Drydock lifting platform

Claim 2

A lifting type drydock having an elongated vertically movable multi-section platform including a plurality of platform sections each extending across the width of said platform and hingedly connected along adjacent edge portions to the next adjacent platform section, each of said platform sections including a main transverse lifting beam extending across the width of the platform section along one edge of the platform section, a plurality of longitudinal beams fixedly connected on one end to said main transverse beam and having their opposite ends pivotally connected to and supported by the main transverse beam of a next-adjacent platform section, secondary transverse support beams fixedly connected to said longitudinal beams and power driven lifting support means connected to the ends of said main transverse beams for lifting or lowering said main transverse beams to effect a unitary vertical movement of said movable multi-section platform.

Claim 3

The invention of said claim 1 wherein said main transverse lifting beams are I-beams and said longitudinal beams each comprise an I-beam of a height less than the height of said main transverse lifting beams.

Claim 4

The invention of claim 2 additionally including horizontal saddle plate members each respectively fixedly positioned on one of said main lifting beams beneath the ends of and providing support for said longitudinal beams adjacent the web of each of said main transverse lifting beams upwardly spaced above the lower flange of the respective main transverse lifting beam on which said saddle plates are mounted.

Claim 5

The invention of claim 3 wherein the pivotally connected ends of said longitudinal beams each include holding lug means extending downwardly from the lower flange of the longitudinal beam in a position adjacent the pivotally mounted end of the longitudinal beam and wherein the saddle plate members beneath the pivotally mounted end of said longitudinal beam each include an upwardly extending retaining lug means cooperable with said holding lug means for preventing axial movement of the pivotally supported end of each longitudinal beam from its supported position on the saddle plate.

Claim 6

The invention of claim 4 additionally including vertical stiffener plates fixedly attached to said main transverse lifting beams on opposite sides of said saddle plates supporting the pivotally mounted ends of said longitudinal beams for retaining said longitudinal beam ends from sidewise movement.

Claim 7

The invention of claim 1 wherein said main transverse lifting beams, said longitudinal beams and said secondary transverse beams are all I-beams.

Claim 8

The invention of claim 6 wherein the upper surfaces of said main transverse lifting beams and said secondary transverse support beams are positioned in a common horizontal plane.

Claim 9

The invention of claim 7 additionally including horizontal saddle plate members each respectively fixedly positioned on one of said main lifting beams beneath the ends of and providing support for said longitudinal beams adjacent the web of each of said main transverse lifting beams upwardly spaced above the lower flange of the respective main transverse lifting beam on which said saddle plates are mounted.

Claim 10

The invention of claim 6 wherein the pivotally connected ends of said longitudinal beams each include holding lug means extending downwardly from the lower flange of the longitudinal beam in a position adjacent the pivotally mounted end of each longitudinal beam and wherein the saddle plate members beneath the pivotally mounted end of each longitudinal beam each include an upwardly extending retaining lug means cooperable with said holding lug means for preventing axial movement of the pivotally supported end of each longitudinal beam from its supported position on its respective supporting saddle plate.

Claim 11

The invention of claim 9 additionally including vertical stiffener plates fixedly attached to said main transverse lifting beams on opposite sides of the saddle plate members supporting the pivotally mounted ends of said longitudinal beams for retaining said longitudinal beam ends from sidewise movement.

Claim 12

A lifting type drydock including an elongated vertically movable multi-section platform formed of a plurality of platform sections each extending across the width of said platform and hingedly connected along adjacent edge portions to the next adjacent platform section, said multi-section platform including a plurality of main transverse lifting beams extending across the width of the platform, a plurality of longitudinal beams extending between and supported by said main transverse lifting beams, each of said main transverse lifting beams being pivotally connected on one side to the ends of a first group of said longitudinal beams and being fixedly connected on its opposite side to the ends of a second group of said longitudinal beams, secondary transverse support beams mounted on said longitudinal beams and power driven cable means connected to the ends of said main transverse beams for lifting or lowering said main transverse beams to effect vertical movement of said movable multi-section platform.

Claim 13

A lifting type drydock including an elongated vertically movable multi-section platform formed of a plurality of platform sections each extending across the width of said platform and hingedly connected along adjacent edge portions to the next adjacent platform section, said multi-section platform including a plurality of main transverse lifting beams extending across the width of the platform, a plurality of longitudinal beams extending between and supported by said main transverse lifting beams, each of said main transverse lifting beams being pivotally connected on one side to the ends of a first group of said longitudinal beams and being fixedly connected on its opposite side to the ends of a second group of said longitudinal beams, secondary transverse support beams mounted on said longitudinal beams and power driven cable means connected to the ends of said main transverse beams for lifting or lowering said main transverse beams to effect vertical movement of said movable multi-section platform.

Claim 14

The invention of claim 11 wherein the individual beams of said second group of longitudinal beams are fixedly connected on each of their ends to two main transverse beams between which said beams of said second group extend and said individual beams of said first group of longitudinal beams are pivotally connected on each of their ends to two main transverse lifting beams between which said beams of said first group of longitudinal beams extend.

Claim 15

The invention of claim 12 additionally including buoyancy providing tank means fixedly positioned between said beams of said second group and the main transverse lifting beams to which said second group of longitudinal beams is connected.

Claim 16

The invention of claim 13 wherein said buoyancy providing tank is a variable buoyancy air tank.

Claim 17

The invention of claim 13 wherein said buoyancy providing tank comprises a "Styrofoam" filled tank.

Claim 18

The invention of claim 12 wherein said main transverse lifting beams and said longitudinal beams are I-beams.

Claim 19

The invention of claim 16 additionally including horizontal saddle plate members each respectively mounted on a main lifting beam fixedly positioned beneath the ends of and providing support for said first group of longitudinal beams adjacent the web of each of said main transverse lifting beams of said first group of beams upwardly spaced above the lower flange of the respective transverse lifting beam on which said saddle plates are mounted.

Claim 20

The invention of claim 17 wherein the pivotally connected ends of said first group of longitudinal beams each include holding lug means extending downwardly from the lower flange of the longitudinal beams of the first group of longitudinal beams in a position adjacent the pivotally mounted end of said longitudinal beams and wherein the saddle plate members beneath the pivotally mounted end of said longitudinal beams each include an upwardly extending retaining lug means cooperable with said holding lug means for preventing axial movement of the pivotally supported end of each longitudinal beam of said first group from its supported position of the saddle plate.

Claim 21

The invention of claim 18 additionally including vertical stiffener plates fixedly attached to said main transverse lifting beams on opposite sides of said saddle plates supporting the pivotally mounted ends of said first group of longitudinal beams for retaining the ends of said longitudinal beams from sidewise movement.

Claim 22

The invention of claim 18 additionally including buoyancy providing tank means fixedly positioned between said beams of said second group and the main transverse lifting means to which said second group of longitudinal beams is connected.

Claim 23

The invention of claim 20 wherein said buoyancy providing tank is a variable buoyancy air tank.

Claim 24

The invention of claim 20 wherein said buoyancy providing tank comprises a "Styrofoam" filled tank.

Claim 25

The invention of claim 11 wherein said longitudinal beams of said second group of longitudinal beams are fixedly connected to the respective sides of said main transverse lifting beams facing one end of said multi-section platform.

Claim 26

The invention of said claim 23 wherein said main transverse lifting beams and said longitudinal beams are I-beams.

Claim 27

The invention of claim 24 additionally including horizontal saddle plate members each respectively fixedly positioned beneath the ends of and providing support for said longitudinal beams of said first group of longitudinal beams, said saddle plates being respectively mounted on one of said main transverse lifting beams adjacent the web thereof.

Claim 28

The invention of claim 12 additionally including buoyancy providing tank means fixedly positioned between said beams of said second group and the main transverse lifting beams to which said second group of longitudinal beams is connected, said buoyancy providing tank means provides an upward force on said platform in an amount so that no more than approximately 10% of the weight of said platform is supported by said power-driven cable means.

Claim 29

The invention of claim 26 wherein said platform is movable between an upper limit position above which it cannot move and a lower position, said buoyancy providing tank means being positioned on said platform in a sufficiently low position to insure that said buoyancy tank means is always below the water level of the body of water with which the platform is associated even when said platform is in its upper limit position.

Claim 30

The invention of claim 27 wherein said buoyancy providing tank is a variable buoyancy air tank.

Claim 31

The invention of claim 27 wherein said buoyancy providing tank comprises a "Styrofoam" filled tank.

Claim 32

The invention of claim 26 wherein said buoyancy providing tank is a variable buoyancy air tank.

Claim 33

The invention of claim 26 wherein said buoyancy providing tank comprises a "Styrofoam" filled tank.

Claim 34

A drydock installation on a body of water having a maximum water level and a minimum water level, a fixed support, movable ship lifting platform means supported by said fixed support by power driven winch means mounted on said fixed support and connected to said movable platform, said platform being movable between an upper limit position and a lower limit position, buoyancy tank means on said platform submerged in said body of water providing a substantial upward buoyant force on said platform wherein said buoyancy tank means is positioned on said platform in a position to be substantially immersed in said body of water when said body of water is at its minimum water level and said platform is concurrently in its upper limit position so that the buoyancy tank means is always effective to provide said upward buoyant force on said platform for all positions of said platform.

Claim 35

A drydock installation on a body of water having a maximum water level and a minimum water level, a fixed support, movable ship lifting platform means supported by said fixed support by power driven winch means mounted on said fixed support and connected to said movable platform, said platform being movable between an upper limit position and a lower limit position, buoyancy tank means on said platform submerged in said body of water providing a substantial upward buoyant force on said platform wherein said buoyancy tank means is positioned on said platform in a position to be substantially immersed in said body of water when said body of water is at its minimum water level and said platform is concurrently in its upper limit position so that the buoyancy tank means is always effective to provide said upward buoyant force on said platform for all positions of said platform.

Claim 36

The invention of claim 32 wherein said buoyancy tank means comprises air tank means.

Claim 37

The invention of claim 32 wherein said buoyancy tank means comprises a tank containing plastic foam material.

Claim 38

The invention of claim 1 additionally including buoyancy providing tank means mounted on said platform sections for providing a buoyant force which is less than the weight of said platform sections.