US2971255A

US2971255A - Method of spinning cables for suspension bridges

Info

Publication number: US2971255A
Application number: US772238A
Authority: US
Inventors: John E Nixon
Original assignee: Colorado Fuel and Iron Corp
Current assignee: Colorado Fuel and Iron Corp
Priority date: 1958-11-06
Filing date: 1958-11-06
Publication date: 1961-02-14
Anticipated expiration: 1978-02-14
Also published as: GB911976A

Description

J. E. NIXON 2,971,255

METHOD OF SPINNING CABLES FOR SUSPENSION BRIDGES Feb. 14, 1961 Filed Nov. 6, 1958 6 Sheets-Sheet 1 J. E. NIXON Feb. 14, 1961 METHOD OF SPINNING CABLES FOR SUSPENSION BRIDGES 6 Sheets-Sheet 2 Filed NOV. 6, 1958 Feb. 14, 1961 J. E. NIXON METHOD OF SPINNING CABLES FOR SUSPENSION BRIDGES Filed Nov. 6, 1958 FIGS 6 Sheets-Sheet 3 J. E. NIXON Feb. 14, 1961 METHOD OF SPINNING CABLES FOR SUSPENSIQN BRIDGES Filed NOV. 6, 1958 e Sheets-Sheet 4 J. E. NIXON Feb. 14, 1961 METHOD OF' SPINNING CABLES FOR SUSPENSION BRIDGES Filed Nov. 6, 1958 6 Sheets-Sheet 5 J. E. NIXON Feb. 14, 1961 METHOD OF SPINNING CABLES FOR SUSPENSION BRIDGES Filed NOV. 6, 1958 6 Sheets-Sheet 6 L l l I I ||-|..|.1 1|| METHDD F SPINNING CABLES FOR SUSPENSION BRIDGES John E. ixon, Langhorne, Pa., assignor to The Colorago Fuel and Iron Corporation, a corporation of Colora 0 Filed Nov. 6, 1958, Ser. No. 772,238

19 Claims. (Cl. 29-407) This invention is concerned with a novel method of spinning and adjusting wires in the formation of the main cables employed in long suspension bridges. Such cables are spun at the site and are of parallel wire construction. A typical cable for such a long suspension bridge may be formed of about twenty strands, each strand being composed of a large number of individual lengths of Wire laid in parallel relation to conform with a predetermined catenary pattern. That pattern is determined and prescribed by the designers of the bridge in accordance with a variety of considerations.

In the formation of a strand, what is in effect a single continuous wireis spun back and forth across the intended bridge structure until the desired number of lengths, say 400 to 500, have been laid. Actually, a single wire as formed is not of sufficient length to form a strand, but a large number of individual wires are connected end to end by suitable ferrules to provide an endless wire of the necessary length. A single wire as produced at the mill may be from 3500 to 6000 feet long and a number of such wires connected end to end by ferrules of the character mentioned will be wound on a reel for shipment to the site of the bridge. In the course of spinning a cable, one reel after another is applied to the unreeling machine and the trailing end of the wire on a reel in use will be connected by a ferrule with the leading end of the wire on the next reel to be used. Also, the final wire put into a given strand in the course of the spinning operation will have its free end connected with the free end of the first wire laid for the strand, so that the complete strand is formed as a large number of parallel lengths of an endless wire.

Prior to the commencement of the cable spinning operation, a great deal of preliminary work will have been done at the bridge site. Foundations will have been constructed at the two anchorages, the supporting towers for the main span of the bridge will have been erected, cable-supported footwalks will have been constructed to follow reasonably closely the path of each of the final cables to be laid, but slightly below the latter, and a tram.- way will have been provided above each of the footwalks to carry'the spinning wheels which must make repeated passages across the several spans of the bridge in laying the wire to form the cables.

Heretofore, the procedures followed in the spinning of a cable have required an excessive amount of time and effort on the part of the workmen, and this has contributed greatly 'to the length of time required for the completion of a bridge. A time-consuming part of the cable spinning operation has been the proper adjustment of the individual wire lengths entering into the various strands to form the cables. It is necessary that each wire be of such an accurately determined length that when it is suspended from the towers and the anchorages it will not depart more than a few inches at any point from the prescribed catenary form. In a conventional suspension bridge there are three catenaries involved, one at each end span, between the anchorage and the adjacent tower, and

States Patet another between the two towers at the ends of the main span of the bridge. It is important that each wire entering into the final cable follow the prescribed catenary in each of the three spans, so that it will carry its proportionate share of the load.

The present invention is concerned primarily with the procedure followed in adjusting the wires as they are spun to insure their uniformity of length in each span with the other wires entering into the strand. In accordance with prior practice, this is achieved by first carrying a guide wire across the length of the bridge, from anchorage to anchorage and over the towers. This wire is of the same character as that to be used in forming the cable in a typical construction. It may be .196 inch in diam eter. It is first anchored at the unreeling station in the location at which the final cable is to be anchored, and it is carried across the bridge structure by the spinning wheel. At the first tower this wire is adjusted by a socalled come-along until its catenary extending from the initial anchorage to the first tower conforms with that prescribed bythe bridge designer. This is done by the use of surveying instruments. When proper adjustment is effected, the guide wire is clamped at the first tower. By a similar procedure, the portion of theguide wire extending from the first tower to the second is appropriately adjusted to conform with the prescribed catenary of the main span portion of the cable, and it is then clamped at the second tower. Subsequently, by a similar adjustment procedure, the guide wire is adjusted at the far end of the bridge structure to conform with the prescribed catenary for that end span, and it is then anchored at the far end substantially in the position in which the cable is to be anchored at that end. This adjusting procedure is usually conducted at night so as to insure uniform temperature conditions. Its precise form is calculated for the particular temperature prevailing at the time it is set to corn form with the specifications of the bridge designer.

In the spinning of the various wires entering into a strand, it has also been the general practice heretofore to adjust each firstly at the first tower, then at the second tower and finally at the anchorage at the far end of the bridge by the employment of come-alongs until the three catenary sections of each wire are made to conform with that of the guide wire. This procedure is very timeconsuming and occupies the time of a number of operators stationed along the footwalk and at the anchorages to determine when each wire conforms in each of its sections with the catenaries of the guide wire and to operate the come-alongs used at the three points mentioned for effecting the necessary adjustment. As each wire which is to enter into the final strand is thus adjusted at each of the three points, it is suitably clamped to maintain its proper adjustment in relation to the guide wire.

In the course of laying the wire by the spinning wheel in accordance with the foregoing procedure, it will be understood that only the anchored dead wire of the loop being carried across the bridge structure can be adjusted in the manner explained upon the travel of the spinning wheel from the unreeling station to the far anchorage. The live wire extending from the unreeling machine and which is carried across the bridge structure simultaneously with the dead wire, as a part of the loop, has had to be subsequently adjusted by a similar procedure carried out in the reverse direction as the spinning wheel has been returned from the far anchorage to the unreeling station. This, again, is a time-consuming operation and has frequently exceeded the time required for the return of the spinning wheel to the unreeling station in preparation for the carrying over of a new loop of wire to be laid and adjusted in the same manner. Thus, it has been found that the wire-adjusting procedure, in accordance with the prior practice, has been a bottleneck in the production of the desired cable. Various expedients have been developed for speeding up the carrying of loops of wire across the bridge structure, as through the use of a plurality of spinning wheels on a single carriage, and the adoption of an arrangement by which separate spinning wheel units are arranged to operate from unreeling stations at the two ends of the bridge structure to the middle of the latter at which point the loops of wire on the two spinning wheel units are interchanged to carry them the rest of the way across the bridge structure. However, it has not been possible heretofore to take full advantage of these expedients because of the delays incident to the adjustment of the various wires in the manner explained.

in contrast with the foregoing, the method of the present invention provides a much simpler and more expeditious method of adjusting the wires entering into a strand of the desired length necessary to conform with the prescribed catenaries. According to the improved method a guide wire is laid across the bridge structure in substantially the same manner as explained above for the old method. After the guide wire has been accurately laid in accordance with the desired contour, markings are placed across the guide wire in alignment with markings also made on a saddle or other stationary part of the structure at each of the towers and also at a point adjacent each of the desired points of anchorage of the strand at the two ends of the bridge. After the markings have been applied to the accurately positioned guide wire the latter is unclamped at the towers and it is allowed to shift or slide to a certain extent over free running sheaves at the towers and at the far anchorage. At suitable intervals along the footwalk the guide wire is placed beneath free running sheaves carried by the footwalk and positioned above the latter at points preferably, though not necessarily, substantially in the path of the desired catenaries of the final cable. A wire or rope is then clamped at one end to a point on theguide wire adjacent the far anchorage and this wire or rope is passed over a sheave and is arranged to have a tensioning force applied to its opposite end, as by means of a counterweight, which is at least adequate to pull the guide wire upwardly against the hold down sheaves carried by the footwalk. Now as a loop of wire is carried across the bridge structure from an unreeling machine, with the dead wire of this loop anchored by a strand shoe or the like at the unreeling station in substantial transverse alignment with the anchorage of the corresponding end of the guide wire, the dead wire is passed beneath successive ones of a plurality of hold down sheaves carried by the footwalk, preferably in transverse alignment with those beneath which the guide wire is held down, to cause the dead wire to conform :ith the catenaries of the guide wire. When the loop thus carried across the structure reaches the far end anchorage, at or slightly beyond the intended anchor point, a wire or rope will be clamped to the dead wire of the loop and passed over a sheave, this rope having applied to its opposite end a tensioning force, as by means of a counterweight, equal in value to that applied to the guide wire. Cross markings are then applied to the dead Wire of the loop in alignment with those placed on the guide wire. Such markings at this time need not be, and generally will not be, in alignment with the fixed markings at the towers and adjacent the near and far anchorages but they insure that the length of the dead wire in the several sections between the markings will be very closely the same as for the guide wire.

The loop is at this time, or if desired before this, re moved from the spinning wheel and when the markings have been applied to the dead wire the loop is placed around a strand shoe to anchor the dead wire at its adjusted length. Upon removal of the loop from the spinning Wheel, the latter may be returned idly to the unreeling station and during this interval the live wire of the loop is adjusted. This is done by placing the live wire under the hold down sheaves previously used for the dead wire and by then applying a counterweight to the live wire at a point adjacent the anchoring strand shoe at the unreeling station. At this time the guide wire is anchored at the far side and the tension of the counterweight at that end is relieved while a corresponding counterweight is applied to the guide wire at the unreeling station near the anchorage point at that end. The counterweights so used in connection with the live wire and the guide wire are of equal weight. To facilitate this alternate application of tension to the guide wire adjacent the opposite ends thereof, the guide wire may be provided with readily flexible but not stretchable sections at its ends. Each of these sections may, for example, be formed of aircraft cord and may extend from the anchorage point to a point short of that at which the counterweight tension is applied. When the live wire has been adjusted in the manner explained it is provided with cross markings aligned with those on the guide wire.

After the live Wire has been adjusted and marked its end at the unreeling station is passed around a strand shoe to clamp the wire and then a new loop of the Wire extending from this anchorage to the unreeling machine is passed around the spinning wheel and the same operation is repeated. Thus a new dead wire and a new live wire will be laid across the bridge structure and adjusted and marked in the same manner to coincide with the length of the various sections of the guide wire. As the successive dead wires and live wires are adjusted, marked, and clamped at their ends by means of the strand shoes, they will be removed from the free running sheaves at the towers and transferred either to a spinning saddle or to the final clamping saddle at each tower. In thus transferring the Wires they are placed in the saddles with their cross markings aligned with those of previously laid wires for the strand being formed and in predetermined relation to fixed markings on or adjacent the saddles. As the wires entering into a strand are thus transferred to one or another of the saddles mentioned they are preferably not made to conform with their final catenaries but are positioned slightly above the latter so that the wires will not come into interference with strands which may have been previously positioned in the final saddles. This may be accomplished, for example, by having special spinning saddles for the strand being currently formed and higher elevation at the towers than the final saddles.

After the desired number of wires to form a strand have been laid and adjusted in the manner described it may be desirable, in some instances, to adjust the completed strand in the conventional way, through the use of hoists and the like and through the use of surveying instruments in the manner described in relation to the guide'wire, to make certain that the strand has the desired catenary form as it is positioned in the final saddles. However, such surveying of the strand may generally be dispensed with in view of the ability to line up the various cross markings on the wires in relation to each other and in relation to the fixed markings at the towers.

In connection with the foregoing it should be understood that in the use of the new adjusting method the various expedients for speeding up the spinning of the wires, as explained earlier, may be utilized to full advantage. Thus if a spinning wheel arrangement capable of carrying four loops of wire across the bridge simultaneously is employed, the four dead Wires may be quickly placed beneath the hold down sheaves, by suitably stationed workmen, as the spinning wheels are carried across the bridge and when the far anchorage is reached a separate counterweight may be applied to each wire and the cross markings may then be simultaneously applied to all four. This results in a very substantial saving of time and effort as compared with the twelve distinct adjustments required for the four wires in accordance with prior practice.

these may be located at a slightly Also, loops of wire may be simultaneously carried from unreeling stations at the opposite ends of the structure to a transfer station adjacent the mid-point of the structure so that the spinning mechanism operating from each end will need to travel only halfway across the entire structure and the loop or loops carried by one spinning carriage may be transferred at said central point to the other, and vice versa. This serves to cut the spinning time in half. As each loop is carried across the bridge structure its dead wire and then its live wire may be adjusted in the same manner explained above. In addition, the present invention makes possible the employment of a single spinning mechanism capable of carrying one or more loops of wire from an unreeling station at one end of the structure and then carrying a corresponding number of loops of the same wires on the return from the far end of the structure back to the anchorage at the unreeling station, thus eliminating the idle return movement of the spinning mechanism. The new adjusting method and means for insuring accurate measurement of the length of the spun wires against the length of the guide wire may be carried out with such expedition and reliability as to make it possible to take full advantage of the saving of time incident to all of the expedients available for speeding up the laying of the wires across the bridge structure.

After one strand has been completed, subsequent strands may be spun and assembled in the same manner as explained above, with due allowances for their varying positions in the completed cable. The squeezing, clamping and wrapping of the total number of strands which are to form the final cable proceeds in the same manner as heretofore.

Other objects, features and advantages of the invention will appear from the detailed description of the invention which will now be given in conjunction with the accompanying drawings, in which:

Fig. 1 is a schematic view illustrating the new method of adjusting wires in the spinning of a cable from an unreeling station at one end of the bridge structure;

Fig. 2 is a view similar to Fig. 1 illustrating the new method of adjusting the wires when the cable is spun from unreeling stations at both ends of the bridge structure with a transfer station at the center of the main span;

Figs. 3 and 4 illustrate schematically an arrangement in which a cable is spun from an unreeling station at only one end of the bridge structure by a spinning wheel which is active in both directions of movement across the bridge structure;

Fig. 5 is an elevational view of the top portion of one of the towers of the bridge structure, taken transversely of the latter, showing the mounting of sheaves thereon for supporting wires delivered from eight unreeling machines provided at one end of the bridge structure, with provisions for carrying loops of wire back from the far end to the unreeling station;

'Fig. 6 is a view taken along the line 6-6 of Fig. 5;

Fig. 7 is a schematic view of a splay casting and its support together with a counterweight system used in connection with a come-along wire gripping device;

Fig. 8 is a side elevational view of a hold down sheave unit applied to the footwalk for use in carrying out the new wire adjusting method;

Fig. 9 is an elevational view of the gripping means of the come-along device shown in Fig. 7; and

Fig. 10 is a view of the hold down sheave structure as seen from the left in Fig. 8.

Referring now to Fig. l, the bridge structure is illustrated as involving two towers 10 and 11 defining the mid span with a footwalk 12 supported thereby and extending from the anchorage at the unreeling station at the left end of the figure to the anchorage at the far side of the bridge structure, this footwalk being positioned below but conforming generally with the form of the catenaries to be provided in the end span and the mid span of the cable. It will be understood that prior to the commencement of a spinning operation there will be suitably mounted from anchorage to anchorage across the tops of the two towers a tramway, not shown, which is adapted to support and move a spinning wheel unit back and forth across the bridge structure.

It will be understood that the tramway is in the form of a loop extending across the bridge structure above the footwalk and along a path generally parallel with the latter. It is in the form of a cable, the opposite legs of which travel in opposite directions. Each leg may be used to carry a spinning wheel unit back and forth across the bridge structure by reversing the direction of movement of the cable. If desired a dual tram system may be provided, with each of the looped cables having a leg extending along the path of each of the two suspension cables which are to support the bridge. The arrangement of the tram cables to be used in any particular situation will depend upon which of the spinning procedures discussed above is to be followed, i.e., whether the spinning units are to be carried completely across the bridge structure or to only a transfer station at the mid point, and whether or not the spinning wheel is made active in both directions of movement.

The tram is first utilized in laying a guide wire 13 which has its left end fixedly retained by a strand shoe 14, or the like, held by anchorage 15 at the unreeling station. To prevent slippage of the guide wire in relation to the strand shoe 14 a free end 16 of the guide wire is dogged off, i.e., held against slippage. The guide wire is carried across the tops of the two towers and accurately set through the use of surveying instruments in accordance with the established practice. It may be carried across sheaves 17 at the top of tower 10 and across similar sheaves 18 at the top of tower 11 and then down to an anchorage at 19 on the far side of the bridge structure. As the end span of the guide wire at the unreeling station is adjusted to its proper catenary form it is clamped at the top of tower 10; similarly as the mid span is adjusted to its proper form the guide wire is clamped at the top of tower 11, and as the end span at the far end of the bridge is adjusted the guide wire is clamped in proper position at the anchorage 19. A wire or rope 20 is then permanently clamped to the guide wire 13 at the far side and this wire 20 is carried over a free running sheave and provided at its lower end with a counterweight 21. This counterweight is arranged to be lifted and locked in an elevated position when it is not desired to apply its tension to the guide wire. At the stage of the operation now under discussion the counterweight will be thus elevated to remove its tension. Cross markings are at this time provided on the guide 'wire in line with fixed markings carried by the towers, preferably on the

sheave units

17 and 18, and such cross markings are also provided on the guide wire in alignment with fixed markings provided adjacent each

anchorage

14 and 19. When this has been done the guide wire is unclamped at the tops of the two towers so that it is permitted to shift to a. certain extent. It is then placed under free running hold down sheaves 27 positioned at suitable intervals along the footwalk, say every 300 feet. At this time the counterweight 21 is permitted to apply its tension to the guide wire and draw it toward the right to a certain extent with a force at least sufiicient to hold it firmly in engagement with the hold down sheaves.

With the guide wire thus positioned, the first loop of wire to enter into the strand to be formed is carried across the bridge structure from a reel 22 at the unreeling station. This reel may be power driven to supply the wire at a desired rate. The wire 23 from the reel is passed downwardly and around a sheave 24 which may, if desired, be permitted to rise and fall to a certain extent under the action of a counterweight and the upward pull exerted on the wire 23 in the course of spinning it. This permits some variation in the speed of unreeling the wire from the reel 22 in relation to the speed of movement of a spinning wheel unit 25 which serves to carry the loop across the bridge structure. Prior to the spinning of the wire in this manner, the free end coming from the reel 22 is first anchored by a strand shoe in substantial alignment with the strand shoe 14 for the guide wire. The loop then carried across the bridge structure includes a dead wire 26 extending from the anchorage end and the live wire 23 extending from the unreeling machine. As the loop is carried across the bridge structure the dead wire is positioned beneath hold down sheaves 28 carried by the footwalk, preferably in substantial transverse alignment with the hold down sheaves 2'7 and the live wire is preferably positioned at the same time beneath similar hold down sheaves. At the towers both wires are placed over sheaves in

units

17 and 18 similar to those used for the guide wire. As the loop reaches the far side a counterweight 29 is attached to the dead wire by means of a wire or rope 30 which passes over a free running sheave and has its end connected with a comealong 31. The nature of this will be hereinafter briefly described. Suflice it to say now that it is adapted to grip the dead wire and by means of counterweight 29 exert a tensioning force toward the right equal to that applied to the guide wire. At this time cross markings are applied to the dead wire in alignment with those previously provided on the guide wire which are no longer in direct alignment with the fixed markings at the various points indicated. This insures that the length of the dead wire in its various sections between markings is substan tially identical with the length of the guide wire in those sections. While thus held by the counterweight 29, the dead wire is laid parallel with the guide Wire to and around a strand shoe at the anchorage 19, provision being made against slippage of the dead wire when thus adjusted.

The spinning wheel unit 25 is now free to return idly from the far side to the unreeling side of the bridge structure. As it is thus returned, the live wire 23 of the loop that has been carried across may be adjusted to conform in length in its various sections with the guide wire. At this time the live wire 23 will have been placed beneath the hold down sheaves 28, from which the dead wire may have been removed, or it will have been placed beneath similar hold down sheaves in substantial alignment with the

sheaves

27, 28. It will also have been placed over sheaves in the

units

37 and 18 at the top of the tower. Counterweight 21 at the far side is lifted and retained in a position to release its tensioning force upon the guide wire while a corresponding counterweight at the unreeling station, connected by a wire or rope 36 through clamping means 37 with the guide wire, is permitted to apply its force to the guide wire tending to pull it toward the left and into firm engagement with the hold down sheaves 2-7. A come-along grip 32 is applied to the live wire 23 at this time, this come-along being drawn toward the left by a counterweight 34 of equal magnitude to counterweight 35 and connected by a wire or rope 33 to the come-along. Cross markings are now applied to the live wire in alignment with those on the guide wire. In this manner the length of the live wire in its various sections between markings is insured to be the same as for the guide wire and the previously marked dead wire.

With the dead wire and live wire of the first loop thus accurately measured, the live wire is passed down and around a strand shoe in alignment with the strand shoe 14 and a new loop of wire between this point and the sheave 24 is applied to the spinning wheel unit and carried across the bridge structure in the same manner. The above-described operations for gauging first the dead wire and then the live wire of this new loop against the guide wire will then be repeated and subsequent loops entering into the strand under formation will be treated in the same way.

In carrying out the foregoing method it may be desirable to provide the guide Wire at each end with a section of flexible but non-stretchable rope or cord, such as aircraft cord, this extending from the anchorage to a point inwardly of that at which the counterweight rope is clamped to the guide wire. Such flexible section at the end toward which the guide wire is being drawn will readily buckle or fold to the necessary extent as the counterweight tension is applied.

While it will ordinarily be desirable to carry loops of wire across the bridge structure from an unreeling station in the manner explained above, the invention may be used in a system in which individual wires are spun across the bridge structure. In this case the free end of the wire will be anchored at 14 in the same manner as before and the wire will be spun from a reel which is carried across the bridge by the tramway in the same manner as the spinning wheel described. As the reel reaches the far end of the bridge the wire may be adjusted by the counterweight method described and the appropriate point on the wire may then be anchored around a strand shoe at 19 and the reel then returned across the bridge in the opposite direction to lay a second wire. This may be similarly adjusted at the initial end of the bridge and then clamped and the reel returned to the far end again. Of course, provision will need to be made for replacement of an exhausted reel by a new one from time to time with the trailing end of the wire from the old reel connected by a ferrule with the leading end of the wire from the new reel. By appropriate selection of the length of the wire on the reel in relation to the length of the desired strand, the replacement of reels may be made to occur at or near one or another of the anchorages.

In the production of a complete cable in accordance with any of the procedures described above and hereinafter, it will be understood that the strand shoes for the, say, 20 strands, entering into the complete cable will be distributed at the anchorage point over a suitable area of, say, 10 by 20 feet. The separate strands will then converge from their strand shoes toward a splay point at each end of the bridge structure which may be from 50 to feet outwardly from the points of anchorage. At the splay points the strands are brought together and clamped and from then on form a single cable which, according to conventional practice, may be suitably wrapped and provided with clamps at spaced intervals. In many instances, the strands in the end spans will pass over bent towers intermediate the anchorages and the adjacent main tower. The splay castings will sometimes be in the region of such bent towers and at other times will be spaced a substantial distance from such bent towers, toward the anchorage points of the cable. When such bent towers are employed additional catenaries will need to be taken into account in the laying of the several wires entering into a strand. But this does not alter the general principle for adjusting the length of the various wires as explained above. In fact, it adds to the advan-' tages of the invention in utilizing its novel adjustment method.

Referring now to Fig. 2, there is schematically shown an arrangement in which wires may be spun simultaneously from each end of the bridge structure. In this arrangement spinning wheels will carry loops from their respective ends of the structure to a transfer station at the midpoint of the mid-span of the cable. Here the loops on the two spinning wheel units will be interchanged and these units will then return to their respective unreeling stations and will carry the loops received from the spinning wheel units traveling to the transfer station from the unreeling station at the opposite end. Thus, an unreeling machine 39 at the left end (Fig. 2) delivers a live wire 40 around a sheave 41 to a spinning wheel 43 which at this time will be slightly to the right of sheave 41. The free end of the wire 40 will be anchored by the strand shoe 38 to provide a dead wire 42 for the loop to be carried across the bridge structure by the spinning wheel 43. The latter will carry the loop over the sheave unit 17 at the top of tower and then on to the transfer station 44. At the same time an unreeling machine 45 at the right end of the structure will deliver a wire 46 to a sheave 45a, the free end of this wire being anchored by a strand shoe 38a and a loop of this wire being placed around the spinning wheel 47 and then being carried by the latter across the top of tower 11. The live wire 46 and the dead wire 48 of this loop will be suitably placed over the sheaves of unit 18 and the loop will then be carried on to the transfer station 44. Here, as explained above, the two loops brought to the transfer station, from the opposite ends of the structure, will be interchanged so that spinning wheel 47 will carry to the right end of the structure the loop formed by live wire 40 and dead wire 42 while spinning wheel 43 will carry toward the left end the loop formed by live wire 46 and dead wire 48.

The adjusting of the wires of the two loops thus carried across the bridge structure from its opposite ends will be performed in substantially the same manner as explained in connection with Fig. 1. It will be understood that a guide wire 37 will have been laid across the structure in the same manner as explained and provided with cross markings to provide gauges for the wires that are spun. A counterweight '49 connected by a wire or rope 37a to the guide wire 37 at the right end of the structure serves to pull this in that direction and draw the several catenaries upwardly against the holddown sheaves 27'. A come-along 50 is caused to grip the .dead wire 42 and draw this in the same direction through a wire 51 carrying a counterweight 52. After the appropriate cross markings have been applied to this dead wire it is clamped at the strand shoe 38a and the live Wire 42 extending from this to the left end of the bridge structure is then adjusted by gripping it by means of a come-along 55 connected by a wire 56 with a counterweight 57. At this time the guide wire 37 will be drawn toward the left by a counterweight 54 con nected by a rope 53 with the guide wire. I An appropriate extension of the live wire is then passed around the strand shoe 38 and a new loop of wire from the reel 39 is in readiness to be carried across the bridge. The loop previously carried from the right end of the structure and having live Wire 46 and dead wire 48 is adjusted in the same manner, firstly at the left end of the structure to gauge the dead wire to which the come-along 55 is at this time connected, and next at the right end where the come-along 50 is connected with the live wire 46 of this loop. It will be understood that the guide wire is tensioned alternately at the left end and at the right end, in the course of adjusting the wires of the two loops, in the same manner as explained above. Upon passing an extension of the gauged live wire 46 around the strand shoe 38a a new loop may be formed and applied to the spinning wheel 47 for a repetition of the same operations.

In connection with all of the foregoing procedures it should be mentioned that it is desirable to place the dead wires and the live wires of the various loops over the sheaves in the

units

17 and 18 as soon as the spinning wheels pass these various sheaves, since much less effort is required to lift and position the wires at this time than after the spinning wheels have passed some distance beyond.

ln Figs. 3 and 4 there is illustrated in a very schematic way an arrangement by which a spinning wheel may be active throughout its movement in each direction across the bridge structure. In this arrangement wire may be spun from an unreeling machine 60 with the free end of the wire suitably anchored by a strand shoe at 61. A loop passed around the spinning wheel 67 is initially carried across the bridge structure to lay a dead wire 62 and a live wire 64. As the dead wire reaches the far end and is gauged against a guide wire in the manner explained above, it is anchored by a strand shoe at 63 to provide a new dead wire 68. The initial live wire 64 will be passed around a turn-around sheave 65 to provide a new live wire 66. As will be apparent from Fig. 3, the spinning wheel 67 will thus carry a new loop from the far side of the bridge structure back to the unreeling station as it is being returned to that point. When this method is used it is necessary to first adjust the dead wire 62 at the far end (left) of the structure, this being preferably done before the spinning wheel commences its return movement. The next wire to be adjusted is the dead wire 68 which is adjusted by the counterweight method at the right end of the structure and then clamped. Following this the live wire 66 may be adjusted in the same manner, and then clamped, at the left end of the structure. Finally, the live wire 64 may be adjusted at the right end of the structure, and after it is clamped by a strand shoe the system is in readiness for a repetition of the same operation on a new loop of the wire.

In Figs. 5 and 6 there is illustrated a sheave arrangement suitable for application to the top of each of the towers in a cable spinning system of the character described above in connection with Figs. 3 and 4. The sheave arrangement here disclosed is adapted to handle wires spun from eight different unreeling machines at the unreeling station with provisions for enabling the spinning wheel units to carry loops of the wire back to the unreeling station from the far end as illustrated in Fig. 3.

The top of one of the towers is indicated schematically at 70 and is shown as being provided with the final saddle 71 which is to retain the finished cable. A plurality of rails 72 extend laterally toward the left (Fig. 5) from the top of the saddle 7.1. These rails, as will be explained, serve to support carriages for the various sheaves at that side of the structure. Similar rails 73 are provided at the right side of the structure. Three

carriages

74, 75 and 76 are arranged to ride upon the rails 72 and similar carriages 77, 7:8 and 79 are arranged to ride upon the rails 73. Each carriage is provided with a number of flanged wheels or rollers 80 arranged to cooperate with head formations at the tops of the rails. Sheaves 81 are mounted on a plurality of transversely extending shafts provided on the carriage. As shown in Fig. 5, four such sheaves are provided in spaced relation on each shaft and as shown in Fig. 6, the shafts are spaced longitudinally of the bridge structure along an arc conforming with that desired for the spun wires. One such wire is indicated at 82 in Fig. 6 and as shown extends over the tops of seven aligned sheaves 81. Adjacent the carriage 76 is a small bracket 83 which is suitably secured to the top of the saddle 71 or other part of the tower structure and carries sheaves similar to the sheaves 81, but only one set. This is to support the guide wire against which the spun wires on the

carriages

74, 75 and 76 are to be gauged. A similar bracket 84 carrying sheaves for supporting another guide wire is secured to the top of the opposite leg of the saddle. This guide wire is used to gauge the spun wires supported by the

carriages

77, 78 and 79.

In the use of the foregoing sheave system, wires delivered from four reels are spun in loops across the bridge structure in the manner previously explained. A single spinning unit having four spinning wheels may be used for this purpose. As the loops are carried over the top of the tower the dead wires are passed over the sheaves on the carriage 76 while the live wires are passed over the sheaves on carriage 74. After the four dead wires have been adjusted win the manner explained and cross marked to conform with the markings on the guide wire extending over the sheave unit 83 and over and under the other sheaves in the system extending across the bridge structure, these dead wires are anchored at the far side and they may then be removed from the sheaves of carriage 76 by a picking beam 85 and then lowered by the latter into the saddle 71. On the return of the spinning wheel unit to the unreeling station the new dead wires will then be passed over the sheaves of the carriage 76 while the new live wires, designated 66 in Fig. 3, will be placed over the sheaves of the carriage 75. The adjustment of the new dead wires and the several live wires may then proceed in the manner previously explained.

At the same time as the foregoing procedure is carried out wires from four other reels may be spun in a similar manner over the bridge structure and positioned in the sheaves of the carriages 77, 7 8 and 79. Carriage 77 may serve to support the dead wires in the same manner as carriage 76 while the carriages 78 and '79 may serve to support the live wires in the same manner as the

carriages

75 and 74, respectively. These wires when adjusted by the tensioning method described will be gauged against the guide wire carried by sheave unit 84.

By having the various sheave units mounted on carriages of the character described it is possible to bring each set of wires relatively close to the guide wire as the adjustment is being performed. For this purpose the carriages may, if desired, be lifted and replaced in a different position on the

rails

72 or 73 in relation to the others so that the particular wires being gauged at any time may be as close as possible to the guide wire in the related sheave unit '83 or 84. Such transposition of the carriages is not essential and it may be found possible, at least in some installations, to eliminate this step. The sheave carrying means may in this event be fixed.

As each set of wires has been gauged and clamped by a strand shoe at the gauging end of the structure, they may be lifted from the sheaves in the various carriages by means of the picking beam 85 and they may be carried by the latter into the saddle 71. As each set of wires is thus transferred the cross markings applied during the guaging operation will preferably be aligned with the fixed markings at the towers. This will insure the proper positioning of the various wires of a strand to conform with the desired catenaries. However, if desired, the various wires entering into a particular strand may be shaken out and made to conform with the desired catenaries independently of the markings and the strand as a whole may be gauged by surveying instruments in the conventional manner.

Referring now to Fig. 7 there is shown schematically the arrangement of one of the come-along devices applied to a wire to be gauged in the manner explained. The come-along is positioned at one side of a splay casting 86 carried by a foundation 87 which projects upwardly at a suitable inclination. At the top of the splay casting a plurality of free-running sheaves 88, similar to those used at the tops of the towers, are provided and if desired may be mounted in carriages similar to those provided at the towers, although this is not necessary. A wire to be gauged is indicated at 89 and this is shown in position to be gripped by the clamping means of a come-along 90 mounted for movement along a rail or track 91, preferably carried by the footwalk 92 at a suitable elevation above the footwalk. A wire or rope 93 connected to the come-along is provided with a relatively light counterweight 94 which normally serves to draw the come-along toward the right whenever it is released from the wire and is released from tension applied by the adjusting counterweight. A rope or wire extending in the opposite direction from the come-along is passed over a sheave 96 carried by the splay casting and then downwardly around a sheave 97 carried by a framework 09 for the main counterweight system. The free end of the rope or wire 95 is connected with a relatively heavy counterweight 98 adapted to perform the adjusting operation in accordance with the invention. Initially the counterweight 98 will be held in elevated position by means of a wire or rope 100 connected with the top of the counterweight and passed over sheaves 101 and then down to a winding or hoisting drum 102. When the counterweight force is to be applied to the wire 89 the drum 102 will be released to enable the counterweight to apply its force. If desired, the drum 102 may be driven for this purpose at a speed faster than the rate of drop of the counterweight in applying its tension to the wire 89, but it may simply be released for free rotation. When the gauging operation has been completed the hoisting drum 102 will be operated to lift the counterweight 98 and retain it in its elevated position until it is next needed to adjust a wire.

Fig. 9 illustrates in somewhat more detail the operation of the come-along in gripping the wire being adjusted. Devices of this general character are well known in cable spinning operations. As shown, the come-along comprises two

housing sections

105 and 106. Two draw bars 103 and 104 are connected at their opposite ends with the wires or ropes 93 and which extend to the

counterweights

94 and 98, respectively. As the draw bars are pulled toward the left upon the application of the counterweight 98, the clamping means of the comealong will cause the wire 89 to be gripped. This is done through upward movement of a bar 107 toward a bar or wedge 108 carried by the housing members and 106. The wire 89 passes between these two bars. Lifting of the bar 107 is brought about by movement of a pin 109 which serves to connect the draw bars 103 and 104 with a link 112. As the counterweight force is applied to the wire 05, and hence the draw bars, the latter will tend to shift the pin 109 toward the left in the elongated opening 109a extending through the housing members of the comealong. A suitable force will be applied to the housing of the come-along at this time, by means not shown, to retain it against movement during the initial movement of the draw bars. The opposite end of the link 112 is connected to the lower end of a pawl 110 pivotally mounted at 111 on the housing of the come-along. It will thus be seen that the movement of the draw bars toward the left will cause the arm 110 to rock in a clockwise direction, thus causing its pointed upper end to lift the bar 107. As shown, there are actually two pawls 110 which are coupled together for parallel motion by a link 113 so as to cause parallel upward movement of the bar 107. Bar 107 is held against longitudinal movement by stops 107a carried by the housing of the unit. Once the bar 107 has been lifted to grip the wire against the bar or wedge 108, the restraining force on the housing may be removed and a firmgrip of the wire to be adjusted is insured.

Upon release of the tension of the counterweight 98, by the lifting of this counterweight, the smaller counterweight 94 will draw the draw bars 103, 104 toward the right and thus, through the pin 109 and link 112, serve to rock the pawls 110 in a counterclockwise direction to release the gripping action of the

bars

107, 108 upon the wire 89 and the come-along as a whole will be restored to its right hand position shown in Fig. 7.

In Figs. 8 and 10 there is shown a preferred form and arrangement of the hold-down sheaves provided along the footwalk. The footwalk itself usually comprises a wire mesh surface 115 (Fig. 9) carried by a suitable number of wire ropes 116 extending across the bridge structure along a path below but corresponding generally with the form of the cable to be laid. At suitably spaced intervals along the footwalk it is strengthened and made more rigid by transverse frames, comprising channel members 1117 and top and

bottom plates

118 and 119, these parts being secured to the ropes and footwalk by bolts 120. The bolts 120 also carry plates 121 to which are secured, in any suitable way, U-shaped brackets 122 which support channel members 123 forming passages for rollers 124 provided at the lower end of a frame 13 structure 125. The latter carries any suitable number of sheaves 126 mounted on anti-friction bearings carried by a bolt 127. In the illustrated embodiment of the invention four such sheaves are provided on bolt 127 (Fig. Each of these sheaves is arranged to cooperate with one of four dead wires 128, for example, spun from four unreeling machines. Pivotally or rockably mounted on the frame 125 above the sheaves 126 is a bracket 129. This is arranged to rock about a pin or bolt 130 carried by upstanding arms of the frame 125 Bracket 129 carries a plurality of sheaves 131 mounted by means of anti friction bearings on a bolt 132 projecting laterally from the bracket. In Fig. 10 four such sheaves are shown arranged to be positioned directly above the sheaves 126 and spaced slightly therefrom. The two member 136 is pivotally mounted on the lever by a pin 136a. A spring 1361) serves to retain member 136 in the position shown. When the member is squeezed against the under surface of the lever 133, by the hand of an operator, a rod 137 will be shifted longitudinally of the lever to a limited extend and this rod at its opposite 'end is connected with the pawl 134 to retract it from the shoulder 135. This permits swinging of the frame 129 in the manner described for the introduction or removal of the various wires by the two sets of

sheaves

126 and 131.

In a system adapted to spin four wires simultaneously across the bridge structure and to enable the spinning wheel unit to carry a new loop of the same wires back across the bridge structure, as explained in connection with Figs. 5 and 6, there will be three hold-down sheave units of the character above described arranged for appropriate positioning across the footwalk to any desired position. The rollers 124 cooperating with the channels 123 permit such free movement. It will be understood that the three units may be used in substantially the same manner as the

sheave units

74, 75 and 76, i.e., one being adapted to retain the first set of dead wires of the .double loops contemplated until these wires have been adjusted. The same units will then retain and hold down the new dead wires formed on the return of the spinning wheel unit, which are substituted for the initial dead wires. The other two units mounted on the same channel members 123 are adapted to retain the live wires of the loops being formed until these have been finally adjusted.

For retaining the guide wire and holding it down along the desired path, there is provided a bracket 138 secured to the channel members 123, this bracket having an up- .wardly extending arm 1 39 carrying bolts 141i and 141 on which are mounted, respectively, a sheave 142 and a sheave 143 for cooperation with the guide wire 144. To permit introduction of the latter between the two sheaves the bolt 141 is mounted in the elongated opening 145 in the arm 139. Thus, the bolt may be loosened and lifted with the sheave 143 to permit the introduction and removal of the guide wire and may then be restored and clamped in the position shown.

While the general principles of the invention and a number of specific embodiments thereof have been described in considerable detail, it will be understood that various changes and modifications may be made in the application of said principles in accordance with the invention defined by the appended claims.

What is claimed is:

1. In a method of forming a parallel wire cable for sets of sheaves serve to retain the wires 128 but permit a suspension bridge having an anchorage at each end and a plurality of towers between the anchorages, the steps comprising laying a guide wire from an anchorage at an unreeling station across the towers to the far side anchorage, adjusting said guide wire to conform with the catenaries desired for the cable in the several sections thereof, providing a fixed marl-n'ng adjacent. each anchorage and adjacent each tower, applying a cross mark to the adjusted guide wire in line with each of said fixed markings, then placing the guide wire under free running sheaves in fixed positions at suitably spaced points along the length of the guide wire and over free running sheaves at the towers to provide a path for the wire approximating the desired catenary pattern of the cable, applying a counterweight to the guide wire adjacent the far side anchorage, said counterweight being of adequate magnitude to retain the wire against the various sheaves, carrying a loop of wire from the unreeling station across the towers along a path approximating the form of the guide wire, said loop comprising a live wire fed from a reel at said station and a dead wire which is anchored at said station, passing the dead wire of said loop beneath spaced hold down sheaves and over sheaves at the towers arranged to retain said dead wire along a path paralleling that of the guide wire, applying to said dead wire adjacent said far side anchorage a counterweight of a magnitude substantially equal to that applied to the guide wire and applying to said dead wire cross markings aligned with those on the guide wire.

2. In a method of forming a cable as set forth in claim 1, the further steps comprising anchoring the dead wire of said loop at the far side anchorage, passing the live wire beneath spaced hold down sheaves and over sheaves at the towers arranged to retain said live wire along a path paralleling that of the guide Wire, releasing the force of the counterweight from the guide wire at the far side anchorage while the same is anchored adjacent said anchorage, applying counterweights of substantially equal mass to said guide wire and said live wire, respectively, adjacent the anchorage at the unreeling station, and applying cross markings to said live wire aligned with those on said guide wire.

3. In a method of forming a cable as set forth in claim 2, the further steps comprising anchoring said live wire at the unreeling station anchorage, forming a new loop of wire between the anchorage of the preceding live wire and the reel of wire at the unreeling station, carrying said loop across the towers to the far anchorage and adjusting the dead and live Wires of said loop and marking the same in the same manner as set forth for the first loop.

4. In the laying of wires for a parallel Wire suspension cable, the method of adjusting the wires to provide the desired length to conform with the prescribed catenaries for at least a main span and two end spans, which comprises accurately laying a guide wire in conformity with the prescribed catenaries, applying cross markings on the guide wire adjacent points on the bridge structure, then positioning said wire beneath anti-friction hold down means at spaced intervals intermediate the ends of each catenary and over anti-friction means adjacent the ends of the main span catenary to conform approximately with the prescribed catenaries, firmly anchoring one end of said wire, applying a tensioning force to said wire adjacent its opposite end, said tensioning force being of adequate amount to retain the wire against all of said anti-friction means, anchoring the end of a cable forming wire adjacent the anchoring point of said guide wire, passing the cable forming wire beneath and over anti-friction means adjacent to those for the guide wire and in the same manner as for the guide wire, applying a tensioning force to the cable forming wire adjacent that applied to the guide wire and of substantially equal amount to that applied to the guide wire, and providing cross markings on the cable forming wire aligned with those on the guide wire.

15 5. In a method of the character set forth in claim 4, laying a loop across the bridge structure, said loop comprising a dead wire and a live wire, alternately adjusting and marking the dead and live wires being laid by applying said tensioning force to the guide wire and the dead wire adjacent one end of the cable being formed and then applying said tensioning force to the guide wire and the live wire adjacent the opposite end of said cable.

6. In a method of the character set forth in claim 4, simultaneously laying a plurality of loops of wire throughout the length of the cable, each of said loops having a dead wire and a live wire, anchoring each of the dead wires adjacent the anchorage of the guide Wire at the starting end of the cable, passing the dead Wires beneath and over anti-friction means adjacent to those for the guide wire, applying a tensioning force to each of the dead wires of said loops substantially equal to that applied to the guide wire and at points adjacent to the point of application of such force to the guide wire, providing cross marks on each of the dead Wires in substantial alignment with those on the guide wire, then, with the guide wire and the dead Wires being anchored at the opposite end of the cable, passing the live wires beneath and over anti-friction means adjacent to those for the guide wire, applying substantially equal tensioning forces to the guide wire and to each of the live wires of the laid loops adjacent the starting end of the cable, and applying cross markings to the live wires in substantial alignment with those on the guide wire.

7. In the art of forming in situ cables for suspended structures, in which component strands of the cable are built up by laying successive filaments between anchorages, and over at least two supporting saddles between said anchorages, said filaments being laid in adjacent catenaries preparatory to being formed into a compact strand, the improvement which consists in first laying a guide wire in predetermined successive catenaries between the saddles and between each anchorage and a corresponding saddle, fixing said guide wire against longitudinal shift at said saddles and anchorages, cross-marking said guide wire and adjacent portions of fixed structure, including saddles and anchorages to establish reference points for the position of the guide wire, freeing said guide wire to move longitudinally between anchorages, and applying a uniform tensile force thereto sufficient to urge the guide wire to rise above its initial catenaries, holding said guide wire down at definite spaced points throughout its length and thereby establishing it as a dimensionally stable gauge wire made up of successive portions which are substantially catenary in form, laying and similarly tensioning, holding-down and crossmarking by reference to the gauge wire-cross-markings, successive component filaments of the cable being formed, while said filaments are positioned by the hold-down action, freeing said filaments from hold down and transferring them to the adjacent saddles with the marks on the filaments adjacent the towers and the anchorages aligned with those on Wires which have been previously transferred to the saddles, and when all filaments are placed, shifting the resulting strand sufficiently to cause the markings on the filaments to register with saddle markings.

8. In the art of forming cables .in accordance with claim 7, firmly anchoring the guide wire and the filament being gauged adjacent one end of the cable being formed, and applying tensioning forces of substantially the same magnitude to the guide wire and said filament adjacent the opposite end of the cable being formed at the time the cross markings are being applied to the filament.

9. In the art of forming cables in accordance with claim 7, laying said filaments as loops each having a dead wire and a live wire, firmly anchoring the guide Wire and the dead wire of a loop adjacent one end of the cable being formed, applying substantially equal tensioning forces to the guide wire and said dead wire adjacent the opposite end of the cable being formed at the time the cross markings are being applied to the dead wire, anchoring said loop at said last-mentioned end of the cable being formed with said dead wire accurately gauged to the length of said guide wire, anchoring said guide wire adjacent said anchorage for said loop, and applying substantially equal tensioning forces to said guide wire and said live wire at a point adjacent the first-mentioned end of the cable being formed at the time the live wire filament is being provided with said cross markings.

10. In the art of forming cables in accordance with claim 8, laying said filaments by carrying a loop comprising a dead wire and a live wire from an anchorage for the dead wire and from a supply reel adjacent one end of the cable being formed to the opposite end there of, anchoring the dead Wire of said loop adjacent said opposite end, passing the live wire about a turnabout sheave adjacent said opposite end of said cable, carrying a loop comprising a dead wire and a live Wire from said second-mentioned anchorage for the first dead wire and said turnabout sheave to the initial end of said cable being formed, and successively gauging in the manner specified said first-mentioned dead wire, then said secondmentioned dead wire, then said second-mentioned live wire and finally the first-mentioned live wire, while said respective wires are anchored at alternate ends of said cable being formed and are subjected to tension at their opposite ends.

11. In a system for forming a parallel wire cable for a suspension bridge having an anchorage at eachend and a plurality of towers between the anchorages, wire unreeling apparatus adjacent one anchorage, a footwalk extending across the bridge structure along a path beneath the cable to be formed, means for laying a guide wire from an anchorage adjacent said unreeling apparatus across the towers to the far side anchorage, means for adjusting said guide wire to conform with the catenaries desired for the cable in the several sections thereof, a fixed marking being provided adjacent each anchorage and adjacent each tower, a cross mark being provided on the adjusted guide wire in line with each of said fixed markings, free running sheaves carried by said footwalk in fixed positions at suitably spaced points along the length of the guide wire and arranged to hold the latter down in approximately its adjusted path, free running sheaves at the towers arranged to hold the guide wire up approximately along said path, a counterweight attached to the guide wire adjacent the far side anchorage, said counterweight being of adequate mass to retain the Wire against the various sheaves, means for anchoring the end of a wire delivered from said unreeling apparatus at a point adjacent said apparatus, means for carrying a loop of wire formed between said anchoring means and the unreeling apparatus across the towers along a path approximating the form of the guide wire, said loop comprising a live wire fed from said unreeling apparatus and a dead wire extending from said anchoring means, hold down sheaves for the dead wire of said loop substantially aligned with those for the guide wire, sheaves for carrying said dead wires at the towers substantially aligned with those for the guide wire, and means for attaching to said dead wire adjacent said far side anchorage a counterweight of a mass substantially equal to that of the first-mentioned counterweight so that said dead wire may be cross marked to delineate lengths equal to those between excess markings on the guide wire.

l2. In a system for forming a cable as set forth in claim 11, means for anchoring the dead wire of said loop at the far side anchorage, hold down sheaves carried by the footwalk and sheaves at the towers for retaining the live wire of said loop substantially parallel with the guide wire, means for removing the counterweight tension from the guide wire at the far side anchorage, and means for PP Y tZ c un erweight tensions of substantially equal aermse mass to said guide wire and said live wire, respectively, adjacent the anchorage at the unreeling station.

13. A system for laying wires for a parallel wire suspension cable, comprising means for laying successive Wires along the length of the cable to be formed, means for adjusting the laid wires to provide the desired length to conform with the prescribed catenaries for at least a main span and two end spans, said adjusting means comprising a guide wire accurately positioned in conformity with the prescribed catenaries, cross markings being provided on the guide Wire adjacent predetermined points on the bridge structure, anti-friction hold down means at spaced intervals intermediate the ends of each catenary and anti-friction means adjacent the ends of the main span catenary for retaining said guide wire along a path approximately parallel with the prescribed catenaries. means for firmly anchoring one end of said wire, means for applying a tensioning force to said wire adjacent its opposite end, said tensioning force being of adequate amount to retain the wire against all of said anti-friction means, means for anchoring the end of a laid wire adjacent the anchoring point of said guide wire, anti-friction means adjacent to those for the guide wire for retaining the laid wire along a path parallel with that of the guide wire, means for applying a tensioning force to the laid wire at a point adjacent that applied to the guide wire and of substantially equal amount to that applied to the guide wire, and means for providing cross markings on the laid Wire aligned with those on the guide wire.

14. In a system of the character set forth in claim 13, said first-mentioned means being arranged to lay a loop comprising a dead wire and a live wire upon each passage across the bridge structure, means for alternately adjusting said dead and live wires being laid by applying said tensioning force to the guide wire and the laid wires adjacent one end of the cable being formed and then adjacent the opposite end of said cable.

15. In a system of the character set forth in claim 13, means for simultaneously laying a plurality'of loops of wire throughout the length of the cable, each of said loops having a dead wire and a live wire, means for anchoring each of the dead wires adjacent the anchorage of the guide wire at the starting end of the cable, antifriction means adjacent to those for the guide wire for retaining said dead wires in a path parallel with said guide wire, means for applying a tensioning force to each of the dead wires of said loops substantially equal to that applied to the guide Wire and at points adjacent to the point of application of such force to the guide Wire,

means for providing cross marks on each of the dead Wires in substantial alignment with those on the guide Wire, means for anchoring the guide wire and the dead wires at the far end of the cable, anti-friction means adjacent to those for the guide Wire for retaining the live wires in a path parallel with said guide Wire, means for applying substantially equal tensioniug forces to the guide wire and to each of the live wires of the laid loops adjacent the starting end of the cable, and means for apply: ing cross markings to the live wires in substantial alignment with those on the guide wire.

16. In a system for forming in situ cables for suspended structures, in which component strands of the cable are built up by laying successive filaments between anchorages, and over at least two supporting saddles between said anchorages, said filaments being laid in adjacent catenaries preparatory 'to being formed into a compact strand, the improvement which consists in means 'for first laying a guide wire in predetermined successive.

catenaries' between the saddles and between each anchorage and a corresponding saddle, means for fixing said 18 anchorages, to establish reference points for the position of the guide wire, said fixing means enabling freeing of said guide wire to move longitudinally between anchorages, means for then applying a uniform tensile force to said guide wire sufiicient to urge the same to rise above its initial catenaries, means for holding said guide wire down at spaced points throughout its length and thereby establishing it as a dimensionally stable gauge wire made up of successive portions which are substantially catenary in form, means for laying and similarly tensioning, holding-down and cross-marking by reference to the gauge wire cross-markings, successive component filaments of the cable being formed, while said filaments are positioned by the hold-down action, means for freeing said filaments from hold down and transferring them to the adjacent saddles with the marks on the filaments adj aceut the towers and the anchorages aligned with those on filaments which have been previously transferred to the saddles, and means operative when all filaments are placed for shifting the resulting strand sufiiciently to cause the markings on the filaments to register with saddle markings.

17. In a system for forming cables in accordance with claim 16, means for firmly anchoring the guide wire and the filament being gauged adjacent one end of the cable being formed, and means for applying substantially the same tensioning force to the guide wire and said filament adjacent the opposite end of the cable being formed at the time the cross markings are being applied to the filament.

18. In a system for forming cables in accordance with claim 16, means for laying said filaments as loops each having a dead wire and a live wire, means for firmly anchoring the guide wire and the dead Wire of a loop adjacent one end of the cable being formed, means for applying substantially equal tensioning forces to the guide wire and said dead wire adjacent the far end of the cable being formed at the time the cross markings are being applied to the dead wire, means for anchoring said loop at said last-mentioned end of the cable being formed with said dead wire accurately gauged to the length of said guide wire, means for anchoring said guide wire adjacent said anchorage for said dead Wire, and means for applying substantially equal tcnsioning forces to said guide wire and said live wire at a point adjacent said one end of the cable being formed at the time the live wire filament is being provided with said cross markings.

19. In a system for forming cables in accordance with claim 17, means for laying said filaments by carrying a loop comprising a dead wire and a live wire from an anchorage for the dead wire and from a supply reel adjacent one end of the cable being formed to the opposite end thereof, means for anchoring the dead wire of said -loop adjacent said opposite end, a turnabout sheave adjacent said opposite end of said cable about which said live wire may be passed, said first-mentioned means being arranged to carry a loop comprising a dead wire and a live wire from said second-mentioned anchorage for the first dead Wire and said turnabout sheave to the initial end of said cable being formed, and means for successively gauging in the manner specified said first-mentioned dead wire, then said second-mentioned dead wire, then said second-mentioned live wire and finally said first-mentioned live wire, while said respective wires are anchored at alternate ends of said cable being formed and are subjected to tension at their opposite ends.

guide wire against longitudinal shift at said saddles and anchorages, means for cross-marking said guide wire and adjacent portions of fixed structure, including saddles and References fitted in the file of this patent UNITED STATES PATENTS 2,191,025 Mitchell Feb. 20, 1940 2,740,459 Kilborn Apr. 3, 1956 2,743,514 Duecy -Q... May 1, 1956 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,971,255 February 14 1961 John E. Nixon It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent, should read as "corrected below,

Column 13, line 18, for "plin" read pin line 3O for "extend" read extent column 16, line 67,v for "excess" read cross Signed and sealed this 12th day of September 1961.

( SEA L) Attest:

ERNES w. SWIDER v DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC-