DOCK AND WHARF FENDERS
United States Patent 3853084
The present invention relates to dock and wharf fenders comprising scissor-like moving pairs of lever members which are connected, at a common point, hingedly to a wale, the opposite ends of each pair being connected in spaced relationship to one another to a longitudinal member which is adapted to be fixedly attached to the dock wall, these spaced ends of the pair of levers being slidingly connected with the longitudinal member and acting against rubber buffers provided within or on the longitudinal member.
US Patent References:
WHARF WITH A SHOCK-ABSORBING DEVICE
Morini - August 1969 - 3459004
/3564858.html
Pogonowski - February 1971 - 3564858
WHARF WITH A SHOCK-ABSORBING DEVICE
Morini - August 1969 - 3459004
/3564858.html
Pogonowski - February 1971 - 3564858
Application Number:
05/364118
Publication Date:
12/10/1974
Filing Date:
05/25/1973
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
405/215
International Classes:
B63C1/10; E02B3/26; B63C1/00; E02B3/20; E02B3/22
Field of Search:
114/219 61/48 293/84,89
Primary Examiner:
Blix, Trygve M.
Assistant Examiner:
O'connor, Gregory W.
Attorney, Agent or Firm:
Toren, Mcgeady And Stanger
Claims:
What is claimed
1. Dock wharf fenders, comprising a first rigid longitudinal member arranged to be affixed to and to extend along a dock or wharf wall, a pair of elongated slots formed in said first member with each of said slots located adjacent an opposite one of the ends of said first member and extending in the longitudinal direction of said first member, a second rigid longitudinal member disposed in generally parallel relation with said first member and being spaced laterally from said first member so that it is located outwardly from the dock or wharf wall, a pair of elongated slots formed in said second member with each of said slots located adjacent an opposite one of the ends of said second member and extending in the longitudinal direction of said second member, a pin associated with each of said slots in said first and second members with each said pin being freely movable through its associated said slot in the direction of said slot and with the axis of said pin extending transversely to the longitudinal axis of said member in which said slot is located, a first lever and a second lever arranged in separated and crossing relationship, said first and second levers each extending between said first and second members and each being connected to a different one of said pins in said first and second members, said first and second levers crossing at a location intermediate their ends, a rubber buffer located at each of the ends of said first and second levers, each said rubber buffer being positioned along a portion of the path of said slot located at the end of said lever with which said buffer is associated so that a force transmitted against said second member in the direction normal to the longitudinal direction of said second member is transmitted over said first and second levers to said first member and is absorbed as said pins in said slots in said first and second members are forced against said rubber buffers associated therewith.
2. Dock and wharf fenders, as set forth in claim 1, wherein said first and second members extend horizontally, said pins in said slots extend vertically and said first and second levers cross at approximately the mid-point between their ends.
3. Dock and wharf fenders, as set forth in claim 1, wherein a wale is attached to and extends in parallel relation with said second member on the side thereof facing away from said first member.
1. Dock wharf fenders, comprising a first rigid longitudinal member arranged to be affixed to and to extend along a dock or wharf wall, a pair of elongated slots formed in said first member with each of said slots located adjacent an opposite one of the ends of said first member and extending in the longitudinal direction of said first member, a second rigid longitudinal member disposed in generally parallel relation with said first member and being spaced laterally from said first member so that it is located outwardly from the dock or wharf wall, a pair of elongated slots formed in said second member with each of said slots located adjacent an opposite one of the ends of said second member and extending in the longitudinal direction of said second member, a pin associated with each of said slots in said first and second members with each said pin being freely movable through its associated said slot in the direction of said slot and with the axis of said pin extending transversely to the longitudinal axis of said member in which said slot is located, a first lever and a second lever arranged in separated and crossing relationship, said first and second levers each extending between said first and second members and each being connected to a different one of said pins in said first and second members, said first and second levers crossing at a location intermediate their ends, a rubber buffer located at each of the ends of said first and second levers, each said rubber buffer being positioned along a portion of the path of said slot located at the end of said lever with which said buffer is associated so that a force transmitted against said second member in the direction normal to the longitudinal direction of said second member is transmitted over said first and second levers to said first member and is absorbed as said pins in said slots in said first and second members are forced against said rubber buffers associated therewith.
2. Dock and wharf fenders, as set forth in claim 1, wherein said first and second members extend horizontally, said pins in said slots extend vertically and said first and second levers cross at approximately the mid-point between their ends.
3. Dock and wharf fenders, as set forth in claim 1, wherein a wale is attached to and extends in parallel relation with said second member on the side thereof facing away from said first member.
Description:
The main function of a dock fender is to prevent ships and also the dock itself from being damaged during moving or berthing of a vessel. In all those cases where an absolute and most perfect control over the movement of the ship can be exercised and, in addition, under the most ideal conditions, a vessel might approach a dock and be berthed without previously striking the dock. However, such conditions are practically unattainable and it is almost impossible to dock a ship in that way since ideal conditions can never be reached. For this reason docks and wharf walls are provided with fenders which, in their simplest form, are horizontal and vertical strips of timber which are fastened to the face of the dock. It is also known to place vertical members such as wooden piles which are driven to the sea bed and which are connected at the top to the dock. All such wooden fenders are quite limited in their absorbing energy capacity mainly because of the limitation of their deflection. For that reason, rubber fenders are now being used. Rubber fenders are deflectable and deformable to a great extent and can therefore absorb a much greater amount of kinetic energy of an approaching ship.
However, rubber fenders which are in use at present are capable of meeting the conditions of vessels of a magnitude in the range of 100,000 tons displacement and it is rather difficult to design fenders which might meet the conditions of larger ships. One of the reasons for this is that the forces which are exerted on the berth are of such magnitude that there will be required very heavy berths which are very costly to construct. Thus, with the use of oil tankers of 200,000 and more tons displacement the fenders are not sufficient to meet the conditions of such a vessel. It would be impossible practically to increase the size of conventional fenders to such an extent that they would be able to meet the requirements of modern huge vessels and be suited to absorb their kinetic energy.
With most of the existing rubber fenders the forces meeting the latter act in a direction normal to the fender and to the dock and the deformation of the fender is in accordance therewith. Rubber fenders will deflect approximately 70 to 80 per cent of the maximum deflection with practically very small force. The efficiency of their energy absorption is only in the latter stages of their deflection, i.e., in the last twenty to thirty per cent which is equal to 2 to 3 inches approximately.
BRIEF SUMMARY OF THE INVENTION
The present invention starts from the deliberation that the deflection of the rubber pieces constituting the fenders will be in a direction parallel to the face of the berth of the dock and due to a linkage system there would be present a rapid increase of the force acting from the ship on the fender and therefore the efficiency of the fender would become much greater. According to the invention, therefore, a fender is suggested which comprises scissor-like moving pairs of lever members which are connected, at a common point, hingedly to a wale, the opposite end of each pair being connected in spaced relationship to one another to a longitudinal member which is adapted to be fixedly attached to the dock wall, these spaced ends of the pair of levers being slidingly connected with the said longitudinal member and acting against rubber buffers provided within or on the said longitudinal member.
It will be seen that in such an arrangement of a fendering system wherein the deflection of the rubber fenders is in a direction parallel to the berth, the system of forces is a closed one. Consequently the rubber units can be deflected to the maximum and the loads which are exerted on the rubber units, although very big, are internal forces in a closed system and do not affect the structure of the berth.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the annexed drawings. FIG. 1, is a schematic sketch illustrating the forces in such an arrangement, FIG. 2 is a plan view of a fendering system according to the invention and FIG. 3 is a like view of a slightly different practical embodiment of the new fendering system.
Turning first to FIG. 1, this will explain the theoretical basis of an arrangement according to the invention. The external horizontal forces P 2 perpendicular to the berth and exerted on the berth are equal to P 1 tgα (see FIG. 1), Tgα decreases with the increase of P 1 , therefore, in spite of the big internal forces P 1 , the external forces P 2 are comparatively small. This fact makes the proposed fender specially suited to be installed in existing berths as well as new ones, and will increase the berthing capacity considerably without endangering the structure.
Turning now to FIG. 2, to the dock wall or berth indicated by the letter B are affixed a number of rigid longitudinal members 1. Near their ends these members are provided with elongated slots 2 in which can move pins 3. These vertical pins serve for connecting thereto the free ends of a pair of levers 4a and 4b. The opposite ends of each of the levers 4a and 4b are connected together at 5 by a vertical pin about which the levers can swing. To the said pin i.e., to the apex of the triangle formed by the levers 4a and 4b and fixed member 1 is attached by means of connectors 6 an elongated wale 7. Near the ends of each member 1 and enclosed in appropriate housings are provided rubber buffer 8 which bear against the ends of the levers 4a and 4b. The wale 7 is connected in this way to a number of pairs of levers, two of which are shown in FIG. 2.
A ship indicated by the letter S strikes against the wale 7 when being berthed, pushing the latter in the direction of the arrow a. This causes all levers 4a and 4b in a pair to spread apart, increasing the angle at the apex of the said triangle and forcing the opposite end of the levers 4a and 4b against the rubber buffers 8 thereby compressing the latter.
It will be seen that in this system the rubber buffers can be compressed to the maximum and that on the other hand the structure of the berths is in no way affected.
In this construction according to FIG. 3 instead of a longitudinal member 1 in each lever unit, there are provided two such members 1 and 1a. The member 1 is affixed to the berth B in the same way as member 1 in FIG. 2, while the second member 1a, parallel to 1 is connected with the latter by means of crossing levers 40 and 40a. These levers cross one another at superposed levels and are not connected at the crossing point. In each of the longitudinal members 1 and 1a are provided the elongated slots 2 in which move the vertical pins 3 while rubber buffers 8 are provided at the ends of the levers 40 and 40a. To the members 1a is attached a wale 7 against which the ship S can be berthed.
Again the ship exerts pressure onto the wale 7 with the result that member 1a is brought nearer to member 1 and the levers 40 and 40a exert pressure on the buffers 8, compressing the latter and absorbing the kinetic energy of the ship approaching.
The following comparative examples will make the invention even more clear:
An existing breasting dolphin of 45 ft. length has to its full length a cylindrical rubber fender of 15 inches O.D. v 71/2 inches I.D. with a maximum deflection of 71/2 inches. The energy absorptive capacity is 135,000 lb./ft. and the maximum horizontal force exerted on the dolphin from the docking ship is 202.5 tons for which load the dolphin was designed. This dolphin is suitable to accomodate berthing ships of 70,000 ton displacement with an approaching speed of 20 ft/min. (0.333 ft. per/sec.) normal to the berth. If Raykin fenders are to be installed, four units of F-50 model will exert a horizontal force of 190 and the maximal and energy absorption capacity is 340,000 1b./ft. suitable for a docking ship of 175,000 ton displacement.
If the proposed fender according to FIG. 3 will be installed, one unit having four rectangular rubber pieces of 12 inches × 12 inches × 5 inches and 4 ft. length each then the energy absorbing capacity of the dolphin will amount to 510,000 lb.ft. and will be capable of taking a docking ship of 250,000 ton displacement with the same speed of 20 ft./m normal to the berth. The horizontal force 2P 2 from the docking ship on the dolphin will not exceed 200 ton for which the dolphin was designed.
However, rubber fenders which are in use at present are capable of meeting the conditions of vessels of a magnitude in the range of 100,000 tons displacement and it is rather difficult to design fenders which might meet the conditions of larger ships. One of the reasons for this is that the forces which are exerted on the berth are of such magnitude that there will be required very heavy berths which are very costly to construct. Thus, with the use of oil tankers of 200,000 and more tons displacement the fenders are not sufficient to meet the conditions of such a vessel. It would be impossible practically to increase the size of conventional fenders to such an extent that they would be able to meet the requirements of modern huge vessels and be suited to absorb their kinetic energy.
With most of the existing rubber fenders the forces meeting the latter act in a direction normal to the fender and to the dock and the deformation of the fender is in accordance therewith. Rubber fenders will deflect approximately 70 to 80 per cent of the maximum deflection with practically very small force. The efficiency of their energy absorption is only in the latter stages of their deflection, i.e., in the last twenty to thirty per cent which is equal to 2 to 3 inches approximately.
BRIEF SUMMARY OF THE INVENTION
The present invention starts from the deliberation that the deflection of the rubber pieces constituting the fenders will be in a direction parallel to the face of the berth of the dock and due to a linkage system there would be present a rapid increase of the force acting from the ship on the fender and therefore the efficiency of the fender would become much greater. According to the invention, therefore, a fender is suggested which comprises scissor-like moving pairs of lever members which are connected, at a common point, hingedly to a wale, the opposite end of each pair being connected in spaced relationship to one another to a longitudinal member which is adapted to be fixedly attached to the dock wall, these spaced ends of the pair of levers being slidingly connected with the said longitudinal member and acting against rubber buffers provided within or on the said longitudinal member.
It will be seen that in such an arrangement of a fendering system wherein the deflection of the rubber fenders is in a direction parallel to the berth, the system of forces is a closed one. Consequently the rubber units can be deflected to the maximum and the loads which are exerted on the rubber units, although very big, are internal forces in a closed system and do not affect the structure of the berth.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the annexed drawings. FIG. 1, is a schematic sketch illustrating the forces in such an arrangement, FIG. 2 is a plan view of a fendering system according to the invention and FIG. 3 is a like view of a slightly different practical embodiment of the new fendering system.
Turning first to FIG. 1, this will explain the theoretical basis of an arrangement according to the invention. The external horizontal forces P 2 perpendicular to the berth and exerted on the berth are equal to P 1 tgα (see FIG. 1), Tgα decreases with the increase of P 1 , therefore, in spite of the big internal forces P 1 , the external forces P 2 are comparatively small. This fact makes the proposed fender specially suited to be installed in existing berths as well as new ones, and will increase the berthing capacity considerably without endangering the structure.
Turning now to FIG. 2, to the dock wall or berth indicated by the letter B are affixed a number of rigid longitudinal members 1. Near their ends these members are provided with elongated slots 2 in which can move pins 3. These vertical pins serve for connecting thereto the free ends of a pair of levers 4a and 4b. The opposite ends of each of the levers 4a and 4b are connected together at 5 by a vertical pin about which the levers can swing. To the said pin i.e., to the apex of the triangle formed by the levers 4a and 4b and fixed member 1 is attached by means of connectors 6 an elongated wale 7. Near the ends of each member 1 and enclosed in appropriate housings are provided rubber buffer 8 which bear against the ends of the levers 4a and 4b. The wale 7 is connected in this way to a number of pairs of levers, two of which are shown in FIG. 2.
A ship indicated by the letter S strikes against the wale 7 when being berthed, pushing the latter in the direction of the arrow a. This causes all levers 4a and 4b in a pair to spread apart, increasing the angle at the apex of the said triangle and forcing the opposite end of the levers 4a and 4b against the rubber buffers 8 thereby compressing the latter.
It will be seen that in this system the rubber buffers can be compressed to the maximum and that on the other hand the structure of the berths is in no way affected.
In this construction according to FIG. 3 instead of a longitudinal member 1 in each lever unit, there are provided two such members 1 and 1a. The member 1 is affixed to the berth B in the same way as member 1 in FIG. 2, while the second member 1a, parallel to 1 is connected with the latter by means of crossing levers 40 and 40a. These levers cross one another at superposed levels and are not connected at the crossing point. In each of the longitudinal members 1 and 1a are provided the elongated slots 2 in which move the vertical pins 3 while rubber buffers 8 are provided at the ends of the levers 40 and 40a. To the members 1a is attached a wale 7 against which the ship S can be berthed.
Again the ship exerts pressure onto the wale 7 with the result that member 1a is brought nearer to member 1 and the levers 40 and 40a exert pressure on the buffers 8, compressing the latter and absorbing the kinetic energy of the ship approaching.
The following comparative examples will make the invention even more clear:
An existing breasting dolphin of 45 ft. length has to its full length a cylindrical rubber fender of 15 inches O.D. v 71/2 inches I.D. with a maximum deflection of 71/2 inches. The energy absorptive capacity is 135,000 lb./ft. and the maximum horizontal force exerted on the dolphin from the docking ship is 202.5 tons for which load the dolphin was designed. This dolphin is suitable to accomodate berthing ships of 70,000 ton displacement with an approaching speed of 20 ft/min. (0.333 ft. per/sec.) normal to the berth. If Raykin fenders are to be installed, four units of F-50 model will exert a horizontal force of 190 and the maximal and energy absorption capacity is 340,000 1b./ft. suitable for a docking ship of 175,000 ton displacement.
If the proposed fender according to FIG. 3 will be installed, one unit having four rectangular rubber pieces of 12 inches × 12 inches × 5 inches and 4 ft. length each then the energy absorbing capacity of the dolphin will amount to 510,000 lb.ft. and will be capable of taking a docking ship of 250,000 ton displacement with the same speed of 20 ft./m normal to the berth. The horizontal force 2P 2 from the docking ship on the dolphin will not exceed 200 ton for which the dolphin was designed.