US2435824A - Apparatus for control of highway crossing gates - Google Patents

Description

Feb. 10, 1948. c. 1.. GOODLIN APPARATUS FOR CONTROL 0F HIGHWAY CROSSING GATES Filed Feb. 11, 1944 3 Sheets-Sheet l 6 013? 6 1 M906 cmzlmz I 0 2 2 W@ H x 2 G l I 1 w Jun WW W INVENTQR C 01! (70006112. BY Z Z 1 HIJ" ATTORNEY Feb. 10, 1948. c. 1.. GOODLIN 2,435,824

APPARATUS FOR CONTROL OF HIGHWAY CROSSING GATES Filed Feb. 11, 1944 3 Sheets-Sheet 2 Gaee 67 MH [Yeofianzlrmf 4 T 3 F 'q 7P1? I" I0! T j I ED G X12 15' 1 tfsw 19 2. 3

INVENTOR 6 01"! Z. 80007122. BY QW HIJ" ATTORNEY Patented Feb. 10, 1943 APPARATUS FOR CONTROL OF HIGHWAY CROSSINGIGATES Carl L. Goodlin, Penn Township, Allegheny County, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application February 11, 1944, Serial No. 521,896

6 Claims. (01. 318-286) My invention relates to apparatus for control of highway crossing gates, and more particularly to apparatus for automatic control of highway crossing gates.

An automatic highway'crossing gate is ordinarily controlled by trains through the medium of track circuits. The gate arm is latched in a raised or non-obstructing position as long as the approach track sections are unoccupied and is moved to a lowered or obstructing position across the highway in response to a train entering an approach track section. When a train has passed beyond the intersection, the gate arm is raised to its non-obstructing position unless a second train or some other trafilc condition makes it unsafe for highway traflic to pass over the intersection. Such automatic control of a highway crossing gate must include safeguards wherewith the lowering of the gate arm is not prevented by high winds or other conditions, and mechanical shock and rebound of the arm at the lowered position are avoided. Also, a circuit arrangement that is reliable, eflicient and of minimum structure is essential.

In view of such circumstances, a feature of my invention is the provision of improved apparatus for control of highway crossing gates.

A further feature of my invention is the provision of control apparatus for highway crossing gates incorporating novel and improved means for power driving the gate arm both up and down, to deenergize the slot magnet while the motor is operated to drive the gate down, to cushion the movement of the gate arm at the lowered position, to avoid lowering the gate arm from an intermediate position and to minimize the circuit and control apparatus without sacrifice of safety and efiiciency.

Other features, objects and advantages embodying my invention will appear as the specification progresses.

The above features, objects and advantages of my invention I attain by providing a novel and improved arrangement of circuits and apparatus for a gate mechanism which includes a motor, a slot magnet and a circuit controller. The motor is operatively connected through a suitable gear train to the gate arm which is movable between a lowered or obstructing position and a raised or non obstructing position. The gate is counterbalanced for the arm to gravitate to its lowered position but I preferably provide a reversible motor which is reversibly nergized through a pole changing means to power drive the gate arm up and down according to the position of the pole changing means as predeterminedby a main control device. That is, the motor is operated in one direction in opposition to the bias to raise the gate arm and is operated in the opposite direction to aid the bias in the lowering of the gate arm. In the raising of the gate arm the motor is disconnected from the current source at a contact of the controller opened at substantially the full raised position of the arm. In the lowering of the arm, the motor preferably is supplied with power during a preselected first portion of the movement, and is disconnected from the current source and is included in a low resistance circuit path or snubbing circuit during the final portion of the lowering movement to eifect a dynamic braking, such switching of the motor circuits being accomplished through the medium of contacts of the circuit controller. In this way the lowering of the arm is not prevented or delayed due to high winds and other conditions that may oppose the gravity bias and mechanical shock and rebound of the arm at the lowered position are avoided.

Again, the counterbalance of the arm may be such that the motor need not be powered only for a preselected portion of a downward movement and then disconnected from the current source and the arm allowed to continue the movement under the force of the bias, the snubbing" circuit being omitted. Preferably the control circuits would include a stick circuit arrangement wherewith once the raising of the gate arm is initiated the motor is operated independent of the main control until the full raised position is reached, at which point the main control is again made eifective. This prevents the gate arm from being lowered from an intermediate position in front of or on top ofa highway vehicle that may have started across the intersection upon the driver observing the gate arm starting to raise.

The slot magnet is preferably of the double winding type having a holding winding and a pick-up winding, the magnet armature being lifted to its latching position only when both windings are energized but retained at its latching position by the energization of the holding winding alone. The holding winding is controlled through a contact of the main control device and current is removed from the slot magnet at the same time current is supplied to the motor to drive the ate arm downward. This prevents the slot latch from being forced in its released position by the motor. The circuit for the pick-up winding is carried through two controller contacts in series, the first one of which two contacts is the contact used to open the motor circuit at the raised osition, The second one of these two contacts is closed just shortly before the first mentioned contact is opened. This first controller contact is of a construction that it is reclosed during the lowerin movement of the arm at a position further removed from the raised position than the point at which such contact is opened during the raising of the arm and the point at which it is reclosed is made subsequent to the openin of the second one of the two contacts. In this way energization of the pick-up winding before the motor is energized to raise the arm is avoided in case the arm is being lowered and the main control is changed to that for raising the arm. Thus, the motor is made to take the shock and stress of arresting the lowering movement of the gate arm rather than the slot magnet when a change of control occurs while the arm is being lowered.

Again, the snubbing circuit includes a contact which is held pen when the motor is powered to drive the gate arm downward as well as a contact held open when the motor is powered to raise the arm.

Furthermore, when the gate mechanism is of the type provided with a case suitable for housing relays, I locate one or two of the control relays in the mechanism to minimize the circuit wiring.

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

In the accompanying drawings, Figs. 1, 2 and 3 are diagrammatic views showing three different forms of apparatus for automatic control of highway crossing gates by trains, and each of which forms of apparatus embodies my invention. Fig, 4 is a chart showing the positions at which controller contacts of the gate mechanisms of Figs. 1, 2 and 3 are opened and closed.

In each of the several views like reference characters are used to designate similar parts.

It is to be understood that apparatus embodying my invention is not limited to automatic control of highway crossing gates by trains and it is useful with apparatus where the gate is manually controlled and where the gate is controlled in part manually and in part by railway traflic.

Referring to Fig. l, the reference characters Ia and lb designate the track rails of a railway intersected at grade by a highway H, and at which intersection two highway crossing gates GI and G2 are located. The track rails are formed by the usual insulated rail joints with two track sections, one on each side of the highway, a section D-E being formed to the left of the highway H as viewed in Fig. 1, and a section E--F being formed to the right of the highway. In other words, section DE is an approach section for eastbound trains and section EF is an approach section for westbound trains,

Each track section D-E and E-F is provided with a track circuit which includes a current source, such as a battery III, connected across the rails at one end of the section, and a winding of an interlocking relay IR connected across the rails at the other end of the section, winding II of relay IR being included in the track circuit of section DE and winding I2 of relay IR being included in the track circuit for section E-F. The connections of windings II and I2 to the track rails are those of common practice to provide the so-called extended shunt protection.

as will be readily understood by an inspection of 4 the drawings, and these connections need not be described in detail since they form no part of my invention.

Highway crossing gates GI and G2 are shown conventionally and are located one on each side of the railway tracks and are adaptable of being operated in a manner such that their respective gate arms I3 and I4 are moved between a lowered position where the arm extends horizontally across at least a portion of the highway H and a raised position where the arm extends substantially vertical. Each crossing gate GI and G2 is provided with an operating mechanism which may be any one of several well-known types and preferably the two mechanisms are of like construction. In the present embodiment of the invention the mechanism for each gate GI and G2 is similar to that shown and described in Letters Patent of the United States No. 1,138,087, granted to John P. Coleman on May 4, 1915, for Railway signals, and to which patent reference is made for a full understanding of the construction of such mechanism. In the application the gate arm is an extended form of the semaphore of the patent.

The mechanism and control for gate GI only is shown in the drawing for the sake of simplicity since the two gates are alike and the mechanism and control of gate G2 would be a duplication of that for gate G I.

Looking at the gate GI mechanism of Fig. 1, a motor MI, slot magnet SM and a circuit controller CI are among the essential elements of the mechanism. Motor MI is a direct current reversible motor having an armature I5 and a field winding I6. Motor MI is operatively connectedby suitable drive mechanism (not shown) to the gate arm I3 and which drive mechanism may be similar to that disclosed in the aforementioned Coleman patent. The mechanism of gate GI is counterbalanced for arm I3 to be gravity biased to the lowered position. Motor MI when supplied with current which flows in its armature in one direction with respect to the flow of current in the field winding is operated as required to raise the arm I3 against the bias force. When motor MI is supplied with current that flows in its armature reverse with respect to said one direction, the motor is driven as required to lower the arm, the motor MI aiding the bias force. In the following description the position of the gate mechanism corresponding to the lowered or obstructing position of the gate arm will be at times referred to as a zero degree or obstructing position, and the position of the gate mechanism corresponding to the raised or non-obstructing position of the gate arm will be at times referred to as a degree or non-obstructing position. It will be understood, however, that apparatus'embodying my invention is not limited to a 90 degree movement of the gate arm. Also, it is to be observed that the arm may be provided with a slightly greater than 90 degree movement in order to permit adjustment.

Slot magnet SM includes a holding winding II, a pick-up winding I8 and an armature 35. As fully explained-in the aforementioned Coleman patent, the armature 35 when picked up latches the gate arm at the 90 degree position, and when the magnet is deenergized and the armature released, the gate mechanism is free to move toward its zero degree position. The arrangement is such that the armature 35 is raised to its attracted and latching position only when both windings I1 and I8 are energized. but once picked'up the armature is held at its latching position by the energization of the holding winding I! alone.

Controller Cl includes a series of contacts 2, 3, 4, 5 and 6, which are shown conventionally for the sake of simplicity. The controller Cl is operatively connected to the gate arm through the gate mechanism in such a manner that the contacts are opened and closed as indicated by the chart of Fig. 4. It is to be observed that contact 4 of the controller is opened at the 89 degree position in the raising of the gate arm and is not reclosed until the 83 degree position of the,

arm when the arm is being lowered. The function of such construction of contact 4 will be pointed out more specifically later in the description. The construction of contact 4 may be that disclosed and claimed in Letters Patent of the United States No. 2,363,936, granted November 28, 1944, to H. L. Bone, for Circuit controllers.

The control means for the gate Gl of Fig. 1 includes a track repeater relay or control device TPR, a control relay XR and two other relays 'DN and SN. Repeater relay TPR is a slow release direct current relay energized by current supplied from a source, the terminals of which are indicated at B and C, the energizing circuit being completed through flagman contacts l9 and 20 in series of the interlocking relay IR. It follows that when both sections D-E and E-F' are unoccupied or either section is occupied by a train receding from the intersection and the other track section is unoccupied, repeater relay TPR is energized and picked up, but that when either section is occupied by a train approaching the intersection the relay TPR is deenergized. Repeater relay TPR governs the control relay XR and the holding winding I! of the slot magnet by obvious circuits which include front contacts 9' and 2| of relay TPR, respectively. The two relays DN and SN are preferably of the type that permits their being located in the gate mecham'sm. Control relay XR governs the two relays DN and SN, the pick-up winding I8 of slot magnet SM and the motor operating circuits, the control of these devices being effected in part through contacts of the circuit controller Cl. It is-believed that these various circuits will best be understood by a description of the operation of the apparatus of Fig. 1. Y

'Normally, that is, when both track sections D-E and E-F are unoccupied, the interlocking relay IR is picked up to close the circuit for repeater relay TPR and that relay is picked up to close front contacts 9 and 2| and thereby com-,

plete'the circuits for the control relay XR and the holding winding ll of the slot magnet. Such energization of the slot magnet winding is effective to retain the gate mechanism at its 90 degree position, it being understood that the mechanism has been operated to that position in a manner to appear shortly.

Assuming an eastbound train enters the approach section D'--E, winding H of the interlocking relay IR is shunted and its armature is released to open front contact [9 and close back contact'22, The opening of front contact l9 deenergizes repeater relay TPR and that relay releases at the end of its slow release period. In accordance with standard practice, the closing of back contact 22 of relay IR completes a warning signal circuit by which a warning bell or lamp, or both, are operated to warn highway users that a: train is approaching and that the gate arm is about to be lowered. The remaining portion of,

. warning signal would be set into operation immediately upon the train entering the section D-E, whereas the release of relay TPR which governs the lowering of the gate is delayed due to the slow release period provided for relay TPR.

The release of relay TPR to open front contacts 9 and 2| dcenergizes control relay XR and holding winding 11 of the slot magnet with the result that relay XR is released and the gate arm is unlatched and is free to be moved to its hori-.

zontal position. Since the gate is normally counterbalanced its arm will gravitate toward its.

lowered position by virtue of its own weight However, the release of relay XR to close backcontacts 23 and 24 completes a circuit for relay DN and prepares an operating circuit for the motor MI. The circuit for relay DN extends from terminal B of the current source through back contacts 23 and 24 in multiple of relay XR, controller contact 3 closed for a preselected portion of the downward movement of the gate arm,"

and winding of relay DN to terminal C. Relay DN is energized and picked up to complete an extension of the circuit which forms the motor' circuit, and current flows from terminal B through back contacts 23 and 24 in multiple, controller contact 3, front contact 25 of relay DN, armature 1-5 of motor Ml from right to left as viewed in Fig. 1, front contact 26 of relay DN and motor field winding IE to terminal C. The connections for the motor Ml are such that the motor is now energized and operated as required to power drive the gate arm in its downward direction, such operation of the motor being effective to move the gate arm even though a high wind and other conditions may exist that would tend to retain the arm at the raised position against the bias force. When the 45 degree position is reached and controller contact 3 is opened, this circuit for relay DN and motor Mt is opened, but the gate arm continues to move toward its lowered position under the influence of the bias.

cult is completed from the left-hand terminal of armature 15 of motor Ml through back contact 21 of relay DN, back contact 29 of relay SN, a resistor 30, field winding 16, and back contact 28 of relay DN to the right-hand terminal of armature I5. Since armature I5 is now driven by the bias force the motor Ml functions as a generator. to brake the movement of the gate arm, the brak-z ing force exerted being predetermined by the adjustment of resistor 30.

' At the 10 degree position in the lowering movement of the gate, the contact 2 of circuit OOH? troller Cl is closed and a short circuit path can be traced from the left-hand terminal of armature l5 of motor M'l through back contact 2! of relay DN, back contact 29 of relay SN, controller contact 2, field winding l6, back contact 28 of relay DN and to the right-hand terminal. of armature 15. Since motor MI is now substantially short circuited the dynamic braking is increased so that at the zero degree position of the arm no severe mechanical shock or rebound of the arm takes place.

The gate arm remains at its lowered position until the train passes beyond the intersection and the rear end of the train vacates section D-E anti gized. The closing of front contact |9c winding completes the circuit for relay TPR and that relay isenergized to close front contacts 9 and II and complete the circuits for control relay XR and'winding ll of the slot magnet. With control relay XR picked up to close front contacts 3| and 32, a circuit is formed for relay SN and a motor operating circuit is prepared, thecircuit for relay SN including terminal B, front contacts 3| and 32 in multiple, controller contact 4, winding of relay SN and terminal C, and relay SNis picked up to close front contact 33. The closing of front contact 33 of relay SN completes an extension-of the circuit which forms a motor operating circuit so that current flows from terminal B through front contacts 3| and 32 in multiple, controller contact 4, front contact 33 of relay-SN, back contact 21 of relay DN, armature of the motor from left toright, back contact 28 of relay DN, and motor field winding IE to terminal C. The motor M| is now operated as required to raise the gate arm against the bias force.

When the arm is raisedto'the 86 degree position thecontroller contact .5 is closed and current flows from terminal B through front contacts 3| and 32 of relay XR in multiple, controller contacts 4 and 5 in series and pick-up winding I8 of slot magnet SM to terminal 0, and the armature 35 of the slot magnet is raised to its latching position since both windings l1 and I8 are now energized.

At the 89 degree position inthe raising movement of the gate, thecontroller contact 4 is operated to open the circuitsfor relay SN, motor M| and pick-up-winding l8, withgthe result relay SN is released, the operation of the motor is discontinued and the gate arm is retained latched in its raised position due to the energization of the holding winding II.

It is to be pointed out specifically that the circuit for energizing pick-up winding l8 of the slot magnet includes the controller contacts 4' and 5 in series, the circuit being-completed between the 86 degree and the 89 degree movement in the raising of the gate arm. Then, when the gate isbeing lowered, contact'5 is opened at the 86 degree position but contact 4, due to-its construction, is not reclosed until the 83 degree position, and the circuit for winding la is not closed at any point during the'loweringcf'the arm.,

Consequently, if the gate is being lowered and the main control should be changed to that for raising the arm, the stress due to stopping the movement of the arm is taken up by the motor and not by the slot magnet, and which stress might be great enough to damage the slot magnet.

It is also to be observed that when control relay XR is picked up in response to the picking up of relay 'IPR, a stick circuit is completed for relay XR, which circuit extends from terminal B through controller contact 6, front contact 34 of relay XR and winding of that relay to terminal C. Consequently, once relay XR is picked up by the main control, that is, through contact 9 of relay 'IPR, and the gate arm is started to raise, relay XR is retained energized independent of relay TPR, and the raising movement of the gate is continued until the 89 degree position is reached and controller contact 8 is opened. In other words, once the raising of the gate arms is started subsequent to a train passing beyond the intersection, the gate arm is raised to its verticalposition before it can be again lowered in response to a second train entering the approachsection; In this way the gate arm is notlowered from an intermediate position to come .downjon top of some highway vehicle that has started.

over the intersection after waiting for the first train to pass.

Again, it is to be observed that the snubbing" circuit is held open at back contact 21 of relay DN during the lowering of the arm under the influence of motor MI, and is held opened at back contact 29 of relay SN during the operation of the motor in raising the gate arm.

It is apparent that the operation of the apparatus of Fig. 1 for a westbound train is similar to that described for an eastbound train, except that the relay TPR is controlled at front contact 20 of winding I: of the interlocking relay.

In Fig. 2, the track layout and the control of repeater relay 'I'PR, control relay XR. and hold ing winding ii of slot magnet SM are the same as in Fig. 1 except the stick circuit for control relay XR, is omitted. The circuit for relays DN and SN and motor MI of Fig. 2 are arranged for the two relays DN and SN to function asa pole changing means, the snubbing circuit for the motor being omitted. It is believed that the circuits of Fig. 2 will best be understood by a description of the operation of the apparatus.

Normally, that is, when both sections D E and E F are unoccupied, the repeater relay TPR.

is picked up toclose front contacts 9 and 2| and the control relay XR and holding winding I! are energized, the energization of winding 11 latching the gate arm at the degree position.

An eastbound train entering section D-E of Fig. 2 to shunt winding of the interlocking relay brings about the deenergization of repeater relay 'IPR and the operation of the warning signal. Relay TPR releases at the end of its slow release period, to cause control relay XR and holding winding I! who deenergized with the result the gate arm is unlatched and is free to be moved to its lowered position. The release of relay XR to close back contacts 23 and 24 completes a circuit which includes in series the wind ing of relay SN and motor Ml, such circuit extending from terminal B through back contacts 23 and 24 of relay XR in multiple, controller contact 3, winding of relay SN, armature I5 02 motor Ml from right to left, back contact 36 of relay DN and the motor field winding Hi to terminal C. Relay SN is now picked up to open back contact 31 and the motor MI is energized as required to drive the gate arm towards its lowered position. With controller contact 3 adjusted to open at 45 degrees as indicated by the chart of Fig. 4, the relay SN and motor Ml become de energized at this point in the lowering orthe gate arm and the gate arm would then continue in its downward movement under the influence oi the bias. It is apparent, however, that controller contact 3 can be adjusted to open at some other position and the motor made to govern any preselected portion of the downward movement.

When the eastbound train passes beyond the intersection; to vacate section D- E causing winding ll of relay IE to be reenergized and bring about the reenergization of repeater relay TPR, the control relay XR and the winding, H of the slot magnet are energized. With relay -XR picked up to close front contacts 3| and 32,

acircuit is completed for relay DN in series with the motor, current flowing from terminal B through front contacts 3| and 32 in multiple of relay XR, controller contact Lwinding of relay DN, armature "l5 fromleft to right, back (:On-

tact 31 of relay SN and field winding l6 of the motor to terminal C. Relay DN is now picked up to open back contact 36 and close front contact 38 and the motor MI is operated as required to raise the gate arm. At the 86 degree position the controller contact 5 is closed and a circuit is formed for the pick-up winding I8, current flowing from terminal B through front contacts 3! and 32 in multiple of relay XR, controller contacts 4 and 5 in series, front contact 38 of relay UN and winding l8 to terminal Both windings I1 and I8 being now energized, the armature 35 of the slot magnet is raised to its latching position. At the 89 degree position of the movement, the controller contact 4 is opened so that relay DN, motor MI and winding l8 are all deenergized leaving the gate arm latched at the raised position due to the energization of the holding winding I! of the slot magnet. Although the stick circuit for relay XR is omitted in Fig. 2, it is obvious that such stick circuit arrangement can be included in the same manner as it is included in Fig. 1, and when thus added to the apparatus of Fig. 2 the apparatus would function in the raising of the gate arm independent of the main control in the same way as described in connection with Fig. 1.

Furthermore, with controller contact 4 adjusted to open at 89 degrees in the raising of the arm and to be reclosed at the 83 degrees position in the lowering of the arm, the circuit for pick-up winding 18 of the slot magnet is held open during the lowering movement and energization of magnet SM cannot take place if a change occurs in the main control to bring about the raising of the arm when the arm is being lowered and stresses created due to stopping the movement of the arm do not fall upon the slot magnet structure. v

It is clear that the apparatus of Fig. 2 will operate in response to a westbound train in a manner similar to that described in connection with an eastbound train.

Referring to Fig. 3, the apparatus is similar to that of Fig. 2 except the second relay SN is omitted and the pole changing of the motor circuit is effected at contacts of the control relay XR Normally, that is, when the sections D-E and E-F of Fig. 3 are unoccupied and track repeater relay TPR is picked up, the circuits for control relay XR. and holding winding H of the slot magnet are completed so that the gate is latched at the 90: degree position, the same as explained in the previous cases.

When an eastbound train enters section D-E 'of Fig. 3, winding 1 I of relay IR is shunted causing in turn the repeater relay TPR to be deenergized and the warning signal to be operated. Release of relay TPR at the end of its slow release period causes control relay XR and winding I! of the slot magnet to be deenergized and the gate is unlatched and free to be moved to its lowered position. With relay XR released current flows from terminal B through back contact '23 of relay XR, controller contact 3, Winding of relay DN, armature I 5 of motor Ml from right to left, back contact 24 of relay XR, and field winding iii of the motor to terminal C.

Relay DN is picked up to open its back contact 39 interposed in the circuit for winding i8 of the slot magnet and motor MI is operated as required to drive the gate arm in a downward direction. At some preselected position in the lowering of the arm and here shown as at the 10 degree position, controller contact 3 is opened to deenergize relay DN and motor MI and further movement of the gate arm is caused by the bias force.

When the eastbound train vacates section D-E, so that winding ll of he interlocking relay is reenergized to bring about the energization of repeater relay TPR, control relay XR and winding I! of the slot magnet are supplied with current. With relay XR picked up current flows from terminal B through front contact 3| of relay XR, controller contact 4, armature l5 of motor Ml from left to right, front contact 32 of relay XR and motor field winding IE to ter-. minal C, and the motor is operated as required to raise the arm. At the 86 degree position of the gate arm the controller contact 5 is closed, and current flows from terminal B through front ccntact ii of relay XR. controller contact 4, back contact 33 of relay DN, controller contact 5 and winding i8 of magnet SM to terminal C. Since both windings H and I8 of the slot magnet are now supplied with current its armature 35 is picked up so that when controller contact 4 is opened at the 89 degree position to open the motor circuit, the arm is latched at the raised position due to the energization of the holding winding I7. Again it is to be pointed out that due to the circuit for winding I8 including the two controller contacts 4 and 5" in series, and the construction of contact 4, winding I 8 cannot be energized during the time the motor MI is operated to power drive the gate arm in a downward movement. I

It is apparent from an inspection of Fig. 3 that the apparatus will operate in substantially the same manner for a westbound train.

The apparatus here disclosed has the advantages that the gate arm is driven both up and down, and the downward driving of the arm by the motor is discontinued at a preselected point and dynamic braking effected so that severe mechanical shock and rebound of the arm at the lowered position are avoided. Again, the slot magnet cannot be energized during the lowering movement of the gate armand stresses of the mechanism effected when there is a reversal in the main control of the gate during a lowering movement are taken up by the motor and not by the slot magnet. Again, the raising of the arm once initiated may be continued until the full raised movement of the arm is effected and the arm is not lowered from an intermediate position without due warning to the highway users. Also, the circuit arrangement is minimized and made simple without sacrificing safety and reliability.

Although I have herein shown and described only three forms of apparatus for control of highway crossing gates embodying my invention, it is understood that various changes and modifications may be made therein within the scope pombination' comprising, a first and a second conobstructing position and the obstructing position respectively; other circuit means including in series said front contact of, said second control relay, said first controller contact and a third controller contact to energize said pick-up winding, said first controller contact operable to be opened subsequent to the closing of said third contact when the mechanism is driven toward the non-obstructing position and to be reclosed subsequent to the opening of said third contact when the mechanism is driven toward the obstructing position whereby stresses of the mechanism when there is a reversal of the motor during a movement toward the obstructing position are taken up by the motor, a short circuiting path including a fourth contact of said controller closed subsequent to the opening of said second contact connected across the motor to provide dynamic braking during a preselected portion of the movement of the mechanism toward the obstructing position, and means to at times energize said first control relay.

2. In control apparatus for a gate mechanism biased toward a zero degree position and operable to a 90 degree position and having a reversible motor adapted when energized to drive the gate mechanism and a controller actuated by movement of the gate mechanism, the combination comprising, a control relay, a relay DN, a relay SN, a first circuit including a front contact of said controlrelay and a first contact of said controller to energize said SN relay, an extension of said first circuit including a front contact of said SN relay and back contacts of said DN relay to energize said motor to operate the gate mechanism to the 90 degree position, a second circuit includ .ing a back contact of said control relay and a second contact of said controller to energize said DN relay, an extension of said second circuit including frontcontacts of said DN relay to energize the motor to operate the gate mechanism a preselected distance toward the zero degree position as predetermined by the opening of said second contact; a low resistance circuit including a resistor, a back contact of said DN relay and a back contact of said SN relay connected across said motor to provide dynamic braking of the motor; a short circuiting path including a back contact of each of said DN and SN relays and a third contact of said controller connected across the motor to provide heavy dynamic braking of the motor, and circuit means to at times energize said control relay.

3. In control apparatus for a gate having a mechanism including a reversible motor adapted .to drive the gate mechanism, a circuit controller actuated by the gate mechanism and a slot magnet provided with a holding and a pick-up winding and made effective by the energizing of its windings, the combination comprising, a control,

a pole changing and another relay; means to at times energize said control relay and said holding winding, a first circuitincluding a front contact of said control relay and a first contact of said controller opened at a non-obstructing position of the gate to energize said other relay, an extension of said first circuit including a front contact of said other relay and back contacts of said pole changing relay to energize said motor to operate the mechanism to the non-obstructing position; a branch circuit path for said first circuit and including said front contact of the control relay, said first contact of the controller and a second contact of the controller to energize said pick-up winding; a second circuit including a back contact of said control relay and a third contact of said controller opened at a preselected point in the movement of the gate to an obstructing position to energize said pole changing relay, an extension for said second circuit including front contacts of the pole changing relay to energize said motor to operate the mechanism toward the obstructing position to a point preselected by the opening of said third controller contact; and other circuit means in eluding a back contact of said pole changing relay, a back contact of said other relay and a fourth contact of said controller to provide dynamic braking of the motor.

4. In control apparatus for a gate mechanism operable to an obstructing and to a non-obstructing position and having a reversible motor adapted when energized to drive the mechanism, a circuit controller actuated by movement of the mechanism and a double winding slot magnet made effective by the energizing of its windings, the combination comprising, a first and a second control relay, circuit means including a front contact of said first control, relay to energize said second control relay and a holding winding of said slot magnet, an operating circuit means including a front and a back contact of said second control relay to reversibly energize said motor to drive the gate mechanism either toward its non-obstructing or obstructing position according as said second control relay is picked up or released, a first and a second contact of said controller interposed in said operating circuit means to deenergize saidmotor as it drives the gate mechanism toward the non obstructing and obstructing positions respectively; other circuit means including in series said front contact of said second control relay, said first contact of said controller and a third contact of the controller to energize a pick-up winding of said slot magnet; said controller of a construction for said third controller contact to be closed prior to the opening of said first controller contact when the motor is driving the mechanism toward the non-obstructing position and for said first controller contact to be reclosed subsequent to the opening of said third controller contact when the motor is driving the mechanism toward the obstructing position, and

means to at times energize said first control trol relay and said holding winding; a first operating circuit including a front contact of said second control relay, first contact of said controller, a winding of said first pole changing relay, said motor and a back contact of said second pole changing relay to energize the motor to drive the mechanism toward the nonobstructing position; a second operating circuit including a back contact of said second control relay, a second contact of said controller, a winding of said second pole changing relay, said motor and a back contact of said first pole changing relay to energize the motor to drive the mechanism toward the obstructing position; another circuit including said front contactof said second control relay, said first controller contact, a third controller contact and a front contact of said first pole changing relay to energize said pick-up winding of the slot magnet, and means to at times energize said first control relay.

6. In control apparatus for a gate mechanism operable to an obstructing and a nonobstructing position and having a reversible motor adapted when energized to drive the mechanism, a circuit controller actuated by movement of the mechanism and a slot magnet provided. with a holding and a pick-up winding and made effective by the energizing of its windings, the combination comprising, a first and a second control relay, another relay, means including a contact of said first control relay to energize said second control relay and said holding winding; a first operating circuit including front pole 14 changing contacts of said second control relay and a first contact of said controller to energize said motor to drive the mechanism toward the non-obstructing position; a second operating circuit including back pole changing contacts of said second control relay, a second contact of said controller, and a winding of said another relay to energize the motor to drive the mechanism toward the obstructing position; another circuit including one of said front pole changing contacts of the second control relay, said first controller contact, a back contact of said another relay and a third contact of said controller to energize said pick-up winding; and means to at times energize said first control relay.

CARL L. GOODLIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,824,152 Howe Sept. 22, 1931 1,893,824 McWhirter Jan. 10, 1933 2,137,196 Sampson Nov. 15, 1938 2,163,838 Hines June 27, 1939 2,219,757 Schleicher Oct. 29, 1940 2,220,154 Howe et al Nov. 5, 1940 2,220,162 Lindner Nov. 5, 1940 2,295,419 Miskelly Sept. 8, 1942 2,312,758 Goodlin Mar. 2, 1943 2,340,816 McCann Feb. 1, 1944 2,368,745 Crago Feb. 6, 1945

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