US2237392A - Apparatus for the control of highway crossing signals - Google Patents

Description

A. R. WHITEHORN APPARATUS FOR THE" CONTROL OF HIGHWAY CROSSING SIGNALS pril 8, 1941.

Filed April 7. 1939 INVENTOR.

7 7 yfdaiw Patented Apr. 8, 1941 APPARATUS FOR THE CONTROL OF HIGH- 1 WAY CROSSING SIGNALS Arthur R. Whitehorn, Downers Grove, Ill., assignor to Western Railroad Supply Company, Chicago, 111., a corporation of Illinois Application April 7, 1939, Serial No. 266,549

14 Claims.

The present invention relates to railroad warning signals in general and particularly to a signalling system designed to accommodate high speed and slow speed trains without variation in the warning period preceding the arrival of the train at a highway crossing. More specifically the invention comprises a signal-operating system for railroad-highway crossings in which a short speed-gauging section is used with complete accuracy and in which variations in the operating mechanisms characteristics due to variable operating conditions have been eliminated.

It is an object of the present invention to provide a new and improved train actuated railroadhighway grade crossing signal control system. Another object of the invention is to provide a crossing signal operating system for railroads in whichthe passage of a train thru a short track section gauges the train speed and causes the signals to be operated with trains at varying distances from. the crossing depending upon the train speed so that the signal is always operated for a predetermined time period before the train arrives at the crossing. Still a further object of the invention is to'provide a signal-operating system in which the operating characteristics of the timing mechanism are fixed and in which no delay for motor starting or acceleration is present. Another object of the invention is to provide a crossing signal operating system, in which the windup and rundown operations are gravity actuated. These and other more specific objects of the invention will appear upon reading the following specification and claims and! upon considering in connection therewith the attached drawing.

Referring now to the drawing in which apreferred embodiment of the present invention is disclosed Figure l is a diagrammatic illustration of the system comprising the present invention in the track-clear condition; and FigureZ is a diagrammatic illustration; of the electrical circuits only of thepresentinvention.

Automatic crossing signalsai'e of course quite old and well known butthe increase in the operating speeds oftrains has presented a problem not previously present. It is recognized as being desirable to cause the signal at a highway crossing to be put into operation a fixed period before the arrival of the train at the crossing. With 1 systems in which thesignal is operated as the train reaches a fixed point spaced from the crossings it is clear that fast trains will reach the crossing in lesser times than slower trains. With train speeds ranging up to 120 m. p. h. the time variations in the systems described is so great as to be objectionable. If such systems are designed to give an adequate warning period for high speed trains then the period for slow speed trains becomes so great as to be unreasonable.

Heretofore systems have been presented which attempted! to gauge the speed of the train and vary the signal operation in accordance therewith. Such systems have had. certain fundamental objections. They have used long sections in which to gauge the train speed and cause the track sections used by the signal to be so long that speed variations affect the operating characteristics. Such systems are objectionable because of the excessive costs of installation caused by the long electrical circuits. Systems heretofore proposed to accommodate high speed trains have been objectionable in that varying operating characteristics in electrical driving units, whether occasioned by voltage or temperature changes, or however, have caused variations in the operation of the timing mechanism. Such variations increase in importance with the decrease in the length of the initial track section in which the train speed is gauged.

In the system constructed in accordance with the present invention it is possible to use a short track section for gauging the train speed and the windup of the timing mechanism, for gravity is used in both the windup and rundown operations, an electrical motor being called upon to restore the system to the track-clear condition after the train has passed.

Referring again to the drawing, and to Figure 1 in particular, a preferred embodiment of the invention is illustrated. A railroad track is seen to approach a highway and to be divided into mutually insulated sections AB, BC and C--D; the highway crossing the tracks adjacent point D. Each track section is energized by a battery, indicated at I, 2 and 3 and across the rails of each section is a relay coil, indicated at 4, 5 and 6. Relays 4, 5 and 6 are normally energized by the batteries l, 2 and 3, respectively, and each is adapted. to be shunted by the entrance of a train into its track section.

Relay 4, in section A-B, is provided with a pair of movable contacts 4A and 4C. With the track clear and the relay energized contact 4A seats on stationary contact 43 but with the relay shunted 4A and 4B open and contact 40 drops onto stationary contact 4D.

Relay 5 in section BC is also provided with a pair of movable contacts 5A and 50 which normally seat on stationary contacts 53 and 5D, re-

spectively, with the relay energized, but which drop therefrom with the relay shunted by a train entering section BC. Contact A drops into contact with a second stationary contact 5F.

Relay 6 in section C-D has a single movable contact 6A which normally engages stationary contact 513, the contacts opening with the relay shunted.

A final relay 1, the current to which all the re mainder of the system is intended to control, is provided with a movable contact 1A and a stationary contact TB which are connected in series with and control the flow of current to the highway signal 8.

The timing mechanism now to be described, and indicated generally at H], is controlled by the relays 4, 5 and 6 and their contacts which in turn are controlled by the passage of a train thru the track section in which they are connected.

The timing mechanism comprises first a relatively large weight M suspended by suitable means, such as a rope, cord, cable or chain l2, from a pulley l3 mounted on a rotatable shaft M. In the track-clear condition illustrated in the drawing the weight M is in its uppermost position and the cord I2 is wound around the pulley I3. The weight normally cannot move downwardly by rotating the shaft for a ratchet wheel l5 on the shaft M is locked by a pawl l6 which is held in place by an energized solenoid When the ratchet 5 is released to permit the shaft M to rotate and the weight I to move downwardly under the force of gravity the weight moves and the shaft rotates at a constant speed, a gear 4| on the shaft cooperating with an escapement 42 to effect this result.

A second weight is suspended from a second shaft 2i which is connected to the shaft |4 thru an electromagnetic clutch 22 which includes clutch discs and a stationary normally unenergized winding 23. As in the case of weight M weight 23, which is the smaller, is connected to its supporting shaft by suitable means such as a rope 24 which winds around a pulley or spiral drum 25 having a definite contour such that the distance traveled by the weight 20 is related to the rotation of the shaft 2| in a predetermined manner, as will be hereinafter explained. Guide l8 restrict the weight to vertical movement.

Carried by the weight 20 and movable vertically therewith is a toothed rack 26. A gear 21 carried by a shaft 28 meshes with the teeth of the rack and is rotated by the rack movement. A second gear 29 adjacent gear 21 On the shaft 28 cooperates with an escapement 30, of a well known type, to restrict gear 29 to a constant speed, although interrupted necessarily, of rotation. As gear 2'! is keyed to gear 29 by a spring-pressed ratchet 34 with the gear 21 rotated by the downward travel of rack 25, it is seen that the rack and the weight 20 will descend at a constant rate. During the ascent of the weight, however, the direction of rotation of gear 21 is such that ratchet 34 does not engage the teeth of gear 29.

In their vertical movement the weights and 20 function to operate certain contacts for reasons to be explained, Weight upon reaching the upper limit of its travel abuts the insulated end of movable contact 3| A of switch 3| to move it to open position relative to stationary contact 3|B. Weight 20 upon moving from its lowermost position permits spring-biased switch 32 to open and close spring-biased switch 33 thru moving from contact with the insulated ends of movable contacts 32A and 33A, respectively, which then move to their biased positions relative to stationary contacts 32B and 33B, respectively.

An electric motor M is provided to wind up the weight II and is connected to the shaft M by a worm gear 36 on a shaft which meshes with gear teeth formed on the gear-pulley I3. Shaft 35 is aligned with the shaft 3! of the mo tor M and is adapted to be connected thereto by a normally unenergized electro-magnetic clutch 38 having a winding 39 and clutch discs. The winding 39 is in the circuit of the motor M and is energized only when the motor is energized. The clutch being normally open the downward movement of the weight M does not rotate the motor. A battery B is provided to drive the motor, the current to which is controlled by two switches 3| and 32 which are in series and are positioned by the weights H and 20, respectively.

The operation of the ystem constructed in accordance with the present invention is as follows, reference being had to both figures of the drawing in which, it is to be remembered, the condition illustrated is the track-clear condition. The condition of the system will now be described for various positions of the train.

Track clear condition In this condition the train has not yet entered the track from A to D and the parts are as related in the drawing. All the track relays 4, 5 and 6 are energized a is the signal-controlling relay 1. The weight M is in its upper position where it is held by the pawl 5 which cooperates with the ratchet l5 to prevent the rotation of shaft M. The winding H of the pawl I5 is en ergized thru contacts 4A and 4B. The weight 20 is in its lowermost or rundown position. The motor circuit is unenergized, the switch 3| being held open by the weight M.

Train enters section A-B A train enters section A-B moving in the direction of the highway crossing, Relay 4 is de-energized and contact 4A separates from 4B. Winding I! of the pawl I6 is thereuoon deenergized and the latter element moves from its locking engagement with ratchet 5. Contacts 40 and 4D close and thereby energize winding 23 of the magnetic clutch 22 and causing that element to connect shafts l4 and 2|. Instantaneously the .weight begins its downward movement and drives the shaft l4 thru the pulley |3, the shaft 2| being connected to shaft l4 thru clutch 22, also rotates. The motor M does not rotate for the clutch 38 is open. The weight M is much heavier than weight 20 and causes that member to be lifted and WOllIld. upon its camshaped pulley 25, the shafts l4 and 21 rotating at the maximum speed permitted by the escapement 42 which contacts the gear 4|.

The downward movement of weight M caused switch 3| to close so that current from battery B would have energized motor M and clutch winding 39 had not the simultaneous upward movement of weight 20 opened switch 32 which is also in series with switch 3|. The upward movement of weight 20 also caused switch 33 to close thereby completing a shunt around contacts 5C and 5D'in the circuit of relay 7 so that the de-energization of relay 5, upon the train entering section BC, will not cause release operation of relay 1.

During the presence of the train in section A-B, and until it enters section BC, the weight I will continue to fall and the weight 20 to move vertically upward, the weight-supporting rope 24 being wound around the cam pulley 25 which is shaped in a definite manner so as to displace the weight 2|] a predetermined distance such that the time (rundown) required for it to return to its initial position at a constant speed will bear a predetermined relationship to the timerequired to lift it (windup). With the shaft 2| rotating at a constant speed under the control of escapement 42 it is clear that the displacement of the weight 20 will be controlled directly by the shape of cam 25'. The escapement 30 is, of course, inoperative in this windup period. The surface of the pulley is so shaped relative to the center of shaft rotation that at any given height to which the weight 20 has been lifted by the pulley 25, its time of descent at a constant speed and under its own gravitational force will bear a fixed relationship to the time of its ascent. If Tex: rundown time; TAB=time required for front of train to pass thru section A-B and so equals the windup time; AB and BD=lengths of section. AB and BB in the same units of measurements; and K221. constant in seconds equal to the period of signal operation before the train reaches the highway, then the formula gives the relationship of the period of windup to the period of rundown. The spiral drum 25 is so contoured that when TAB is the Windup time TBx as indicated by the formula will be the rundown time.

Train enters section B-C' The forward end of the train passes from section A--B into section B--C. Relay is immediately de-energized; contacts 5A, 5B and 5C, 51) open while 5A, 5F close. The closing of contacts 5A, 5F throws a shunt around open contacts 4A,

the reverse direction under the torque exerted by the weight 2|] thru its cam-pulley 25.

The opening of contacts 50, 5D had no effect for the initial upward movement of weight 20 caused switch 33 to close to effect a shunt there'- around, as described supra.

During the descent of weight 20 the circuit condition remains as described. The weight, traveling downwardly under gravity at a constant speed controlled by the escapement 30, arrives at its lowermost position in the time Tex set forth above which time is a period K before the arrival of the train at the point D. As this is the time it is desired that the signal be placed in operation this result is effected by the opening of the contacts 33A, 33B of the switch 33 by the weight. Current is thereby cut off from the relay I which upon being de-energized causes its contacts 1A, TB to open whereupon current ceases to flow to the signal a which is thereupon placed into operation. It is to be understood that the signal 8 is of any common and well known type.

Train enters section CD The section CD is only a safety section. It is intended that the signal shall be operated normally before the train reaches 0. Should there be a failure for any reason so that the signal has not been operated by the time the train reaches C the entrance of the train into section CD causes immediate operation. The contacts 6A and 6B of relay 6 of section CD are in series with the relay 1 and upon relay 6 being shunted by the entrance of the train in section CD the contacts 6A, 63 open and relay I is de-energized with resulting signal operation, as above set forth.

The re-setting of the mechanism To place the system in condition for the arrival of a subsequent train it is necessary to lift the large weight M to its initial or waiting position. To accomplish this function there is pro vided, as described, a motor M connected in series with a battery B. and a switch 3| and a switch 32. The contacts 3IA, 3| B of switch 3| are biased to a closed position except when held open by the weight 2'0 in its upper position, a condition which does not exist subsequent to the passing of a train. The contacts 32A, 32B of switch 32 are normally biased open but are held closed by the weight 20 in its lower or waiting position.

The weight 2|] having arrived at its lowermost position and the signal operated for the passing train the closing of the switch 32 causes the flow of current to the motor M and to the winding 39 of clutch 38 which is in series therewith. The clutch is closed and motor shaft 31 is connected to shaft 35 and the instantaneous rotation of the motor causes the gear 36 to rotate gear-pulley l3 to wind up the weight I to its original position. The motor is de-energized by theweight opening the switch 3| at the top of its travel, the winding 39 being also tie-energized. The downward movement of the weight is again prevented by the pawl |6, the winding ll of which has been energized by the closing of contacts 4A, 43 upon the train passing from section A--B.

The formula which is used above is arrived by the following reasoning. v

Regardless of the train speed it is desired that the signal begin its operation a predetermined period before the train reaches the highway. This warning period is a constant which may be called K and can be taken, for example, to be 20 seconds. Referring to Figure 1 the dotted line X-X is a variable position on the track between B and D at which the train is positioned when the signal begins operation. Let Tex be the time required to travel thedistance B to X for any particular train. Obviously for a fast train X will befarther from D than for a slow train for both are to reach the crossing during the same elapsed period from position X. Itis clear that if the signal can be put into operation for each particular train when it reaches its X position that the desiredresult will accrue. It has been calculated that for any given train Where the constant K is decided upon and the distances A-B and BD known, itis olearthat Tex can be calculated by substituting in the formula the value of TAB- Of course TAB is the time required by the train to travel the distance A--B,- etc. As the range of train speeds is known the calculation can be done by assuming values of TAB. It is of course obvious that the proper units must be used, for example, K, TAB and Tex in seconds and BD and AB in feet.

The formula is derived in the following manner:

The advantages of the present system are many but its ability to act instantly under all conditions, together with its inherent use of a short initial track section, made possible by the instantaneous operation, are not the least.

I claim:

1. In a railroad-highway signal control system a plurality of mutually insulated track sections including a measuring and an operating section approaching a highway, a signal at the highway, a normally energized relay in each of said sections adapted to be shunted by the entrance of a train into the section in which it is connected, and means responsive to the passage of a train through said sectionsto cause the operation of the signal at a predetermined constant time interval prior to the arrival of the train at the highway; said means comprising an element, gravity actuated means controlled by the relay in the measuring section to operate said element, a member displaceable at a variable rate by said element, means to release said member to return by gravity to its initial position controlled by the relay in the operating section, means to eiTect a constant speed return of said member, and motor-operated means to return said system to its initial condition, and means to energize said last-mentioned means upon the train passing the highway and the cessation of the operation of the signal.

2. In a railroad-highway signal control system, a plurality of mutually insulated track sections approaching a highway, a signal at the highway, a normally energized relay in each of said sections adapted to be shunted by the entrance of a train into the section in which it is connected, and means responsive to the passage of a train thru said sections to cause the operation of the signal at a predetermined time interval prior to the arrival of the train at the highway; said means comprising a statically energized energy-storing unit adapted to expend energy during a time interval required for a train to travel one of said track sections and controlled by the relay in that section, deenergized energy-storing unit adapted to receive energy from the loaded unit during the said time interval and to expend it upon the shunting of the relay in a second section nearer the highway at a different rate thereafter, means to place the signal into operation upon the release of the energy stored in said unloaded unit, and electrical means to reload said statically energized energy-storing unit.

3. In combination, a railway track intersected by a highway, a signal at the intersection, and signal-controlling means to operate the signal at a predetermined constant time period prior to the arrival of trains traveling at varying speeds at the intersection; said signal-controlling means comprising an element normally occupying a raised position and adapted to fall by gravity when released, means to release said element to fall by gravity during the time interval required for an approaching train to travel a fixed distance on said track spaced from said intersection, a second element normally occupying a lower position, means to connect said second element to said first element to be raised thereby at a varying rate during the fall of said first element, means to release said connecting means upon said train reaching a fixed point after leaving said fixed distance, means to maintain a constant return speed in said second element, and means effective when said second element has reached a predetermined position to place said signal in operation.

4. In combination, a railway track intersected by a highway, a signal at the intersection, and signal-controlling means to operate the signal at a predetermined constant time period prior to the arival of trains traveling at various speeds at the intersection; said signal-controlling means comprising a first weight positioned to fall by gravity and a second weight positioned to be raised against gravity, means to release said first Weight to fall by gravity during a time interval required for any train approaching the highway to travel a predetermined fixed distance, means actuated by the movement of said first weight to lift said second weight at a varying rate, means to release said second weight at the end of said time interval to fall by gravity, means to maintain a constant rate of fall in said second weight, and means efiective when said second weight has fallen to a predetermined position for placing said signal in operation.

5. In combination, a railway track intersected by a highway, a signal at the intersection, and signal-controlling means to operate the signal at a predetermined constant time period prior to the arrival of trains traveling at various speeds at the intersection; said signal-controlling means comprising; a movable element, means effective upon said element returning to a predetermined position for placing the signal in operation, traincontrolled gravity-operated means to raise said element from said position at an increasing rate during the period required for a train approaching the crossing to travel a predetermined distance spaced therefrom, and means to return said element under gravity toward said position upon said train reaching a predetermined point and at a rate having a predetermined relationship to the rate of original movement.

6. In combination, a railway track intersected by a highway, a signal at the intersection, and signal-controlling means to operate the signal at a predetermined constant time period prior to the arrival of trains traveling at various speeds at the intersection; said signal-controlling means comprising: a movable weight, means effective upon said element falling to a predetermined lower position for placing the signal in operation, train-controlled gravity-operated means to raise said weight from said position at a varying rate during the period required for a train on said track approaching the crossing'to travel a predetermined fixed distance spaced therefrom, and means to effect the constant speed return of a said weight toward said position upon said train reaching a predetermined point. i

'7. In combination, a railway track intersected by a highway, a signal at the intersection, and a railroad-highway signal control system to operate said signal and including a first weight normally biased to fall by gravity, means to maintain a constant speed of fall of said weight, a second weight, means to raise said second weight at a varying rate upon the fall of said first weight, train-controlled means to release said first weight to fall during the time interval required for a train on said track approaching a highway crossing to cover a fixed distance spaced therefrom, train-controlled means to release said second weight to fall at the termination of the said time interval, means to restrict said second weight to a constant rate of fall, and means efiective when said second weight has fallen to a predetermined position for placing said signal in operation.

8. In combination, a railway track having sections and intersected by a highway, a signal at the intersection, and a railroad-highway signal control system to operate said signal and including means to place the system in operation upon a train entering a track section comprising a gravity actuated windup mechanism operative during the time required for a train approaching the intersection to traverse one of said sections,

a displaceable element movable by said windup the operation of a signal upon the return movement of said displacement element to a predetermined position, and means to return said wind up mechanism to initial condition.

9. In combination, a railway track intersected by a highway, a signal at the intersection, and signal-controlling means to operate the signal at a predetermined fixed time period prior to the arrival of trains traveling at'various speeds at the intersection; said signal-controlling means comprising a first weight, normally energized means holding said first weight in an upper position, means to tie-energize said holding means upon a train approaching the highway, means to effect a constant speed movement of said weight under the influence of gravity, a second weight, normally unenergized clutch means to connect said second weight to said first Weight upon a train approaching a highway, means to raise said second weight at a varying rate upon the movement of said first weight under gravity, means to de-energize said clutch means to disconnect said second weight from said first weight after the train has traveled a predetermined fixed distance from its position at the time of the release of said first weight, means to effect a constant speed return of said second weight to its initial position, and means effective when said weight has reached its initial position for placing said signal in operation.

10. In combination, a railway track intersected by a highway, a signal at the intersection, and signal-controlling means to operate the signal at a predetermined fixed time period prior to the arrival of trains traveling at various speeds at the intersection; said signal-controlling means comprising a first weight, normally energized means holding said first weight in an upper position, means to de-energize said holding means upon a train approaching the highway, means to effect a constant speed movement of said weight under the influence of gravity, a second weight, normally unenergized clutch means to connect said second weight to said first weight upon a train approaching a highway, means to raise said second weight, at a varying rate upon the movement of said first weight under gravity, means to deenergize said clutch means to disconnect said second weight from said first weight after the train has traveled a predetermined fixed distance from its position at the time of the release of said first weight, means to effect a constant speed return of said second weight to its initial position, means effective when said weight has reached its initial position for placing said sig nal in operation, an electric motor to return said first weight to its initial position, normally unenergized clutch means to connect said motor to said first weight, and means to energize said clutch to connect said motor to said first weight and to energize said motor to raise said first weight upon said signal being placed in operation.

11. In a railroad-highway signal control system, a plurality of mutually insulated track sec tions approaching a highway, a signal at the highway, a normally energized relay in each of said sections adap-tedto be shunted by the entrance of a train into the section in which it is connected, and means responsive to the passage of trains traveling at various speeds thru said sections to cause the operation of the signal at a predetermined fixed time interval prior to the arrival of the train at the highway; said means comprising a first weight unit including a gravity actuated weight, means holding said first weight against gravity, a motor to lift said weight, and electrical clutch means to connect said motor to said first weight; and a second weight unit including a gravity actuated weight, means to lift said weight at a variable rate, means to effect a constant speed descent of said weight under the action of gravity; means to actuate the weight holding means of the first weight unit to release said weight to fall by gravity upon a train entering a first track section and controlled by the relay of that section, means to clutch said first weight to the weight lifting means of the second weight unit with said train in said section and controlled by the relay of that section to cause said second weight to be lifted, said means to clutch also being controlled bythe relay of an adjacent second track section and adapted to declutch said first weight from said second weight unit upon the train entering the second section to release said second weight, and means effective upon the return of said second weight to its initial position for placing said signal in operation.

12. The construction defined in claim 11 characterized in that means are provided to clutch said motor to said first Weight and to energize it upon the return of said second Weight to its initial position.

13. The construction defined in claim 11 characterized in that means are provided in said first weight unit to effect a constant speed movement thereof under the actuation of gravity.

14. In a railroad-highway signal control sys tem, a plurality of mutually insulated track sections approaching a highway, a signal at the highway, a normally energized relay in each of said sections adapted to be shunted by the entrance of a train into the section in which it is connected, and means responsive to the passage of a train thru said sections to cause the operation of the signal at a predetermined time interval prior to the arrival of the train at the highway; said means comprising a statically energized energystoring unit adapted to expend energy dynamically during a time interval required for a train to travel one of said track sections and controlled by the relay in that section, a deenergized en- 10 ergy-storing unit adapted to receive energy from the energized unit during the said time interval and to expend it at a different rate thereafter, said ole-energized unit being controlled by the relay in a second track section between the first section and the highway, and means to place the signal into operation upon the expenditure of the energy stored in said unloaded unit.

ARTHUR R. WHITEHORN.

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