US2225766A - Switch frog for the overhead conductors of electric traction systems - Google Patents

Description

Dec. 24, 1940; BRQOM ETAL 2,225,766

SWITCH FROG FOR THE OVERHEAD CONDUCTORS OF ELECTRIC TRACTION SYSTEMS Filed Dec. 14, 1959 5 Sheets-Sheet 1 lA l IVTUF 724W w r ifi, M WME/MM Dec. 24, 1940. c BROQM AL 2,225,766

SWITCH FROG FOR THE OVERHEAD CONDUCTORS OF ELECTRIC TRACTION SYSTEMS Filed Dec. 14, 1939 5 Sheets-Sheet 2 24, 1940- T. c. BROOM ET AL 2,225,766

SWITCH FROG FOR THE OVERHEAD CONDUCTORS OF ELECTRIC TRACTION SYSTEMS Filed Dec. 14, 1939 5 Sheets-Sheet s Fig. 3.

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army/v57 1940- T. c. BROOM ETAL 2,225,766 7 SWITCH FROG FOR THE OVERHEAD CONDUCTO RS OF ELECTRIC TRACTION SYSTEMS Filed Dec. 14, 1939 5 Sheets-Sheet 4 Dec. 24, 1940. Q BROOM ETAL 2,225,766

SWITCH FROG FOR THE OVERHEAD CONDUCTORS 0F ELECTRIC TRACTION SYSTEMS Filed Dec 14, 1939 5 Sheets-Sheet 5 arrow 5y I Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE SWITCH FROG FOR THE OVERHEAD CON- DUCTORS F ELECTRIC TRACTION SYS- TEMS Application December 14, 1939, Serial No. 309,194 In Great Britain December 24, 1938 4 Claims.

This invention relates to automatically operable switch-frogs which are used in overhead electric traction systems, and is particularly concerned with switch-frogs which are adapted to be operated by current collectors moving along the associated conductors. Such a switch frog comprises a switch-plate pivotally mounted so as to be movable about a vertical axis, adapted to be set normally in a primary position to permit movement of a current collector in one path and to be moved automatically into a secondary position by a collector entering the'switch-frog along another path. In both primary and secondary positions the corresponding path is completed by a movable tongue formed integral with, and consequently movable with, the switch-plate into or out of the desired position. A switch-frog of this nature may be a cross over, the entry side of which is approached by two paths which intersect and continue from the'exit side of the frog as separate paths. In another form the switchfrcg may be a trailing frog, the entry side of which may be approached by a collector moving along either of two paths which converge to form a single path extending from the exit side of the frog. With this latter form of switch-frog the switch-plate may be formed with two movable tongues, one adapted to complete a path in the primary position, and the other adapted to complete the other path in the secondary position, and each tongue being movable into an inoperative position as the other tongue is moved into an operative position. The path which is completed when a movable tongue is in the primary position will be referred to as the primary path, and the other path, completed by a tongue in the secondary position, will be referred to as the secondary path.

According to this invention a switch-frog is provided with means operable by a current collector to move a switch-plate into the secondary position as a collector enters the switch-frog along the secondary path, and into the primary position as the collector leaves the switch-frog. The switch-plate is normally set in the primary position, a movable tongue formed thereon thereby completing the primary path, which may conveniently be the most frequently used path. Furthermore, the invention also provides means whereby the switch-plate is locked automatically in both primary and secondary positions, so that it cannot be displaced by any lateral forces which may be exerted by the passing collector.

The improved means comprises two cranks,

each rotatable about a vertical axis located at the side of the frog, one crank, referred to hereinafter as the entry crank, being located adjacent the secondary path on the entry side of the frog, and the other, hereinafter named the exit crank, being similarly located on the exit side of the frog. The cranks are so coupled together and to the switch-plate that rotation of either crank effects simultaneous movement of the switch-plate and of the other crank. Each crank is adapted to occupy an operable position in which it will be engaged by a collector moving along the adjacent secondary path and to be moved thereby into an operated position. The relative disposition of the interconnected cranks and switch-plate is such that when a tongue is in the primary position the entry crank is in the operable position, and the exit crank is in the operated position. The entry crank is adapted to be turned into the operated position by engagement with an entering collector, a movable tongue being thereby moved into the secondary position, and the exit crank being simultaneously turned into the operable position. The exit crank is adapted to be returned to the operated position by engagement with the collector leaving the frog, thereby resetting the primary path by returning a movable tongue into the primary position, and at the same time turning the entry crank into the operable position whereby the mechanism is again set to be operated by the next collector which enters along the secondary path.

The relative disposition of the coupling between the cranks and switch-plate is such that in both primary and secondary positions any force directed from' the switch-plate to the cranks acts in a direction passing through the axis of rotation of one of the cranks, thereby ensuring that the cranks cannot be rotated by the application of such a force. Each crank is also acted upon by a biassing force to ensure that the mechanism moves completely into the secondary position upon displacement by an entering collector, and completely into the primary position upon displacement by the collector on leaving, a fixed stop being associated with each crank to determine the extent of its movement into the operable position.

Each crank may comprise one arm of a bellcrank lever mounted in a bracket onthe side of the body of the frog. The other arm of the bellcrank may be coupled to the switch-plate by a connecting rod, pivotally connected with the bellcrank and switch-plate, and capable of transmitting movements both under tension and compression. The relative dispositions of cranks and connecting rods may be such that in the primary position one connecting rod extends in a direction passin through the centre of rotation of its associated crank and in the secondary position the other connecting rod is similarly disposed with relation to its associated crank. The biassing forces, whereby the complete movement of one crank into the secondary position and of the other crank into the primary position are ensured, may be provided by a spring associated with each crank in such a manner that the force exerted by a spring, through its associated crank, on the connecting rod increases as the crank approaches the position towards which it is urged by the spring.

In order to minimise the wear of the projecting portion of each crank and of the collectors which engage it, that portion of the crank which projects into the secondary path may be constituted by the surface of a freely rotatable wheel mounted on the crank. The rim and central part of the wheel may be distinct members separated by a resilient construction capable of absorbing the shock of the impact between the rim and a current collector. The resilient means may consist of a rubber filling, or a spiral spring attached to both rim and central part, or any other suitable device.

The invention is further described by way of example hereinafter with reference to the accompanying drawings which illustrate a cross-over adapted to be used at theiin-tersection of a primary and a secondary path, and to provide for the passage of a current collector in either direction along the primary path and in one direction only in the secondary path. In the drawings Figure 1 is a view from above of part of the cross-over in the operable, or primary, position;

Figure 1A is a view from above of the other part of the arrangement shown in Figure 1;

Figure 2 is a view from below of partof the cross-over in the position shown in Figure 1;

Figure 2A is a View from below of the other part of the arrangement shown in Figure 2;

Figure 3 is a view from above of part of the cross-over in the operated, or secondary, position;

Figure 3A is a View from above of the other part of the arrangement shown in Figure 3;

Figure 4 is a view from below of part of the cross-over in the position shown in Figure 3;

Figure 4A is a view from below of the other part of the arrangement shown in Figure 4;

Figure 5 is a side view of part of the cross-over in the primary position; I I

Figure 5A is a side view of the other part of the arrangement shown in Figure 5;

Figure 6 is a diagrammatic illustration of part of' the cross-over showing the relative positions of the movable parts in both primary and secondary positions; and

FigurefiA is a diagrammatic illustration of the other part of the arrangement shown in Figure 6.

The cross-over consists of a body I provided on the-underside thereof with four fixed tongues, each of which is adapted to be connected at its outer end in any known manner with an overhead tra'ction conductor. The fixed tongues are arranged in pairs, one pair 2, 2 being in alignment with the conductors which form the primary path P, and the other pair 3, 3 being in alignment with the conductors which form the secondary path S. A switch-plate in the form of a movable tongue 4 is pivotally mounted at its centre point on the underside of the body I. The movable tongue is capable of being turned about a vertical axis 5 at its centre point, which coincides with the intersection of the two paths, to complete either the primary or the secondary path. In Figure 2 the movable tongue 4 is shown in the primary position bridging the gap between the pair of primary fixed tongues 2, 2 to form the primary path. In Figure 4 the tongue is shown in the secondary position, bridging the gap between the pair of secondary fixed tongues 3, 3 to form the secondary path. The cross-over is adapted, in the primary position, to permit the movement of a current collector 3| in either dimotion along the primary path as indicated by the double-ended arrow P, but in one direction only along the secondary path as indicated by the arrow S. The end of the cross-over which is approached by a current collector moving in the secondary path is referred to as the entry side, the other end being referred to as the exit side. At the entry side of the cross-over and adjacent the fixed secondary tongue 3 a bracket 6 is bolted to a seating I formed on the side of the body I. A vertical pivot pin I, freely rotatable in the bracket 6, carries at its lower end a bifurcated arm 8 and at its upper end an arm 9. The upper arm 9 is clamped to the pivot pin I and is set at an angle of about 60 to the lower arm 8, so that the two arms 8 and 9 function as a bellcrank. The end of the bifurcated arm 8 carries a wheel 32 freely rotatable about a vertical axis and consisting of a metallic rim II connected with the hub of the wheel by a resilient disc of rubber I2. On the upper end of the pivot of the movable tongue 4 is clamped a horizontal projection I6. A connecting rod I3 is pivotally joined at one end I5 to the projection I6 and at its other end I4 to the upper arm 9 of the bellcrank. At the exit end of the cross-over there is a similar arrangement of bracket 22 bolted to a seating 23 formed on the side of the body I adjacent the other fixed secondary tongue 3, carrying a bell-crank consisting of an upper arm 24 and a lower arm 25 fixed to a common pivot 25 which is freely rotatable about a vertical axis in the bracket 22. The lower arm 25 carries at its outer end a freely rotatable pulley 33 having a metallic rim 21. The connecting rod 28 is pivotally attached at one end 29 to the upper arm 24 and at the other end 30 to the projection I6.

At a short distance from its point of connection I-5 with the projection It the first mentioned connecting rod I3 carries a horizontally projecting arm I8. The other connecting rod 28 similarly carries a projecting arm I9. Both of the arms I8 and I9 extend substantially at right angles with the associated connecting rods, in a direction away from the intersection of the paths. The ends of these arms I8 and I9 are connected by a helical spring I! maintained under tension. It will be appreciated from Figure 5 that the projection IS, the connecting rods I3 and 28, and the upper arms 9 and 24 of the bell cranks lie substantially in the same horizontal plane of rotation in which the spring I1 is also located.

When the cross-over is normally set in its primary position, in which the movable tongue completes the primary path (Figures 1 and 2), the bell-crank on the entry side is in such a position that the rim II of the associated wheel 32 projects into the path of movement of a current collector 3| entering along the secondary path S. In this position the lower arm 8 of the bell crank lies against a fixed stop 20 and the connecting rod [3 extends, together with the upper arm 9 of the bell crank, in line with the axis of rotation I of the bell crank. The connecting rod I3 is thus in a dead centre position with reference to the bell-crank, which cannot, therefore, be rotated by a force exerted along the connecting rod 13 from the movable tongue 4. The movable tongue 4 is thus effectively locked in the primary position in alignment with the fixed tongues 2, 2 to complete the primary path. The other bell-crank, that is on the exit side, is in such a position that the rim 2'! of the associated wheel 33 is held clear of the adjacent secondary path S, the upper arm 24 of the bell-crank and the associated connecting rod 28 being out of alignment as shown. The relative arrangement of the movable parts in the primary position is indicated in full line in the diagrammatic Figure 6.

The other position of the movable tongue, that is, the secondary position, is shown in Figures 3 and 4, and in this position the bell crank at the entry side is turned into such a position that the associated wheel 32 is held clear of the secondary path S, the upper arm 9 of the bellcrank and the connecting rod l3 being out of alignment. On the exit side of the crossing the bell-crank is in such a position that the rim 21 of the wheel 33 overlaps the secondary path S and the upper arm 24 of the bell-crank and the assooiated connecting rod 28 are together in line with the axis of rotation 26 of the bell-crank. The connecting rod 28 is thus in a dead centre position when the movable tongue 4 is in the secondary position, thereby locking the tongue in this position. The relative arrangement of the movable parts in the secondary position is indicated in dotted lines in the diagrammatic Figure 6.

The operation of the mechanism is as follows. The cross-over is in the primary position as a current collector 3| approaches the entry side along the secondary path S (Figures 1 and 2). The collector strikes the wheel rim H and partially rotates the associated bell-crank in the direction of the arrow A. During the initial part of this rotation the angular movement of the connecting rod I3 is great compared with a slight movement of the movable tongue 4. In consequence, the movement of the connecting rod about the point of connection I5 with the projection I 6 causes the spring I! to be stretched. As the rotation of the bell-crank proceeds the connecting rod I3 is subjected to a longitudinal movement and the extension I6 is rotated so that the movable tongue is moved towards the secondary position as indicated in Figures 3 and 4 and the other connecting rod 28 approaches the dead centre position with reference to the pivot 6 of the bell-crank on the exit side. During the final stage of the movement the spring l1, being under tension, tends to collapse and pulls the connecting rod 28 and the upper arm 24 of the bellcrank lever on the exit side into the dead centre position, in which the lower arm 25 of the bellcrank is arrested by a fixed stop 2!. The rim 21 of the wheel 33 on the exit side now overlaps the secondary path S.

The current collector 3i traverses the movable tongue now in the secondary position (Figures 3 and 4) and eventually strikes the wheel rim 21, causing the associated bell-crank to be rotated in the direction of the arrow B. The various parts of the mechanism now move in a reverse manner to that above described, the connecting rod I3 on the entry side being drawn by the spring I! into the .dead centre position, and the movable tongue returned to the primary position. The movable tongue has thus been automatically moved from the primary position by the entry of a current collector along the secondary path S and automatically returned to the primary position as the current collector leaves the cross-over. It is locked in both primary and secondary positions, and is only displaced from the primary position during the short time in which the current collector, moving along the secondary path, traverses the cross-over between one wheel 32 on the entry side and the other wheel 33 on the exit side.

It will be appreciated in what manner the invention can be applied to a trailing frog. In a frog of this form there will be provided only one fixed tongue, on what has been called the exit side, to combine both primary and secondary 0 paths in a common path. A movable tongue, or aswitch-plate on which one or two tongues may be formed, will be pivoted about a suitable point so that in the primary position the primary path will be completed between the primary fixed on the exit side, the tongue will be locked in I position, and a collector will be enabled to move freely in either direction along the primary path. In this position also the Wheel (such as the wheel 32 above described) on the entry side Will overlap the secondary path, so that on the approach of a current collector along that path, the mecha- In the other position nism will be immediately operated to move the apparatus into the secondary position, and as the collector leaves along the common path the apparatus will be reset.

The arrangement of the cross-over which has been described may be re-adjusted in several Ways. For instance, it may be arranged in such a manner that the secondary position is obtained by the passage of a current collector in a direction opposite to that already indicated. This is readily eifected by altering the positions of the fixed stops 2t and 2|, and by adjusting on their axes of rotation the various movable members in such a way in relation to one another that in the primary position the wheel 33 overlaps the secondary path and the other wheel 32 is held clear of that path. The connection of the projection IS with the movable tongue will be required to be slackened and reset with the latter in its desired setting and the former on the 0pposite side of the point of intersection. Furthermore, the body I of the cross-over is provided with additional sea- tings 34 and 35 on which the brackets 6 and 22 may be mounted for the purpose of reversing the primary and secondary path, so that the above described secondary position of the movable tongue now becomes the normal position. These changes can similarly be made in connection with the apparatus as applied to a trailing frog.

What We claim as our invention is:

1. In a switch-frog for an overhead traction conductor system, a movable switch-plate having a primary and a secondary position, means op-' erable by a current collector moving in a secondary path to move the switch-plate from the primary to the secondary position as the collector enters the frog and to return the switch-plate to the primary position as the collector leaves the frog, the said means comprising an entry crank projecting into the secondary path when the switch-plate is in the primary position, an exit crank projecting into the secondary path when the switch-plate is in the secondary position, coupling means connecting the cranks and switchplate whereby movement of either crank produces simultaneous rotation of the other crank and of the switch-plate, and, in the primary and in the secondary position, force applied through the switch-plate to one of the cranks acts in a direction passing through the axis of rotation of that crank.

2. In a switch-frog for an overhead traction conductor system, a movable switch-plate having a primary and a secondary position, means operable by a current collector moving in a secondary path to move the switch-plate from the primary position to the; secondary position as the collector enters the frog, and to return the switch-plate to the primary position as the collector leaves the frog, the said means comprising two bell-cranks, an arm of one bell-crank projecting into the secondary pathwhen the switch-plate is in the primary position, an arm of the other bell-crank projecting into the secondary path when the switch-plate is in the secondary position, connecting rods coupling the other arms of the bell-cranks to the switch-plate, one connecting rod being on dead-centre in the primary position and the other connecting rod being on dead-centre in the secondary position, each with reference to the centre of rotation of its associated crank.

3. In a switch frog for an overhead traction conductor system, a movable switch-plate having a primary and a secondary position, means operable by a current collector moving in a secondary path to move the switch-plate from the primary to the secondary position as the 001- lector enters the frog, and to return the switchplate to the primary position as the collector leaves the frog, the said means comprising an entry crank projecting into the secondary path when the switch-plate is in the primary position and an exit crank projecting into the secondary path when the switch-plate is in the secondary position, coupling means connecting the cranks and switch-plate whereby movement of either crank produces simultaneous rotation of the other crank and of the switch-plate, and, in the primary and in the secondary position, force applied through the switch-plate to one of the cranks acts in a direction passing through the aXis of rotation of that crank, biassing means acting upon the said cranks and ensuring that the mechanism moves completely into the secondary and primary positions, and a fixed stop associated with each crank to determine the extent of the movement of that crank into the secondary path.

4. In a switch-frog for an overhead traction conductor system, a movable switch-plate having a primary and a secondary position, means operable by a current collector moving in a secondary path to move the-switch-plate from the primary position to the second position as the collector enters the frog, and to return the switchplate to the primary position as the collector leaves the frog, the said means comprising two bell-cranks, an arm of one bell-crank projecting into the secondary path when the switch-plate is in the primary position, an arm of the other bell-crank projecting into the secondary path when the switch-plate is in the secondary position and the other arm of each bell-crank being coupled to the switch-plate by a connecting rod, and spring means acting on the connecting rods whereby is ensured the complete movement of each connecting rod with its crank arm into a dead centre position.

TALBOT COTTOM BROOM. HOWARD JENKINS POWELL.

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