US2187406A - Time measuring apparatus - Google Patents

Description

Jan. 16, 1940. Q E, STAPLES 2,187,406

TIME MEASURING APPARATUS Original Filed March 13, v1935 2 Sheets-Sheet 1 V T S 222 3g 1 5 L JF 1671 F 7 F 20 9 INVENTOR H15 ATTORNEY Jan. 16, 1940. c, STAPLES 2,187,406

TIME MEASURING APPARATUS Original Filed March 13, 1935 2 Sheets-Sheet 2 Time 60-- 20 40 60 50 Tfiam 5,09% [12 M RH.

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H15 ATTORN EY Patented Jan. 16, 1940 UNITED STATES PATENT OFFICE TIME NIEASURIN G APPARATUS Crawford E. Staples, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania.

7 Claims.

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

A feature of my invention is the provision of novel and improved means to actuate a circuit controlling contact member in accordance with the lapsed time of an event, such as, for example, the time required for a railway train to operate over a stretch of track. Other features and advantage of my invention will appear as the specification progresses.

This application is a division of my application, Serial No. 16,869, filed March 13, 1935, for Apparatus for the control of highway crossing signals, now Patent No. 2,089,919, granted August 10,1937.

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

In the accompanying drawings, Fig. l is a View partly diagrammatic and partly in elevation of one form of apparatus that may be employed in carrying out the embodiment of my invention. Fig. 2 is a plan view partly diagrammatic of a portion of the apparatus of Fig. 1. Fig. 3 is a detail view of the biasing spring for the apparatus of Figs. 1 and 2. Figs. 4 and 5 are diagrams illustrating certain characteristics of the apparatus of Figs. 1, 2 and 3.

Similar reference characters refer to similar parts in each of the views.

Although a particular application of apparatus embodying my invention is here disclosed, it will be understood the invention is not limited to this one application and many places will suggest themselves where time measuring apparatus embodying my invention will be useful.

Referring to. Fig. l, the reference characters i and l designate the track rails of a stretch of railway track over which traffic normally moves in the direction indicated by an arrow and which stretch is intersected by a highway H. Two highway crossing signals Si and S2 are located adjacent the intersection and are indicated on the drawings by symbols commonly used in the art to designate a flashing light highway crossing signal. As is common practice, these two signals are set for one to be plainly exhibited to highway traffic approaching the crossing in one direction and the other signal to be plainly exhibited to highway traflic approaching the crossing from the opposite direction.

As here shown, the track rails I and I are divided by the usual insulated rail joints to form three track sections RS, S- I and T.-V, which sections are traversed successively in the order named by a train approaching the highway I-I when moving in the normal direction of traffic. Each track section is provided with a track circuit comprising a battery 3 connected across the track rails at one end of the section and a track relay designated by the reference character R plus an exponent corresponding to its location connected across the rails at the other end of the section. For the purpose of this description I shall refer to the track section RS as a measuring section, section ST as an operating section, and the section TV as a positive operating section. As will appear hereinafter, the speed of a train as it traverses the measuring section R-S is measured, the highway signals Si and S2 are set into operation in accordance with this measured speed after the train has entered the operating section 5-1 and positive operation of the signals SI and S2 occurs during the time the train occupies the section T-V irrespective of whether it is moving or not.

In order to more easily understand the apparatus embodying my invention I shall assume a maximum speed for all trains approaching the highway H of miles-per hour. I shall also assume a time interval of 20 seconds exhibit of the highway signals before a slow moving train reaches the intersection and that this interval is uniformly increased as the speed becomes greater until an exhibit of 30 seconds of the highway signals for a train traveling at the maximum speed of 60 miles per hour is provided. I shall further assume the measuring section R-S to be 889 feet in length, that is, the section RS is of such length that a train moving at the maximum speed of 60 miles per hour consumes approximately 10 seconds in advancing therethrough. The combined lengths of the operating section S-T and the positive operating section TV are substantially 2640 feet since a train traveling at the maximum speed of 60 miles per hour moves 2640 feet in 30 seconds and, as above stated, a 30 seconds exhibit of the highway crossing signals before a train traveling at the maximum speed reaches the intersection is desired. The section T--V is preferably just long enough, say 200 feet, that operation of the highway crossing signals with a train occupying the intersection whether it is moving or not is assured. It follows that with the track arrangement here assumed the highway crossing signals S!- and S2 are set into operation for a train traveling at the maximum speed immediately upon the train entering the'operating section S--T, but that for a train having a lower speed the starting of the .operation of the signals SI and S2 is delayed after the train enters the operating section ST, this delay being such that the period of oper-- ation of the highway signals before a train reaches the intersection becomes proportionally less as the speed becomes lower until at a speed of 20 miles per hour the period of operation is only 20' seconds whereas at the maximum speed the period of operation is 30 seconds. For speeds lower than 20 miles per hour the period of oper ation remains substantially constant at 20 seconds. It will be understood, of course; that my invention is not limited to the above-stated Values of speeds, lengths of track sections and operating intervals of the highway crossing signals, and such values may be selected best suited for the location at which the apparatus is installed.

The operation of the signals SI and S2 is gov erned by anoperating unit here shown as an oscillator or code transmitter designated as a whole by the reference character CT. This oscillator CT may take different forms but a preferred form is that described and claimed in Letters Patent No. 1,858,876, granted May 17, 1932, to Paul N. Bossart, for Coding apparatus. It is deemed'sufficient for the present application to give but a brief description of this oscillator CT. A magnetic field structure 5 has mounted between its two poles PI and P2 a spindle 8 on which an armature 6 is fixed so as to swing freely between the pole pieces. The armature 6 and the spindle 8 are normally biased to the position illustrated in Fig. 1 by any convenient biasing means such as a coil spring not shown, and the armature 6 is adapted to be attracted toward the pole pieces of the field structure in response to a magnetic field created therein. As indicated schematically by dotted lines, three cam members 9, I0 and II are fixed on the spindle 8. These cam members 9, I0 and II are each effective when rotated with the spindle 8 in a manner to shortly appear, to actuate a pair of circuit controlling contact fingers. A field winding I is mounted on the field structure 5 and is provided with a plurality of energizing circuits all of which include the pair of contact fingers actuated by the cam member II. When the relay R is deenergized and its back contact I2 is closed, a circuit is completed which extends from the B terminal of any convenient source of current such as a battery, not shown, over wire l3, back contact I2 of relay R wire I4, winding I, contact I5-I6 actuated by the cam II and thence to the opposite terminal C of the same source of current. In the event the track relay E is shunted and its back contact I! is closed, or if the track relay R is shunted and its back contact I8 is closed, a circuit extends from the B battery terminal over the back contact ll of relay R or over the back contact I8 of the relay R wire I4, winding I, contact I5I6. and to the C battery terminal. It follows that as long as any one of the track relays R R and R is shunted, the field winding I is supplied with current. but that when all three of these relays are picked up the winding I is without current. With the winding I energized and a magnetic field created in the field structure 5, the armature 6 is attracted toward the pole pieces and the spindle 8 is rotated in a counterclockwise direction against the force of the bias. After a slight movement of the armature 6 in the counterclockwise direction, the cam member II actuates the contact finger I5 out of engage- I ment with the contact finger I6 and the circuit connection therethrough is broken with the result that the field winding I is deenergized. The

armature 6 rotates a little farther and then its movement is reversed due to the bias and it swings clockwise toward its normal position. The cam member II is now rotated back toward its normal position and the contact I5I6 is again closed and the winding 1 is reenergized. Armature 6 swings clockwise slightly past its normal position due to the inertia of its parts and it is then again rotated in a counterclockwise direction due to the influence of the magnetic field.

Consequently, as long as any one of the track relays R R or R is shunted and the field winding I is supplied with current, the armature 6 oscillates at its natural period, the period of oscillation being determined by the bias and the weight of the parts. Although the period of oscillation may be any convenient frequency, I shall consider it to be 30 cycles per minute.

As stated above, the cam members 9 and III are fixed on the spindle 8, and hence the cam members 9 and I0 are rotated in response to the operation of armature 6. The cam member 9 is so shaped that when rotated counterclockwise the associated contact fingers I9 and 20 are forced apart to break engagement and open the circuit connection therethrough, but that when rotated in the clockwise direction within the limits of the movement of the armature 6, the contact fingers I9 and 20 remain in engagement to close the circuit connection therethrough. The cam member I0 is so shaped that when rotated clockwise the associated contact fingers 2! and 22 are forced apart to open the circuit connection therethrough but when rotated in the counterclockwise direction within the limits of the movement of the armature 6, the contact fingers 2| and 22 remain in engagement. It follows that as the armature 6. is rotated counterclockwise the contact I9--2Il is opened and as the armature 6 swings clockwise past its normal position the contact 2I-22 is opened, but that at all other times these two contacts are closed.

The contacts I920 and 2 I -22 govern the circuits for lighting the lamps of the highway crossing signals SI and S2. With positive current supplied to the wire 23 in a manner to subsequently appear, current fiows thence through contact Ill-20 over wire 24, lamp 25 of signal SI and to the negative terminal C of the. source of current. Branching from the wire 24 the cur- I rent flows over a circuit includingwire I5, lamp 26of signal S2 and to the negative terminal C of the current source. Current also flows from wire 23 through the contact 2I--22 and thence over wire 21 and the lamps 28 and 29 of signals SI and S2, respectively, in parallel and to the negative terminal C of the current source. It is to be seen, therefore, that with positive current supplied to the wire 23 and the oscillator CT inactive, both lamps of each signal SI and Si! are steadily illuminated, but that with the oscillator operated in the manner explained and the contacts 19-20 and 2l-22 alternately opened and closed, the lamps 25 and 28 of signalSI and the lamps 26 and 29 of signal S2 are alternately fiashed, the rate at which the signals are flashed being substantially 30 times per'minute since the frequency of the oscillator CT is 30 cycles per minute.

The oscillator CT in addition to governing the operation of the highway crossing signals SI and S2 in the manner just described, also actuates a time measuring mechanism effective to determine the speed of the train approaching the highway H and by which mechanism the time of starting of the operation of the signals S! and S2 before the train reaches the intersection is governed. I shall now describe this time measuring mechanism which is designated as a whole by the reference character TE. A worm 3!! is rigidly mounted on the spindle 3 and rocks a lever 3! pivoted at 32 and on which lever a pawl 33 is pinned for engaging with a ratchet gear 34 with the result liig. 2 against the force of the spring 41.

that-the ratchet gear 34 is rotated clockwise as viewed'in Fig. l, in response to oscillations of the armature 6 of the oscillator CT. A latch 35 holds the ratchet gear 34 on the return stroke of the pawl 33. 36 journaled at 3'1 and 38 (see Fig. 2). 39 and a cam are loosely mounted on the shaft 35 between the bearings 31 and 38, and between the gear 3% and the cam 40 a clutch member 4! and two springs 42 and 43 are provided. The clutch member 4! is secured to the shaft 36 by a feather key not shown, and hence, it rotates with the shaft 36 and may be moved along the shaft toward either the gear 33 or toward the cam 4c. The forkedv end of a lever 44 pinned at 45 rides in a slot 46 of the clutch member 4!. The lever 46 is biased upward as viewed in Fig. 2 by a spring 4'7 and is in magnetic relationship with an electromagnet 48, the arrangement being such that the magnet 48 when energized is effective to draw the lever 44 downward as viewed in It is to be seen, therefore, that magnet 48 when .en-

' ergized is effective to move the clutch member 4! and spring 43 into frictional engagement with the cam 4% whereby the cam 46 is made to rotate clockwise in response to clockwise movement of the ratchet gear 34, but that magnet 48 when deenergized permits the spring 4'! to draw the lever 44 upward and move the clutch member 4! out of engagement with the cam 46 and into engagement with the gear 33 through the spring 472 and that gear is rotated clockwise in response to clockwise movement of the ratchet year 34. In other words, the cam 46 is rotated clockwise in response to operation of the oscillator CT and ratchet gear 34 when the clutch magnet 48 is energized but is left free to turn on the shaft 36 when the clutch magnet 48 is deenergized, whereas the gear 322 is rotated clockwise in response to operation of the oscillator CT and ratchet gear 34 when the magnet 48 is deenergized and is left free to turn on the shaft 36 when the magnet -58 is energized. The cam 46 is provided with a counterweight H and is so proportioned that it is immediately restored to its normal position, that is, to the position illustrated in Fig. 1, whenever the clutch magnet 48 is deenergized.

The gear 33 meshes with a gear 49 keyed to a shaft at which is journaled at 5! and 52 and on which shaft is keyed a restoring cam 53. A stationary spring case 54 has contained therein a coiled spring t5 (see Fig. 3) which is secured to the shaft 513 as well as to the case 54. The spring 55 isefiective to bias the shaft 56 in the clockwise direction. Consequently, when the gear 39 is coupled to the shaft 36 through the clutch member 4! is rotated clockwise, the gear, shaft 5% and cam 53 are rotated counterclockwise "against the force of the spring 55 except when the mutilated portion 10 of gear 49 is adjacent the gear 38. Furthermore, when the gear 39 is rel ased from the shaft 33 the spring 55 is effective to rotate theshaft-SO. and cam- 53 clockwise The ratchet gear 34 is keyed to a shaft A gear unless the cam 53 is restrained by other means in a manner to later appear.

The cams 4!] and 53 are utilized to operate a circuit contact controlling member or element and here shown as an arm 56. The arm 56 is pivoted at 5! and is provided with cam followers 58 and 59 positioned to ride on the cams 40 and 53, respectively. A contact finger 60 is secured to the arm 56 by proper insulation and this contact finger 60 makes engagement with a stationary contact 6! when the arm 56 occupies the normal" position, that is, the position illustrated by solid lines in Fig. 1, but breaks engagement with the contact 6! as soon as the arm 56 is rotated upward about its pivot 51. An armature 62 of suitable magnetic material and a second contact finger 63 are also secured to the arm 56, the contact finger 63 being properly insulated from the arm. An electromagnet 64 is located for magnetic relationship with the armature 62 when the arm 56 is rotated upward to a reverse position illustrated by the dotted lines in Fig. 1, and on the casing of the magnet 64 a stationary contact 55 is secured for making engagement with the contact finger 63 when the arm 56 is moved to its reverse position. The function of the magnet 64 and the contacts 666! and 6365 will appear when the operation of the apparatus is described.

In describing the operation of the apparatus, I shall assume the track sections R,-S, 5-1 and T-V are unoccupied and the respective track relays are picked up so that the oscillator CT is inactive, the magnet 48 is energized, and the lamps of the highway crossing signals S! and S2 are all dark. Furthermore, I shall assume the cams 4t and 53 and the arm 55 occupy their normal positions, that is, the positions illustrated in the drawings. It is to be noted that in this normal position of the apparatus, the magnet 48 is supplied with current from the B terminal of the current source over front contact 66 of relay R front contact fi'l of relay R wire 68, winding of the magnet 48 and to the opposite terminal C of the current source, and the magnet 48 is energized to attract the lever 44 and draw the clutch member 4i into engagement with the cam 46. A train approaching the highway H from the right and entering the measuring section B shunts the track relay R and its back contact !2 is closed with the result that current is supplied to the field winding of the oscillator CT and the armature 6 is set into operation. Although the cam members 9 and It! are operated to actuate the contacts !926 and 21-22 the lamps of the highway crossing signals S! and S2 remain dark since the wire 23 is connected to a back contact 69 of the magnet 48 and that magnet is now energized and its back contact 69 is open. Operation of the oscillator CT at this time causes, however, the ratchet gear 34 to be rotated, and hence the cam 46 is moved clockwise since the magnet 48 is energized and the clutch member 4! is in frictional engagement with the cam 46. In the event this train I have assumed to be approaching the highway H is traveling atthe maximum speed of 60 miles per hour, it consumes approximately 10 seconds in advancing through the measuring section R-S and entering the operating section S-T where it shunts the track relay R The cam 46 is so shaped that its movement caused by the first 10 seconds of operation of the oscillator CT effects no upward movement of the arm 56 and. consequently, the contact 666! is still closed when the train enters the section S- -T. That is 4- is an arc of a circle, the center of which is the center of shaft 36. The shunting of the track relay R and'the closing of its back contact I l continues the supply of current to the field winding l of the oscillator or, with the result that the oscillator continues to operate as long as the train occupies the section ST notwithstanding the fact the rear of the train may vacate the section R-S and the track relay R may be picked up. Since the magnet 48 is deenergized and its back contact 69 is closed when the track relay R is shunted, current is supplied to the signals SI and S2 for illumination of their respective lamps. This circuit is traced from the B battery terminal over contact 6I3Gl operated by the arm Kit, back contact 69 of magnet 48, wire 23, contacts i9'2ll and 2i-22 in parallel and thence to the lamps of the signals S! and S2 as previously traced.

Since the cams 9 and it are now alternately opening and closing the contacts i9-28 and 2l 22; the two lamps of each of the signals SI and S2 are alternately flashed to exhibit a flashing signal to the highway users. When this train advances and enters the section TV and the track relay R is shunted, the field winding 7 of the oscillator CT is still supplied with current over the back contact E8 of the relay R and hence the signals Si and S2 are flashed until such time as the rear of the train has advanced to the left of the highway H and vacated thesection TV, since the magnet 43 is deenergized with relay R released. Inasmuch as the combined lengths of the sections ST and TV are equal to 2640 feet, there is a 30 seconds operation of the highway signals before the train traveling at the. maximum speed of 60 miles per hour reaches the intersection. During the entire time the train occupies the sections S--T and T--V the ratchet gear 34 is rotated clockwise and the gear 39 is proportioned and adjusted that it is effective to hold the shaft 5t, gear 39 and cam 53 in the normal position where the cam 53 is in engagement with the cam follower 59 of the arm 55, but it is not of sufficient force to rotate the cam 53 against the weight of the arm'56 at such time as the gear 39 is released and free to turn on the shaft 36. Consequently, for a train traveling at the maximum speed of 60 miles per hour the cam :36 is rotated clockwise during the time the train is advancing through the measuring section but with no movement of the arm 56, the highway crossing signals are flashed for 30 seconds prior to the arrival of the train at the intersection, and 1 they continue to flash until the rear end of the train has passed beyond the highway and cleared the section TV. The cam id is restored to its normal position immediately upon the train entering the section ST due to the influence of the counterweight ll, since the magnet 48 is now deenergized.

In the event a train approaches the highway H travelling at a speed less than the maximum speed, an operating interval different from the ,30 seconds interval of operation obtained for the maximum speed is effected, the interval decreasing from 30 seconds in proportion to the decrease in the speed. I shall now assume a train traveling at 40 miles per hour approaches the highway.

The relay R isshunted and the oscillator CT is set into operation as this train enters the measuring section RS the same as explained for the train traveling 60 miles per hour. The train traveling 4 .0 miles per hour consumes approximately 15 seconds in advancing through the section Pt--S and entering the section S--T. During this 15 seconds the cam 40 is rotated clockwise since the magnet iii is energized, and during the first seconds the cam 40 is rotated there is no upward movement of the arm 56 due to the circular surface of the cam as explained before,

but the surface of the cam it is so shaped that after the first 10 seconds movement thereof the arm 56 is raised at a variable rate. In other words, the cam 31! is so shaped that from each one second operation of the cam after the first 10 seconds period the arm 56 is caused tomove a different angular movement about its pivot. 51, this angular movement progressively increasing for a limited time. The result of this upward movement of the arm 56 is to cause the contact 60 to move away from engagement with the stationary contact 5! During the upward movement of the arm 55 the spring 55 is effective to rotate the shaft 5t and cam 53 clockwise with the result that the cam follows along after the arm 56 maintains its engagement with the cam follower '59. The gear 49 on the shaft 56 is now brought into mesh with the gear 39 but since the gear 39 is now free to turn on the shaft 3% it offers but slight opposition to the spring 55. When this train advances and enters the section ST and shunts the track relay R the magnet 48 is deenergized as previously explained. The immediate efiect of deenergizing the magnet 53 is to release the clutch member ll from the cam fill and to permit the clutch member M to move into frictional engagement with the gear 38' under the influence of spring ll. The cam id upon being released is at once restored to its normal position due to the counterweight 1 i. Engagement of the gear 39 by the clutch member M is effective to cause the cam 55% to be rotated counterclockwise from the position to which it had advanced along with the arm 56 back toward its normal position in opposition to the spring 55, the arm 56 follow ing the cam 53 due to the weight of its parts. As here shown, the surface of the cam 53 is so shaped as to cause a uniform rate of movement of the arm 56, that is, for each one second operation of the cam 53 the arm 56 is moved an equal angular distance about its pivot. The parts are so proportionedthat for the train traveling at the speed of 40 miles per hour the arm is moved back to its normal position from the position to which it had been advanced by the cam 4t during the seconds the train was advancing through the measuring section in approximately seconds. Since the train traveling 40 miles per hour requires approximately l5 seconds to travel the 2640 feet between the entrance of the section S-T and the highway H, and since the arm 56 is not restored to its normal position where it closes the contact til-61 for a period of 20 seconds, it follows that the highway crossing signals SI and S2 are flashed to warn highway users for a period of seconds before the train reaches the intersection.

Again, a train traveling 20 miles per hour consumes seconds in moving through the measuring section RS and entering the operating section S-T. The cam M! is rotated clockwise during thislSO seconds period and is then released and allowed to swing back to its normal position. When this train occupies the operating section S'I the cam 53 is rotated counterclockwise in response to operation of the oscillator CT as explained for the previous train. The cams 40 and 53 are so shaped that the arm 56 is moved upward by the cam 46 during the 30 seconds the train occupies the measuring section to a position where it requires substantially 70 seconds operation of the cam 53 before the arm 56 is restored to its normal position and the contact Bil-61 is closed. Since a train of a speed of 20 miles per hour requires 90 seconds to advance the 2640 feet from the entrance of the section S-T to the highway H, it follows that 20 seconds operation of the signals SI and S2 is effected before the train reaches the intersection.

The curve tam of Fig. 4 illustrates the time the highway crossing signals are to be operated for the diiferent speeds up to the maximum speed of 60 miles per hour, as arbitrarily assumed in the foregoing description. The curve trs illustrates the time consumed in the measuring section R-S by trains of difierent speeds and which time determines the upward movement of the arm 56. The curve .tso illustrates the time required by trains of different speeds to advance from the entrance of the operating section S--T to the intersection. The curve tszr is approximately the difference between the curve tsv and the arbitrary curve tzcu and illustrates the delay in setting the signals into operation after the train has passed the entrance of the section ST to assure that the operating time of the signals before the train reaches the intersection is in accordance with the curve tau. The curve to of Fig. 5 illustrates the relationship between the curves tits and tar of Fig. 4 and from which curve to the shape of the cam 40 is obtained.

. From an analysis of these curves and from the foregoing description of the operation of the apparatus at train speeds of 60, 40 and 20 miles per hour, it is apparent that with the apparatus constructed in the manner described the time measuring member (arm 56) is moved upward about its pivot at a variable rate and is restored at a uniform rate, and the highway crossing signals are set into operation at least 20 seconds prior to the arrival of a train at the intersection when the speed is 20 miles per hour and the operating time is increased for the higher speeds until 'at the maximum speed of 60 miles per hour the signals are set into operation 30 seconds prior to the arrival of the train at the intersection. As stated hereinbefore, my invention is not limited to the specific speed limits, operating time and track layout here described; The essential thing of my invention is that a time measuring member is moved away from a normal position at one rate during a measuring period the duration of which is determined by the speed of the train, and the member is then returned to its normal position at a second rate. In the form of the invention described hereinbefore, said one rate is based upon the duration of the movement and upon a predetermined speed-time curve, and said second rate is based upon a predetermined speed-time curve, and the two rates are so proportioned that the highway crossing signals are set into operation at least a predetermined minimum interval prior to the arrival of a slow speed train at the intersection, and are set into operation a predetermined maximum interval prior to the arrival of a train traveling at the maximum speed and the operating time for trains'of speeds intermediate these two speeds is made to vary between the minimum and maximum intervals in proportion to the speed. It will be apparent, however, that the cam surfaces of the cams 40 and 53 may be shaped so that the rate of movement of arm 56 away from its normal position may be a uniform rate and the rate of movement of the arm back toward its normal position may be something other than a uniform rate should it be so desired, and warning periods of the highway crossing signal may be substantially a constant interval prior to the arrival of a train at the intersection for all train speeds rather than the variable interval described hereinbefore. I

Furthermore, with apparatus constructed in the manner here disclosed, a single operating unit (oscillator CT) is effective to actuate the time measuring device in both its forward and backward movements and also to operate the highway crossing signals.

In the event a train should stop or otherwise consume an unusually long time in the measuring section R-S, the cam 40 would be rotated an unusual movement clockwise and the arm 56 would be raised to the reverse position as illustratedby the dotted lines in Fig. 1. In this reverse position of the arm 56 the contact finger 63 makes engagement with the contact finger 65. Since the magnet 48 is energized while the train occupies the section R-S and its front contact 86 is closed, current is supplied from the B terminal of the current source over a simple circuit which includes contact 86, contact 63-65 and the winding of magnet 64 and that magnet is energized andattracts the armature 62 on the arm 56 with the result that the arm 56 is retained in this raised position notwithstanding the fact that cam 40 may be rotated clockwise on past the position where it engages the cam follower 58. The spring 55 is effective to rotate the cam 53 and retain it in engagement with the cam follower 59 with the arm 56 in this reverse position, thegear 49 being in mesh wtih the gear 39. At such time as the train which stopped in the section R-S advances and moves into the section ST and shunts the track relay R the magnet 48 is deenergized, the cam 40 is released and assumes its normal position, and the arm 56 is released by the magnet 64 and is restored to its normal position by the cam 53 in response to operation of the oscillator CT. In the event a train stops in the operating section ST and the arm 56 is restored to its normal position, prior to the train vacating the section,

further operation of the cam 53 is avoided due to the portion 10 of the gear 49.

A check circuit is provided and the normal position of the time measuring device is checked. This check circuit extends from the B battery terminal over the contact 6!l6 l, front contact 18 of the magnet 48 and thence to a signal 19. In the event the arm 56 fails to return to its normal position for any reason and the contact 60--6| is open, or if for any reason-the magnet 48 is not energized and its front contact I8 is not closed, the signal 19 is without current and assumes a stop position in the usual manner for such signals. The signal 19 set at the stop position requires all trains to approach the highway H at a restricted speed.

By making the relay R one element of an interlocking relay, the other element of which is governed by traflic to the left of the highway H, the highway crossing signals SI and S2 may be governed in the usual manner for trains moving only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without depart-' ing from the spirit and scope of my invention.

Having thus described my invention, what I claim is: V r p 1. In combination, a time measuring device including a ratchet gear and a circuit controlling element which element normally occupies a given position, operating means including a winding effective when energized to actuate the ratchet gear in its forward direction, a first means operated by said gear and including a first cam effective to move said element away from the given position at a variable rate, a second means operated by said gear and including a second cam eiTective to restorethe element toward the given position at a uniform rate, and

means for selectively governing said first and second means.

2. In combination; a time measuring device including an oscillating armature, a ratchet gear and a circuit controlling element, said ratchet gear operated in its forward direction in step with oscillations of the armature and said element normally occupying a given position; a first control means operated by said gear and including a first cam effective to move said element away from the given position atone rate fective to move the member away from said normal position for positioning the member in accordance with the time interval said cam is operated, a second cam adaptable of operation by said unit when the winding is energized and 'eiiective to restrain movement of said member by its bias andto permitthemember to gradually return to its normal position, clutch means including a clutch magnet to select said first or said second cam for operation by said unit ac cording as the magnet is energized or is deenergized,'and controlmeans for controlling the energization of said winding and said magnet.

4. Time measuring means comprising, acircuit controlling contact member normally occupying a given position, an operating unit including a winding and an armature which is oscillated at; a predetermined rate when the winding is energized, a ratchet gear connected withthe armature for rotationstep by step in response to oscillation of the armature, a cam disposed when rotated to move said member away from said given position,'saidcam shaped for imparting a varied displacement to the member in accordance with the time interval the cam is rotated, means including a clutch magnet to op- 'erati'vely connect the cam with said gear when tact member, a first drive means efiective to move said member in a forward direction in response to the rotation of said ratchet gear, a

second drive means efiective to govern the move ment of said member in a backward direction in response to rotation of said ratchet gear, a clutch magnet operative to render either the first drive means or the second drive means effective according as said magnet is energized or is deen ergized, and control means for governing the energization of said winding and said magnet.

6. Time measuring means comprising, a circuit'controlling contact member biased to a normal position, an operating unit including a winding and an armature which is oscillated at a predetermined rate when the winding is energized, a ratchet gear connected with the armature for rotation step by step in response to oscillation of the armature, a first cam disposed when operated to move said member away from said normalposition for imparting a displacement to the member in accordance with the time interval the cam is operated, means including a second cam to restrain movement of said member by itsbias and to permit said member when said second cam is operatedto return to the normal position at a predetermined rate, clutch means including a clutch magnet to connect either said first cam or said second cam with said ratchet gear for operation thereof according as said magnet is energized or is deenergized, and control means for governing the energization of said winding and said magnet.

7. Time measuring means comprising, an operating unit including a winding and an armature which is oscillated at a predetermined rate when the winding is energized, a ratchet gear rigidly mounted, on a first shaft, means operative to rotate the ratchet gear step by step in its forward direction in response to oscillation of said armature, a first drive means including a first cam loosely mounted on said first shaft, a second drive means including a second cam rigidly mounted on a second shaft and a gear train having a drive gear loosely mounted on said first shaft and a driven gear rigidly mounted on said second'shaft, clutch means including a clutch magnet V for selectively connecting either said first cam or said drive gear with the ratchet gear according as said magnet is energizedor is'deenergized, a contact controlling arm biased to a normal position and having two cam fol lowers one engaging each of said cams for movement away from the normal position in response I trol means for governing the energization of said'winding and said magnet.

CRAWFORD E. STAPLES.

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