US2095861A - Time measuring apparatus - Google Patents

Description

Oct. 12, 1937. A. w. FISHER TIME MEASURING APPARATUS 2 Sheets-Sheet 1 Filed Jan. 25, 1957 k 7 5 L M H B T Z LL! 2 5 W 4 h B 5 v w W M, Z

INVENTOR Amlzu wlzep ATTORN EY HIS Oct. 12, 1937, A. w. FISHER TIME MEASURING APPARATUS 2 SheetsSheet 2 Filed Jan. 23, 1937 lnyulazion HIS ATTORN EY Patented Oct. 12, 1937 UNITED STATES PATENT OFFliCE TIME MEASURING APPARATUS Application January 23, 1937, Serial No. 122,050

8 Claims.

My invention relates to time measuring apparatus, and particularly to electrically operated time measuring apparatus.

More specifically, an object of my invention is the provision of novel and improved means for checking the operation of time measuring appara tus adaptable of movement away from an initial position during the lapsed time of an event, such as the time consumed in performing a desired operation; and which apparatus is automatically reset to its initial position at a predetermined rate of movement, desired control over other devic s being effected by the apparatus during the resetting movement. Other objects and ad vantages of my invention will appear as the specification progresses.

I will describe one form of apparatus embodying my inven and will then point out the novel features thereof in claims.

Apparatus embodying my invention is particularly useful in time measuring apparatus employed in control systems for highway signals located at the intersection of a railway and a highway at grade, which control systems provide a warning operation of a signal prior to the arrival of a train at the intersection the period of which is substantiaily uniform over a wide range of train speeds. It will be understood that my invention is not limited to this one application of time measuring apparatus, and it will be useful at many places where time measuring apparatus of the type here contemplated is employed.

In the accompanying drawings, Fig. 1 is a diagrammatic view of one form of apparatus embodying my invention when applied to a control system for highway crossing signals. Figs. 2 and 3 are inverted plan and elevation views, respectively, partly section, of a time measuring device that may be used with the apparatus of Fig. 1.

In each of the several views, like reference characters designate similar parts.

Referring to Fig. 1, the reference characters la and ib designate the track rails of a stretch of railway track over which traffic normally moves in the dire tion indicated by an arrow, and which is intersected at grade by a highway H. A highway crossing signal S is located adjacent the intersection. The signal S may be any one of the standard types of highway crossing signals, and is here shown as an audible signal in the form of an electric bell.

Preferably, the track rails Ia. and lb are divided by the usual insulated rail joints to form three track sections WX, XY and YZ, which sections are travelled successively in the order named by train. approaching the highway H when moving in the normal direction of trafiic. Each track section is provided with a track circuit consisting of a source of current, such as a battery 2 connected across the rails at one end of the section and a track relay designated by the reference character R, plus a distinguishing exponent connected across the rails at the oppo ite end of the section.

For the purpose of this descrpition, I shall refer to the track section WX as a measuring section, section XY as a first operating section and the section YZ as a second or positive operating section. As will appear hereinafter, the speed of a train as it travels the measuring section WX is determined by a time measuring device set into operation to measure the time consumed by the train in advancing through the section. The signal S is set into operation to sound a warning in accordance with such measured time after the train enters the first operating section XY. Positive operation of the signal S effected when the train occupies the section YZ.

In order to more easily understand my invention, I shall assume that the maximum speed of all trains approaching the highway H is miles per hour and 20 seconds warning period of the signal S prior to the arrival of a train at the intersection is desired. A train moving at 99 miles per hour advances 132 feet per second, and the combined length of the operating sections XY and YZ is made 2640 feet (132x since operation of the signal is initiated when a train enters the section X-Y unless the warning period is modified through the medium of a time measuring device, to be referred to later. The section YZ is preferably short, say, for example, 200 feet, and by virtue of this section, operation of the signal, while a train occupies the crossing, is assured. To agree with the above assumed train speeds and the operating period of the associated time measuring device, the measuring section WX is preferably 2640 feet in length.

The immediate control of the signal S is effected through the medium of a control relay L, the arrangement being such that when relay L is released, closing its back contact a simple operating circuit for the signal S i completed, but, when the relay L is energized and red up, the circuit is open and the signal S is si. sill). The relay L, in turn, is controlled jointly by the track relays 2R and 3R, 2. time measuring device designated as a whole by the reference character TM, and a check relay CR. The control circuit for relay L be traced from the B term nal of any convenient source of current, such a battery not shown, over front contact of relay line wire 5, front contact 6 of relay 3R, winding relay L, and to the C terminal of the current source. This control circuit is provided with a branch path that extends from the B battery terminal over the 14th step contact of the time measuring device TM, to be shortly described,

front contact I of the check relay CR, Wire 8 to line wire 5, and thence as before traced. It follows that, when both track sections XY and Y Z are unoccupied and the two track relays 2B and ER are picked up, the relay L is energized and the signal S is silent, but that, when section XY is occupied and relay 2R is released, opening front contact 4, the relay L is deenergized to initiate operation of the signal S, unless the branch path including the 14th step contact of the time measuring device TM and the front contact i of the check relay CR is closed. Again, when the section Y-Z is occupied and the relay 3R is released, opening front contact 6, the relay L is deenergized and operation of the signal S is efiected, irrespective of the condition of the time measuring device TM and check relay CR, or of the track relay 2R. Furthermore, unless the check relay GR is energized and picked up to close its front contact 1, the time measuring device TM is ineffective to control the relay L.

The time measuring device TM may take different forms, among them being that disclosed in Figs. 2 and 3. Looking at Figs. 2 and 3, the time measuring device TM comprises two operating units which are mounted in a frame-work 3'! secured by screws not shown to a top plate 39 of suitable insulation material. The top plate 39 also has mounted therein standard terminal posts 55 for making connections with outside circuits. The top plate 39 would be mounted on a suitable dust and weatherproof case not shown such as is commonly provided for electrically operated devices of this type. A first one of the two units of the device TM includes as its essential elements a motor magnet WM and a wiper contact assem- V bly WA. The second unit includes as its essential elements a' motor magnet LM and a contact actuating lever assembly LA. The wiper contact assembly WA includes an insulation drum 9 and a series of insulation discs II. The drum 9 and discs ii are clamped together and mounted for rotation in unison around an axis I 2 which is suitably journalled in the frame work 31. The surface of the drum 9 is formed with grooves in which brass slip rings in are secured, and each of which rings has engaging therewith a wire spring brush it, there being one brush for each slip ring. The several brushes I3 are held at their outer ends between two insulation blocks I5 and I5a which are fastened to the frame work by screws 5?. Each such brush I 3 is formed with a terminal E6 to which a lead wire lfia may be fastened as by soldering and connected to a definite one of the terminal posts 55. A series of circuit controlling contact wipers or fingers, to be shortly described, are spaced between the insulation discs H, and these contact fingers are connected by lead wires it to the slip rings It, each contact finger being connected to a particular slip ring. In Fig. 2 these lead wires 89 are shown for the sake of clearness as outside of the discs II and drum 9, but it will be understood that in actual practice these lead wires would pass through holes drilled in the discs and drum and would not interfere when the wiper assembly WA is rotated about the axis E2 in a manner to be later described.

Referring to Fig. l as well as to Figs. 2 and 3, the circuit controlling contact fingers mounted in the insulation discs I I are disposed'to form circuit controlling contacts designated by the reference characters 14th step contact, 49th step contact, synchronous contact CNS and check contact CH. The 14th step contact includes two resilient contact fingers I ia-and l ib spaced apart in the discs II and biased by their own spring action to make engagement and complete a circuit connection therethrough. The contact fingers I ia and Nib are formed at their outer ends to receive a cooperating insulation contact actuating member M0, to be referred to later, and which member, when brought between the two contact fingers, forces the fingers apart to break the circuit connection therethrough. The 49th step contact likewise includes two resilient contact fingers 49a. and 4%, which are biased to make engagement for completing a circuit connection therethrough and are formed at their outer ends to receive an insulation contact actuating member G90, which when moved between the contact fingers as will shortly appear forces the contact fingers apart to break the circuit connection. The synchronous contact ONS also includes two resilient contact fingers Sa and Sb, which are spaced apart and biased into engagement, and are formed at their outer ends to receive an insulation contact actuating member Sc, and by means of which the contact fingers are forced apart for opening the circuit connection. The contact finger Sb is also disposed to engage a contact finger Ca to close the check contact CH at such time as the contact actuating member So is positioned between the contact fingers S54 and Sb to open the synchronous contact ONS. Each of the contact fingers Ida, Mb, 49a, 49b, 80., Sb and Ca are connected as described hereinbefore by means of a lead wire E9 to a corresponding slip ring ID on the drum 9. It follows that each of these contact fingers is electrically connected with a corresponding terminal it, whatever its angular position about the axis I2, and that operation of the contact fingers by their respective contact actuating members into and out of engagement is effective to make or open circuit connections between terminals l6 and, in turn, between the corresponding terminal posts 56.

The contact actuating lever assembly LA includes two radially extending arms Ill and i8 secured together and mounted for rotation about the axis I2 independent of the wiper assembly WA. The outer ends of the arms I? and I8 are each formed to extend parallel with the axis 12 and carry the insulation contact actuating members Sc and see, respectively. The insulation member S0 is positioned to operate between the contact fingers Sc and Sb of the synchronous contact ONS, and the member 490 is positioned to operate between the contact fingers 49a and 49b of the 49th step contact. The contact actuating member Me is made an arcuate member of some length and is mounted on the two arms 5? and I8 in a position to operate between the contact fingers Ma and Mb of the 14th step contact. The function of the several contacts and the operation thereof will appearwhen the operation of the system is described.

The wiper contact assembly WA and the contact actuating lever assembly LA are actuated step-by-step by the respective motor magnets WM and LM through the medium of ratchet wheels 33 and 26, respectively. The motor magnet LM is provided with an armature 2i journaled at 2m and 2th on an armature shaft 22. The armature 21 carries a ratchet operating arm 23, which, in turn, carries a propelling pawl 2d. The propelling pawl 2 is pivoted at 253 on the outer end of the arm 23 and is biased, by means of a spring 25 carried on the operating arm 23, to a position in which the lower end of the pawl 1 tion around the axis l2.

engages an adjacent tooth of the ratchet wheel 25. The ratchet wheel 26 is free to rotate on the axis l2 and is in fixed relation with the lever arms I! and I8 of the contact actuating lever assembly LA. Also cooperating with the ratchet Wheel 26 is a retaining pawl 21, which permits rotation of the ratchet wheel 26 in one direction only, that is, in the counterclockwise di rection as viewed in Figs. 1 and 3. A drive spring is hooked between a stud 29 on the operating 23 and a fixed support 30. When the motor magnet LM becomes energized, armature 2| is attracted toward the right, as viewed in Figs. 2 and 3, and upward, as viewed in Fig. 1, thus raising the operating arm 23 and the propelling pawl 24 against the force of the drive spring 28. When the motor magnet 1M becomes deenergized, the drive spring 28 draws the operating arm 23 and the propelling pawl 24 downward, thereby stepping the ratchet wheel 26 one step in the counterclockwise direction. Thus, periodic energization of the motor magnet LM is efiective to step the ratchet wheel 26, and in turn the lever assembly LA, in a counterclockwise direc- The parts are so proportioned that 50 steps make one full revolution.

As shown in Fig. 2, the motor magnet WM is provided with an armature 3| journaled at 31c. and 3lb on the armature shaft 22, and has rigid therewith an operating arm 32, which arm carries on its outer end a propelling pawl 35. The propeling pawl 35 is biased into engagement with a tooth of the ratchet wheel 33 in the same manner as the propelling pawl 24 is biased into engagement with a tooth of the ratchet wheel 26. The ratchet wheel 33 is free to rotate on the axis !2 and is in fixed relation with the drum 9 and the series of discs H of the wiper contact assembly WA. A retaining pawl 34 permits rotation of the ratchet wheel 33 in one direction only, that is, in the counterclockwise direction as viewed in Figs. 1 and 3. In other words, the ratchet wheels 26 and 33 are capable of rotation in the same direction about the axis I2. A drive spring is attached to the operating arm 32 in the same manner as the drive spring 28 is attached to the operating arm 23. Consequently, when motor magnet WM is periodically energized, the ratchet wheel 33 and the wiper contact assembly WA including its contact fingers are rotated step-by-step around the axis l2 in a counterclockwise direction. The parts are so proportioned that 50 steps of the ratchet wheel 33 complete one full revolution.

The relationship between the movements of the wiper contact assembly WA and the contact actuating lever assembly LA will now be described. The normal and synchronous position of these two assemblies is that illustrated in the drawings, the two associated motor magnets being inactive. In this synchronous position the contact actuatmeinber Sc of the assembly LA occupies the position between the contact fingers Sa and Sb of the assembly WA to open the synchronous contact ONS, the contact actuating member Me of the assembly LA is positioned between the contact fingers [4a and Mb to open the 14th step contact, and the contact actuating member 43 of the assembly LA occupies a postion out of engagement with the contact fingers 49a and 49b and the 49th step contact is closed. In this synchronous position the contact finger Ca. makes engagement with the contact finger Sb to close the check contact CH. With the assembly LA remaining stationary and the motor magnet WM energized to operate the assembly WA one step away from the synchronous position, the contact fingers Sc and so advance away from the member Sc, and the synchronous contact CNS is closed. When the contact finger Sb moves off the member So at the end of this first step, it springs away from the contact finger Ca and the check contact OH is opened. With the assembly LA reraining stationary and the assembly WA operated 14 steps away from the synchronous position, the contact fingers [4a and Nb advance away from the member H and the 14th step contact is closed. When the assembly WA is operated 49 steps away from the synchronous position, that is, one step prior to a full revolution, the contact fingers 49 and 4% move into the postion where the member 490 of the assembly LA passes between these contact fingers to open the 49th step contact. One side of the circuit for the motor magnet WM includes the 49th step contact, and it is to be seen that operation of the assembly WA is stopped just prior to one full revolution if it is not stopped prior to this 49th step bythe control apparatus in a manner to shortly appear.

On the assumption that the motor magnet WM has operated the wiper assembly WA to the 49th step and the operation stopped, operation of the motor magnet LM is effective to step the lever arm assembly LA around to the position where the member Sc passes between the contact fingers Sc. and so to open the synchronous contact ONS, this contact ONS being included in the circuit for the motor magnet LM as will be later pointed out. As a matter of fact, operation of the assembly WA to any intermediate position between the synchronous position and the 49th step position and the operation then stopped. when followed by operation of the motor magnet LM, drives the lever assembly LA until the member Sc engages the contact fingers Sc and so to open the synchronous contact ONS. It is to be pointed out that the 14th step contact is closed when the assembly WA is operated 14 steps away from the synchronous position and remains closed until the lever assembly LA is subsequently operated and reaches a point 14 steps from the synchronous position. That is, the 14th step contact is closed when the two assemblies WA and LA occupy a predetermined position with respect to each other. Again, it is to be noted that the check contact CH is closed only at the synchronous position.

Periodic impulses of current are supplied to the motor magnets WM and LM through the medium of an oscillator or flasher relay FR, which may take any one of several well-known forms. As here shown, the armature 48 of relay FR is biased to a midposition where it engages an arcuate contact Al, the energizing circuit for the relay including the contact 4G-4L When the winding 42 of the relay FR is energized, the armature is swung to the left, as viewed in Fig. l, breaking the contact tit-Al and deenergizing the relay. The armature it is now operated to the right under the influence of its biasing element to again close the contact it-4i and reenergize the relay. When the armature 46 is swung to the right under the influence of the biasing element, it will move somewhat past the midposition due to the inertia of the parts and complete a second contact 40- 53. It follows that when positive current is supplied to the wire 50 connected with the armature 40, the relay FR is operated at a predetermined rate, closing the contact Gil-d3 once each cycle of the operation. To agree withthe train speeds and the lengths of track sections assumed hereinbefore, the relay FR is proportioned and adjusted to complete a cycle of operation in substantially one and one-half seconds.

The check relay CR is provided to check the operation of the time measuring device TM, and to that end is provided with an energizing circult that includes B battery terminal, contact finger Sb, contact finger Ca, winding of relay CR, and to the C terminal. The relay CR is provided with a stick circuit that includes front contact 55 of the track relay 3R, as well as its own front contact t5. Consequently, the relay CR, once deenergized, can be reenergized only in the event the time measuring device TM is operated to the synchronous position, closing the check contact CH, but, once picked up, it is retained energized subsequent to operation of the ti e measuring device away from the synchronous position until such time as the track section Y-Z is occupied by a train and the track relay SP. is shunted. As set forth hereinbefore, a front contact l of the check relay CR is interposed in the branch path of the control circuit for the relay L.

Normally, that is, when the track sections VVX, XY and Y-Z are all unoccupied, the track relays ER, 2R and 3B. are picked up and the time measuring device TM occupies the synchronous position, that is, the position illustrated in the drawings. Under this normal condition, the relay L is energized and the signal S is silent. The check relay CR is also picked up, since the time measuring device occupies its synchronous position, and the check contact CH is closed,

I shall now assume that a train operating at a relatively low speed of 24 miles per hour, or approximately 35 feet per second, approaches the highway crossing from the left. This train, upon entering the measuring section W-X, shunts the track relay IR, and that relay upon releasing closes its back contact ii and completes a circuit for operating the relay FR. This operating circuit includes battery terminal B, front contact 23 of track relay 2R, back contact Q? of track relay HR, wire 59, contact l@5l, winding @2 of the relay FE, and to the C terminal of the current source. Relay FR is thus set into operation and is operated at its predetermined rate of approximately 40 times per minute, that is, 1 cycle each one and one-half seconds. Current impulses are new supplied to the motor magnet WM of the time measuring device, the circuit extending from B terminal over front contact &8, back contact ll, wire 56, contact t ll-53 of relay FR, wire 5!, a second front contact 52 of relay 2R, a second back contact 53 of relay lR, winding of motor magnet WM, contact fingers a and @5311 of the 49th step contact, and to the C terminal. Consequently, the wiper assembly WA of the time measuring device is stepped around one step for each cycle or" operation of the relay FR. On the first step away from the synchronous position, the contact fingers Sc and S5 of the synchronous contact OHS move out from engagement with the member Sc, and the contact ONS is closed. Subsequent to the first step, the flasher relay and, in turn, the motor magnet WM may be supplied current from B terminal over contact CNS of the time measuring device, wires 59 and 55,

contact lidll, winding d2 of relay ER and to the C terminal for the relay FR, and from wire 50 over contact 45-43, and, as previously traced for the motor magnet WM. It follows that entry of the train into the section WX results in the flasher relay FR being set into operation and the wiper assembly WA of the time measuring device being rotated step by step.

This train operating at substantially 35 feet per second requires about '75 seconds to advance through the measuring section W-X, which is taken here to be 2640 feet in length. On the 49th step of the wiper assembly WA the contact fingers 59a and 49b engage the member 590 of the lever assembly LA, and the 49th step contact is opened, discontinuing the operation of the motor magnet WM, the flasher relay FR still being operated since the synchronous contact ONS still remains closed. Just after the wiper assembly has completed its 49th step, the head end of the train enters section XY, shunting the track relay 2B and closing back contact 5i. An impulse of current is now supplied to the motor magnet LM of the lever assembly LA each cycle of operation of the relay FR over a circuit that may be traced from B terminal, contact ONS, wires 59' and 59, contact fill-43, wire 5|, back contact 555 of relay 2R, wire 55, winding of motor magnet LM, and to the C terminal, and the assembly LA is advanced step by step.

When the relay 2R is shunted in response to entry of the train into the section X-Y, the front contact 4 in the control circuit for the relay L is opened, but the relay L is now energized over the branch path that includes the 14th step contact of the time measuring device and the front contact 1 of the check relay CR, since the contact fingers Ida and Mo were moved away from engagement with the member i i-c when the wiper assembly WA had completed its 14th step away from the synchronous position and relay CR is held energized over its stick circuit. When the motor magnet LM has stepped the lever assembly ahead to within 14 steps of the position of the wiper assembly, that is, when the lever assembly LA has advanced 35 steps, the member Mic is moved between the contact fingers Mia and lb to open the 14th step contact and to remove current from the control relay L, with the result that the relay L is released and operation of the signal S is initiated. The motor magnet LM requires substantially 52.5 seconds to make these 35 steps, and hence the train has advanced about 1838 feet (525x35) into the section XY, and is about 802 feet from the intersection when the operation of the signal is initiated. This train requires about 22 seconds to advance 802 feet, and hence there is a warning period of approximately 22 seconds prior to the arrival of the train at the intersection.

When the motor magnet LM has advanced the control lever assembly 49 steps, the member Sc passes between the contact fingers Sc and Sb to open the synchronous contact ONS, with the result that the flasher relay ER and the motor magnet LM are deenergized. The train, upon entering the section Y-Z, shunting track relay SE to open front.contact 45, causes the check relay CR to be deenergized and released. This relay CR, however, is reenergized when the lever assembly LA has been advanced and has been brought into synchronism with the wiper assembly WA in the manner described above, since the check contact CH is reclosed, completing the pickup circuit for relay CR. t is to be noted that, if the motor magnet LM fails to advance the lever assembly LA to the synchronous position with respect to the wiper assembly WA and the check contact OH is not reclosed, the relay CR remains deenergized, with the result that control of the relay L over the time measuring device is made ineifective by virtue of the front contact 1 of relay CR which is interposed in the control circuit for relay L. Thus, with apparatus embodying my invention, the operation of the time measuring device TM is checked and a failure of the time measuring device to operate or to restore. itself to normal synchronism results in annulling its control of the highway crossing signal and restores the crossing signal control for all trains to the first operating track section.

I shall next assume that a train operating at the maximum speed of 90 miles per hour approaches the intersection. This train, upon entering the section WX and shunting track relay IR to close the back contact 41, starts the operation of the flasher relay FR and, in turn, of the motor magnet WM, the same as described for the first train. This train operating at 90 miles per hour consumes substantially 20 seconds in advancing through the section WX and entering the section X-Y. Thus, just after the motor magnet WM has advanced the wiper assembly WA 13 steps, the track relay 2R is released to open the front contact 52 thereof and discontinue the operation of the motor magnet WM. Release of relay 2R, opening front contact 4, causes the control relay L to be deenergized, since the branch path, including the 14th step contact of the time measuring device, is still open, with the result that operation of the signal S is initiated in response to entry of the train into the section X-Y. With the release of relay ZR, closing back contact 54, the motor magnet LM is supplied with current impulses and the lever assembly LA is advanced toward the position of the wiper assembly, which, it will be recalled, advanced 13 steps during the period the train was passing through section WX. When the motor magnet LM has advanced the lever assembly 13 steps, the synchronous contact CNS is opened, discontinuing the operation of relay FR, and of the motor magnet LM. Entry of the train into the section YZ, shunting track relay 3R, causes the release of the check relay CR, but this check relay is reenergized over the check contact CH of the time measuring device when the device TM is restored to its synchronous position. Again, it is to be pointed out that the relay CR checks the operation of the time measuring device annulling its control of the highway crossing signal in the event that the device is inoperative or is not returned to the normal synchronous position and, in lieu thereof, restores the crossing signal control for all trains to the first operating track section.

An analysis of the apparatus of Fig. 1 will disclose that a similar operation will take place for all train speeds between the maximum speed of 90 miles per hour and the relatively low speed of 24 miles per hour, the delay in starting the operation of the signal S effected by the time meas= ently rotatable in the same direction about a common axis, said members having a synchronous position with respect to each other which may occur at any angular position, a check contact operated jointly by said members and closed only at the synchronous position, a circuit controlling contact operated jointly by said members and closed when the members occupy a predetermined position with respect to each other, motor actuated means operatively connected to said members, control means to eifectively energize the motor actuated means to rotate the first member away from the synchronous position during the lapsed time of an event and then at the expiration of said event to rotate the second member until the synchronous position is again established, and an operating circuit governed jointly by said circuit controlling contact and said check contact.

2. In combination, a time measuring means including a first and a second member independently rotatable in the same direction about a common axis, said members having a synchronous position with respect to each other which may occur at any angular position, a check contact operated jointly by said members and closed only at said synchronous position, a first motor effective when energized to rotate said first member, a second motor effective when energized to rotate said second member, control means effective to energize said first motor to rotate the first member during the lapsed time of an event and to then energize said second motor to rotate the second member until the synchronous position is reached, a circuit controlling contact operated jointly by said members and closed when the members occupy a predetermined position with respect to each other, an operating circuit including said circuit controlling contact and another contact, and checking means including said check contact for governing said other contact.

3. In combination, a time measuring means including a first and a second member independently rotatable in the same direction about a common axis, said members having a synchr nous position with respect to each other which may occur at any angular position, a pair of contacts jointly operated by said members and made to engage when said first member isrotated a predetermined distance ahead of the synchronous position, a check contact operated jointly by said members and closed only at the synchronous position, a first motor effective when energized to rotate said first member, a second motor efiective when energized to rotate said second member, control means effective to energize said first motor to rotatethe first member during the lapsed time of an event to engage said pair of contacts and to then energize the second motor to rotate the second member until the synchronous position is reached to disengage said pair of contacts, an operating circuit serially in cluding said pair of contacts and another contact, and checking means including said check contact for governing said other contact.

4. In combination, a time measuring means including a first and a second member independently rotatable in the same direction about a common axis, said members having a synchronous position with respect "to each other which may occur at any angular position, a check contact operated jointly by said members and closed only at said synchronous position, a first motor effective when energized to rotate said first member, a second motor efiective when energized to rotate said second member, control means effective to energize said first motor to rotate the first member during the lapsed time of an event and to then energize said second motor to rotate the second member until the synchronous position is reached, circuit controlling contacts operated jointly by said members and closed when the members occupy a predetermined position with respect to each other, a relay, an energizing circuit for said relay including said check contact and a winding of the relay, a stick circuit for said relay including a winding of the relay and another contact, an operating circuit including said circuit controlling contacts and a front contact of said relay, and means for operating said other contact to deenergize at times said relay.

5. In combination, a time measuring means including a first and a second member each rotatable by step in the same direction about a common said members having a synchronous position. with respect to each other which may occur at any angular position, a pairof contacts jointly operated by said members and made to engage when said first member is rotated a predetermined number of steps in advance or the synchronous position, a check contact operated jointly by said members and closed only at the synchronous position, a first motor magnet effective when periodically energized to rotate the first member step by step, a. second motor magnet efiective when periodically energized to rotate the second member step by step, control means effective to periodically energize the first motor magnet to rotate the first member during the lapsed time of an event to engage said pair of contacts and to then stop the first motor to periodically energize the second motor magnet to rotate the second member until the synchronous position is reached to'disengage said pair of contacts, operating circuit serially including said pair of contacts and another contact, and checkin means including said check contact for governing said other contact.

6. In combination, a time measuring means including a first and a second member independently rotatable in the same direction about a common axis, said members having a synchronous position with respect to each other which may occur at any angular position, a first pair of contacts jointly operated by said members and said contacts disengaged only at the synchronous position, a second pair of contacts jointly operated by said members and said contacts made to engage When said first member is rotated a predetermined distance in advance of the second member, a first motor efiective when energized to rotate said first member, a second motor effective when energized to rotate said second member, a first control circuit to energize the first motor for rotating the first member during the lapsed time of an event to engage said second pair of contacts, a second control circuit including said first pair of contacts to energize said second motor subsequent to said event for rotating the second member until said first pair of contacts are disengaged and the synchronous position is reached, a check relay, an energizing circuit for said relay including a particular one of the first pair of contacts in its synchronous position and a winding of the relay, a stick circuit for said relay including a winding of the relay and a remote contact, an operating circuit serially including a front contact of said relay and said second pair of contacts, and means for operating at times said remote contact to deenergize said relay.

'7. In combination, a stretch of railway track formed into a first and a second track section which a train normally travels in the order named and which are each provided with a track circuit including a track relay, a first motor actuated timing unit including a first member rotatable about an axis in a given direction, a second motor actuated timing unit including a second member rotatable about the same axis in said given direction, said first and second members having a synchronous position with respect to each other which may occur at any angular position, a circuit controlling contact operated by said first member when the member is rotated a predetermined distance away from the synchronous position, a check contact operated jointly by said members and closed only at the synchronous position, a first control circuit including a back contact of the track relay of the first section and a front contact of the track relay of the second section to energize the motor of said first unit for rotating said first member during the time a train is advancing through said first section, a second control circuit including a back contact of the track relay of the second section to energize the motor of said second unit for rotating the second member until the synchronous position is reached, a check relay, circuit means for energizing said check relay and including said check contact, and a signaling circuit including said circuit controlling contact and a contact of said check relay.

8. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a time measuring means including a first and a second member each rotatable in the same direction about a common axis, said members having a synchronous position with respect to each other which may occur at any angular position, a pair of cooperating contacts operated jointly by said first and second members and said contacts made to engage when said firstmem-ber is advanced a predetermined distance from the synchronous position ahead of said second member, a check contact operated jointly by said members and closed only at the synchronous position, an operating circuit means for setting the signal into operation when a train approaching the intersection reaches a fixed point; a branch circuit including said pair of contacts and another contact to render said operating circuit inefiective to operate the signal when said pair of contacts engages and said other contact is closed, a first motor actuated device for rotating said first member to engage said pair of contacts and effectively energized during the time it takes a train to travel a given distance preceding the fixed point, a second motor actuated device for rotating said second member to disengage said pair of contacts and efiectively energized when the train reaches the fixed point, and check circuit means including said check contact for operating said other contact. r

' ARTHUR W. FISHER.

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