US2488313A - Grade crossing gate - Google Patents

Description

1949 s. MISKELLY 2,488,313

GRADE CROSSING GATE Filed Sept. 15, 1944 5 Sheets-Sheet l Nov. 15, 1949 s. MISKELLY 2,488,313

GRADE CROSSING GATE Filed Sept. 15, 1944 5 Sheets Sheet 2 1949 s. MISKELLY GRADE CROSSING GATE 5 Sheets-Sheet 5 Filed Sept. 15, 1944 NOV. 15, I 5 M LLY 2,488,313

GRADE CROSSING GATE Filed Sept. 15, 1944 5 Sheets-Sheet 4 NOV. 15, 1949 s, MlSKELLY 2,488,313

GRADE CROS S ING GATE Filed Sept. 15, 1944 5 Sheets-Sheet 5 v m 1 C l t -i5 101 3/02 102 2.5 J }/02 $101 Patented Nov. 15, 1949 GRADE CROSSING GATE Samuel Miskelly, Downers Grove, Ill., assignor to Western Railroad Supply Company, Chicago, 111., a corporation of Delaware Application September 15, 1944, Serial No. 554,309

2 Claims.

The present invention relates to railroad grade crossing gates and more particularly to a new and novel grade crossing gate-actuating mechanism which is so constructed and arranged as to provide a more efficient performance with an economical construction.

Grade crossing gates at the intersections of railroads and highways must be absolutely reliable in their operation. Economy of construction at the expense of perfection in operation cannot be tolerated. The gate must give the warning signal when the train is passing and it must give the clear signal and move to the clear position when the train and the danger have passed. Because of the absolute necessity of these requisites of performance gate signal constructions in the past have been expensive in construction.

It is an object of the present invention to provide a new and improved grade crossing gate. It is another object of the invention to provide a new and improved grade crossing gate-actuating mechanism. It isa still further object of the invention to provide a new and improved actuating mechanism for grade crossing gates in which the driving motor reaches substantially its full speed of rotation before assuming the gate-moving load. A still further object of the invention is to provide a gate-actuating mechanism in which the driving motor is normally declutched from the gate and is clutched thereto only upon reaching substantially its full speed of rotation, brake means being provided to prevent excessive speed of gate movement in either the up or down direction of travel. A still further object of the invention is to provide a grade crossing gate which moves to the warning position under the influence of gravity and which is raised to the clear position by a driving motor which is normally declutched except upon reaching substantially its full speed of operation. Another object of the invention is to provide a grade crossing gate in which the driving motor drives the gate both up and down, is normally declutched, and is connected to the gate only upon reaching substantially its full speed of operation. These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawings to which they relate.

Referring to the drawings in which preferred embodiments of the present invention are disclosed and in which the same reference characters refer to the same parts throughout:

Figure 1 is a front view looking toward the railroad track at a grade crossing gate construction in accordance with the present invention and with the gate arm positioned in the raised or clear position;

Figure 2 is a vertical section through the gateactuating mechanism upon the line 2--2 of Figure l Figure 3 is a vertical section upon the line 3-3 of Figure 2;

Figure 4 is a section upon the line 4-4 of Figure 2 and shows a contact-actuating cam;

Figure 5 is a front view of the slot mechanism;

Figure 6 is a side view of the slot mechanism;

Figure 7 is an end view of the centrifugal brake looking in the direction of the arrows upon the line l--'! in Figure 2;

Figure 8 is an electrical circuit diagram showing the electrical connections including the track circuit when the gate is to be driven upwardly only;

Figure 9 is a circuit diagram similar to Figure 8 but showing the connections when the gate arm is to be driven both upwardly and downwardly Referring now to Figure 1 in particular a complete crossing gate constructed in accordance with the present invention isillustrated. A mast I having a base 2 is securely fastened upon a concrete foundation. The mast supports and carries a stop sign of a common and well known type, indicated by the reference character 3, which carries the usual warning Stop on red signal which may be of any suitable material and which \preferably is light-reflecting. A second sign, indicated by the reference character 6, carries an indication of the number of tracks guarded by the gate or gates, and in the present instance reads 2 Tracks. Cross arms 1 and 8 carry the usual wording Railroad crossing formed of letters which are also preferably lightreflecting. Flashing lights 9 are secured to the mast by suitable means I I and preferably include hoods i2 and background discs l3.

The main housing of the gate-actuating mechanism is indicated at I4 and is secured to the mast about four feet above the ground by suitable securing means l6. Within housing I4 is positioned the actuating mechanism for the gate arm which will be hereinafter disclosed. As illustrated in Figure 1, however, it is seen that the gate arm is pivotally carried upon a supporting shaft I8 which extends transversely thru the housing, one side of the gate arm being extended a short distance beyond the pivotal axis comprising the shaft l8 and carrying an armcounter-balancing weight I9. With the gate in the vertical position the weight I9 ispositioned substantially directly below the pivotal axis 18 of the gate arm while with the gate in horizontal position the counterweight moves to the dotted line position. Weight I9 is preferably adjustable towardand from the pivotal axis I8 to permit adjustment of its counterbalancing effect.

The housing l4 for the gate-actuating mechanism is provided with a removable cover 2| which may be pivoted outwardly and downwardly upon its supporting means 22 by the use of its handle 23 provided for that purpose. The movement of the cover 2| to its open position operates to expose the gate-actuating mechanism positioned within the housing which, when viewed from the front, appears as is illustrated in Figure 2.

The gate arm shaft I8 is rotatably mountedin bearings the housingsof which are indicated at :26. To drive the gate there is provided a motor indicated generally by the reference character 3| which includes a shaft 32 which extends substantially parallel tothe gate shaft l8 and which is connected thereto through suitable gearing means and a centrifugal clutch as will now be described.

Beginning with the gate-carrying shaft I8 a toothed sector 34 is fixedly connected thereto and -pinion'39 upon a stub shaft 4| which also carries a second large gear 42. The latter gear in turn meshes with a third pinion 43 carried by a second stub shaft 44 to which is keyed a third large gear 46 which meshes with a small gear 41 carried by a final shaft 48 positioned in alignment with the motor shaft 32. The gear reduction is such that the shaft 48 rotates approximately 700 times for each rotation of the gate-carrying shaft l8.

Motor shaft 32 is connectible to gear-carrying shaft 48 by means of a centrifugal clutch indicated generally by the reference character and which includesa suitable friction surface 52 carried by a plate 53 rotatable with the motor shaft 32. Pivoted centrifugally operable clutch fingers 54 which are'carried by the plate 5| and which may be, if desired, spring urged to open position, function to draw a juxtapositioned clutch plate 56 upon the shaft 48 against friction disc 52. Ac-

tually the operation of the weighted centrifugal clutch fingers at the predetermined speed of motor operation may be merely to move the motor shaft 32 axially within its permitted range of end movement and to shift the friction disc 52 into holding contact with the clutch plate 56. The clutch 5| is characterized in that until the motor 3! :has reached a predetermined speed of rotation, preferably approximately its full speed, the clutch will not close and the motor will not assume the driving load. This relationship permits the use of a relatively small driving motor instead of a larger more expensive motor having a higher torque at reduced speeds of operation.

To prevent excessive speed of rotation of shaft 48, and so excessive speed of travel of the gate arm in either direction, a centrifugal brake is provided, the rotating parts of which are car- 6| fixedly mounted upon a bracket 62 in the casing I4. Within the housing v6| and fixedly-keyed to the shaft 48 by means of a retaining screw 62 is a radially extending plate the outlines of which are shown in dotted lines and which is indicated by the reference character 63. Plate 63 carries three pins, two outer pins 64 at substantially the same distance from the axis of rotation, and a third pin 66 at a lesser distance. Positioned adjacent the plate 63, and also within the brake housing 6|, is a second plate 61 upon which are mounted brake shoes 68 upon pivot pins 89. Plate 6'! is loosely mounted upon the carrying shaft 48 and is provided with an arcuate slot 1| of limited extent into which extends the axially-extending pin 66 on the plate 63. The travel of the pin 66 in the slot 1| fixes the relative movement permitted between the plates 63 and 61.

Between the outer movable end of each pivoted brake shoe 68 and the radially fixed pivot pin 69 of the other brake shoe there extends a coiled tension spring 12. Spring 12 is not connected directly to the outer end of a brake shoe 68 but instead connects to a bell crank lever 13 pivoted on the shoe and formed with an inner end 14 sloped as a cam and which abuts a shoe-carried pin'l6 to "limit its pivotal movement under the forceof the'spring.

The cam end 14 of each spring-attached lever 13 is positioned circumferentially adjacent a pin 64 on the plate 63 'rigid with the shaft 48. With the shaft 48 rotating in one direction and with the pin 66 in one end of the slot II, that illustrated in Figure 7, the pin 64'will be spaced'from the cam surface 14 and the initial tension of the spring 12 opposing outward travel of the brake shoe 68 will be the normal tension of the spring. With the shaft 48 rotating in the opposite direction, however, and with the pin 66 moved to theopposite end of the slot 1| from that illustrated in Figure '7, a pin '64 will have moved'into contact with the cam end 14 of each pivoted lever 73 resulting in the pivotal movement thereof and in the placing of an additional tension in the spring .12. A greater resistance to the outward radial travel under centrifugal force is thereby provided the brake shoe 68. In operation this means that with the shaft "48 rotating in one direction the spring 12 will exert a greater resistance than in the other direction, and accordingly in the first-mentioned direction of rotation a higher'speed of rotation of the shaft will be'permitted before the brake shoes 68 fly outwardly into contact with thebrake housing 6| toprovide a braking action. The arrangement is such that the levers l3 are cammed inwardly during the movement of the gate arm moving to the upper the warning position. In a preferred embodiment the time of upward travel is seven to eight seconds and the time of downward travel twelve to fourteen seconds.

Tt is desirable to provide means whereby the gate arm is held in its upper clear position when the protected track is clear and this is accomplished by providing what is known as a -.slot,'as illustrated in Figures 6 and 7, which comprises a pair of electrical magnets 8| provided with movable armatures 82. .A pivoted bell crank lever 83 is spring-pressed against the armature -82 at one end and at its opposite end carries a pivoted lever 84 which in turn carries a pawl 85 pivoted at B7 and normally drawn downwardly shaft 48 is locked against rotation in a direction which would result in the lowering of the gate arm. The engagement of the pawl with the ratchet wheel takes place whenever the slot is energized and the bell crank lever 83 is pivoted to effect the lowering of the pawl-carrying lever 84. With the slot de-energized the bell crank lever 83 drops away from the solenoid, the lever 84 is pivoted upwardly, and the pawl 86 is moved out of contact with the ratchet wheel teeth whereupon the shaft 48 is free to rotate and the gate arm I'I moves to its horizontal warning position.

It is necessary to provide means whereby the driving motor is energized and de-energized in the performance of its arm-actuating function. In one preferred embodiment of the invention as illustrated in Figure 8 the motor is connected to drive the gate arms up only. In the second preferred embodiment illustrated in Figure 9 the motor drives the gate arms both up and down. With either circuit connection, however, it is necessary to provide means within the mechanism itself whereby the motor and the slot will be energized and de-energized upon the gate arm reaching certain angular positions. This is accomplished by providing a plurality of contact-actuating cams upon the rotatable gate shaft I8. One of these cams, which may be taken as illustrative, is clearly shown in Figure 4, being indicated by the reference character 96. A movable contact bearing the reference character 9'! is urged against the cam by its own resilience and is adapted to cooperate with a stationary contact 98. In certain angular positions of the gate arm shaft I8 the rigidly connected cam 95 will hold the contacts 91 and 98 open while in other angular positions the cam 96 will be so positioned that contact 9'! under its own resilience will close upon contact 98. While but a single contact-actuating cam and actuated contact is illustrated in Figure 4 it is to be understood that as many of these are provided as is necessary. The cams, it should be understood, are to be angularly spaced upon the shaft I8 to accomplish the actuation of the con-- tacts in the desired angular positions of the gate arm.

Referring now to Figure 8, in particular, a circuit diagram is illustrated in which the driving motor, indicated by the reference character Si is adapted to drive the gate arm upwardly only, the downward movement being accomplished by gravity. The signal is arranged to protect a pair of tracks, each comprising a pair of rails IEiI divided into insulated sections by insulators I32. Across each insulated track section is a battery B and also a track relay I03, each relay being provided with a pair of movable contacts I30 and I0'I. Movable contacts I06 are connected in series by a lead I08. The movable contact I0? of one relay is connected through a connector I09 to one of the front contacts III of the other relay which cooperates with the remaining movable contact I01, thereby placing movable contacts III! in series. The front contacts H2 and one of the relays I03 are connected to a source of positive current through leads H3. Each relay IE3 is provided with a back contact II4 for the movable contacts I01, the back contact being through a common lead H6 to common. Movable contacts I06 are connected in series with the winding of a relay H9 by means of a connector I2I connected to a front contact 4 'III- of relay I03. Relay H9 is connected to a Cil common ground through a conductor I22 and is provided with a pair of movable heavy duty contacts I23 which are directly connected to a current source and which make contact with front contacts I24 which are connected through a conductor I26 with the front contact 980, cooperating with a movable contact 910. which is cam-actuated as previously described.

The movable contacts I0'I of the track relays I03 which are connected, as stated, in series are connected by a lead I21 directly to the winding of a delayed action relay I28 the opposite side of which is connected through lead I29- to ground. Relay I28 includes a movable contact I3I connected directly to a positive power source and which cooperates with a front contact I32 connected by means of a lead I33 to the high resistance winding I34 of the aforedescribed slot 8!. High resistance solenoid I34 is connected through a lead I36 to the low resistance solenoid winding I31, the connector I36 being connected through a lead I38 to a ground and also through a lead I39 to one side of the motor 3|. The opposite side of the winding of solenoid I31 is connected through a lead I4I to a second cam-actuated contact 9'! the front stationary contact 98 of which is connected through a lead I42 to the aforementioned movable contact 91a. The latter is directly connected by means of a lead I43 to the field of the motor 3|.

The operation of the signal when connected in the circuit as illustrated in Figure 8 is as follows: Upon a train approaching the highway upon either of the two tracks, and upon entering a track section between the insulators I02, the battery B is shorted and the relay I03 de-energized whereupon it drops its movable contacts I06 and I01. Regardless of'which relay I03 is de-energized the opening of contacts results in the de-energizing of quick acting relay I I9 which promptly drops its movable contacts I23 thereby de-energizing the front contact 98a.

Relay I28 is also de-energized upon the dropping of movable contact I01 which, however, drops into contact with the back contact -II4 thereby connecting the relay I 28 to common. As the opposite side of the relay winding was originally so connected it thereupon becomes'shortcircuited and this increases the retardation to three seconds or more in the release of the movable contact I3I. An operating advantage accrues in that lights, bells, etc., which form no part of this invention have an opportunity to operate before the gate begins to lower. After the passage of the delay period in the operation of relay I28 the movable contact I3I opens thereby de-energizing the holding coil I34 of the slot. As described the de-energization of the slot coil results in the upward movement of the slot lever 84 and the release of the ratchet wheel 9| by the slot-controlled pawl 06. Immediately the gate arm I! begins its downward travel under the influence of gravity, the driving motor 3| remaining stationary and de-energized and disconnected from shaft 48. The latter is rotated through the gear train previously described which connects it to the gate arm shaft I8.

Excessive downward speed of travel of the gate arm is prevented by the centrifugal brake 6| operating as described. The direction of movement of the shaft 48 with the gate moving downwardly is such that the pins 64 carried by the plate 63 are spaced from the cam end 14 of the levers I3. This means that the springs 12 are untensioned and exert aminimumretaining force upon. the

. gear train.

brake shoes ".68 which are-therefore permitted to iiy outwardly a't .alower. speed of rotation tov provide a relatively. slow. speed of downward travel -.of the .gate :arms thereby permitting trafiic to clear.

The downward'travelcofthe gate arms with the accompanying :rotationof .the shaft [8 has effected the rotation of the contact-actuating cams 96 of which thereis one for .each of the contacts 91 and 91a. The cooperating cam 95 is so positioned and contoured that movable .contact 91 *is normally closed .with the gate arm between eighty-six degrees and ninety-three degrees, zero wardmovement of the gate arm resulted in theopening of contact 91 and the closing of contact 91a .at eighty-six degrees .and eighty-three degrees, respectively.

:Upon'the gate reaching its horizontal position the de-energized relay 'IJ03 remains de-energized so longas the .trainremains within the insulated :section or sections .and :theparts remain :as described, the slot.=andmotor both being de-ener- .gized' 7 Upon the passing train clearing the insulated section, however, the short upon :the battery B and the relays I03 is :removed zandthe. movable contacts 106 and I01 are-picked up. Immediately relay H9 is energized and:the.movab1e:contacts 123 thereof are.v picked .up and current flows through the connector 1:26 -to the :front contact 98a, the .contact 91a of whichjs closed thereon,

and to the motor through the connecting lead 143. The opposite sideof the :motorloeing connected through the leads J39, -l.38to:g1tound':the

motor is instantly energized -andthe armature thereof begins to rotate. .The motor does :not pick up the load comprising thegate arm :until it has reached substantially .:its ,full operating speed at which time the centrifugal 11f orjce acting upon the pivoted clutch :fingers :54 throws -=th em radially outward with -sufficient'force to clamp the disc :56 to the driving plate .5;3'and; compress the friction suriace52 therebetween. Thereupon the shaft 48 begins sto. rotate; the :drivingmotor :assumesiits'load, fflIIdFthB gate arm :moves upwardly, the :movement of the shaft :48 being transmitted to the gate-arm it-through described 7 In this directionnf movement .of the shait =48 the-pin .66 is at the opposite end :of the slot "II from that illustrated in Figure 7 :and the pins 64 :are :in contact'with the cam ends M of the .pivoted levers 13. .Thisresultsinrthetensionin of the springs 12 which-thereupomexert argreater restricting :force upon the brake ishoes'58. In terms of operating vcharacteristics,this means :that the shaft 48 can rotate.'at :a'higher :SpEBd without the :brake shoes BBbeing moved;outw ardlyunder centrifugal :force into contact with .the "brake drum 6| .and'so-aniincreased speed ofzupward movement of the :gate arm is permitted.

The upward movement of thegate :arm;-requires ,substantially'seven .to eight seconds as.;comp.ar.ed to twe1ve :to .fourteen seconds for 'thedownward movable contact .910 reflects ft'he...openin-g pfrthat contact with respect tozitss-stationary contact 98a. While this contact was closed, however, current had been able to flow through the lead 142 to the front contact 98, through movable contact 91 to lead 14! and thence to the low resistance solenoid 131 of the slot 8| which resulted in the picking up of the movable armature 82, the opposite side thereof being connected through the lead I38 toground. Thepicking up of the slot armature with the accompanying movement of thepawl BS-into contact with the rotating ratchet "wheel 9,! did not effect the looking or prevention of movement thereof due to the shape of the ratchet teeth. As illustrated in Figure 6, -.the shaft 18 can rotate in a counterclockwise direction due to the shape of the teeth of the ratchet wheel 9!. Upon the'opening of the contacts 91a, 98a, however, solenoid winding I3! is de-energized. Current continues to flow through the high resistance holding solenoid coil 134,..the latterfloeing connected directly to ground through the leads I36, I38 while its opposite side is connected to-apositive current source through the lead I33 to 'the front contact I32 of the relay 23 the movable contact l3! of which is connected to positive current. The slot, therefore, does not open and the'pawl remains in position to prevent reverse ,movement of the ratchet wheel 9i corresponding tothe downward travel of the .gate arm. Upon the gate .arm reaching substantially eighty-nine degrees from the vertical the movable contact 97 is moved to open position by its actuating cam 96. From'approximately eighty-three degrees to its vertical rest position atsubstantialiy ninety degrees .thcgate arm travels through under its own momentum. Upon reachingthe end of its travel further movement of the arm is prevented by the abutment of the toothed sector 34 rotatable with the gate 5 arm shaft l8 .againstthe resilient contact abutment 14!, which may be .of any well known design, for example, as shownmore fully in applicants co pending application Serial No. 389,- 541.(Patent 2,362,710). If desired a similar resilient abutment Mi may be provided tocontact he sector 34 at the opposite end of its travel when the gate arm moves into the horizontal position, abutments positioned to accomplish both functions being illustrated in Figure 3.

Referring now .to Figure 9 a second circuit diagram illustrates the manner in which the gate-arm-actuating mechanism may be electrically connected in .order that the driving motor will rotate in opposite directions and drive the gate arm both upwardly and downwardly. In this tym of operation, as in thatpreviously described, thec-entrifugal clutch 5,! operates to connect the driving motor to its load only when .the driving motor has reached substantially its full speed, and similarly the centrifugal brake 6| operates to prevent excessive speed of arm travel in both directions, the characteristic being as before that the upward speed of movement is ,greater than the downward speed.

In Figure 9 the parts which are identical to thoseillustrated-in Figure 8 bear the same reference lcharacters and .only'those parts which have been substituted or have been added are additionally identified. Each insulated track section is again provided with a battery B and a relay .133 connected between its track rails llll. Movable contacts [96 and H37 of each relay I03 operate effectively as in the first-described embodiment- Aduick actin relay 9 is a ain onnected series with the' ovable contact J06 by a lead I2I and has its opposite side connected by lead I22 to ground. Relay H9 again includes movable contacts I23, with front contacts I24 connected in the manner of the first embodiment, and also with back contacts I5I which are connected through a lead I52 to a third and additional front contact 98b cooperating with a movable cam-actuated contact 9112, these contacts being closed between forty-five degrees and ninety-three degrees, approximately. The latter is directly connected by means of a lead I53 to a movable contact I54 which is actuated by the slot armature 82 and which cooperates with a stationary contact I56. The exact construction of movable contact I54 and its stationary contact I56 is not important and may be of the type illustrated in applicants co-pending application Serial No. 389.541 (Patent 2,362,710), it being only important that when the slot armature is picked up the contacts I54 and I56 are open and when the slot is de-energized, and the pawl 86 is in inoperative position, the contacts I 54 and I56 are in contact. This contact is important for by carrying the drive down motor current over this contact it is insured that the motor cannot start pulling downwardly until after the hold-clear mechanism comprising the slot has been de-energized and released. The stationary contact I56 is directly connected by a lead I51 to the lead I43 between the field of the motor 3| and the movable cam-actuated contact 91a.

As in the first-described circuit the delayed action relay I28 is connected between the contacts I61 of the track relays and ground. As before a movable contact I3I of that relay connects to a positive source of current and its cooperating front contact is connected by a lead I33 with the high resistance winding I34 of the slot. In this form, however, relay I28 is provided with a second pair of contacts and for a purpose to be explained.

The cam-actuated relays 91, 98 and 91a, 98a are connected and operate as in the first embodiment.

In the present embodiment it is necessary that the motor reverse its direction of travel for the upward and downward movements of the gate arm and to effect this result it is necessary to provide a pole-changing relay indicated by the reference character I6I. Relay ISI has its windings connected, by means of a lead I62, to an additional front contact I32 of the delayed action relay I28 which is also provided with an additional movable contact I3I connected to positive current. The opposite side of the winding of relay I6I is connected by a lead I63 to the lead I38 leading to the common ground. Relay I 6| is provided with a pair of movable contacts I64 each of which is adapted to cooperate with front and back contacts I66 and I61, respectively. The front contacts I66 are connected to opposite sides of the armature of motor 3| as are the back contacts I61. As one movable contact I64 connects directly to the motor field through a lead I68 and as the other contact connects directly to the common ground lead I38 via a lead I69, it is clear that the direction of current travel through the motor armature is in reverse direction with the movable contacts I64 up and down. The relationship is such that with the relay I6I energized and the contacts I64 picked up the motor rotates in one direction while with the relay IBI de-energized and the contacts I64 dropped the motor rotates in the opposite direction.

ly the movable contacts I66 and I61 drop downwardly effecting the de-energization of quick acting relay H9 and delayed action relay I28. The

de-energization of relay II9 effects the dropping.

of contacts I23 against their back contacts I5I thereby effecting the passage of current to the front contact 981) through the movable contact 9112 and lead I53 to the movable contact I54- which is slot-operated and held in the open position with respect to back contact I56 so long as the slot 8I remains picked up and in locking posi-.

tion.

After its period of delay relay I28 drops the.

movable contacts I3I to de-energize both the po1e-changing relay I6I, which is connected thereto through the lead I62, and also the holding coil I34 of the slot which is connected thereto through the lead I33. It is to be notedthat the slot 8I is de-energized and so the ratchet wheel 9I' released before the motor is energized. The slot being de-energized the movable contact I54 drops onto its back contact I56 and positive current is passed to one side of the motor field. Current flows therefrom through a lead I68 to a movable contact I64 of the solenoid I6I in the dropped position, the solenoid being:

de-energized, through the motor armature and to ground through a second movable contact I64, the

lead I69 and through the lead I38 to common.

The slot being released the gate arm is free to move downwardly. The motor 3I is energized and, upon reaching its full speed of operation, drives the gate downwardly as previously described. Upon reaching substantially a forty-five degree position contact 91b is moved by its cooperating cam to its open position thereby deenergizing the motor and the gate moves the remaining distance to its horizontal position under gravity and under the momentum required by the motor propulsion. In the downward movement of the gate movable contact 91a closes at eightythree degrees but no current flows therethrough, connecting lead I26 being open-circuited at the de-energized relay II9.

After the train has passed through the insulated section the controlling relay I63 is again energized whereupon the relays I I9 and I28 are immediately energized being connected to the movable contacts of relay I63 as described. Positive current now passes through the movable contacts I23 of relay H9 to the upper contacts I24 and through the lead I26 to the stationary contact 98a. Contact 91a being closed between zero degrees and eighty-three degrees current is passed directly through lead I 43 to one side of the motor field and through lead I42 to the stationary contact 98.

The picking up of relay I28 effects the movement of the movable contacts I3I thereof into contact with the stationary front contacts I 32. Immediately current flows through lead I62 to the pole-changing relay I6I which effects the movement of the movable contacts I64 upwardly from contact with the back contacts I61 into contact with the front contacts I66. Accordingly the direction of current flow through the motor armature is reversed. The motor is energized, one contact I64 being connected to ground and the asses/re 11 ot er, tofthe 11m otor held, as described, and begins to rotate assuming the load of moving the 'gate unon reaching substantially its full speed of rotation'bv virtue .o'f'the operation .of the centrifual clutch As 'the ate :moves upwardly under the actuation of the motor at substantially the eightysix degree position contact 91 closes upon 'contact 98 thereby energ zing the pickup winding I31 of "the slot '81 which moves the pawl 86 into lockin posit on withregard to the ratchet wheel/91.. The 'highresistance holding coil 134 had been previously energized by the pickup of movable contact I3I of relay [28 to which it is connected via lead 133 and front contact I32. Coil I, however, .d'oes'not exert suffic ent force to actuate the slut armature 82 "although capable of holding 'it'in a setposition. At substantially eight-nine degrees in the clearing movement movable contact 'S'Tais cam-moved tof'rts open position'and 'currentto both themotor, through the Ilead M3, andto the pickup coil ='l3'1,'through the contacts 9'8, 91 and'lead' "Wlfiiscu't oif. Current "to the same side the motor from the contact 'Qlb had previously been cut off with the picking up of the slot armature and "the opening of contacts 154, P56 connected between the leads 153 and T5]. "The slot remains picked up, however, as the holding coil remains energized. The motor .is thus -de-energized and the holdingslo't energized and again the arm movementlisst npefi Jay the contact of the sector 31! with the resilient abutment I41 and thereafter is lre'tained in .the elear ,position by 'the holding gallyactuated elements carried and actuated by saidshait, a second shaft, a complementary .part of .said centrifugal clutch .cannied Joy said secondshaft, .a centrifugal brake including -a stationary mart and centrifugally actuated elements mounted on said second shaft, speed-reducing gear means connecting said second shaft to said .gate, said brake being normally inoperative to permit the gate arm to start lowering Thy gravity ffreely and being rendered op- I erativelby a predetermined .speed of said second .shaft to brake the lowering of said arm,

said "bra ire being further actuated 'by the :speed nected to said-second 's'ha 'ft to hold said shaft against and 'to release said shaft for rotation independent of the =rotation 'of said first shaft.

2. a ra'i-lroadcross'ing signal, a piveted'gate arm counterbalanced for self lowering by gray ity, a driving moton a centrifugal "fl'lOlliOIlfCl'lliiGI-l normally open and having centrifugal elements and a driving plate actuated by the motor when the clutch is open for-closing the clutch, aslraft anda d-riven' plate carried thereby forsaid clutch normally free of 'said dri-ving plate, speed reduc ing power-transmittin 'means connecting said driven clutch plate shaft '--with said arm, a normally free centrifugal brake connected to said:

driven clutch plate shaft and adapted to be driven by said power-transmitting means, said brake being 'centr'ifugall-y actuated to limit the speed-of rotation "of said arm in either direction, gravity releasable electrically energized means connected with said clutch plate shaft for bolding the gate raised, the ceuriterbalanci-ng and the power-transmission means :and the normally open clutch cooperating in allowing the gate to lower by gravity when "the motor is not :energized and without causing rotation of the motor upon the release of said releasable means and thereby actuating said brake "to control the rate of descent of said gate, said friction clutch permitting simu'ltaneous diiferent speeds of the dr iving and 'driven plates whereby overloading cf the motor is rendered less likelyand the speed limiting action-of the brake may be effective even when said clutchis cl'osed.

'HEFERENCES "CITED The following references are of record .in the file :of this patent:

STA'I ES BAlDEN- I S Number Name Date 94(1178'6 Cook 'Nov. '23, 1909 138.4544 "'Billett et al. .July 12, 1921' 1522,6115 Watson -LMay 24,1927 1,'7!73,243 Stewart Apr. 19,, 1930 1,9l69g286 'Wornick Aug. 7, 1934 2.,010i92'5 -Nakashian Aug. '13,, I935 2,267,632 'Wunsch 'Dec. 23, .1941 2,295,419 Miskelly Sept. 8, 1942 2,353,942 Stephenson July 18, 1944 2,362,710 Miskelly "Nov. 14,, 1944 23721579 Jefferson et a1 .Mar. 21,1945

Images