US1797974A - Grade-crossing signal - Google Patents

Description

March 1931- H. N. BRANDALL 1,797,974

GRADE CROSSTNG SIGNAL Filed Aug. 15. 1928 5 shee rfsqheet' 1 l' GUM/Mud,

March 1931- H. N. B RANDALL 1,797,974

GRADE CROSSTNG SYGNAI:

Filed Aug. 15. 1928 5 Sheets-Swami 2 7 H/VT Bran/Jazz.

March 1931- H. N. BRANDALL GRADE CROSSING SIGNAL Filed Aug. 15, 1928 5 Sheets-Sheet 3 1? mzrandazz.

March 24, 1931. H. N. BRANDALL ,9

GRADE CROS S ING S IGNAL Filed Aug. 15, 1928 5 Sheets-Sheet 4 4f 40 H JVIZfanaa/ZZ.

March 24, 1931. BRANDALL 1,797,974

GRADE CROSSING STGNAT.

Filed Aug. 15, 1928 5 Sheets-Sheet 5 imme/MM H. NBranJa/Z Patented Mar. 24, 1931 UNITED STATES HARRY N. BRANDALL, OF FAIRFIELD, IOWA GRADE-CROSSING SIGNAL Application filed August 15, 1928. Serial No. 299,793.

This invention is a signal mechanism intended particularly for use at grade crossings and to be operated by an approaching train to notify users of a road that a train is about to reach the crossing. A particular object of the invention is to provide an apparatus which will cause a signal to be given only while the train is approaching the crossing so that pedestrians and the occupants of vehicles upon a road which intersects a railway will not be misled by false alarms and, consequently, induced to ignore a signal, when given, by reason of having been misinformed by the improper operation of signals. An- 16 other object of the invention is to provide means whereby, when the signal is applied to a single track road, the alarm will be given only when a train is approaching the crossing and will be inoperative when the train is passing or has left the crossing. Another object of the invention is to provide a signal mechanism which will operate the signals through a predetermined period. Other objects of the invention will appear in the course of the following description, and the invention resides in certain novel features which will be particularly pointed out in the appended claims.

In the accompanying drawings which illustrate the invention Figures 1, 2 and 3 are sectional elevations of one embodiment of the invention, showing the actuating mechanism in different positions assumed as car wheels are passing thereover in one or the other direction;

Fig. 4 is a vertical transverse section on the line 44 of Fig. 2;

Fig. 5 is a top plan view with the cover of the casing removed;

6 is a detail plan view, partly broken away and in section, of the oscillatory container in which circuit-closing elements are mounted;

Fig. 7 is a detail perspective view of a trigger which forms a part of the operating mechanism;

8 to 12 inclusive are longitudinal sections through the oscillatory container showing the same in different positions and illustrating the operation of the circuit-closing .5 elements;

Fig. 13 is a diagram of the apparatus applied to a grade crossing;

Figs. 14, 15 and 16 are views similar to Figs. 1, 2 and 3 but showing another form of the invention;

Figs. 17 and 18 are longitudinal sections of the container shown in Figs. 14, 15 and 16, illustrating different positions assumed by it in operation; I

Fig. 19 is a section on the line 19-19 of Fig. 17, and

Fig. 20 is a detail section on the line 20-20 of Fig. 14.

-In carrying out the invention, there is secured to the side of a track rail 1 a casing 2 in which the circuit-controlling elements are mounted. This casing is secured to the web of the track rail by bolts 3 inserted through bosses at the corners of the casing and through the web of the rail, as will be understood upon reference to F i s. 1 to 4. The casmg may be constructed 0 any suitable material, preferably sheet metal, and is formed with a longitudinal vertical partition 4 whereby it is divided into an outer trigger chamber and an inner circuitclosing chamher, and a cover 5 is fitted over the casing so as to entirely close the same and protect the interior of the same from the action of the weather and prevent the operation being clogged or hindered by moisture or an accumulation of dirt or other foreign matter, the cover being constructed with transverse slots 6 to accommodate the working ends of triggers which are mounted within the trigger chamber and intended to be actuated by the wheels of passing cars. Pivotally mounted upon the upper bolts 3 are resilient trip levers-7 which extend over the cover from the opposite ends thereof and are formed of spring-tempered metal having sufficient strength to normally occupy the positions shown in Fig. 1 and resist depressing action exerted thereon by any weight less than that imposed through the car wheels, a portion of one of the car wheels being shown at 8. It will be noted that these trip levers are provided at their outer edges with longitudinally extending depending lips or flanges 9 which are disposed at the outer side of the casing and that the trip levers are of such width that they will extend to the longitudinal shoulder or ridge in the cover and thereby serve to prevent the entrance of moisture or other matter through the slots 6 in the cover. Pivotally mounted within the upper portion of the trigger chamber of the casing, between the center of the same and the respective ends thereof, are triggers 11 and 12 each of which consists of a pendent body and an angular arm 13 projecting laterally from one side of the body at the upper extremity thereof and terminating in a finger 1a which is adapted to project upwardly through the respectively adjacent slot 6 and bear against the under side of the respective trip lever 7. The weight of the body of each trigger is obviously greater than the weight of the arm and its terminal finger so that normally the triggers will assume the positions shown in Fig. 1 with the bodies vertical or substantially vertical and the trip levers extending obliquely inward over the cover of the casing and out of contact therewith. Pivoted to the trigger 11,

near the lower end thereof, is a pull bar 15 formed in its under side with a notch or re cess 17 having a vertical shoulder 18 at one end and having its opposite end beveled or inclined, as indicated at 19. Mounted in any convenient or suitable manner in the lower portion of the casing at the center of the same is a rock shaft 20 and secured upon this rock shaft within the trigger chamber is a forked lever or crank 21 through the upper forked portion of which the pull bar passes, as shown clearly in Figs. 1 to 4. When the mechanism is at rest, as shown in Fig. 1, the pull bar rests upon the lever 21 between'the tines 22 of the same with its vertical shoulder 18 engaging the edge of the lever between the lower ends of the tines. By referring particularly to F igs; 1, 2 and 8, it will be seen that the device is intended to be operated by a train traveling from right to left in the drawings in whichevent the car wheel 8 will impinge against the right hand trip lever 7 and depress the same so as to rock the trigger 11, as shown in Fig. 2, and thereby draw upon the pull bar 15 so that the crank or lever 21 will be rocked toward the right; If the train approaches from the left, the wheel impinging upon the left hand trip lever 7 will depress the same and rock the trigger 12 toward the right and, a a result of this action,'the pull bar will be lifted about its pivotal connection,

with the trigger 11 so that it will be disengaged from the crank or lever 21, and when the car wheel subsequently depresses the right hand trip lever and rocks the trigger 11, the pull bar will bev merely drawn through the crank or lever 21' without actuating the same, as will be understood upon reference to Fig. 3.

As shown in Fig. 4c, the rock shaft 20 extends entirely across the casing, and within the circuit-closing chamber there is secured to the shaft a container 23 of insulating material which is substantially triangular in side view. This container is constructed with a central partition 24 radial to the rock shaft and having a large opening 25 there through adjacent its lower end, and constructed in or near its lower edge with a central notch or passage 26 of very restricted area which constitutes a percolating orifice to permit a retarded return flow of the mobile circuit-closing element from the right hand chamber of the container to the left hand chamber thereof. Secured in any convenient manner upon the right hand side of the partition 241- in position to cover the opening 25 therethrough is a check valve 27, shown in Fig.4 and Figs. 8 to 12, in the form of a flap of leather or other flexible material which is secured at its lower edge below the port and has its upper portion free to move toward and from the partition. Mounted in the top of the container at the right of the partition are conductorterminals 28 and 29, these terminals being of like formation and the terminal 28 being shorter than the terminal 29. A body of mercury, indicated at 30, is placed within the container and is adapted to bridge the terminals 28 and 29 so as to complete an electric circuit therethrough, but normally, as shown in Fig. 8, the level of the mercury isbelow the end of the terminal 28 so that the circuit will be broken and the signal. will be inoperative. When the container is rocked, the body of mercury will be shifted so that its level will rise inv comparison with the terminals and the circuit will be closed between the terminals 28 and 29 and will remain closed until the mercury, through its inherent action in seeking to return to a level, recedes below the shorter terminal and breaks the circuit. Obviously, the signal will be sounded through an interval which may be predetermined and, in actual practice, the terminals will be fixed in the top of the container and the relative lengths thereof will be such that the signal will be sounded through such an interval as experience has shown to be desirable. In the drawings, however, I have shown the shorter terminal 28 as provided with threads 31 along its upper portions so that in assembling the device the terminal may be adjusted as desired, the terminal passing through a nut 32 embedded in the body of the container and having its upper extremity constructed to be engaged by screw driver or other similar tool.

In order to avoid oxidization which is apt to.

occur through contact of mercury with other metals, a thin film of glycerine, indicated at 38, 1s deposited upon the top of the mercury Ibo iio

and this film, being lighter than the mercury, will always be 011 top thereof notwithstanding variations in the level of the mobile body and it will not only resist oxidization but will also serve to cleanse any surface upon which oxidizing effects may appear.

Conductors 34 are embedded in the walls of the container and each conductor has its end secured to one terminal. One of the conductors extends to one side of a battery or other source of current, indicated at 35, Fig. 13, while the other conductor extends to one side of the signal, indicated at 36, and this signal may be a hell or a lamp or any other approved form of audible or visual alarm, one side of the signal being connected to the corresponding side of the battery by a conductor 37. It will now be obvious that, when the terminals 28 and 29 are electrically connected, the circuit will be closed through the signal and the battery and the signal operated. It will also be understood that the car wheels and axles do not form part of the circuit although it maybe convenient at times to utilize the track rails as portions of the conductors 34.

Referring now more particularly to Figs. 8 to 12, it will be noted that in the normal posi tion of the container shown in Figs. 1, 3 and 8, the level of the mercury will be below the terminal 28 with the greater body of the mercury in the lower portion of the left hand chamber in the container, although a small quantity of the mercury will be in the bottom of the right hand chamber owing to the presence of the minute orifice 26 in the lower end of the partition 24. Assuming the trigger 11 to be actuated by a car wheel approaching from the proper direction, as indicated in Fig. 2, the container will swing toward the rightwith the rock shaft 20, and the initial move ment will cause the mercury to bank against the partition 24, as shown in Fig. 9. The weight of the mercury will be thrown against the check valve 27 and will open said valve so that the mercury will rush through the port 25 into the right hand chamber of the container, the level of the mercury dropping in the left hand chamber. When the mercury surges into the right hand chamber of the container, it will momentarily close the circuit through the terminals 28 and 29 and cause a very short initial operation of the signal but it immediately subsides and breaks the circuit, the shape of the outer wall of the chamber and the volume of the mercury being such that the surface of the mercury will be below the terminal 28 as long as the container is in any of the positions shown in Figs. 8, and 10. As the container makes its return movement, the weight of the mercury will act in the opposite direction upon the check valve and will close the valve, as shown in Fig. 11, so that the mercury will be banked about the terminals 28 and 29 and will maintain the circuit closed for such period as is required to permit it to return to the left hand chamber through the percolating port or orifice 26. The rocking movement of the container is certain and is rather sharp, an expansion spring 38 being provided to receive the impact of the container upon its movement to the right and immediately expand and start the return movement thereof, and to cushion the return movement a buffer 39 of rubber or other suitable material is provided in the casing, as shown in Figs. 1, 2 and 3. The triggers 11 and 12 being overbalanced so that they tend to remain in the vertical pendent position shown in Fig. 1, the trigger 11 will return to normal immediately after the car Wheel has cleared the trip lever 7 acting thereon, the pull bar riding through the forked lever 21 and through the opening 16 in the trigger 12 so that the crank 21 will then be free to rock with the container and will not retard nor arrest the movement thereof but will ride under the pull bar which will drop by its own weight into the position shown in 1 when the parts have 7 assumed their initial positions. The strength of the spring 38 is not so great that it would prevent the container moving the full distance to the right but it is strong enough to start the return movement and move the container to the position shown in Fig. 11. At this time the mercury will be banked. high in the right hand chamber of the container and bearing against the partition but will. be percolating through the orifice 26 into the left hand chamber and, consequently, the weight of the mercury will tend to continue the return move ment of the container, but the circuit is closed and the signal is operating. Eventually, the

flow through the orifice 26 into the left hand chamber will bring the level of the mercury below the terminal 28 and thereby break the circuit, whereupon the operation of the signal will cease. The triggers and the container will have returned to initial position.

It will be understood that the signal-closj in g container and the parts cooperating therewith will be located. several hundred feet from the crossing so that any one who may be crossing when the signal is operated will have an opportunity to leave the track before the train reaches the crossing. The apparatus which has been described is intended for use on single track roads but it may be applied to double track roads and when so applied the only thing that needs to be done is to remove the left hand trigger 12. Crossing signals, as heretofore constructed, have been operated by the closing of a circuit through the car wheels and the track and, consequently, the signal was sounded whenever the train was in the signal block, whether the train was in motion or at rest. In my apparatus, the signal is closed by the passing car wheel but does not extend through the Wheel and is ..i

. adapted for use upon side tracks where motionless cars make the use of other signaling systems impossible but where there is great danger from the switching of cars at unguarded crossings. The casing or my device is practically watertight and the oscillatory container is absolutely water-tight so that the action of the air or the weather will have no effect upon the operation of the device. The device will, of course, be actuated by each wheel of the passing train and will operate for a predetermined period after the last wheel has passed, but if a wheel should come to rest over the trigger 11the container will not make its return movement but will he held in a position determined by the depth of depression of the trigger, and the signal will not operate because the level of the mercury will be below the terminal 28. Due to this fact, the circuit is broken as each wheel passes but closes instantly as the container returns to normal. A false alarm, therefore, cannot be given. It will be noted that the signal has an intermittent action, being operated for a very short interval, a preliminary warning or flash being thus given, followed immediately by cessation of the signal and then a longerperiod of operation as the mercuryslowly recedes from the circuit terminals. A very rapidly moving train, therefore, would'cause the signal to operate at frequent intervals which, in some instances, would be practically continuous owing the very short periods of broken circuit while a slowly moving train would cause greater interruption to the signal activity because the trigger would'be depressed tor the longer period of time a car wheel was over it.

The embodiment of the invention which has been described is preferred for installation where an irregular flashing of a light is permitted, or it is not requiredthat a light flash a given number of times in a stated period. The latter type of signal requires a continuous current up to the signal and the flashing is controlled by electrical mecha nism at or near the signal. To meet this condition, I provide the structure shown in 14 to 20 in which a longer closed work ing condition of the circuit is attained.

The casing 40 is secured to the side of a track rail by bolts 41 and at the upper con ncrs thereof are mounted trip levers 42, 43., corresponding in all respects to the trip levers 7 of Figs. 1 to 4, the top of the casing having openings therethrough tor the ac coinlnodation of hearing, at their upper ends, against the respective trip levers, as shown. The trigger 4 is pivotally mounted, as at 46, and is offset or bent in the region of its pivot so that the t ers 44 and its upper extremity is disposed between its pivot and the adjacent end of the casing, but

the trigger 45 is straight and has its lower end seated in an expansion spring 47 whereby it is held to the trip lever .43, said trigger 45 being readily reciprocable vertically but having practically no oscillatory movement. In the lower end portion of the trigger 45 an opening 48 is formed there through to receive and slidably support the free end or" a pull bar 49 which is pivoted at or near its opposite end to the lower end of the trigger 44, and a retractile' spring 50'is provided between the trigger 44 and the. adjacent end ofthe casing to normally hold the parts in the positions shown in full lines in Fig. 14. Fixed to the pull bar, between the triggers, is an upstanding bracket 51 having its upper extremity turned, toward the Assuming a car toapproach from the left,"

as indicated in Fig. '14, the trip lever 42 will be depressed and the trigger 44 thereby rocked, asshown by the dotted lines, the pull bar sliding through the trigger 45 and also swinging upwardly. The dog 53.will be carried against and past the cam 55 and will rock upon its own pivot to clear the cam, dropping into normal position against the bracket 51 as soon as it is free of the cam so that, upon return movement, it will be in position to engage the shoulder 56 and actuate the cam and rock shaft. As the car wheel, however, leaves the trip lever 42, it at once passes onto and depresses the trip lever 43 so that the trigger 45 is pushed down and the free end of the pull bar likewise moved downward to carry the dog-to a position below the cam. Consequently, the return movementof the pull bar and dog, which is caused by contraction of the spring 50 and occurs while the trigger 45 is depressed, will have no e'fiect on the rock shaft and the signal will not be operated. When a car approaches from the right, the wheel will depress the trip lever 43 and the trigger 45 which will resume their raised positions as the'wheel passes from the trip lever. As the wheel leaves the trip lever 43, it passes onto and depresses the trip lever 42 and thereby, in the'manner before described, swings the dog into the position shown in dotted lines in Fig. 14 and full lines inFig. 15. When the dog now makes its return movement as the wheel leaves the trip lever 42, the cam will be engaged and rocked inasmuch as the trigger remains in its raised position, as will e understood on reference to Fig. 16.

An oscillatory container 57 is fixed upon the rock shaft and is substantially triangular in side view but is relatively longer than the container 23 first described and its apex is at its top instead of the bottom. A transverse partition 58 divides the container into two chambers, and it may be here noted that the partition may be integral with the body of the container or formed separately tached thereto and the body may he produced in parts to be subsequently united as necessities of manufacturing may dictate but all joints must be hermetically sealed. At 59 I have indicated a plugged and sealed opening through which mercury 60, was placed in the container and at 61 is indicated a weight upon the more attenuated end of the container to assist the mercury in holding the container in normal position shown in Figs. 14 and 15 and returning it slowly to said position. The partition is formed with a relatively large port 62 and a very small orifice 63 below said port. Flow through the port 62 is controlled by a check valve 64 in the form of a very thin flexible tube having one end sealed around the port and its opposite end free in the right hand chamber of the container. When the container is rocked to the position shown in Figs. 16 and 18, the mercury rushes through the tube but the free end of the tube will float with the rising level of the mercury and, when the flow ceases, will close under the surrounding pressure. Terminals 65 are provided in the right hand chamber of the container and are constructed in the same manner as the terminals 29 but are located adjacent the end wall of the container and are disposed at a greater angle to the partition so that submersion in the mercury will continue through a longer period and there will be less frequent breaking of the circuit. As long as the left hand end of the container remains elevated, the cam will be out of the range of the operating dog and as it slowly returns to normal the cam will be engaged in propor tion so that the right hand chamber will be kept filled with mercury with a minimum operation of the container.

My apparatus may be installed at a low cost and Will practically cost nothing to maintain so that it may be employed in all places where crossings are now left unguarded because of the prohibitive cost of present signals. The resilient trip levers absorb the shock due to impact from the car wheels and also serve as shields for the trigger mechanism against rain, snow and ice and safeguards it from malicious or accidental tampering.

Having thus described the invention, I claim:

1. An apparatus for the purpose set forth comprising an oscillatory container, means within the container for intermittently closing an electric circuit through a predetermined interval, a rock shaft carrying the container, a trigger mounted in proximity to the container to oscillate in a vertical plane parallel with the side of the container, means whereby said trigger may be actuated by a passing car wheel, and means operatively connected with the lower end of the trigger for at times rocking the shaft and the container.

An apparatus for the purpose set forth comprising an oscillatory container, means within the container for intermittently closing an electric circuit through a predetermined interval, a rock shaft carrying the container, a trigger mounted in proximity to the container, means whereby said trigger may be actuated by a passing car wheel, means operatively connected with the trigger for rocking the shaft and the container, and an ex pansion spring arranged to receive the impact of the container when the same is actuated by the trigger and to impart an initial return movement to the container.

3. In an apparatus for the purpose set forth, an oscillatory container, means within the container for closing and breaking an electric circuit, a rock shaft carrying the container, a projection on the rock shaft, a trigger arranged adjacent the container and adapted to be actuated by a passing car wheel, and a pull bar connected to the trigger and adapted to engage the projection whereby ac tuation of the trigger will rock the container in one direction to close the circuit.

4. In an apparatus for the purpose set forth, an oscillatory container, means within the container for making and breaking an electric circuit, a trigger arranged adjacent the container and adapted to be actuated by a passing car Wheel, a rock shaft carrying the container, a projection on the rock shaft, a pull bar pivoted to the trigger and normally engaging the projection, and a second trigger arranged to be operated by a passing car wheel and engaged with the pull bar whereby actuation of the second trigger will release the pull bar from the projection to prevent rocking of the container except by a car wheel passing in a given direction.

5. An apparatus for the purpose set forth comprising a casing, a rocking container mounted in the casing, means within the container for making and breaking an electric circuit, a trigger mounted within the casing and having a terminal normally projecting above the casing, means whereby rocking of the trigger will rock the container to close an electric circuit, and a trip lever fulcrumed adjacent the end of the casing and extending over the same to bear upon the projecting end of the trigger whereby the passing of a car wheel over the trip lever will actuate the trigger.

6. In an apparatus for the purpose set forth, an oscillatory container, a pull bar, means to be actuated by the pull bar for rockin the container, a trigger connected to the pu 1 bar, and a secondtrigger engaged With the pull bar and controlling the engagement ofthe same with the container-rocking means whereby the container Will be rocked or Will remain at rest according to the order in which the triggers are actuated.

7 In apparatus for the purpose set forth, an oscillatory container, means Within the container for closing an electric circuit when the container is rocked from normal position, a rock shaft carrying the container, a projection on the rock shaft, a pull bar, a dog carried by the pull bar and arranged to yield to the projection on the rock shaft when moving in one direction and to engage the projection when moving in the opposite direction, a

trigger connected with the pull bar for actuating the same, and a second trigger engaged with the pull bar to hold the dog clear of the projection or permit its engagement therewith.

I In testimony whereof I afi'ix my signature,

HARRY N. BRANDALL. [n s]

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