US2755493A - Lift bridge - Google Patents

Description

M. MILLER LIFT BRIDGE July 24, 1956 5 Sheets-Sheet 1 Filed March 15, 1952 INVENTOR Max M a liar M. MILLER LIFT BRIDGE July 24, 1956 3 Sheets-Sheet 3 Filed March 15, 1952 INVENTOR M x .M ler:

LIFT BRIDGE Max Miller, Philadelphia, Pa.

Application March 15, 1952, Serial No. 276,757

8 Claims. (Cl. 14-42) The present invention relates to lift bridges, particularly of the character which extend over rivers and other bodies of water and are raised at intervals to permit the passage of ships and other water craft.

The invention has for its purposes to increase the economy of construction of lift bridges; to reduce the weight of the movable structure; to subdivide the traffic deck into two or three articulated spans, the outer of which have cantilever support; to prevent the live or dead load on one deck span from influencing another; to prevent bumping of unloaded portions of the traflic deck; to support the trafiic deck partly by pivoted suspenders; to prevent the suspenders from reaching dead center; to interconnect the deck spans by pins having respectively tight and loose fits; to apply pulls from counterweights to the deck spans where they might otherwise deflect under live loads; to reduce the number of hanger interconnections to a minimum; and to use hangers whose depth is independent of the depth of the stationary overhead span.

In the drawings I have chosen a few only of the numerous embodiments in which my invention may appear, selecting the forms shown from the standpoints of convenience in illustration, satisfactory operation, and clear demonstration of the principles involved.

The drawings are diagrammatic, the intention being to show main features of the structure, but to omit the cross bracing and the like which are well known in the art and brakes, limit stops and the like in mechanical and electrical equipment in the interest of simplicity of the illustration.

Figure 1 is a side elevation of the preferred embodiment of the lift bridge of the invention, the piers being broken away below the water line.

Figure 2 is a top plan view of the structure of Figure 1 illustrating especially the mechanical equipment.

Figure 3 is an enlarged section of one form of traffic deck in accordance with the invention, the section being taken on the line 3-3 of Figure 1.

Figure 4 is a fragmentary side elevation of Figure 3 corresponding in position to the line 44 of Figure 3.

Figure 5 is an enlarged vertical section of Figure 1, suitably taken on the line 33 and illustrating a variant form of traffic deck.

Figure 6 is a fragmentary side elevation of Figure 5, corresponding in position to the line 66.

Figure 7 is a side elevation similar to Figure 1 showing a modification.

In the drawings like numerals refer to like parts throughout.

In accordance with the present invention, the trafiic deck is constructed in such a way that pounding does not occur, and live load stress and deflections are minimized. The trafilc deck is sub-divided into two or three deck spans, and the deck spans are articulated for relative motion in the vertical plane, so that when the bridge is in the traffic carrying position each deck span flexes wholly independently and is not capable of transmitting 2,75,493 Patented July 24, 1956 a moment to the next span. In order that this may be accomplished, the respective spans are pivotally inter-- connected, and the pivot can transmit a longitudinal force due to traction, and vertical force due to vertical support supplied by the end of one span to the adjacent end of the adjoining span, but not transmit moments when the bridge is in the traffic carrying position. Thus under live load each deck span is supported as a simple span, either from a pier and an adjoining span or from rigid suspenders near its ends.

In addition in traffic position each deck span is further supported at an intermediate point against deflection under live load stresses by counterweighting adequately to bear the bulk of the dead load, but located intermediate between the end supports of the deck spans.

Each of the deck spans is suitably interconnected with one adjoining deck span in endwise position by a pair of vertically spaced pins, one of which functions as a pivot pin and has a tight fit, and the other of which acts as a lost motion and limiting pin to control rotation. This interconnection functions in three Ways:

1. When the trafiic deck is in trafiic position, it allows the individual deck spans to relatively rotate slightly as live load is applied to one and thus prevents transmission of uplift force on the next span. This action is possible because all of the deck spans in traflic position are free to rotate in their vertical plane independent of one another. It will be understood that in traffic position only the pivot pin at each connection between the deck spans is in engagement, the other pin being in lost motion position.

2. When the trafiic deck is raised to elevated position, the endmost deck spans rotate (the outer ends move down) about the pivot pin, while the walls of the cooperating openings close in to grip the lost motion pin, and thus transmit pressure between adjacent spans, taking up the lost motion, and supporting the endmost deck spans in cantilever relation. At the same time the counterweighting applied at intermediate points on the endmost deck spans bears the bulk of the dead weight, the cantilever support merely sustaining the difference.

3. When the traflic deck moves from elevated position down into traffic position, as soon as the remote ends of the traffic deck engage the piers, rotation takes place in a reverse direction, pivoting around the pivot pins, while the lost motion pins revert into lost motion relation to the engaging openings, ending the cantilever action.

The suspenders are desirably rigid so as to provide tolerable stretch and also to aid in restraining any lateral motion. These suspenders will desirably collapse vertically in the space below the stationary span and above the traific deck. This can be conveniently accomplished by toggle arms pivoted at the two ends and pivoted to one another at the middle, which are restrained in vertical position against reaching dead center. By placing two sets of toggle arms in opposed relation and positioning striking blocks at the pivots interconnecting the arms of each set, the sets of toggle arms themselves prevent attainment of dead center.

The counterweights are suitably interconnected with intermediate points on the deck spans by ropes passing over sheaves, and individual for each deck span. In order to avoid snaking, the number of deck spans in the trafiic deck should be either two or three, and the use of more than three deck spans on the lift portion is not recommended.

The sheaves are desirably interconnected through gearing such as sprockets and chains, so that all ropes move in unison and so that a single motive power source will operate all ropes.

It will be evident that in the system of the present invention when the sheaves which guide the counterweighting ropes for different deck spans are inter-geared, there would be possibility of reaction of the live load on one deck span upon another deck span. I overcome this by providing clutches and de-clutching in tralfic position.

it will further be evident that since the counterweighting means functions actively in traffic position there would be danger of reaction by the counterweighting system on the driving means if the driving means remained interconnected with the counterweighting system in trafiic position. I further overcome this by providing clutches between the driving means and the counterweighting means, and de-clutching in traflic position.

When reference is made herein to ropes, it is of course intended to use the term in the senseordinarily employed in lift bridges to designate metallic wire cables as usually employed.

Consider now specifically the form of Figures 1 to 4 inclusive. Piers 2t) and 21 are provided at oppositesides of a ship-way or the like having a water line 22. On the piers is supported a stationary span 23 consisting of towers 24 elevated to suitable heights at the ends and an upper span portion 25, constructed in any suitablemanner whether of steel, standard reinforced concrete, prestressed concrete or otherwise as desired. The stationary span performs a supporting function and will be designed to carry the mechanism mounted on the stationary span and also to carry the dead loads and all the live load except that portion carried directly by the piers.

The traflic deck 26 is positioned below the stationary span, and moves in space 27 between the lowermost traffic position 28 shown in solid lines in Figure 1 and an elevated position 30 shown in dot-and-dash lines in Figure 1. The tratfic deck 26 is formed from a plurality of deck spans arranged end to end, the number being preferably three and less desirably two. It is not ordinarily desirable to use more than three lift deck spans because of the danger of misalignment or snaking. In the embodiment of Figures 1 to 4 inclusive, the middeck span 31 is interconnected to end deck spans32 end to end, making the complete trafiic deck. The interconnections 33 between the respective deck spans are pivotal, so that the endrnost deck spans 32 are enabled to rotate with respect to the mid-deck span 31 both under live load and in raising and lowering. The pivotal connection between the deck spans suitably comprises two pin joints displaced vertically or in depth of the deck spans. Either of the pin joints is suitably a pivot and the oher a lost motion connection capable of providing limitation of motion and contributing to cantileversupport. As best seen in one form in Figures 3 and 4, one deck span 31 has an underlying nose or protrusion 34 suitably extending in depth approximately half way up the web, and the adjoining deck span 32 has an voverlying protrusion 35 suitably extending down for half the depth of the web of the span, the two overlying and underlying portions and the adjoining portions of the spans meeting in an upper vertical abutting space or slot 36, a lower vertical abutting space or slot 37 and anilitermediate or horizontal space or slot 38, theispaces or slots providing the requisite freedom for rotation without interference.

Each of the adjoining overlying and underlying portions of the adjoining spans has a cooperating semicircular opening or hole 49. A hanger plate 41 is secured as by rivets or other fastenings 42 on each side of each span element to one of the spans, suitably at span 31. A hole is provided in hanger plate 41 in line with the semicylindrical portions 49. On the outside of hanger plate 41 and suitably against the side thereof is placed tie plate 43 on each side of each span element, which is secured to the opposite span, in this case span 32, asby riveting or other fastening 44. The tie plate likewise has a hole in line with the semicylindrical portions 40 and the hole in hanger plate 41. Pivot pin 45 for each span element passes through all of the cooperatingholesin tie plate 43, hanger plate 41 and the horizontal edges of spans 32 and 31.

At a position removed in depth from pivot pin 45 on each span element and suitably below, semicylindrical openings 46 are provided at the abutting ends of the deck spans 31 and 32. Tie plates 47 on either side of the span elements are secured by any suitable fastening as by rivets 48 to one span, in this case the span 31, and each tie plate 47 hasa hole in line with the semicylindrical portions 46 of the abutting ends of the span. Cooperating tie plates 50 on both sides of each deck span element extend on the opposite sides respectively of tie plates 47 and are secured to the mating deck span, in this case span 32 by any suitable fastenings, here rivets 51. The tie plates 50 have holes in line with the hole in tie plates 47 and in line with the semicylindrical openings 46 in the abutting ends of the spans 31 and 32.

A pin 52 passes through these openings in each span element, and is of a diameter suificiently smaller than the holes so that adequate lost motion will be provided in order that, under no condition of live loading when the deck span is in traffic position, can the pin 52 be engaged in clamping relation by the opposite walls of the holes. It will'be understood that the tie plates 43 and 50 are suitably packed out away from the webs of the respective spans by fillers as well known.

'At a suitable point directly above each pivot connection between the deck spans and out of the way of trafi'ic, and conveniently ,at the sides and where required at an intermediate point, I place upper hanger plates 53 suitably secured and integrated to the structure of the stationary span and having transverse piovtal openings toreceive toggle pivot pins 54 on which toggle arms 55 of rigid suspenders 56 are mounted. Lower toggle arms 57 are pivotally connected to lower hanger plates 41 by pivot pins 58. The respective toggle arms 55 and 57 are pivotally interconnected conveniently at the middle by pivot pins 60.

It is important that the toggle arms in vertical position do not reach dead center and they are prevented from reaching dead center by mutually engaging striking blocks 61 which are conveniently mounted in laterally extending position on the toggle arms, suitably the lower toggle arms.

The rigid suspenders consist of solid metallic elements rather than cables, thus having tolerable extension. The suspenders move between lower vertical positions as seen in solid lines in Figure 1 and vertical collapsible positions as seen in dot-and-dash lines in Figure 1.

On the piers, in position to engage the remote ends of the-traffic deck, I place bearing shoes 62 which engage and support the remote ends of the endmost deck spans in traific position. At intermediate points between the ends of each deck span and suitably at the sides, or at the sides and intermediate positions, to avoid the traflic, I place cable connections 63 which engage vertical counterweightropes 64 for the endmost spans and vertical counterweight ropes 65 for the middle span. The counterweight ropes 64 are carried over sheaves 66 1'0- tatably mounted on the stationary span, andthen suitably reverse direction over rotatably mounted sheaves 67 mounted above the towers. Counterweights 68 on the ends of the ropes 64 counterweight the bulk of the dead weight of the endrnost deck spans. The counterweights 68 suitably move up and down in the towers and may or may not have guides.

The ropes-65 of which suitably two are provided for each side of the mid-deck span, are carried over sheaves 70 rotatably mounted in the upper portion of the stationaryspan, andare then carried over sheaves 7l positioned in the towers out of line with other counterweights. Counterweights 7,2 are provided at the opposite endsiotthe rope.65.and they collectively compensate for the bulk of and preferably substantially all the dead weight of the mid-deck span.

Any suitable mechanism may be used to interconnect the sheaves at the two sides and to drive the sheaves. As shown a prime mover 73, suitably an electric motor, drives duplicate speed reducers 74 through clutches 75. The speed reducers through clutches 76 drive bull gears 77 which interconnect through speed reducing and reversing gearing to gears 78 on the shafts of sheaves 70.

Sheaves 67 are interconnected through clutches 80 by shafting 81. Sheaves 71 are likewise interconnected by shafting 82. The shafting 81 between the two clutches and 82 is suitably interconnected as by sprocket and chain mechanism 83.

During traffic conditions, it is likely that slight defiections of the deck spans will cause slight downward pulls on cables 64 or 65 as the case may be, and it is important for this to occur and have the corresponding sheaves rotate without causing rotation of the sheaves of another deck span through the sprocket and chain mechanism 83. This is prevented by opening or declutching the clutches 80 when the traffic deck is in service.

Likewise it is desired to avoid having deflection of the mid-span cause motion of the sheaves to be transmitted to the driving mechanism, and this is prevented by opening or de-clutching clutches 76.

In Figure 2, ropes 65 have for convenience in illustration been diverted from their correct straight course between sheaves 70 and 71 so that they will not overlie sheaves 66 and 67 and rope 64.

In the construction of Figures 1 to 4 inclusive, simple beams 84 are extended transversely between the deck span elements to support the actual floor 85 of the bridge. This construction is particularly suited for highway bridges. Where heavier center loading is expected as in railway work, it is preferable to provide transverse trusses as illustrated in Figures and 6, and in this case the deck spans are suitably brought in beneath the load as best seen in Figure 5. Here transverse trusses 86 are provided, having upper transverse elements 86', which are connected to lower transverse elements 87 by cross bracing 88. Gusset plates 90 are integrated with the trusses at spaced points along the bottom and support shelf angles 91 which form seats for the deck spans 31. Hanger plates 41 are secured to the upper and outer ends of the transverse trusses, and receive the lower toggle arms 57 of the suspenders.

The railroad ties 92 here rest on the deck span girders and carry rails 93 as well known.

In some cases as in short spans it may be preferable as a matter of convenience to employ two deck spans rather than three as shown in the preferred embodiment. In Figure 7 I illustrate deck spans 32', each of which is counterweighted by two ropes 64 on each side, passing over sheaves 66 and 67 in one case and 66' and 67' to counterweights 68 and 68 at the remote ends in line with the towers. The sheaves are suitably intergeared and drive in the same manner as in the form of Figures 1 to 4.

It will be evident that the invention is applicable to any lift bridge installation in which it is desirable to obtain articulation between deck spans, to support articulated deck spans by rigid live load suspenders at pivotal interconnections, and to compensate for dead load by application of counterweighting at points intermediate between the ends of the spans and suitably at the middle of the deck spans.

It will also be evident that by the invention the counterweighting is not inactive or inoperative when the trafiic deck is in traflic position, but actively functions not only to support dead load, but to exert forces opposed to the deflection and the stresses applied by live load during active service conditions. I believe that I am the first to thus employ counterweighting in a lift bridge.

It will furthermore be evident that by interconnecting the sheaves of ropes belonging to different deck spans I obtain drive and operation in unison, while by de-clutching I permit the individual ropes to react independently to the effects of live load.

While in Figure 2 the mechanical driving assembly is shown located centrally at mid-span, it will be understood that if desired it may be placed at any other position on the stationary span, for example, near the top of one of the end towers, thus avoiding the loading of the fixed span 23. Wherever the mechanical driving assembly is placed, however, it will be understood that the sheaves 70 will be suitably intergeared so that the effects of the driving mechanism will be transmitted through the entire assembly of counterweight sheaves.

It will further be evident that by the present invention I am able to change the type of support of the endmost deck spans from cantilever support in elevated position to simple span support in traffic position. In other words I release the cantilever condition when the traific deck is lowered to traflic position and thus avoid the reaction which otherwise would occur on an adjoining span if the endmost deck spans and mid-span remained fully connected through both pins under live load.

It will further be evident that I avoid the objectionable bumping which otherwise would occur if the trafiic deck span were a continuous beam for its entire length.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and I therefore claim all such insofar as they fall within the reasonable spirit and scope of my claims.

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

1. In a lift bridge, a stationary span, a traffic deck extending beneath the stationary span and movable from a lower trafiic carrying position to an upper elevated position, the traffic deck having interconnection articulated for relative movement in a vertical plane which separates the traffic deck into a plurality of relatively rotatable deck spans, piers supporting the outer end of the traffic deck in the end spans of the articulated lower position, counterweight means supported on the stationary span and interconnected with the traific deck at an intermediate point on each deck span and thereby creating bending stresses and deflections opposite to those caused by the traffic in any deck span, and articulated suspenders interconnecting the stationary span with one of the spans remote from the ends of the trafiic deck.

2. A lift bridge according to claim 1, in which there are three deck spans, and the articulated suspenders interconnect the stationary span with the middle deck span.

3. A lift bridge according to claim 1, having pivot supports on the stationary span above the articulated interconnection between the deck spans, pivot supports from the sides of the traffic deck adjacent the articulated interconnection between the deck spans, the articulated suspenders comprising toggle arms pivotally interconnected with the respective pivot supports for outward movement and pivotally interconnected to one another, in combination with means for preventing the toggle arms from reaching dead center vertical postion.

4. A lift bridge according to claim 1, having at the articulated interconnection between each pair of deck spans an upper pivot pin making a tight fit between the two deck spans and a lower pin having lost motion between the deck spans, providing controlled freedom for rotation about the upper pin at all times and making engagement at the limits of rotation, the respective deck spans having freedom from one another at the ends except where pin engagement is provided.

5. A lift bridge according to claim 4, in which one deck span at each articulated interconnection overlies a portion ofitheadjoining deck span andibelow theoverlying part abutsagainstl the adjoining deck span, the upper p nlislocated betweenthe overlying and underlyingportionsof the deck spans and the lower pin is located between the endwise abutting portions of the deck spans.

6. A lift bridge according to claim 1, in which the counterweight means comprises counterweight ropes extending vertically above the intermediate points on the deck spans and: interconnected, thereto, sheaves supported on the stationary span andlsupporting the counterweight ropesfrorn the endmost deck spans, countctweights on the remote endsof the ropes fromthe endrnost deck spans, counterweight ropes from a middle deck span extending vertieally above the same andconnectedat an intermediate point on the middle deck span, sheaves supported on the stationary span and supporting the counterweight ropes from the middle deck span, counterweights on the remote ends of the counterweight ropes from the middle deck span and means for interconnecting the sheaves for the counterweight ropes on the end deck spans with the sheaves for the counterweight ropes on the middle deck span so that all of the sheaves will operate in unison.

7. A lift bridge according to claim 1, in which the counterweight means comprises sheaves supported on the stationary span and located at the ends thereof andat intermediate points, counterweights located at the ends of the traflic deck and movable within the stationary span, ropes passing over the sheaves connected to the counterweights and connected to the trafiic deck at points inter- '8 mediate between the suspenders .and between the sus penders and the ends of the traffic deck, the .connterweigh-ts connterhalaneingthe bulk of the. deadzload and the-.suspendcrsabearingzthe remainder of the dead loadand the tributary; trafiic load,iand means.for driving the sheaves to movethe traffic deck.

8. ln-alift-bridge, a stationaryspan, trafiic, deck means extending beneath the stationary Span and movable from a lower traflic carrying position to. an upper elevated position, piers supporting theouter ends of the traflicdeck means in the lower position, articulated collapsibletsuspenders interconnecting the stationary span ,with the trafiic deck-meansintermediate the ends thereof, counterweight means supported on the stationary span ,andinterconnected with thetraffic deck means. at an intermediate point and thereby creatingbending stresses-and deflections opposite to those caused by the trafltc.

References Cited in the file ofthis patent UNITED STATES PATENTS 1,087,233 Hedrick et al Feb. 17, 191.4 1,676,994 Lamond July 10, 19 28 1,855,520 Howard Apr. 26, 1932 2,473,126 Alexander June 14, 1949 2,556,175 Frost June 12,1951

FOREIGN .PATENTS 358,004 Italy Apr. 4, 1938 665,427 Germany Sept. 24, 1938

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