate the energy of said second storage means being a measure of the time required for the vehicle to traverse the path of predetermined length.

3. In timing apparatus, the combination comprising, an energy source, an energy storage means, a second energy storage means capable of storing greater amounts of energy than the first energy storage means, and means operative upon initiation of a timing cycle to alternately transfer energy from said energy source to the first energy storage means and transferring the energy of the first energy storage means to said second energy storage means, said operative means including means to alternately transfer the energy of the second storage means to the first storage means and dissipate the energy of the first storage means upon termination of the timing cycle, the time re quired to dissipate the energy stored in said second energy storage means being a measure of the time of the timing cycle.

4. In timing apparatus, the combination comprising, an energy source, an energy storage means, a second energy storage means capable of storing greater amounts of energy than the first energy storage means, means operative upon initiation of a timing cycle to alternately transfer energy from said energy source to the first energy storage means and transferring the energy of the first energy storage means to said second energy storage means, said operative means including means to alternately transfer the energy of the second storage means to the first storage means and dissipate the energy of the first storage means upon termination of the timing cycle, and a control element operative when the energy stored in the second storage means reaches a predetermined value, and maintained operative until the stored energy of the second storage means is reduced to a second predetermined value.

5. In timing apparatus, the combination comprising, an energy source, a first energy storage means, a second energy storage means capable of storing greater amounts of energy than the first energy storage means, oscillatory means operative at a predetermined frequency upon initiation of a timing cycle for alternately transferring energy from said energy source to the first energy storage means and transferring the energy of the first energy storage means to said second energy storage means, said operative means including means operative upon termination of the timing cycle for alternately transferring the energy of the second storage means to the first storage means and dissipating the energy of the first storage means, the time required to dissipate the energy stored in said second energy storage means being a measure of the time of the cycle.

6. In timing apparatus, the combination comprising, an energy source, a first capacitor, a second capacitor of larger capacity than said first capacitor, means operative upon initiation of a timing cycle for alternately charging said first capacitor from said energy source and transferring the charge on said first capacitor to said second capacitor, and means operative upon termination of the timing cycle to alternately charge said first capacitor from said second capacitor and dissipate the charge stored on the first capacitor, the time required to dissipate the charge accumulated on said second capacitor being a measure of the time of the cycle.

7. In timing apparatus, the combination comprising, an energy source, a first capacitor, a second capacitor of larger capacity than said first capacitor, means operative upon initiation of a timing cycle for alternately charging said first capacitor from said energy source and transferring the charge on said first capacitor to said second capacitor, means operative upon termination of the timing cycle to alternately charge said first capacitor from said second capacitor and dissipate the charge stored on the first capacitor, and a control element operative when a charge of a predetermined value is accumulated on the second capacitor and maintained operative until the accumulated charge on the second capacitor is reduced to a second predetermined value.

8. In timing apparatus, the combination comprising, an energy source, a first capacitor, a second capacitor having a larger capacity than said first capacitor, oscillatory means operative upon initiation of a timing cycle and operated at a predetermined frequency for alternately charging said first capacitor from said energy source and discharging said first capacitor into said second capacitor, and means operative upon termination of the timing cycle to operate said oscillatory means at the predetermined frequency for alternately charging said first capacitor from said second capacitor and dissipating the charge on the first capacitor, the time required to dissipate the charge accumulated on said second capacitor being a measure of the time of the cycle.

9. In timing apparatus, the combination comprising, an energy source, a first capacitor, a second capacitor having a larger capacity than said first capacitor, oscillatory means operative upon initiation of a timing cycle and operated at a predetermined frequency for alternately charging said first capacitor from said energy source and discharging said first capacitor into said second capacitor, means operative upon termination of the timing cycle to operate said oscillatory means at the predetermined frequency for alternately charging said first capacitor from said second capacitor and dissipating the charge on the first capacitor, and a control element operative when a charge of a predetermined value is accumulated on the second capacitor and maintained operative until the accumulated charge on the second capacitor is reduced to a second predetermined value.

10. In timing apparatus, the combination comprising an energy source, two capacitors of equal capacity, a third capacitor having a larger capacity than either of the two capacitors, means operative upon initiation of a timing cycle for alternately charging one of said equal capacitors from said energy source and transferring the charge on said capacitor to the third capacitor, means operative after a predetermined time interval after initiation of the timing cycle to increase the charging rate of the third capacitor by connecting the two equal capacitors to said charging means, and means operative upon termination of the timing cycle to alternately charge one of said equal capacitors from said third capacitor and dissipate the charge stored thereon, the time required to dissipate the charge accumulated on the third capacitor being a measure of the time of the cycle.

ll. In timing apparatus, the combination comprising an energy source, two capacitors of equal capacity, a third capacitor having a larger cpacity than either of the two capacitors, means operative upon initiation of a timing cycle for alternately charging one of said equal capacitors from said energy source and transferring the charge on said capacitor to the third capacitor, means operative after a predetermined time interval after initiation of the timing cycle to increase the charging rate of the third capacitor by connecting the two equal capacitors to said charging means, means operative upon termination of the timing cycle to alternately charge one of said equal capacitors from said third capacitor and dissipate the charge stored thereon, and a control element operative when a charge of a predetermined value is accumulated on the second capacitor and maintained operative until the accumulated charge on the second capacitor is reduced to a second predetermined value.

12. In timing apparatus, the combination comprising an energy source, two capacitors of equal capacity, a third capacitor having a larger capacity than either of said equal capacitors, oscillatory means operative upon initiation of a timing cycle and operated at a predetermined frequency for alternately charging one of said equal capacitors from said energy source and transferring the charge on said capacitor to the third capacitor, means operative after a predetermined time interval after initiation of the timing cycle to increase the charging rate of the third capacitor by connecting the two equal capacitors to said oscillatory charging means, and means operative upon termination of the timing cycle to operate said oscillatory means at the predetermined frequency for alternately charging one of said equal capacitors from said third capacitor and dissipating the charge stored thereon, the time required to dissipate the charge accumulated on the third capacitor being a measure of the time of the cycle.

13. In timing apparatus, the combination comprising an energy source, two capacitors of equal capacity, a third capacitor having a larger capacity than either of said equal capacitors, oscillatory means operative upon initiation of a timing cycle and operated at a predetermined frequency for alternately charging one of said equal capacitors from said energy source and transferring the charge on said capacitor to the third capacitor, means operative after a predetermined time interval after initiation of the timing cycle to increase the charging rate of the third capacitor by connecting the two equal capacitors to said oscillatory charging means, means operative upon termination of the timing cycle to operate said oscillatory means at the predetermined frequency for alternately charging one of said equal capacitors from said third capacitor and dissipating the charge stored thereon, and a control element operative when a charge of a predetermined value is accumulated on the second capacitor and maintained operative until the accumulated charge on the second capacitor is reduced to a second predetermined value. I

14. In timing apparatus for measuring the speed of a vehicle traversing a path of predetermined length, the combination comprising, a capacitor, a second capacitor of larger capacity than the first capacitor, means initially controlled by the entry of the vehicle onto the path for alternately charging the smaller capacitor from an energy source and transferring the charges to the larger capacitor, means controlled by the charge on the larger capacitor after a predetermined time interval of vehicle occupancy of the path for controlling said charging and transferring means when the vehicle leaves the path to discharge the larger'capacitor in steps by alternately charging the smaller capacitor from the larger capacitor and discharging the smaller capacitor, a control element normally operated when the vehicle leaves the path, and means controlled by said controlling means for introducing a time delay in the operation of the control element when the vehicle leaves the path in accordance with the time required to discharge the larger capacitor.

15. In timing apparatus for measuring the speed of a vehicle traversing a path of predetermined length, the combination comprising, a capacitor, a second capacitor of larger capacity than the first capacitor, means initially controlled by the entry of the vehicle onto the path for alternately charging the smaller capacitor from an energy source and transferring the charges to the larger capacitor, means controlled by the charge on the larger capacitor after a predetermined time interval of vehicle occupancy of the path for controlling said charging and transferring means when the vehicle leaves the path to discharge the larger capacitor in steps by alternately charging the smaller capacitor from the larger capacitor and discharging the smaller capacitor, the discharge rate of the larger capacitor by the smaller capacitor being less than its charging rate by the smaller capacitor, a control element normally operated when the vehicle leaves the path, and means controlled by said controlling means for introducing a time delay in the operation of the control element when the vehicle leaves the path in accordance with the time required to discharge the larger capacitor.

16. In timing apparatus for measuring the speed of a vehicle traversing a path of predetermined length, a capacitor, a second capacitor having a larger capacity than the first capacitor, means initially controlled by entry of the vehicle onto the path for alternately charging the smaller capacitor from an energy source and transferring the charges of the smaller capacitor to the larger capacitor, a relay having predetermined pickup and release values of energy at which said relay will close its front contacts and open its front contacts, said relay being picked up when the charge on the larger capacitor reaches the predetermined pickup value, and a front contact completing a holding circuit for said charging and transferring means so that when a vehicle leaves the path said means discharges the larger capacitor in steps by alternately charging the smaller capacitor from the larger capacitor and discharging the smaller capacitor to release said relay when the charge on the larger capacitor is lowered to the release value of the relay, and a control element normally operated when a vehicle leaves the path, a second front contact for said relay for maintaining said control element inoperative when said relay is energized, said second front contact opening to operate said control element when the relay is deenergized.

17. In timing apparatus for measuring the speed of a vehicle traversing a path of predetermined length, a capacitor, a second capacitor having a larger capacity than the first capacitor, means initially controlled by entry of the vehicle onto the path for alternately charging the smaller capacitor from an energy source and transferring the charges of the smaller capacitor to the larger capacitor, a relay having predetermined pickup and release values of energy at which said relay will close its front contacts and open its front contacts, said relay being picked up when the charge on the larger capacitor reaches the predetermined pickup value, and a front contact completing a holding circuit for said charging and transferring means so that when a vehicle leaves the path said means discharges the larger capacitor in steps by alternately charging the smaller capacitor from the larger capacitor and discharging the smaller capaci tor to release said relay when the charge on the larger capacitor is lowered to the release value of the relay, and a control element normally operated when a vehicle leaves the path, a second front contact for said relay for maintaining said control element inoperative when said relay is energized, said second front contact opening to operate said control element when the relay is deenergized, the discharge rate of the larger capacitor by the smaller capacitor being less than its charging rate by the smaller capacitor.

18. In timing apparatus for measuring the speed of a vehicle traversing a path of predetermined length, the combination comprising, a capacitor, a second capacitor having a larger capacity than said first capacitor, means initially controlled by the entry and occupancy of the path by a vehicle for alternately charging the smaller capacitor from an energy source and transferring the charges to the larger capacitor, a third capacitor, a relay having predetermined pickup and release energy values at which said relay closes its front contacts and opens its front contacts, said relay being picked up when the charge on the larger capacitor reaches the predetermined pickup value, a front contact connecting said third capacitor with the smaller capacitor to increase the charging rate of the larger capacitor when said relay is picked up, a second front contact completing a holding circuit for said charging and transferring means so that when a vehicle leaves the path said means discharges the larger capacitor in steps by alternately charging the smaller capacitor from the larger capacitor and discharging the smaller capacitor to reduce the charge on said larger capacitor to the release value of said relay, and a control element normally operated when a vehicle leaves the path, a third front contact for said relay for maintaining said control element inoperative when said relay is energized, said third front contact opening to operate said control element when the relay is deenergized.

19. In timing apparatus for measuring the speed of a vehicle traversing a path of predetermined length, the combination comprising, a code transmitter operated when a vehicle enters and occupies the path, a capacitor, a second capacitor of larger capacity than the first capacitor, the larger capacitor being charged in steps by the alternate charging of the smaller capacitor from an energy source and discharging the smaller capacitor therein by the operation of the code transmitter contacts, a relay having predetermined pickup and release values of energy and picked up when the charge on said larger capacitor is equal to the pickup value of the relay, said relay when picked up completing a holding circuit for the code transmitter; the operation of the code transmitter contacts when a vehicle leaves the path discharging the larger capacitor in steps by alternately charging the smaller capacitor from the larger capacitor and discharging the smaller capacitor thereby lowering the charge on the larger capacitor to the release value of the relay, a control element normally operated when a vehicle leaves the path, and means controlled by said relay to maintain said control element inoperative when said relay is energized.

20. In a highway crossing signal control system in which a railway track which intersects a highway is divided into a timing section and an operating section arranged so that a train approaching the intersection occupies first the timing section and then the operating section, the combination comprising, a code transmitter operated when a vehicle enters and occupies the path, first and second capacitors, a third capacitor of larger capacity than the first and second capacitors, the third capacitor being charged in steps by the alternate charging of the first capacitor from an energy source and discharging the first capacitor therein by the operation of the code transmitter contacts, a relay having front and back contacts and predetermined pickup and release values of energy at which said relay closes its front contacts and opens its front contacts and closes its back contacts; said relay being picked up when the charge on said third capacitor is equal to the pickup value of said relay, a first front contact to complete a holding circuit for the code transmitter, a second front contact to complete a circuit connecting said second capacitor with the first capacitor to increase the charging rate of the third capacitor; the operation of the code transmitter References Cited in the file of this patent UNITED STATES PATENTS 2,086,913 Kelly July 13, 1937 2,114,016 Dimond Apr. 12, 1938 2,209,225 Evans et al July 23, 1940 2,298,575 Mackey Oct. 13, 1942 2,411,573 Holst et al. Nov. 26, 1946

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