US2568751A - Graving dock - Google Patents

Description

Sept. 25, 1951 E. T. LARsEN YGRAVING DOCK e Sheets-Sheet 1 Filed Nov. 22, 1946 lNl/EN TOR E/NAR 7T LARSE/V 8K WY 1 Sept. 25, 1951 E. 1 LARSEN 2,568,751

' GRAVING DOCK 6 Sheet-Sheet 2 Filed Nov. ,22, 1946 INVENTOR E/NAR 7. QARSEN B) W Y Sept. 25, 1951 Filed Nov. 22, 1946 E. T. LARSEN 2,568,751

GRAVING DOCK 6 Sheets-Sheet 5 INVENTOR E/NAR 7: LARSEN Sept. 25, 195i E. T. LARSEN GRAVING DOCK v 6 Sheets-Sheet 4 Filed Nov. 22. 1946 J lzvvclv ran ff/VAR r LARSEIY I I I 6 Sept. 25, 1951 E. T. LARSEN GRAVING DOCK 6 Sheets-Sheet 5 IN l/ENTOR EINAR 7'. LARSEN er W E. T. LARSEN GRAVING DOCK Sept. 25, 1951 6 Sheets-Sheet 6 Filed Nov. 22, 1946 INVENTOR E/NAR 1t LARSEN llllll Ill Patented Sept. 25, 1951 UNITED STAT E S PAT ENT OFFI CE 2,568,751 GRAviNG DOCK Einar T. Larsen, akland,-.,balii.,, assi gnor to Kaiser Steel Corporation Application November 22, 194d, Serial N6. 711;741

11 Claims.

This invention relates to gates for graving docks'which afford a dry basin, in' which ships can be repaired or otherwise serviced and new ships canibebuilt.

Such docks are conventionally located with the gate at the sea or other body of water in which: the ships can be floated which are to be serviced, repaired or built in the docks. The function of the gate when closed is to seal ofi the basin from such water so that the basin can be pumped dry to permit repair or other service, or construction of a ship therein, without substantial leakage of such water thereinto. The gate is opened-so that a ship to be repaired can be floated into the basin or a serviced or newly built-ship can be floated out of it. It has been considered necessary that graving dock gates be large and heavy w here large-ships are to be accommodated, v'v'ith theres'ulfithat it has taken a considerable period of time-to open or closethem. I Among the objects of this invention are to providea gate which can be opened and closed faster than'heretoiore'; to provide such agate and appurtenant parts which are simple inconstruct'ion and: easy to operate, and to provide means for easily and quickl'y opening and closingit. v

S uch objects are" accomplished by having the gate" move vertically, up to closed position, and down'toopen positionf'into a chamber below the docltni'outh; and another object of the invention isto prevent too great an accumulation of siltfor debris injsuch chamber.

Further objects of this' inven'tion are to provide. means which'operateat the end of the closing movement of r the gate to improve the sealing efiect, and also to provide means which break's the" seal at the beginning of the opening movement;

Still further object's'of this invention are todecrease the: gravity efiect'of the actualma's's of the gate, tovariably" control such gravity effect to causetlie gate to ascend, desce'ndor 'rei'nai1'1 stationar'yi-and to provide asafety means to retain the gate in'its upper onclosed'position.

Additional objects of the invention will heap parent on reading specification.

The above" objects are attained by application of' novelprincip'les antifby' novel structural features of theg'ate and appurtenant parts, as will appear more detailxli'reina' ft'er. The pre fe'rred exemplific'at'ion of the invention is illus'? determine accompanying dravvings, on'which' vFi mouthof the 'basin in section, with the gate in upperor closed position;

Fig.2is'a section on the line 22 on. Fig. 1; Fig. 3' is an enlargement of a part of Fig. 1, showing more details;

Figs. 5, 6 and "1 are sections on the'lin'es 4-4', 5' 5, 6 '6"an'd 1 1 respectively, on Fig. 3';

Fig-8 is a detail viewishowing a holding pin in lilafi iiifid' a Dpuf-i'i t-l'naI'll;"limi -11S in 1101120111331 Sdtibl'ff Fig. 9 is a sectibnon the l'ine 9-9 on Fig. 8; Fig. 10 is a top pla'ri view of the gate and basin mouth; Fig. 11 is a'section of the 'gate on the'line I [-11 on Fig. 10;" I

Fig.- 12 isfifs'ctidn Oh the lifie' 12-4 2 OIIFig 11;. Fig. 1 3' is a s'ec'tifin o th l-iifie' I3l3 0n Fig. 1; Fig. 14 is n enlarged vertical cross section through the gate and ate chamber; -s'1'i0'W'ifig' the gate in its' lower, c1osedpositionj I Fig. 'l5"is a-'s"dti the'liniFE-lfi on Fig. 14'; Fig. 16 is a'i'sectib'n'onth l'in'e iii-Won 1'4; Fig. 17 is an enlarged section' of a detail: and Fig; 18i's' a schematic view eta-"double act'ing hydraulic cylinder. I

k The preferred features of the invention fol-' low. The gateisibog like' and hollow, beingm'a' de of plates'yof stee'lor of any other suitable mat'eriaL-wit'h any 's'uitabl'e type of bracing that may be desired ftjrioyes"-prin eipally vertically, from its uppermofstjor" fully closed position into-a chairi her in which it assumes ,its'i lowermost or fully; open position; and *vice ve'rs'a. It also undergoes transverse movements-at the end" of its closing and-at ;the begfii ning of its opening movement's, t1ie f0flfl'i6i {brine purpose off rnaking' a seal, and thelatter'ior the' purpose-of breaking the sea-1, so that the sealing material will'n'ot be abraded or tornby the movement of the gate. Passages are providedin the te to allow watertofiow through it" a it"le' r enters the chamber.

Thegate' s provided itiithibne' ormore buoyancy'chambers'which is or arelocated tobalance the gateand arei below the, lowest water level;

for the'pu 'se of decreasing the weight eithegate. It is also providedwith-'o'neorrnore ballast chambers with riieans to" run water thereintol and'means preferably of tn jompr s ed air, typefto'ievacuate such water. The buoyancy and ba'l astsrsi be s qr e at t t r; ejfi' ct's ,bman e; each other so; that the gate will float stationary w en the' balla'st -chamber or chambers are fiI1ed to a predetermiiiedde'gref' a ntif se' wfith ess ball v t water pr sent; makin -1 cor'itr'ol of the "movement of the gate easy" and and will sink with more Sensitive to the amount of ballast water present so that the gate will move up or down as fast as desired. Springs resiliently terminate the upward and downward movements of the gate. In its lowermost position the gate rests on suitable supports at the bottom of the gate chamber; and it is held by safety means in its uppermost position. Means are provided to prevent an accumulation of silt or sediment at the bottom and mouth of the gate chamber. Although the gate has preferably all of these features, yet one or more may be omitted as occasion may make expedient. Referring now to the drawings for a detailed description, the gate 21 (Figs. 1, 2, 10, 11 and 12) which selectively closes and opens the mouth of the graving clock 22 moves downwardly into the gate chamber 23, Fig. 2, formed by a casing 24 preferably made of concrete and integral with the dock bottom 26 and dock opening sill 21. When open,

the gate permits a ship to float into or out of theydock, and when closed, it seals off the opening to permit evacuation of the water within the dock. The gate has a pluralityof hollow, boxlike subdivisions 28 (Fig. 11) some of which have openings 29 to permit water to pass through the gate as it is raised or lowered. Some of these subdivisions, as those designated 3| can be sealed off completely by suitable means to provide buoyancy chambers which lend buoyancy to the gate and thus make it lighter. Access to such chamber is provided by manholes 32 with a cover 33 to seal them, the covers being held in sealing position by a clamp 34 and a bolt 35 passing through a threaded opening in the clamp and pressing upon the cover. There may be one or more of such buoyancy chambers, any number of them that may be found expedient; and it is preferred that they so balance the effective Weight of the gate that there is no tendency for any part of the gate to rise or sink faster than another. Such chamber or chambers are to be sealed during the construction, installation or repair of the gate, before they are submerged.

One or more of the subdivisions of the gate, as for example that designated 36, has (or have) means to hold a controllably variable amount of ballast water, to provide a ballast chamber. The ballast chamber or chambers, similarly to the buoyancy chambers, is or are located so that no part of the gate has a greater tendency than another to rise or sink. Each ballast chamber 36 has a normally closed, inwardly opening valve 31 (Fig. 11) and a normally closed, outwardly opening valve 38, the former being preferably but not necessarily at the top and the latter at the bottom for a purpose which will appear hereinafter. The valve 38 is normally held closed by a spring 39, aided by the water pressure on the outer face of the valve. A vertical push rod 41 is of a length to loosely contact both the lower face of the valve 31 and the upper face of the valve 38. Brackets 42, through which the rod can slide, maintain it in proper position. A hydraulic cylinder 43, shown enlarged on Fig. 18, is carried by the gate, its piston rod 44 normally resting loosely on the upper face of the valve 31. Pipes 46 and 41 lead into the cylinder at one end, thereof, that is at one side of the piston 41a and pipes 48 and 49 at the other. Valves 51, 52, 53 and 54 control flow through each of these pipes respectively. Pipes 46 and 48 are each connected to a source of water under pressure (not shown), and pipes 41 and 49 are exhaust or waste pipes. A pipe 56 controlled by a valve 51 is connected to the ballast chamber 36 and to a source (not shown) of compressed air. All of the valves 51, 52, 53, 54 and 51 are located for convenient operation. The piston 41 at which carries the rod 44 can be moved selectively down or up by means of the valves 5|, 52, 53 and 54. With the valves 51 and 54 open and the valves 52, 53 and 51 closed, the hydraulic pressure will move the piston down, the piston rod 44 then opening the valve 31 as shown in dotted lines. This moves the push rod 4| down-to open the valve 38 against the pressure of the spring 38, as shown in dotted lines. With the valves 51, 54 and 51 closed and the valves 52 and 53 open, the piston and its rod will be moved upwardly by the hydraulic pressure, permitting the spring 39 to close the valve 38, which closes the valve 31 by means of the rod 4|. The gate is lowered by admitting suflicient water into the ballast chamber or compartment 36, which is accomplished by opening the valves 31 and 38, air within the compartment then escaping therefrom through the open valve 31 while water enters through the open valve 38 and perhaps also through the open valve 31. The gate. is raised by removing sufiicient water from the compartment 36, Which is accomplished by opening the compressed air valve 51. The air is under suificient pressure to open the valve 38 and force water present out therethrough. The push rod 41 then does not maintain the valve 31 closed, but the air pressure in the ballast compartment does. By properly designing the gate features afiording'buoyancy, and the ballast feature, with respect to each other and to the weight of the gate, any practical maximum speed of ascent and descent of the gate is attainable and such speeds of ascent and descent are easily variably controllable to any not greater than such maxima.

Projecting upwardly from the end walls of the casing 24 which receives the'gate when open, are walls 61 (Figs. 1, 6 and 7) which are preferably of concrete and may be integral with such end walls. Such walls 6| preferably have flanges 62 to form opposite U-shaped members which together form a passageway within which the gate moves. The gate itself hasa tapered cross section, being narrower at its sea side than at its dock side. Attached to its oblique ends are upperguide shoes 63 and lower guide shoes 64, by means of brackets 66 and 61 respectively. Guide rails 68 are attached to the walls 61 the guide shoes sliding along such rails as the gate ascends or descends. The major part of eachguide rail 68 is straight and vertical so that most of the movement of the gate in opening and closing is vertical. 7 There are however two jogs 69, 16

in each guide rail, one for the upper guide shoe and one for the lower, which cause the gate to move a short distance toward the dock side at the end of its closing movement and in the reverse direction at the beginning of its opening movement. Vertical portions 11 (Figs. 6 and 7) of a U-shaped sealing striplie between the end-v wise parts ,of the dock side face of the gate and the adjacent faces of the dockside flanges 62 when the gate is up, these vertical portions being connected by a portion '12 (Fig. 2) extending across between the lower part of the dock side face of the gate and the, dock side sill 13. The sealing stripmay be attached to either one of the members between which it is compressed, although it is often preferred to attach it to the gate. It extends upwardly (as at 11) to a point above the highestwater level, and ispreferably made of rubber or equivalent flexible waterproof material. It preferablyhas a cross section simi- ,-.over the shelf I01.

'"Blocks'I'OIi (Figs. 1, 13,

l'arto'that of a lamb chop, having aflatpor-tion 16 fo'r attachment purposes and an enlarged rounded portion'TI for sealing purposes. Ilan1ps 18 held by bolts I9 and nuts 80 aifix the sealing strip, for example to the gate. It is nowapparent that a water-tight seal is made between the gate and the structure forming themouth of the-dock basin by the movement of the gate at the end of its closing movement toward such structure; and similarly the gate moves away from such structure at the beginning of its opening movement to free the sealing material to minimize abrasion and tearing thereof.

The upper face of the bottom of the gate chamber is formed to have a series of bowl-like lconcavities or depressions 81 (Figs. '1, '2, 13, 14 and 16) extending across the width thereof, with the depressions closely adjacent each other and adjacent ones having common defining walls 82. Alpipe or conduit 83 is embedded or formed in such bottom, which has a cross section which increases from a smaller closed end 84 to. the larger open end 86, the latter being the outlet end. The gate chamber bottom has perforations 81 at the lowermost points of the depressions 8I, and the pipe 83 has perforations 88 connecting therewith. The end .86 of the pipe '83 opens into a well 89 in which is a pump 9I which pumps water within and flowing into the bottom .of the well 89 upwardly through a pipe 92 having an outlet 93 at the sea side of the gate and appurtenant .parts or at some remote point. This produces suction at the openings .81. Means such as a motor 94 is provided to drive the pump. Thus sediment and small debris which can build up a pile or cake within thegate chamber 23 will flow out with water removed by the pump 9|. Water will flow into the gate chamber from the sea as the pump is operated. Pipes 96 supply water under pressure to jets 91 which preferably have flared elongated outlets. These jets are arranged at or adjacent the bottom of the gate chamber, they are so orientated with respect to each other as toproduce a heavy swirl of water in each depression BI, and they can be used to break up any cake that may have formed and to aid in flushing out the bottom of the gate chamber. A riser 9,8 is connected to a suitable source of water under pressure and to the pipes 96. In the case of very large gates, the pump 9! may have a capacity of the order .oftwelve thousand (12,000) gallons per minute, and, the pipes 95 may have a diameter of the order of three (3') inches.

The gate sometimes remains closed for long periods of time, and means can be provided, if desired, to then prevent ingress of silt and debris into the gate chamber to lessen the necessity for frequent flushing thereof if conditions would otherwise require it. Such means may comprise aflat shelf II'II (Figs. 2 and 17) of steel or other suitable material attached to, and projecting from the face of, the gate, and a thick somewhat flexible sheet I 02 of rubber or equivalent mae terial attached to the gate sill and projecting The parts IOI and-I02 are so located that they contact to form a self-sealing means as the gate is closed to decrease. very substantially any ingress of silt or other solids into the gate chamber. A pipe I03 (Fig. 2) to which a series of nozzles l04 is connected with the nozzles directed toward the parts IOI and 1.02, can be used to project water, and thereby break up and remove any deposit, at the parts I04. and I02. 7 v c I 14 and 16) of wood or other :suitable materiaLrestonsQme of the high partsr82 of the bottom of thegate chamber which may-have fiat tops for this purpose, and are fixed in position .by attachment to the concrete by bolts 101. The blocks extend cross wise, in the direction between sea side and basin side, and the gate'rests upon them when in its lowermost 11051.- .tion, but its weight thereon is controllable to .a minimal. amount by controlling the buoyancy of the gate. The blocks are spaced apart from each other and need be but' few in number. Softening of. the .blow of the gate as it descends, upon the blocks, even though. it descends comparatively fast, can be accomplished by means of springs 108 located at both ends of blocks which are between the center of the bottom of the gate chamber and each end thereof. Vertical movable cyli-ndrical casings I09 of which the top ends are closed and the bottom ends are open, rest upon the springs, and prevent ingress of sediment'and debris to the spring. The springs rest upon depressed abutments III formed in. :the chamber bottom, surrounding which are annular passages M2 to permit axial movement .of the casings I09. The tops of the casings I09 are normally above the tops of the cross blocks, to receive and lessen the impact of the descending gate. Truncated-conical aprons .3 of rubber-or thexlike, attached suitablyto the bottom by .annur- Iar plates H4 held in place by bolts H6, contact the casing I09 as they move up and down and prevent ingress .of silt and. debris.

The gate is also stopped resiliently at therend of its upward movement by means shown on Figs. 1 and 3'. Brackets lI'I .are attached to the gate and cups [I18 are attached. to the brackets, as. by bolts H9. Coiled springs PM are suitably attached to the cups with their lower ends inthe bottoms thereof, the upper ends of the springs zheingfree. Brackets I 22 are attached, as by bolts I23, to convenient parts of each wall .6I, such brackets projecting over the springs I2 I. It is now apparent that the springs II9 strike against the brackets I22 as the gate rises, so that its :upward movement is resiliently stopped. I

'Thegate (Figs. 1, 11 and 12) has valve-con!- trolled passages I26 therethroughto permit water to flow from the sea to the dock basin, when work on a ship in the basin has been completed and it is desired to float the ship out. Valves I21 which control them comprise plate-like gate valve members I28 which are moved by-hydraulic cylinders I29 having appurtenant parts similar to those illustrated on Fig. 18 and operating simi-.-

direction by hydraulic cylinders I36 having appurtenant parts like, and operating similarly to, those illustrated on Fig. 18. Members I31 adapted to receive the pins are-attached to the gate and have vertically elongated grooves or openings I38 into which the pins can extend. The hydraulic cylinders are operated to extend the pins'when the gate hasreached its'uppermost position. The elongated grooves I33 are so, posi- 'tioned that the tops thereof are slightly above the pins I 33 to permit easy entrance of the pins there into. The gate can then be allowed to. remain there or to descend the very short distance 118095.- sary to make the tops of the grooves contact the pins. There need not be much weight onthe pins, due to the controllable buoyancy of the gate. Once the gate has been closed, the waterin the dock basin can be evacuated by suitable means, conventional or otherwise; and the increasing pressure of the water on the sea side of the gate holds it tightly closed. When the dock basin has again been filled with water, the hydraulic cylinders I36 are operated to withdraw the pins I33, raising the gate slightly first if this is necessary,

and the gate can then be opened by admitting A water to the ballast chamber.

Means can be provided to raise and support the gate for servicing or repairing it while a caisson gate (not shown) is used to prevent access of water thereto. The supporting means (Figs. 1, 2, 3, and 4) comprises crane carriages I4I .over each end of the gate and mounted to be moved in either direction between the sea side and the dock basin side. With this in view, girders I42 are supported on structural members I43 to form a, bridge over them and over each end of the gate. Rails I44 are afiixed to the girders and the carriages are mounted on flanged wheels I46 which ride on the rails. Threaded bars I41 are .suspended from the carriages by means of nuts, I48, they can extend through openings in attachment members I49, withdrawal from which can be prevented by nuts II. The members I49 can be permanently or removably attached to the gate by conventional means. The carriages I4I'oan be rolled to the proper positions, the bars I41 inserted through the attachment members I49 which may be attached to the gate at both ends thereof, and the gate can then be raised to any convenient height by turning the nuts I48 in the proper direction. Certain details have been illustrated and described for the purpose of explaining the invention without limiting it, and may be changed or omitted without departing from the spirit of the invention, the scope of which is set forth in the appended claims.

What is claimed is: 1; A graving dock having walls forming a mouth for a ship to pass through, a vertically movable gate to close and open said mouth, sealing means between said walls and said gate, shoes on said gate, guide rails on which said shoes ride to guide the vertical movement of said gate while preventing said sealing means from making a seal between said walls and said gate,

said guide rails having jogs therein to guide the gate to cause said sealing means to make a seal between said walls and said gate at the end of .the closing movement of said gate and to open for raising and lowering said gate including curved guide members attached to said wall and cooperating with projections on the edges of said 'gate for moving said gate laterally so as to bring said sealing strips into engagement with said tion, and means to support, said gate in open position with its bottom above the bottom of said chamber comprising a series of horizontally disposed blocks at the bottom of said chamber which project thereabove and a series of resilient members adjacent to andprojectin above said blocks to thereby cushion the impact of said gate as it comes to rest on said blocks.

3. A graving dock having walls forming a mouth for a ship to pass through, a, vertically movable. gate to close said mouth, a casing forming a chamber, to receive said gate under said mouth, said gate being opened by lowering it into said chamber and closed by raising it above the water level sealin strips on said gate, means for raising and lowering said gate including curved guide members attached to said walls and cooperating with projection on the edges of said gate for moving said gate laterally so as to bring said sealing strips into engagement with said walls when said gate is raised to a closed position, and resilient means to limit the upward movement of said gate comprising brackets attached to said gate having spring means mounted thereon and bracket projecting from the walls of the chamber and so positioned that both brackets resiliently engage each other and restrict the upward movement of said gate as it rises to the closed position.

4. A graving dock having walls forming a mouth for a ship to pass through, a vertically movable gate to close said mouth, a casing forming a chamber to receive said gate under said mouth, said gate being opened by lowering it into said chamber and closed by raising it above the water level sealin strips on said gate, means for raising and lowering said gate including curved guide members attached to said walls and cooperating with projections on the edges of said gate for moving said gate laterally so as to bring said sealing strips into engagement with said Walls when said gate is raised to a closed position, and means to remove water and sediment from the bottom of said chamber comprising laterally disposed spray pipes adapted to project water over the bottom of said chamber insuch manner as to dislodge deposits of sediment and a pump means adapted to discharge the water and sediment from the chamber.

5. A graving dock gate comprising walls forming a ballast chamber having first and second openings a first valve member at said first opening and operable by pressure from without said chamber, a second valve member at said second opening and openable by pressure from within said chamber, said members being openable by movement in the same direction, means to connect said chamber with a source of compressed air, a valve in said connecting means, means to exert pressure from without said chamber on said first member means to maintain said second member normally closed, means to cause said second member to open with said first member and said first member to close with said second member, said second member being openable independently of said first member, said first member being closable independently of said second member.

6. In a graving dock having walls and a mouth for ships to pass through, the combination of a vertically movable gate, means for alternately moving said gate upward to close and downward to open said mouth, sealing members rigidly fastened to the bottom and side edges of said walls, when said gate is raised to a closed po'si gate and adapted to contact the mouth portion of said dock when said gate has been elevated to close said mouth, and curved guide means located along and fastened to the side edges of said mouth and cooperating with projection on the side edges of said gate for moving said gate laterally to bring said sealing members into engagement with the mouth of said dock upon the elevation of the said gate.

'7. In a graving dock having walls forming a mouth for ships to pass through, the combination of a vertically movable gate, sealing strips rigidly fastened. to the bottom and side edges of said gate and adapted to contact the walls of said mouth, when the gate has been elevated to close said mouth, and means for alternately moving said gate upward to close said mouth and downward to open said mouth including curved guide elements fastened to the walls of said mouth and cooperating with projections on the side edges of said gate for moving said gate laterally to bring the sealin strips on said gate into complete contact with the walls of said mouth when said gate is elevated, and for isengaging said sealing strips from the walls of said mouth when said gate is lowered.

8. In a graving dock having a bottom and walls forming a mouth for ships to pass through the combination of a vertically movable gate, means for alternately moving said gate upward to close and downward to open said mouth, a casing forming a chamber below said mouth and adapted to receive said gate, when it is lowered, a plurality of flanges projecting inwardly from each side wall of the dock mouth so as to provide vertical channels adapted to receive the opposing side edges of the gate therein, sealing strips rigidly secured to the side edges of said gate and adapted to contact the flanges on said walls, a separate sealing strip secured to the bottom portion of said gate and adapted to contact the bottom of said dock when said gate is elevated and curved guide means located within the channel on the said walls and cooperating with projections on the said edges of the gate for moving the gate laterally to bring the said ber and closed by raising it about the water level,

sealing members fastened to the side and bottom edges of said ate and adapted to engage the bottom and walls of said dock so as to continuously encompass thermouth of said dock up to the water level when said gate is in a raised 5:

position, means for alternately raising and lowering said gate including curved guide means secured to the walls of said mouth and cooperat- 10 ing with projections on the side edges of said gate for alternately causing said sealin members to become engaged with and disengaged from the mouth of said dock, when said gate is raised and lowered and means for positively locking said gate while in a raised position.

10. A closure for graving docks and like comprising a compartmented gate adapted for vertical movement and to serve as a closure when in its upward position, U-shaped vertically extending channels located opposite each other at the entrance to the graving dock and extending below the bed of the dock a distance equal to at least the height of compartmented gate to thereby form a gate chamber, sealing strips rigidly fixed to the side edges and bottom of said gate, vertically extending rails having a plurality of jogs therein fixed to the base wall of each channel and adapted to cooperate with projections on the sides of said gate when said gate is raised, so as to move the gate laterally and bring the sealing strips on the side edges of said gate into engagement with the inner portions of said U-shaped channels.

11. In a graving dock having walls and a mouth for ships to pass through the combination of a vertically movable gate, means for alternately moving said gate upward to close and downwardly to open said mouth, resilient sealing members rigidly fastened to the bottom and side edges of said gate and adapted to contact the mouth portion of said clock, when said gate has been elevated to close said mouth, curved guide means located on the side edges of said mouth and cooperating with projections on the side edges of said gate for moving said gate laterally to bring said sealing members into engagement with the mouth of said dock upon the elevation of the said gate, a casing forming a chamber to receive said gate under said mouth when said gate is lowered, means for removing water and sediment from the bottom of said chamber comprising spray pipes laterally disposed in the bottom of said chamber and in such a manner as to dislodge deposits of sediment and a pump means adapted to discharge the water and sediment from the chamber, and means for positively locking said gate while in an elevated position.

EINAR T. LARSEN.

REFERENCES CITED The-following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,530,394 Muller Mar. 17, 1925 1,618,545 Mann Feb. 22, 1927 FOREIGN PATENTS Number Country Date 25,970 Great Britain 1901

Images