US2510948A - Pontoon bridge support - Google Patents

Description

June 13, 1950 J. w. BERETTA PONTOON BRIDGE SUPPORT 5 SheetsSheet 1 Filed Sept. 24, 1946 8111mm for June 13, 1950 J. w. BERETI A' PONTOON BRIDGE SUPPORT 5 Shee ts-Sheet 2 Filed Sept. 24, 1946 1 2 15 1 2 15 Ill: 15 8 J Ian Z0 ref/a,

m as June 13, 1950 J. w. BERETTA 2,510,948

PONTOON BRIDGE SUPPORT Filed Sept. 24, 1946 5 Sheets-Sheet 3 5 Snowdrop 5 Sheets-Sheet 4 nventor fll'l'orucqo I I I I i J. W. BERETTA PONTOON BRIDGE SUPPORT llllllllrllllll Filed Sept. 24, 1946 Fig.10.

June 13, 1950 June 13, 1950 J. w. BERETTA PONTOON BRIDGE SUPPORT 5 Sheets-Sheet 5' Filed Sept. 24, 1946 ef/cb I rm atrornm a Patented June 13, 1950 UNITED STATES PATENT OFFICE PONTOON BRIDGE SUPPORT John W. Beretta, San Antonio, Tex.

Application September 24, 1946, Serial N 0. 699,070

15 Claims. (01. 14-27) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) Theinvention described herein may be manufactured and used by or for the Government for governmental purposes, without payment to me of any royalty thereon.

This invention relates to bridges, more particularly it is directed to the shore connection of a floating bridge structure.

In floating bridges, particularly those of a military nature, it has been customary to connect the floating section of the bridge with the bank by a short connection consisting of trestle-supported sections, the number of sections being dependent upon the depth of water and other inshore conditions. The trestle next to the inshore boat of the floating section is connected to the floating section by a hinge span, and like the other trestles, consists of a transom fixedly connected to columns supported by mud shores or th like. This type of connection is satisfactory in a low capacity bridge having a flooring system of the balk and chess type but has the Weakness that the entire load coming onto the floating section is thrown on the end span of that section as a concentrated load with the result that it is difficul to get enough floating support under that portion of the bridge. In a new type of high capacity floating bridge now coming into use a flooring system of hollow beams is used in lieu of the earlier balk and chess decking and the difliculties inherent in the hinge span connection of the earlier bridge referred to above are avoided by projecting the beams beyond the inshore boat to the first transom of the shore connection. It has been found, however, that when a heavy load passes over the bridge the beams in the span between inshore boat and its adjacent transom are overstressed due to the fact that the transom is relatively fixed While the inshore boats sink deeper into the water as the load passes over them. With this in mind, and in accordance with a feature of my invention, means are provid d for permitting heightwise movement of the flooring at the transom support concomitantly with the heightwise movement of the adjacent inshore boats. As illustrated, this means consists of a transom fixedly connected to supporting columns, a floor supporting member located above the transom and yieldable means interconnecting the transom and supporting member arranged to permit heightwise movement of the floor supporting member as the load passes over it.

A further object of the invention is to provide a floating bridge structure including yielding supports at the end of the floating portion of the ponton bridge, using trestle supports, which will I enable the use of a continuous span of bridge flooring between the last ponton and the first trestle support.

Another object of the invention is to provid a yielding support for a. ponton bridge which may b incorporated on top of the transom of a trestle support adjoining each of the ends of the bridge.

Another object of the invention is to provide a toggle spring or yielding support for a ponton bridge, which will enable the extension of continuous balk or flooring of the floating portion of the bridge from the last ponton to the first trestle transom at each end of the bridge, by yielding vertically and thus reducing the slope of the roadway and thereby preventing the overstressing of the balk in the last span and also providing the necessary articulation between the continuous ponton end span of balk and the first trestle span of balk.

With the above and other objects and advantages in view the invention consists of certain features of construction and operation of parts, which will hereinafter be described and shown in the accompanying drawings, in which:

Fig. 1 is a side elevation of the invention applied between a transom adjustably mounted on columns at one end of the floating portion of a ponton bridge and a load carrying bridg floorsupporting beam mounted for up and down movement on the columns, with bumper carrying brackets adjustably mounted on the columns for limiting the downward movement of the floorsupporting beam and means for limiting the upward movement thereof;

Fig. 2 is a longitudinal sectional view taken on line II-lI of Fig. 1;

Fig. 3 is an enlarged fragmentary side elevation of the left end portion of Fig. land illustrating the invention in full lines and other parts of th supporting trestle of the ponton bridge in broken lines;

Fig. 4 is a vertical sectional view taken on line IV--IV of Fig. 1;

Fig. 5 is another vertical sectional view taken on line VV of Fig. 1;

Fig. 6 is an enlarged detail vertical sectional view through a bottom roller, track and connected parts used in carrying out the invention;

Fig. 7 is an enlarged side elevation of a bumper carrying bracket for limiting the downward Fig. 10 is a fragmentary detail view of the lower end of the bumper carrying bracket;

Fig. 11 is an enlarged vertical sectional detail view taken on line XI-XI of Fig. 3;

Fig. 12 is an enlarged vertical sectional detail view taken on line XlI-X[I of Fig. 1;

Fig. 13 is a diagrammatic view illustrating the invention applied on orieend of a ponton bridge at the point where the floating portion of the bridge connects to a fixed portion or approach" nearthe riverbank. ,7

Fig. 14 is a schematic view showing a typical floating bridge section and trestle supported'shore connection.

Referring to the drawings; t eini'pidvedtran' som assembly is designated generally by A andjs adapted. for use on one or more or the trestles at each end of the bridge. The transom assembly trestle 5 adjoining the end of the floatingpor- I tion 6 of the ponton bridge 1, Fig. l3. Theheight of the transom 2 on the vertical column 4 may be adjusted to meet changes'of water level,'or otherwise to alterthe elevation "of the trestle bridge floor, by means of chain hoists, for exampleg'or similar devices well known in the art, attached to the tops of columns '4 and to the ends of the transom 2. Typical hoisting means are described at pages 5 to 9 of War DepartmentTeichnical' Manual :TM5-276, Octber"19,-1943, entitled Ten-ton trestle bridge. The yieldirig support includes an upper transversely extending supporting beam 8 movably mounted onthe columns 4 by means of guide brackets 9 'onits'ends and having a balk adapter I0 having longitudinal balk or floor members I I mounted thereon. The balk adapter It] consists of dual swivelpipes lzf-Fig' shl and 5, which 'extend'transvers'el'y in spaced parallel relation on the supporting beam-8 an'd ar'eheld in their spaced relation by mea s or suitably spaced tie angle members [3. The's'wivel pipes I2 are provided with collars I'4 attheir'endS 'a'nd have a plurality of bearings l arrahged'in 'spaced relation thereon, which bearings l5 are provided withth' tie angle members [3 which'ar welded or otherwise connected to the upper surface of the supporting beamB- Interposed between thelower'beam l and the upper supporting beam 8 is a transversely extending and contracting mechanism -'or"spring'*oper-' ated toggle indicated generally by B of the yielding support and consists of a suitable number of intermediate diagonal pivot arms or levers l1, ll and ll" of equal lengths and 'formediritg pairs providing lazy tongs with the pairs of intermediate levers crossing 'each 'otherfa't their medial points and pivotally connected in spaced relation at these points by intermediatepivotpins l8 illustrated in detail inFig.'11. I Onebf each pair of the end link arms {Band 19" of thelaiy tongs at one of their ends arepivoted in spaced relation by means of end pivot pins 20 illustrated in detail, Fig. 12. The intermed ate-" ivotpins l8 extend transversely with respecttb""tl'ie'iipper and lower beams 'l-"and8 rspectivelyfwith 'the end pivot pins 20 extending parallel to and in the sam plane as the intermediate pivot pins l8.

The upper ends of the intermediate link arms H are pivotally connected in spaced relation by a pivot pin 2| to a bracket 22 mounted on the lower side and at the middle of the upper beam 8 and the lowerends of the levers 1"! are pivotally connected in spaced relation 'by a pivot pin 23 to a bracket 24 mounted on the upper side and at :tne middle of the lower beam l of transom 2, ,Figs. land fl, each of the pivot pins l8 forming them-crummy each pair of crossed levers. lower ends oi'the levers i1, i1" and 19 have lower The rollers 25 mounted thereon, which engage in tracksremained-dame upper side and extending longitudinally of the lower beam l and the upper ends or levers l1, l1 and end levers l9 have upper ro'lle'rs 21 provided thereon, which engage in trackstfl mounted on the lower side of and extending longitudinally of the upper beam 8; Figs. '1 and 5. Trie -rollers 2'! engaging the upper 'tracks'id are mouhtedon the upperends of the link arms in thesame manner as therollers 25 on the lower ends of the -'link"arms engaging the lowertrajcks '26 as shown in enlarged detail of a roller 25'01'1 the lower track, Fig. 6, wherein the ends of a roller shaft 29 are reduced indiariieter and threaded-for receiving nuts so which retain the lowe ends of the link "arms'on the roller shaft 29, I V

The-intermediate and end'pivot ins -I 8 alndflfl, respectively, areelongatdffo c6nne'ctingtension springs 3| jther eto at each 'end th'ereof, which tensitn spiing's -'3 I extend in Horizontal alignment ends 'therebf, and on the outer erids '-'of the sleeves "are plates 38 for holding one end "Of a spring on the -c'ollars"36. he-sew pivot'pins 2'0 are identical with 'the' int'err'r'iediate' pivot-pins i la except that the "states 34 6h the reduced "end 1 'ornonsj 32" exterlding'ffoin the interni'e'diate ene r-retur ihe g s ia xsn in lfi x F rkinlen h:then h ve of the intermediatepijfot pins l'e, alsothe collars 3'61 on the end pivot' 'pin's i iiare isliortrin length than; the centres Gbn'the intermediate pivot I8 and there are ribrings the collars 36 be- Call S e each collaar 'iiiiifhasfcinlyfbiie end of a tension spr ng-[s l conneote'df'the'rto,with the plates as frno i teuj n' tne ncs ef thes ev'es 34' nora- "e d: f 'n me b it s' 'if i The columns" 'areproviddwith bumper memb'e'rs indicate ei all'y by C as moreparticularly illustratedin eruargg utanm Figs. 7 to in inclusive. 'Eachfof;tlie temper-members C'co'nsists of -a "bracket f3}! "adjustafbly mounted on a column 4 andjhaving "clamping iqriefnbers 4O hinge t j ii s *a: between twohirigdpla'te s '42 onthe ipp'era wee-a ias, or the 'biacketfw'ith the free ends efcla'mpir'ig hieinibers "being where the free ends of the clamping members are detachably held by means of nuts 44 mounted on the threaded ends of the clamping members. In Fig. 10, which shows a fragmentary lower end of the bracket, the clamping member 40 is removed from the hinge plates 42. A chain 45 is connected at one end to the upper end and on the outer side of the bracket 39 and has a pin 46 connected at its other end, which is adapted to be placed through a vertically extending slot 41 formed in the bracket 39 and to enter suitably spaced vertically arranged holes 48, Fig 1, provided in the columns 4 for adjusting the bumper bracket 35 on the columns. n the inner side of the bracket 39 is :a reinforcing rib 49 having a. bumper block 50 suitably mounted on the upper end thereof. A bumper block is mounted on the bottom of, and at each end of the upper beam 8, Figs. 1 and 2, which bumper blocks 5| are positioned above the bumper blocks 50 on the upper ends of the reinforcing ribs 49 of the brackets 39. Chains 52 are each connected at one end to a lift pin 53 adapted to be inserted through apertures formed in angle clips 54 mounted on the bottom of and adjacent to the ends of the upper beam 8. The other ends of chains 52 are connected to pins 55 on angle clips 56 mounted on the bottom beam I at its ends.

In the construction of the bridge support, the balk or longitudinal floor members I I of the ponton bridge are connected to the balk adapter [0 which provides not only the balk connectors, but also the necessary articulation as the support yields vertically under the passage of vehicles or other loads such as troops. The load is carried onto the supporting beam 8, which distributes the vertical reaction to upper interconnecting points of the link arms of the toggles, the center ones I l of which are fixed by a pin 2| to the bracket 22 on the supporting beam 8, while the other upper interconnecting points of the toggles are free to move against the action of springs Si laterally in opposite directions on the upper rollers 27 as the support yields vertically. The horizontal components of the several vertical load reactions are carried from the diagonal toggle members through the pivot pins l8 and 20 to the horizontally arranged tension springs 3| which provide yielding resistance to the load reaction. The vertical components of the several load reactions are carried by the lower interconnecting points of the link arms of the toggles, the center ones ll of which are fixed by a pin 23 to the bracket 24 on the lower beam I, while the other lower interconnecting points of the toggles are free to move against the action of the springs 3i laterally in opposite directions on the lower rollers 25 from the pin 23. The load reactions are transmitted from the lower beam I to the transom 2 through the transom adapters 3. The yielding support is limited in its vertical upward movement by means of the restraining chains 52 and in its downward movement by means of the bumper members 50 and 5|.

It will thus be seen that this invention provides a novel and eflicient form of yielding support for the shore connection of ponton bridges which is well adapted for the purpose intended. Even though there has herein been shown and described the invention as comprising certain features of construction and operation of parts, it is nevertheless to be understood that various changes may be made therein, if the changes do not depart from the spirit or scope of the claims.

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

1. A floating bridge structure comprising in combination, a fixedly supported lower beam, an upper beam adapted to support a load and mounted to move vertically relative to said lower beam, a yielding support connectin said lower beam with said upper beam, said yielding support comprising a lazy tong lever system laterally expandable relative to said structure comprising a series of diagonal levers pivoted together intermediate their lengths and at their ends, the center pivots thereof being joined to each other by tensional springs resisting lateral expansion of said system, the knuckles formed by the end pivots of one side of said system being adapted to sustain said upper beam and the knuckles formed by the end pivots of the opposite side being adapted to be sustained by said lower beam, for permitting vertical movement of said upper beam relative to said lower beam upon a load being applied to said upper beam, flexible restraining members connected to said upper and lower beams for limiting the upward vertical movement of said upper beam and means for limiting the vertical downward movement of said upper beam.

2. A floating bridge structure comprising in combination, columns, a lower beam fixedly supported on said columns, an upper beam adapted to support a load and mounted to move vertically on said columns relative to said lower beam, at yielding support connecting said lower beam with said upper beam, said yielding support comprising a lazy tong lever system laterally expandable relative to said structure comprising aseries of diagonal levers pivoted together intermediate their lengths and at their ends, the center pivots thereof being joined to each other by tensional springs resisting lateral expansion of said system, the knuckles formed by the end pivots of one side of said system being adapted to sustain said upper beam and the knuckles formed by the end pivots of the opposite side being adapted to be sustained by said lower beam, for permitting vertical movement of said upper beam relative to said lower beam upon a load being applied to said upper beam, chains connected to said upper and lower beams for limiting the upward vertical movement of said upper beams and bumpers mounted on said columns and upper beam for limiting the downward movement of said upper beam.

3. A floating bridge structure comprising collumns, a transom secured to said columns, a fixed bridge portion, a floating bridge portion connected to said fixed bridge portion above said transome and a yielding support mounted on said transom at the connecting point of said floating bridge portion and said fixed bridge portion, said yielding support including a lower beam mounted on said transom, an upper beam adapted to support a load and mounted to move vertically on said columns relative to said lower beam, an expandin and contracting mechanism arranged between said upper and lower beams, said expanding and contracting mechanism including a series of levers having upper and lower ends pivoted together and formed into pairs, said pairs of levers crossing each other at their medial points, pivot pins connecting said pins of said levers together in spaced relation at their medial points and pivot pins connecting one of the ends of each pair of end levers together in spaced relation,

, said upper ends of the middle levers pivoted to acme/i3 saia opp'er: beam and said abwer ends or other middle levers pivoted to said lower beam, rmiers carriedzonmhevotlrerrupper endsaof safd'levers and engagingasaid upper ibeanr, rollers eanriedeonthe other lower ends of jsaidiievers'and'zengagmgsaid lower beam and horizontally aligned tension sprin connecting said pivot pins togetherpsaid' roller carrying upper and lower ends of said-11eveis adapted to :move against the action ifi said springs laterally on :said rollersvfromsaid pivoted connected upper and lowereends 20f said middl levers under said-upper beam and ion-said low-ii beamesvsaid iupper beam yields ventically'gunder arlond.

4.: A" yielding .supportfor :a floating3hr ig.e .QQX prising in combination, a fixedlyisupported base, an upper beam thereabove adapted-to sunpont an eccentricandvariable*loadzand mounted to moyevertically relative to said base :While remaining parallel thereto, a lazy tongilever =-system' late rally expandable relative toy-said base and ,beam and interposed between the same, said system comprising a series-of-diagonal levermpivotedtogether --at their Emiddles andat their ends, the

center pivots thereof'being joined together-by tensional springs V-resisting lateral-expansion of the system, the knuckles formed by the upper endipivots of said system sustaining said loaded beam and the knuckles iformedby the JOWBIH'GIld pivots bein sustained by said base, A each ofsone pair -of :oppositeknuckles being epivotally connected \to rsaid base and said beam trespecltively andtheremaining upper-Fahd lowenknuckles earrying'bearing-meansadapted: to bear. against said base and beam respectively, :and cooperating:

guide means carried vby I the :baseand :beam for maintainin said baseandbeam in vertical alignment. 7

-5. A yielding support for a floating bridge comprising in combination, a fixedlyrsupported :base, an upper beam thereaboveadaptedto support-an eccentric and variable load-and mounted to move vertically relative to :said 'base While remaining parallel thereto, a lazy tong lever'system laterally=expandable relative to: said base :and :beam' Oppositeimuokles being mivotaliy :eonnected 5110' said- .base anti'saidbeam respectively-and :the remaining' upper and. lower knuckles carrying rollers'z adapted to doear againstsaLid :base and beam respectively, tracks mounted on said base "and beam engagingsaid rollers whemthe'latteymove laterally; as said beam yields :verticallyumderaa load, cooperating :guide cmeans carried by the basezand: the beam" for maintaining saidibase and beam in vertical alignment, bumpers carricd t'by the guide means .to limit :downward xmovement of.said beam, andzflexible connections between said: base and beamltolimit upward; movementiof the latter.

-..6.'.=A ".ponton bridge structureicomprismg .in

combination; supporting c01umns,:a-.transom:fix-T edly :snpported :thereon, an ;upper :beam :above said transom adapted :to support ;a' load and mounted to; move verticallyzorrsaid columns relativei'to'saida transom; abalk'adapter mounted'zim' said anpperabeam ifor :supporting :longitndirmt 75* 8f floamgfofia; zooniiinuous ponton .spam'm firstiitrestlespanwfithexbridger a lazy tong-lever system izlaterally expandable relative to said bridge strirctmie and interposed between said.

transom andzsaidimpperribeam, said system :commiis'ingmi-senies-of ini'a'gonal levers pivoted to.- gather intermediate their lengths and at their enda the eentermpivots thereof being joined together :by :t-EDSiOZXaii springs resisting lateral expansion lofathesystem, the knuckles formed: by the iupperiiendspivotsaof said system being adapt.-

ed to said. upper beam and the knuckles formed-iiby ithe lower end. pivots beingadapted to be: sustained by said transom, each of one pair of iopposite knucklesxbeing pivotally connected tossrid anansomandosaid beam respectively, and:

meansaonssaidi balkxadapterzzfor connecting the longitudinal flooring ithereto endprovidinganticulationcbetween thezcontinuous end span and the firstitnestle span oaths-bridge.

A-yieldingeupportfor a floating bridgecomprising :in :combmation,...a transom fixedly..isup ported byiwertical moiumns, van beam slid,- ably mounted on saiclcolumns abovesaidtran: som::gandi=.-adapted to support an eccentric and varyinguioadaaslazy i-.tong.vlever system lateraliy expandable lelatine 'ItO sm'd transom and beam. and interposed between the same, said system compnisingia seriemofizdiagonal levers @pivotedrtogather intermediate: their. lengths and: at their ends, the -center aivots thereof being joined togetherzby ztensionalz springsresisting zlatemlaaxpansiorr or ithe system; the knuckles formed (by thezunper pivots of said system being adapted to: sustain said movablezbeam .andzthe ak nuckles formed by-ithe lower-end lpivots being adapted=to:be sustainedzbyzsaid transom; eachotoneapairiofoppositezsknuckles being; pivotally conneoted to said transom-: and saidtbeam respectively and the remaining upper: and lQWEIikDUCklGS carryingbeaning means-adapted to-bearwagainstsaid transom and beam respectively, atracks mounted on'said transom zand :beamzengaging said bearings means as-theilatterrmove:laterallywhen saidbeam' yields veiztically'mndereailoadpand means to limit :both

downward and mpii ard movement .of said beam.

18.- ,Res l1ient supporting structure for supporting anditransm ttina anableloa s, w ch c mpris s, inicombmation, a-.-mova-b1e loadsupp rting m mbcrsa-nd fi1i3 Qn@ yLh3S mem er. and r s n meansinterposed between and connected to the load supporting member and :to the .base member andmaintainimz these members substantially parallelfithe said::resilient means comprising a lazy tcn-g dever system yieldable under variable loads iapplied ;to':any portion of the movable :load supporting :member :for enabling movement of thedoad supporting member EtOVZIdS the base member -under:the zforcerof a load applied thereto-;:the.:lany tonglever system including aseries of rdiagonali-levers :centrally :pivoted :together at theinends, and tensionalsprings; interconnecting the centerlpivots of ithe ilevers and resistinglateral expansion of the said levers,.the end pivots ofronelsid'esof the 'lever systemcontacting the movableaload supporting member and defining knuoklesmiaptedi to sustain the: said: movable load supportingemember; :the end :pivots of the. oppositeiside Qof :the lever: system.:contacting the base member and being. sustainedby the said base member.

J9. loadesupporting'; and transmitting istructare; which comprises. a: movable load supporting member sand :'a -:stationary base a member -towards Which .nthe' cmovable (load supportingamembemis moved by the force of a variable load applied to any portion of the surface thereof, a lazy tong lever system interconnecting the load supporting member and the base member, the said lazy tong lever system including a series of laterally expandable diagonal levers pivoted together centrally and at their ends, tensional springs interconnecting the center pivots of the levers and resisting lateral expansion of the lever system, the end pivots of one side of the lever system forming pivotal connecting knuckles with the movable load supporting member which knuckles sustain the said load supporting member, end pivots of the opposite side of the lever system forming pivotal connecting knuckles with the base member and being sustained by the base member, and guide instrumentalities interconnecting the movable load carrying member and the base member and including upright guide means mounted on the base member and guide brackets mounted on the load carrying member extending around the upright guide means for maintaining the load carrying member and base member in alignment.

10. A load supporting and transmitting structure which comprises. in combination, a movable load supporting member and a stationary base towards which the movable load supporting member is moved by the force of a variable load applied to any portion of the surface thereof, a lazy tong lever system interconnecting the load supporting member and the base member, the lever system including a series of laterally expandable diagonal levers pivotally connected together centrally and at their ends, tensional springs interconnecting the center pivots of the levers and resisting the lateral expansion of the said system, the end pivots of one side of the lever system forming pivotal connecting knuckles with the movable load supporting member, which knuckles sustain the load supporting member, end pivots of the opposite side of the lever system forming pivotal connecting knuckles with the base member and being sustained by the base member, guide instrumentalities interconnecting the movable load carrying member and including vertically disposed guide-standard means mounted on the base member and guide brackets mounted on the load carrying member and extending around the vertically disposed guide-standard means for maintaining the load carrying member and base member in alignment, and bumper means carried by the vertically disposed guidestandard means for limiting motion of the load carrying member toward the said base member.

11. A load supporting and transmitting structure which comprises, in combination, a movable load carrying member and a stationary base member towards which the movable load carrying member is moved by the force of a variable load applied to any portion of the surface thereof, a lazy tong lever system interconnecting the load carrying member and the base member, the lazy tong lever system including a series of laterally expandable diagonal levers pivotally connected centrally thereof and at their ends, torsional springs interconnecting the center pivots of the lever and resisting the lateral expansion of the said system, the end pivots of one side of the lever system forming pivotal connecting knuckles with the movable load carrying member,

which knuckles sustain the load carrying mem-- ber, end pivots of the opposite side of the lever system forming pivotal connecting knuckles with the base member and being sustained by the base ('10 member, guide instr'umentalities interconnecting the movable load carrying member and the base member and including vertically disposed guide standard means, and guide brackets mounted on the load carrying member extending around the vertically disposed guide standard means for maintaining the load carrying member and the base member in alignment, bumper means mounted on the said guide standard means for limiting motion of the load carrying member towards the base member, and flexible restraining means interconnecting the load carrying member and the base member for limiting motion of the load carrying member.

12. A load supporting and transmitting structure which comprises, in combination, a movable load carrying member and a stationary base member towards which the movable load carrying member is moved by the force of a variable load applied to any portion of the surface thereof, a lazy tong lever system interconnecting the load carrying member and the base member, the lever system including a series of laterally expandable diagonal levers pivotally connected centrally thereof and at their ends, torsional springs interconnecting the center pivots of the levers and resisting the lateral expansion of the said system, end pivots of one side of the lever system forming pivotal connecting knuckles with the movable load carrying member, which knuckles sustain the load carrying member, end pivots of the opposite side of the lever system forming pivotal connecting knuckles with the base member and being sustained by the base member, cooperating guide instrumentalities intercomnecting the movable load carrying member and the base member for maintaining the load carrying member and the base member in alignment, means carried by the base member for limiting movement of the load carrying member toward the base member, and flexible means interconnecting the load carrying member and the base member for limiting movement of the load carrying member away from the base member.

13. A load supporting and transmitting structure which comprises, in combination. a movable load carrying beam, and a stationary base member towards which the beam is moved by the force of a variable load applied to any portion thereof, a lazy tong lever system interconnecting the beam and base member, the lever system including a series of laterally expandable diagonal levers pivotally connected centrally thereof and at their ends, torsional springs interconnecting the center pivots of the levers and resisting the lateral expansion of the lever system, end pivots of one side of the lever system forming pivotal connecting knuckles with the said beam. which knuckles sustain the beam. end pivots of the opposite side of the lever system forming pivotal connecting knuckles with the base member and being sustained by the base member. bearing means carried by end pivotal connections of diagonal levers intermediate the end levers of the system, certain of the bearing means bearing against and supporting the said beam and others of the said bearing means bearing against and being supported by the said base member, guide means carried by the base member and the beam and cooperating to maintain the said beam and base member in vertical alignment, means carried by the base member for limiting downward movement of the beam, and flexible means interconnecting the beam and base member for limiting upward movement of the beam.

enema l4; :A load supporting and transmitting -struc--- ture comprising era :movable-Joad earrylng member and a/ relatively stationary base toward which the-load earryinggmember is 'moved :by the force or .e variable loadiapplied lto any -portion =of the surface thereoflrand w lazy -tongdever system interconnecting the loed carrying member-and the base and including: .a :plurality ot diagonal levers pivotelly interconnected at their centers andends, andlbe'mgclatma-lly expandable; sand tensional springs interconnected i at: the-center pivots'of the leversandlresistinglaterelexpansion or the lsaid levers, end ipivots 'of -One :side-ofithe lever system forming sustainmgknuckles-engaging the movable load earryi-ng member for sustaining.- the same; end v-pivotsiof i-the. opposite side of the leversystem engaging-the base and being sustainedbythesaid base.

'15. -A load supportingand transmitting strueture comprisinga movable load=carrying member and -a stationary base --towarde which 'the loa-d carrying member is. moved -=by theforce of a variablelload appliedlto anysportion either-surface oitbe load-carrying member, st-lazy tong lever system engaging the load marrying member and the stationarybase and i-eomprising a, series of diagonal levers pivoteditegether eezxtrallyand at their ends, tensional springs iinteseonnecting the center EPiVOtS of: the. lever system and :resisfing lateral expansion oi the lever System, the end pivotsoi oneside -of the lever system forming knuckles engaging and sustaining the movable load fcarrying member, endipivots on the opposite side-efthe lever system being engaged by the base and :sustained' thereby, and guide means on the load earrying member and on the base for maintaining-the load carrying member and [the base-inverticalalignment. =10

JOHN W. BERETTA.

REFERENCES CITED Thefollowing-referencesare of record in the fife of this patent:

GT-HER REFERENCES 'WarDepartment Manual TM-'5'276, October 13,1943. ('COpy in 14-27;)

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