US409700A - Bridge - Google Patents

Description

(No Model.) 2 Sheets-Sheet 1. G. H. PEGRAM.

BRIDGE.

No. 409,700. Patented Aug. 2'7, 1889.

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UNITED STATES PATENT ()FFICE.

GEORGE H. PEGRAM, OF WILMINGTON, DELAlVARE.

BRIDGE.

SPECIFICATION forming part of Letters Patent No. 409,700, dated August 27, 1889. Application filed March 27, 1885. Serial No. 160,175. (No model.)

T0 at whom it may concern:

Be it known that I, GEORGE H. PEGRAM, of the city of \Vilmington, in the county of New Castle and State of Delaware, have invented a new and useful Improvement in Bridges, of which the following is a specification.

My invention has reference to draw or, more properly, swing bridges; and it consists of two separate contiguous parts or draws swinging about different centers of motion, which, when closed, form three spans for traffic, and when opened form three separate water passage-ways; further, in a bridge, such as above specified, in which the draws or pivot-spans may be caused to operate simultaneously or independently, and in details of construction, all of which are fully set forth in the following specification, and shown in the accompanying drawings, which form part thereof.

In the drawings, Figure 1 is an elevation of a double-pivot draw-bridge embodying my invention. Fig. 2 is a plan view of same when closed, and shows the spans open in dotted lines. Fig. 3 is a sectional elevation, on line w w, of one of the rest-piers or abutments, showing the manner of retaining the inner ends of the swinging trusses from vertical movement. Fig. 4 is a cross-section of same on line x 00. Fig. 5 is a sectional plan View, on line g y, of one end of one of the bottom chords of the truss. Fig. 6 is a plan view of the turning mechanism of one of the trusses, and Fig. 7 is a cross-section of part of same on line 22'.

P P are pivot-piers, and R R are rest-piers or abutments, as the case may be.

B B are two draws or pivot spans supported upon the piers I and P. As shown, they are the same in length, although in practice they would be made of different lengths in some special cases. These draws may be made of any suitable construction or design, the same being immaterial to my invention.

G is a curved anchorage-girder, usually a rail or eye-beam, under which the tail of the draw swings and by which it is held down, the said girder being held down to the piers by suitable anchors. \Vhere the end of a iiXed span rests on the pier, the girder might be attached to and held in position by it in place of the anchorage.

A chain or rope X is connected to the turntable of the two draws, and runs from one to the other through pipes or boxes under the water, which chains are guided by pulleys Z. By means of these chains the draws may be operated together-that is to say, opened or closed simultaneously from either draw.

U is a ring, of angleiron or other suitable shape, around the outside of the balancewheels of the turn-table, and is supported and guided by the horizontal and vertical friction-rollers W, (see Fig. 7,) secured to and carried by the draw. The said ring is free to move about the center except when confined by the sliding bolts or looks B carried by the draw proper.

The chains X X, hereinbefore referred to, are supported in the same vertic tl plane, but pass one above the other and are fastened to the ring U at the points Y. This arrangement is duplicated in the other draw, to which the chains run under the water, as shown in Fig. 1. \Vhen the bolts 13 are drawn, one draw may be operated without any motion being communicated to the ring U, and through it to the other draw. By having the chains lead in the same plane their tension causes an internal stress in the ring U with out tending to turn it or bring a side pressure 011 the draw center, and the only resistance to the turning of the draw will be that due to the weight of the ring and the supported chains, which is reduced to a minimum by the use of anti-friction rollers WV. WVhen both draws are to be operated together, the bolt B is thrown, entering a notch or hole in the ring U, causing it to move with the draw. The motion of one draw is thus communicated to the other. By the set of chains X, attached to the rings U, through the chains X, and running to the shore, as indicated in dotted lines in Fig. 2, one orboth draws may be operated from that place in the same manner in which it is proposed to operate one from the other. It is thus seen that I have a swing-bridge composed of two separate parts or draws, one or both of which may be operated from the same point of application of power. The outer arms of the said truss form together a span of two cantalevers over the main opening, and the inner or shore arms'form single spans, subject to the corn bined action of cantalever and fixed span, according to the condition of loading.

M is a roller attached to the shore ends of the lower chords of the truss on the axle A, which is made eccentric upon the ends and carried in a suitable frame on cross-plate of the girder, whereby by turning the axle the roller may be elevated or depressed. This is accomplished by means of a disk-plate D, Secured to the axle A by a key K, or in any other known manner, which disk has holes at intervals in a circle, through one or more of which the bolts 1) pass and are secured into the fixed part of the draw, thus fixing the axle and thereby the elevation of the roller M. It is unimportant whether the roller is fixed to the chord of the draw, as shown, or to some other part; but it is essential that 1it should be free to act both on top and hot G is a portion of the anchoragegirder, which is preferably fastened to and held in position by heavy standards, which will be made of somewhat different shapes to suit diiferent constructions, and which standards are anchored to the masonry by bolts.

'1 is a rail which supports and guides the rollers M, of which there are two or more, and those rollers are confined between the girder G and rail T, rolling on one or the other, according as the pressure is upward or downward. WVhen the draw is in place for traffic, the rollers are confined and held in position by the standards S.

I do not confine myself to any manner of attachment between the draws at their outer end whereby the difference in deflection of the two arms may be provided for. In small spans, particularly for highway bridges, this will be too small to consider, and in large spans it may be neutralized by wedges arranged to make the arms deflect together; or the deflection of the trusses maybe unchecked and the roadways connected by aprons, such as are sometimes used at the ends of our present draw-bridges. It is clear that the tail or shore arms need not necessarily be of the same length as the outer arms. The main upward force of the tail-arm is produced by the live load and will occur when the bridge is closed, in which case the total strain is taken directly by the standards. The anchorage-girder, having only a small unbalanced load to provide for, may be made verylight.

I am aware that old English bridges with two cantalevers spanning a single water-way have been used. In these bridges the shorearm is heavily counterweighted to balance any live load which may come on the outer arm. This counter-weight must be supplied at some cost, the structure must be strengthened and constructed to carry it at a further cost, and a railway must be constructed and kept in a good level state to carry it when turning at a still further cost. This latter would operate to limit the size of the bridge to small lengths. The power necessary to turn an unbalanced load running on a rail at a distance from the center would ordinarily be several times that necessary to turn a balanced load of the same total amount carried on a central pivot, (which renders anti-frictional devices-such as steel-roller nests possible,) and when this total load is very much less by the absence of the counterweight the showing is so much more favorable. Now in the bridge proposed by me the load turned is inall cases abalanced weight, either of the bridge itself or with the addition of a counter-weight in some rare cases where the arms are of different lengths, which counter-weight would be infinitesimal in comparison with that required in the English bridges referred to. The live load is balanced by the dead-weight of the rest-pier or abutment, which, acting at the end, has a greater leverage than the counter-weight in the English bridges.

In reference to navigation, if it were practicable to make the English draws of such size that boats could be admitted through a part of the opening, which the expense would render doubtful, the passage could not be used with safety on account of the projecting arm of the other draw, into which boats might drift or be blown, and which would strike them in a weak place.

In the bridge proposed by me there are three waterways which the railway in the English bridges would render impossible with that construction. These passages have fenders on both sides and are free from overhanging obstructions, and when a small opening is needed a safe passage maybe obtained with the operation of only one Part of the draw.

Some of the advantages claimed for the draw proposed are as follows: I

First. The obstructions to the currents are distributed by having two small piers in place of one large one, thus creating a smaller disturbance of the river-bed.

Second. In small streams the piers may be put on the shores and a large opening obtained at about half the cost that would be required to build a span having one large arm covering the waterway, as is now the custom in such cases.

Third. There may be a choice for boats for three separate parts of the river in place of two.

Fourth. For tugs, vessels, and ordinary craft it will be necessary to operate but one draw, thus reducing the time and avoiding delays to navigation and traffic.

Fifth. Having two draws of like construction, it is highly improbable that both would ever be out of order or require to be repaired at the same time, and thus there is less danger of obstruction to trafiic and navigation from such causes.

Sixth. The fenders would be but half the length required for an ordinary draw having the same clear opening, thus taking up less length of rivers, which is an important item in small harbors.

Seventh. The weight of the two draws will which would be impracticable in the large draws.

Tenth. It is possible to get alarge opening for boats without a large draw, which would look unsightly in a small harbor by dwarfing everything around it, (my design having the appearance of two small spans.)

Eleventh. There is much less ambiguity of strainin fact where no wedges are used between the outer arms there can be no ambiguity whatever; and, further, the parts subjected to reverse strains-21 e., alternating tension and compression-are few in number and near the end of the shore-arms, while they are great in the present style of drawbridges, due to an excessive elevation of the ends by the wedges or failure to throw the wedges, or the eii'ects of temperature like the heating of the exposed top chord, while the bottom chord is sheltered, thus depressing the ends of the bridge, all tending to increase the ambiguity that exists under the best conditions.

Twelfth. The benefit to be derived from the proposed roller at the end of the draw is in allowing motion during a time when the bridge maybe partially loaded with the least resistance to moving.

It frequently happens in highway bridges that people will run onto the bridge before it is completely closed, and this device is proposed to meet such a disturbing influence.

Thirteenth. Although designed to operate one draw from the other, it is proposed to make the draws so that they may both be swung independently in the usual manner, which the simple drawing of the bolts will allow. Both can be swung simultaneously with much less power than is necessary to move one large draw of the same total length.

Fourteenth. There are numerous streams and harbors where it is only on rare occa sions that the maximum opening for boats is required, and in such places there is a great waste of power through the necessity of moving the large draw required.

My invention looks to the use of but one of the draws for the greater part of the time.

Having now described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. A draw or swing bridge composed of two separate contiguous parts or draws swinging in a horizontal plane about di'lferent centers of motion, which parts may be turn ed independently or together, in combination with connecting mechanism, substantially as set forth, for operating both of said draws simultaneously from one or the other thereof, substantially as and for the purpose specified.

2. A horizontally swinging drawbridge consisting of the combination of two pivotpiers and two rest-piers with two horizontallyswinging cantalevers having tail-arms adapted to span the three water-ways between said piers, the middle water way between the pivot-piers being spanned by the two cantalevers and the side water-ways being spanned by the tail-arms, and means, substantially as set forth, upon said rest-piers to anchqr/fiid tail-arms when the bridge is closed to keep the cantalevers in line, but which tail-arms are entirely free when the bridge is open, substantially as and for the purpose specified.

3. A draw-bridge composed of two parts or draws adapted to swing in the same horizontal plane and each having two arms, the respective outer arms of which form two cantalevers, while the. inner arms are firmly held in position by rest-piers or abutments, in combination with anchorage-girders attached thereto, and under which the tailarms of the draws swing, substantially as and for the purpose specified.

4. A draw or swing bridge having a central water-way spanned by two cantalevers arranged upon separate pivots and adapted to swing in a horizontal plane, each of which cantalevers is counterbalanced when open by an unsupported tail-arm, and when closed by said tail-arm, in combination with standards attached to the abutments or rest-piers, the said parts being combined with the said pivot and rest piers, substantially as and for the purpose specified.

5. The combination, in a draw or swing bridge adapted to swing in a horizontal plane, of an anchorage girder or beam with standards which are anchored to the abutments or i'est piers, the draw when closed being held down directly by the standards, and when moving being guided and held down by the said beam or girder, substantially as and for the purpose specified.

6. The combination of a roller attached to the end of the bridge with top and bottom anchorage-guides, between which the roller runs and. by which the end of the draw is guided and its vertical motion limited, substantially as and for the purpose specified.

7. In combination with a draw or swing bridge, an axle carrying a roller to guide the draw when turning, which axle has its end bearing eccentric with the roller-bearing, substantially as and for the purpose specified.

8. In combination with a draw or swing bridge, an axle having its end bearing eccentric with the roller-bearing, and to the end of which axle a disk-plate is attached, by which the axle is turned and held in position, and a roller carried by said axle to guide the draw when turning, substantially as and for the purpose specified.

ITO

9. In a draw or swing bridge a ring turning freely about the center or pivot, in combination with locks to secure said ringto said bridge, and chains or ropes secured to said ring, by which the bridge may be turned, substantially as and for the purpose specified.

10. In a pivot or swing bridge, the pivotpier surrounded by water, in combination with a horizontally-swinging draw pivoted upon said pier chains or cables extending from the shore or distant place to said pivotpier and passing under the water, guide-rollers for said chain or cable, and connections between said chain or cable and horizon tally-swinging draw, whereby the said draw may be operated from a distant place sepa-

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