US2311360A - Control system - Google Patents

Description

Feb. 16, 1943. J. 1. BARKER common SYSTEM Original Filed March 50, 1940 INVENTO R BY Jon/v L BAR/(El? c -odkd (21w ATTORNEY Patented Feb. 16, 1943 John L. Barker, Norwalk, Conn, assignor to Automatic Signal Corporation, East Norwal Conn., a corporation of Delaware Original application March 30, 1940, Serial No.

327,020. Divided and this application September 26, 1940, Serial No. 358,466

15 Claims.

This invention relates generally to a control system for operating counting devices or indicating devices and the like. More particularly the invention relates to indicating or registering apparatus responsive to concurrent closure of two or more switches for more than a predetermined time in a multiple switch control system having the switches normally operated in overlapping sequence and more specifically relates to such apparatus in a control system employing a multiple switch treadle and a group of relays actuated thereby to operate counting devices only responsive to actuation of the multiple switches in an overlapping sequence. I

This application is a division of my copending application, Serial Number 327,020, filed March 30, 1940, for "Control system.

Control systems of this character are particularly useful in the counting of road vehicle trafiic at toll checking points for example where a multicontact treadle in the roadway is actuated by a vehicle wheel rolling over its contacts in sequence and it is desired to operate one counter for recording vehicles passing in a forward direction and another counter for vehicles passing in the reverse direction, and where it is desired to have the mounting of vehicle axles as accurate as possible and substantially free of actuation by pedestrians or toll collectors on random closure of one or more of the treadle contacts.

Toll checking systems are ordinarily arranged to count the number of axles and in some cases supplementary manual classification is made of the various types of vehicles having different numbers of axles. In some instances the toll rate is related to the number of axles, and in the case of restricted roads such as parkways the trafflc is frequently limited to the two axle pleasure vehicle.

An object of this invention is to provide an indicating device responsive to the concurrent closure of two or more switches for more than a predetermined time limit in a control system of the character described.

Referring now to the drawing negative and positive power supply wires I and I I are shown at the left and right sides.

A multiple switch treadle is shown schematically in cross section in the upper part of the drawing, with the several switch contacts I, 2, 3 and 4 arranged side-by-side and adapted to engage contact plate 5 individually when actuated. The treadle 6 is shown in the drawing with the common plate 5 over the contact plates I, 2, 3 and 4 for simplicity of illustration in the drawin but is preferably placed in the surface of a roadway with the plates I, 2, 3 and 4 over the common plate 5. Four separate plates may be used in place of the common plate 5 so that both upper and lower plates are entirely separate switches if desired, but in any case the 'four switches in the treadle 6 are spaced so closely side-by-side that a vehicle wheel rolling over the treadle will close the switches in an overlapping sequence in which at least three switches are closed concurrently.

The four switch treadle 5 may be made with the assembly of switches all sealed in an outer envelope of rubber or other flexible insulating material or a rubber covering for the plates I, 2, 3, 4 may be bonded to plate 5 and the latter made more rigid where the plate 5 is under plates I, 2, 3, 4 for example. The plates I, 2, 3, 4, 5 are preferably of relatively narrow width and considerable length extending across a traffic lane in the case of use with road traffic for example and the plates I, 2, 3 and 4 are kept properly spaced laterally from each other preferably by separation strips of rubber and these plates may be maintained normal separated from plate 5 by employing resilient separation strips or by employing other very narrow separation strips extending transversely across the several plates and spaced at intervals along the length of the treadle.

The narrower plates I, 2, 3 and 4 are preferably resilient and the separation strips are narrow enough to permit the individual plates to flex on either side into contact with the'bottom common plate even though the tire of the vehicle wheel rides directly over the separation strip.

The details of construction of the treadle are in general immaterial to the subject matter of the present control system except that the system is designed for operation by an overlapping sequence of closure of the treadle switches as will be more fully described below.

In the case of a wheel rolling from left to right, which is hereafter referred to as the forward direction, plate I will first contact with plate 5, then plate 2 will contact with plate 5 while I and 5 remain in contact, then plate 3 contacts with plate 5 while'l and 2 are in contact with 5. Next plate 4 contacts with plate 5 and finally plates. 2, 3 and 4 break contact with plate 5 in succession as the wheel continues to roll forward and oil the treadle. It is not essential that all four plates least three switches for proper operation of the I with 5 in order during the sequence.

Shown below the plates I, 2, 3, 4 inthe drawing is a group of relays A, B, C, D connected to the respective plates, so that each relay will be operated individually when its associated plate is in contact with plate 5.

The common plate 5 is connected to negative power by wire I and relay A is connected on one side via wire 8 to switch I and on the other side via wire 9 to positive power so that relay A is energized whenever switch I5 is closed. Relays B, C, and D are similarly connected to plates 2, 3 and 4 respectively to be energized by closure of switches 2-5, 3-5 and 4-5 respectively, the right side of the relays being connected to wire 9. I

The relays A, B, C and D when operated in the proper sequence operate relay P and in cooperation with relay P operate the relays R and RS for a wheel rolling in the reverse direction or operate the relays F and F8 for a wheel going in the forward direction. The relay RS operates the electro-magnetic counter or other electrical device RC for actuation in the reverse direction and the relay FS operates the similar counter or electrical device F for actuation in the forward direction.

The relay P is operated by concurrent closure of any two of the contacts I, 2, 3, 4 and in turn operates a retarded pickup time delay relay T to operate an alarm lamp L, a printer 61 and a bell BL if the concurrent contact closure persists more than the time delay interval for which the relay T is set. The time may be of the order of several seconds for example and the time relay T is preferably, of the quick reset type.

Time delay relay devices of the type in which a condenser is charged through a control resistance to a predetermined voltage to operate an electronic tube and relay are particularly suited to this timing operation, and an example is disclosed in the Patent 1,909,471 isued to F. G. Kelly, Jr.

The printer 61 indicated schematically in the drawing would ordinarilybe of electro-magnetic type to print a record, at the side of the timed trafi'ic count record tape, used in toll checking for example, of the instances of excessive time of concurrent actuation of two or more switches of the treadle. Any one or more of the several forms of alarm devices such as lamp L, printer 61, or bell BL may be omitted if desired.

The relay A has four make contacts al to 0.4 inclusive which are closed when the relay is energized and restore to normal open position when the relay is deenergized, andthis relay also has one break contact which is normally closed when the relay is deenergized and is opened when the relay is energized.

Similarly relay B-has four make contacts bl to M inclusive and one break contact b5, relay C has four make'contacts cl, 0!, c3, c5 and one break contact 04, and relay D has four make contacts dI, d2, d3, d5 and one break contact d4.

Relay P has two make contacts pl and p2 and one break contact 113. Relay R has, two make contacts H and re and one break contact 12, and relay RS has two make contacts rSI and-m2. Relay F has two make contacts fl and, f3 and one break contact 12, and relay FS has two make contacts fsl and js2. Relay T has one make contact tI.

Electromagnetic devices RC and PC are shown as counters, the coils RC and PC operating the armatures ml and fcl respectively to actuate the respective counter ratchet wheels II and I0, and to open the contacts 1'02 and I02 respectively upon actuation of the counter wheel. The bar I2 is connected to armature rcl to actuate arm I6 to open contact rc2 only when the counter ratcheting armature rcl has been pulled down far enough by the coil RC to assure advance of the counter wheel I0 one digit. Bar 13 serves a similar purpose on arm 11 to open contact ,fcZ when coll F0 is energized to advance counter wheel II.

The counter ratchet arrangements are shown with thecounter advanced one step on the energizing stroke of the armatures ml and jcI but it will be appreciated that the ratchet arrangement could be reversed if desired to have the armature take the next tooth of the ratchet wheel on the energizing stroke and advance the ratchet wheel on the return stroke by spring action.

All of the armatures and contacts of the several relays and electromagnetic devices are shown in their normal deenergized condition in the drawing as in the absence of treadle actuation, and these elements are restored to their normal condition by spring action or other suitable methods.

It will be understood that other contacts may be added if desired to the electromagnetic devices RC and PC, the relay T or other relays for operation of indicating devices or the like, or the armatures MI and fcI may be arranged to operate contacts for signalling circuits if it is desired to use the control system of the invention for signalling instead of counting.

Considering now the operation of the system in more detail responsive to actuation of the treadle switches by a rolling wheel for example, assume first the wheel rolls over the treadle in the forward direction, actuating the switches in the order 1-2-3-4.

Plate I first engages plate 5 and completes a circuit from negative power wire I0 via wire I, plate 5, plate I, wire 8 relay A wire 9 to positive power wire I I, thus energizing relay A and causg is completed via contacts al and bl.

ing the latter to close its make contacts and open its break contact a5. Next plate 2 engages plate 5 while plate I is still engaged with plate 5 by the pressure of the wheel, and this closes a circuit from negative power via wire I, plates 5 and 2, relay B and wire 9 to positive power, thus energizing relay B while relay A remains energized.

With relays A and B now both energized one of a group of several circuits for energizing relay P These several circuits for relay P involve different pairs of the first three contacts of the relays A, B, C, and D in combinations of two at a time. In each case the circuit through the pair of contacts connects negative power viawire I4 to relay P and the other side of relay P is connected via wire 58 to positive power.

The first of these circuits for relay P includes contact all wire I2, contact bl and wire I3 to wire contacts pi and p2 and opens its break contact 93.

. v asirscc and 2 as stated above, and relay P closes its make wire as, wires 34, as, contact as. wires as, a, relay Closure of contact pl completes a circuit from negative power via wires 60, II, contact pi, wire 2, relay T, but relay T is of the retarded operating time delay type and will close its contact ti only after continuous energization for a predetermlned time period of several seconds for example provided relay P is continuously energized for such time period. In the latter case relay '1' closes its contact tI and completes a circuit via wires 88, 86, contact tl, wire 85 to alarm lamp L, and via wire '88 to alarm bell BL, and printer Bl, as previously described.

Under normal conditions of operation by a vehicle wheel however the wheel moves over the treadle quite rapidly and the relay P and relay T are not energized sumciently long to permit time delay relay T to operate its contact 12 I Returning to the sequence of operations as the wheel continues to roll forward over the treadle, the operation of contacts p2 and p! by energization of relay P by closing of contacts at and bi has no immediate effect and the significance will be described subsequently below.

With the concurrent actuation of plates I and 2 and energization of relays A and B, the closure of contacts at and b4 completes a circuit for relay F from negative power via contact a4, wire 23, contact b4, wire 24, break contact T2 of relay R (now deenergized) wires 25, 28, relay F, wires 16 and 58 to positive power, thus energizing relay F.

Relay F is held energized by a lock-in circuit from wire 26 at relay F via wire 59, contact f3.

wires 29, 30 and contact p2. of relay P to negative power, so that after the wheel rolls forward enough to open switch I-5 and deenerslze relay A and interrupt the initial operating circuit of relay F at contact (14 the relay F will remain energized as long as relay P remains energized.

As the wheel continues to roll forward so as to bring plate 8 into contact with plate 5 the relay C is energized from negative power via plate 5, and the break contact c4 of relay C is opened and the remaining make contacts are closed. Now relays A, B, and C are concurrently energized.

Another energizing circuit for relay P has been completed via contact b2, wire I9, contact c2 and wire 29 to wire I4. The latter circuit will hold relay P energized during the next step in the sequence when the wheel has rolled further to release plate I from plate 5 and thus deenergize relay A and open contact al and a2.

The auxiliary energizing circuits for relay P via contacts 02 and cI and wires I6 and I8 to I4, and via contacts a3 and (II and wires I1 and It to wire I4, and via contacts b3 and d2 and wires 2| and 22 to wire l4 are primarily for operation of the alarm devices through relay T in case two of the plates should become permanently closed or remain closed more than the predetermined time limit of relay T, and these auxiliary circuits are not required in connection with the counter operating relay system in the normal rolling wheelseq'uence.

Relay F at contact fl has prepared a circuit for energization of relay FS as soon as relays C and D are energized and relay A or relay B is deenergized, which occurs when the wheel has rolled forward far enough to release plate I from plate 5 and to engage plates 2, 3 and 4 with plate 6.

Under these conditions a circuit to energize relay FS is completed from negative power via contact c5, wire 3!, contact 115, wire 82, contact II,

F8,wires 28, 58 to positive power, and relay F8. a

closes its contacts Isl and-{82. .The relay FS now has a holding circuit com pleted from negative power via wires ll, 45, arm

'I'I. contact lc2 of the electromagnetic counter FC,

wire 40, contact a5 and wires 26, 31 to relay F8. Contact b5 of relay B will also serve to maintain this holding circuit when the wheel rolls far enough to deenergize relay B as plate 2 is released from plate b.

Now the wheel is holding only plates 3 and 4 in contact with plate 5 and relay P is held energized only by a circuit from negative power via contact 03, wire 21, contact (13, wire 28 to wire l4 and relay P, and as the wheel rolls oil of plate 3 so that only plate 4 is held in contact with plate 5, relay Cis deenergized and opens its contact 03, which deenergizes relay P. Thus contact p2 of relay P closes and completes a circuit from negative power via contact p8, wires 42, 43, contact fsZ, wire 4% through coil FC to positive power. This energizes the coil FC and pulls down armature fcI to advance the counter ratchet Ii one count and by insulated bar 13 opens contact 02. This in turn interruptsthe holding circuit of relay FS and deenergizes relay F3 to open contact I82 and deenergize coil FC and restore the armature lcl to I prepare for any subsequent all restored to the normal condition illustrated in the drawing.

It will be observed that by the us of series circuits through the make contacts of relays A-B and relays 0-D and by parallel circuits through the break contacts such as a5-b5 of these relay pairs the permanent closure of any one of the plates I, 2, 3 and 4 against plate 5 by failure or otherwise or the grounding of any one of the plates to relay'circuits of relays A, B, C, D to negative power will not interrupt the proper operation of the relays F and F8 to cause a forward count, nor will this as subsequently described interrupt proper operation of relays R and RS to cause a reverse count. Relay F will be energized asplate 2 is operated to close contact b4 by the wheel rolling forward for example, and relay FS will be energized as the plate 2 is released by the wheel to close contact 175, even if relay A alone were permanently energized for example.

However, if relay B alone were permanently energized relay F would be energizd by contact at upon actuation of plate I and relay FS would be energized by contact at upon release of plate I in the forward direction the operation of relays C and D remaining the same as usual as previously described for the forward direction.

' If relay C alone should be permanently energized, the relays F and FS would be energized as usual in the forward direction. In any case if any one of the relays A, B and C alone was permanently energized the counter FC would not be operated until the wheel rolled entirely of! the treadle to release plate 4 and relay D and interrupt the last circuit for relay P and release relay P so as to complete the counter operating circuit at contact 323. This merely delays the count momentarilybu't does not prevent a proper count.

the forward count being completed via contact In to'energi'ze coil PC and release relay F8 at contact {of to release coil l"C-at contact is! as wheel rolling in reverse direction has actuated plates 4 and 3, a circuit is completed to energize relay R, from negative power via contact 05, wire 3|, contact at, wire 32, contact 12, wires 45,48,

through relay R and wires 41, I8 to positive power. Relay R thus closes its contact 13 providing a holding circuit from negative power via contact p2 wire 30, contact 13, wire 46 to relay R. Relay R also preparesa circuit for energizing relay-RS as soon as the wheel has rolled in reverse direction sufficiently to operate plates 2 and l and relays B and A and to release plate 4 or plate 3, and relay D or C the circuit for relay RS being then completed from negative power via contact a4, wire 23, contact b4, wire 24, contact rl, wires 48, 49, contact d4 (or wire 50, contact 04, wire Si), wire 52, through relay RS, wires 53, 58 to positive power.

Relay RS now completes its holding circuit via its contact rs] and contact T02 of the reverse cuit for relay' P is interrupted and contact p3 closes completing a circuit via contact rsi to the reverse electromagnetic device RC so that the armature rcl will be pulled down to operate the reverse counter ratchet I0, and the insulated bar 12 will operate arm I6 to open contact ml to interrupt the holding circuit of relay RS and release this relay-to open its contact rs! to deenergize the coil'RC and release armature rcl to prepare for any subsequent reverse count.

As in the case of the forward direction the circuits for the reverse direction are arranged to permit proper counting with any one of the relays A, B, C, and D permanently energized, the operating circuits employing parallel contacts 04 and d4 for relay RS and series contacts 05 and d5 for relay R.

In the case of an axle counting system for toll checking the treadle is placed a short distance.

beyond the toll station so as that the car wheels will cross' the treadle after toll is paid and the car moves forward in leaving the toll station. However, the restriction of the traillc lanes at and near the toll station to permit cars passing 65 ward directions so that the forward count lea the reverse count provides an accurate net forward count.

Another problem in toll check counting is that 5 the front wheels of a carmay roll partway onto the treadle. Such'a condition is sometimes also caused by the toll collector's recalling the driver on account of an error in change or some other question about the money or the driver returns to ask some question.

It is a feature of the present construction that such rolling back and forth will not interfere with a correct net forward count. The forward preparatory relay 1! and the reverse preparatory relay R are interlocked electrically by having the initial energizing circuit of each pass through a break contact of the other, 1" being energized through contact 12 and R being energised through contact 12, so that the initial operation of one prevents the operation of the other until the first has released again on completion of the appropriate count. Whichever of relays F and R is energized, is locked in over a holding circuit via make contact 92 of relay P as previously described. Also the completion of the operating circuits to the respective counters-depends on closure of break contact p3 of relay P.

Thusas long as an two of the plates remain actuated as the wheel rolls back and forth then relay P will remain energized over one of' the several circuits of the first four sets of contacts ofrelays A, B, C, D, and whichever relay R or F is operated will remain locked in and the other locked out, and neither counter'will be operated.

3 The counter will be operated only by the rolling of the .wheel ofi all but one plate in the original direction so as to release relay P which in turn y will operate the appropriate counter and will also release whichever relay, R or F was energized 40 by the initial movement in the original direction.

Since the counter also is reset to normal by releasing relay FS or RS as thecase may be, the system is then ready to operate for another count.-

It will be observedihat both the initial energizing circuit and the holding circuit for the relay FS include break contacts a5 and hi on relays A and B, and both such circuits for relay RS include break contacts 04 and d4 on relays C and D, as previously described. Thus if a then rolls backward to reactuate plate I the relay contact a5 will again open and sincecontact b5 is also open the relay FS will become deenergized again. No count will then have been made since relay P has remained energized and contact p3 open. If the wheel continues backward oil the treadle, or of! all but plate I, the relay P will then be released and also the relay F so that the system will be ready for the next count in either direction, so that if the wheel now again rolls forward across the treadle completely only one forward count and no reverse count will be recorded.

If however the wheel should initially roll forward far enough to release all but the last plate and cause a forward count, and then roll backward but not far enough to release all but the first plate and then forward again, no reverse count will be recorded because relay contact M will remain open and relay RS will be released by contacts 04 and d4 reopening on the final forward-movement and only thefirst forward countwillbemade. 1

It will be appreciated that although iour switches l, 2,8, 6, and four corresponding relays A, B, C, D are employed in the present embodiment this ismerely illustrative of the preferred arrangement, and more than four switches could readily be employed side-by-side and additional relays connected thereto in similar manner to relays A, B, C, D and additional contacts and cir- 1 cuits for relay P provided similar to those illustrated. The additional plates may conveniently be arranged between plates 2 and 8 for example and the additional relays arranged betweenrelays B and 0- without changing any 01 the cir 15 and 04, d6 could be extended to include addiof any two oi said switches and adapted to have its timing-reset quickly responsive to interruption of concurrent actuation of all combinations of any two of said switches, and means operated by said timing means responsive to completion of its timing. v

2. In a control system, a multiple switch device having more than two switches and arranged for actuation in an overlapping sequence by units of traflic passing by, means responsive only to actuation of said switches in an overlapping sequence, timing means connected to have its timing initiated byconcurrent actuation of any two of said switches and adapted to have its timing reset quickly responsive to interruption of concurrent actuation of all combinations of any two of said switches, and means operated by said timing means responsive to completion of its timing.

3. In a control system having a multiple switch treadle of more than two switches and meansoperating responsive to closure of said switches in an overlapping sequence, timing means connected to the last named means have its timing initiated by concurrent closure of any two of tional series or parallel contacts respectively on 25 adjacent relays so that three adjacent plates must be, operated concurrently to complete the initial operating circuits for relays F, R, FS and RS and the circuits of relay P could similarly be extended over three contacts so that ener- 3o gization of relay P would require actuation of three plates concurrently instead of two. This arrangement would permit the permanent closure of any two plates and still provide proper\ counting. In such arrangement the plates would 85 preferably be narrower and more closely spaced if more than four plates are used.

It will also be appreciated that the fourth plate 4 and relay D could be omitted if desired to prosaid switches, and indicating means operated by said timing means responsive to completion of its timing.

4; In combination, a multiple switch trafiic actuatable device of more than two switches, a plurality of relays, operating circuits for said relays controlled by said switches to operate'each- Irelay individually by a separate one of said switches, time controlled switch means having an operating circuit and a,switch operated'responsive to completion of a time period of enervide a three switch treadle employing plates i, 2

and 3 and relays A, B and C in which case the contacts d4 and d5 would be transferred to relay B, and the circuits would operate as previously described, the system providing the forward and reverse counting and protective feature already described for the four switch treadle arrangement.

It will therefore be observed that the principles of the present-circuit arrangement in accordance gization of said operating circuit and connections for said operating circuit including all combinations of pairs of contacts operated by difierent pairs of said relays for energization of said operating circuit responsive to concurrent operation of any two of said relays.

5. In a control system having a multiple switch device of more than two switches, relays operated individually by said switches, time controlled.

switch means operating its switch responsive to completion of a timing period of continued acwith the invention provide the basis for consider- 5) able variation in the number of plates and relays and further flexibility of design.

It will be understood that other rearrangements or substitutions may be. made in the various parts of the system without departing from 5 the spirit of the invention as defined by the claims.

Where the concurrent actuation of more than two plates, or at least three plates, or three or more plates is stated as required herein it will be understood that the operation of the system 6 depends on having not less than two plates actuated at anytime during the overlapping sequence and that this requires at least a momentary overlap of actuation of three adjacent plates as the actuation is transferred from plates l and 2 to plates land 3 and so on through the sequence.

I claim:

1. In a control system having a multiple switch device of more than two switches arranged to be actuatedin sequence and means responsive to actuation of all said switches in sequence, timing means connected to the last named means to have its timing initiated by concurrent actuation 7 tuation and adapted to restart its timing responsive to cessation of actuation, a plurality of ac tuating circuits for said switch means. includin pairs of contacts operated by all combinations ofsaid relays taken two at a time to actuate said switch means by concurrent operation of any two of the first mentioned switches forsuch tim period.

6. In a control system having a multiple switch I treadle of more than two switches and means operating responsive to closure of said switches in an" overlapping sequence, said means including relays operated individually by the respective switches, an additional relay, a plurality oioperating circuits for said additional relay including pairs of contacts operated by all different pairs of the first mentioned relays for operation of said additional relay whenever any two of said switches are closed concurrently, and a retarded pickup quick dropout time delay relay operated by operation of said additional relay, and an output circuit controlled by said time delay relay.

7. In a control system having a multiple switch treadle of more than two switches and means operating responsive to closure of said switches in an overlapping sequence, said means including relays operated individually by the respective latter.

8. In a control system including more than three switches arranged closely side-by-side for operation in a progressive sequence in which more than two adjacent switches are closed concurrently, relays connected to be operated by closure of the respective switches, another relay connected to be operated by concurrent operation of any two of the first mentioned relays,-an additional relay connected to be operated by concurrent first operation of the first two of the first mentioned relays, and to be maintained operated by operation of said other relay, a further relay connected to be operated by concurrent operation of said additional relay and of a third and fourth of said first relays together with concurrent release of one of said first two relays, and

- an output circuit controlled by operation of said further relay and concurrent release of said other relay; time controlled switch means having a de-' .layed action of its switch and connected to be operated by operation of said other relay, and an output device including a circuit controlled by the last mentioned switch to indicate prolonged concurrent operation of two or more'of the first mentioned relays which may interfere with proper operation of the first mentioned output circuit by preventing such relay release.

9. In a control system including more than three switches arranged closely side-by-side for operation in a progressive sequence in which more than two adjacent switches are closed ,concurrently, relays connected to be operated by closure of the respective witches, another relay connected to be operated by concurrent operation of any two of the first mentioned relays, an additional relay connected to be operated by concurrent first operation of the first two of the first mentioned relays, and to be maintained operated by operation of said other relay, :3. further relay connected to be operated by concurrent operation of said additional relay and of a third and fourth of said first relays together with concurrent release of one of said first two relays, and an output circuit controlled by operation of aid further relay and concurrent release of said other relay: a retarded pickup time delay relay connected to be operated by operation of said other relay, and an output device controlled by said time delay relay by pickup of the latter to indicate prolonged concurrent operation of two or more of the first mentioned relays which may interfere with proper operation of the first mentioned output circuit by preventing such relay release.

10, In a control system, a multiple switch treadle adapted to have its switches actuated sequentially by a wheel rolling thereover, time controlled switch mean having a switch operated only after a time period of actuation of said means, circuit means operated by concurrent actuation of two of the first mentioned switches to actuate said time controlled switch means and a control circuit controlled by said time controlled switch,

11. In a control system, a multiple switch treadle adapted to have its switches actuated sequentially by a wheel rolling thereover, time controlled switch means having a switch operated only after a time period of actuation of said means, circuit means operated by concurrent actuation of two of -the first mentioned switches to actuate said time controlled switch means and an indicating device controlled by said time controlled switch.

12. In a control system, a multiple switch treadle adapted to have its switches actuated in an overlapping sequence by a wheel rolling thereover, time controlled switch means having a switch operated only after a time period of actuation of said means, relays connected to be operated individually by the respective first mentioned switches, contacts operated by the respective relays, and a plurality of operating circuits for said time controlled switch means including pairs of said contacts for all combinations of said relays two at a time to actuate said time controlled switch means throughout concurrent operation of every pair of said relays.

13. In a control system, a multiple switch treadle adapted to'have its switches actuated sequentially by a wheel rolling thereover, relays connected to be operated individually by the respective switches, contacts closed by operation of the respective relays, time delay relay means, a plurality of operating circuits for the last said means each including in series a pair of contacts of a diflerent pair of said relays, and an output circuit including a contact operated by said time delay relay means at the end of its time delay.

14. In a control system including a multiple switch treadle adapted to have its switches closed sequentially by a wheel rolling thereover, a pinrality of relays having coils connected to be energized individually by closure of the respective switches and each relay having contacts closed by energization of its associated coil, a further relay having a coil and contacts closed and further contacts opened by energization of the latter coil, a plurality of energizing circuits for the last mentioned coil each including in series contacts of a different pair oi! said plurality of relays, and output means including other contacts of said relays to be operated by deenergization of said further relay after energization of said plurality of relays and deenergization of one of said relays in overlapping sequence; a time delay relay having an operating coil connected to be controlled by the contacts of said further relay and having contacts operated by said operating coil after its time delay, and another output device controlled by the contacts of said time delay relay to indicate any prolonged concurrent energization of a plurality of the first-mentioned relays which may interfere with such operation of the first mentioned output means by preventing such deenergization of relays.

15. In a control system including a multiple switch device having more than two switches and arranged for actuation in an' overlapping sequence by units of trafilc passing by, relays connected to be operated by operation of the respective switches, another relay connected to be operated by concurrent operation of any two of the first mentioned switches, an additional relay and an alarm device and an operating circuit for said device controlled by the last mentioned switch whereby prolonged operation of two or more of said first mentioned switches will be indicated by said device to warn of possible interference with normal registration of trafilc.

JOHN L. BARKER.

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