US3016256A

US3016256A - Apparatus for landing loads on a rolling ship

Info

Publication number: US3016256A
Application number: US612282A
Authority: US
Inventors: Loerwood C Wasson
Original assignee: AO Smith Corp
Current assignee: AO Smith Corp
Priority date: 1956-09-26
Filing date: 1956-09-26
Publication date: 1962-01-09
Anticipated expiration: 1979-01-09

Description

L. c. wAssoN 3,016,256

APPARATUS FOR LANDING LOADS ON A ROLLING SHIP Jan. 9, 1962 2 Sheets-Sheet 1 Filed Sept. 26, 1956 I a l v INVENTOR. LOERWOOD C. WAssoN BY 4.40am

Nitorneys Jan. 9, 1962 c. wAssoN 3,016,256

APPARATUS FOR LANDING LOADS ON A ROLLING SHIP Filed Sept. 26, 1956 I 2 Sheets-Sheet 2 zzvmvron Lomwo 0D C. WASSON NilornagS United States Patent 3,016,256 APPARATUS FOR LANDHNG LOADS ON A ROLLING SHIP Loerwood C. Wasson, WauWatosa, Wis., assignor to A. 0.

Smith Corporation, Milwaukee, Wis., a corporation of New York Filed Sept. 26, 1956, Ser. No. 612,282 6 Claims. (Cl. 294-67) This invention relates to an apparatus for transferring loads to a moving platform such as the deck of a ship which is rolling or pitching in a heavy sea.

A big problem in the transferring of men and materials to the deck of a ship that is moving in a heavy sea is the timing of contact between the load and the deck. It is necessary to provide a contact between the load and the deck which will not result in dangerously high impact forces. For example, if a load makes contact with the deck of a ship at a point Where it has its greatest upward velocity (estimated to be 6.28 ft; sec. from a sea running 6 feet Waves at intervals of 3 seconds) the load, assumed to be stationary at the point of impact, will have to take on the velocity energy that would be associated with this maximum velocity of the deck. In order to impart that much energy, a force of acceleration between the deck and the load would have to be developed which would accelerate the load to the required velocity in a very short time. A dynamic analysis of such a system would be rather complex, but by use of a well known relationship in mechanics the limiting factors in the system can be determined. That relationship is that a dynamic load applied to a spring system (which is in this. case exemplified by the deck structure as the spring system, and the energy being imparted as the dynamic load) will deflect the spring system until it has stored up as much energy as was in the dynamic load. By assuming reasonable deflections of the load When it contacts the deck, one can estimate the amount of force exerted on the deck by the necessity of accelerating the load to the velocity of the deck at the moment of impact. For example, if the deck were of such a construction that it would deflect one half an inch when a load was encountered at the 6.28 ft. per second velocity, the force on the deck would be 30 times the weight of the load. For example, if a load weighing 1000 pounds were contacted with the deck when the deck had an upward velocity of 6.28 ft. per sec. the deck would experience a force that would be equivalent of a 30,000 pound load resting on the deck under static conditions. If the deck were strengthened so that the deflection were only inch, the force would go up to 60,000 pounds. For this reason, strengthening of the deck to absorb the loads.does not solve the impact problem.

Another problem that is encountered in the transfer of men and materials from a stationary platform to a boat moving in a heavy sea is the fact that the load will not always hit the deck in such a way that the impact force is centered on the load. Consequently, the force that is imparted to the load becomes a couple rather than a straight upward force. For example, if the load mentioned before were to contact a sloping deck so that 3,016,256 Patented Jan. 9, 1962 load and to absorb that energy over a considerably greater distance. According to the invention, the maximum force developed by the load can be brought down the outer side of the container carrying the load were the' point at which the impact. force were applied, "it would set up a reaction inthe load thatwould cause theload to rotate'about its center of gravity. With a force ofsuch great magnitude (30 to 60 times the weight of the load) the turning moment could easily causethe load to tip over, spilling the contents of the carrier on the deck, with possible injury to men, and damage to materials.

The invention is directed to absorbing the energy that has to be imparted upon the change in; velocity of the V .5, which is carried by a pistonrod 6, is slidably disposed.

to any desired amount limited only by the static weight of the load and the distance over which the energy is absorbed.

More specifically, the loading apparatus of the invention consists of a basket for carrying men or material with three or more cylinders mounted in spaced relation on the periphery of the basket. Pistons are slidably disposed within the cylinders and the lower end of each piston rod is connected to a leg, and the inner end of each leg is pivotally attached to the basket. The outer end of each leg terminates in a foot which is adapted to engage or contact the surface of the deck or other platform onto which the load is to be deposited. In another embodiment, the feet are connected directly to the lower end of the piston rods.

As the basket is lowered toward the deck, one or more of the feet contact the deck and the pistons are thereby forced upwardly in the cylinders against the fluid pressure therein to absorb the shock of contact with the deck. If the ship or platform contacts the load while the platform has its maximum velocity in the upward direction, the distance that the fluid cylinder pistons will move is at a maximum. The maximum load that can be applied to the deck is limited by the force that can be sustained by the cylinders and since this force is adjusted to a value just slightly higher than the weight of the load, the impact forces the load on the deck will be at a minimum. Since the maximum force that can be applied to the basket on any one piston location is the force that can be sustained by that piston, the moment forces that can develop to overturn the basket can be controlled to a point where they cannot become high enough to accomplish an overturning action. i

Other objects and advantages of the invention will appear in the course of the following description.

In the drawings:

FIGURE 1 is a top plan view of the loading apparatus shown in FIG. 2 with parts broken away,

FIG. 2 is a section taken along lines 2-2 of FIG- URE 1;

FIG. 3 is a vertical section similar to FIG. 2 of modified form of the invention using a liquid for the fluid pressure medium;

- FIG. 4 is a side elevation of a second modified form of the invention using a central fluid cylinder and showing the portion of the apparatus as the same contacts the deck of a ship; and I 1 FIG. 5 is a view similar to FIG. 4 showing the apparatus resting on the deck. 7

Referring to the drawings, there is shown an apparatus for loading materials onto a moving'platform such as the deck of a ship rolling in heavy seas.

The apparatus comprises a generally cylindrical basket 1 or other supporting member which is mounted on a base plate'2 and is adapted to contain or support the material to be transferred. The basket may be formed as'a solid member of metal, plastic or the like or'it may be a screened or perforated member as shown in the drawing. I M a Three fluid cylinders 3 are-secured to projections .4 formed in the base plate 2v and are. disposed at spaced locations around the'periphery of the basket. A piston within eachof the cylinders 3. Each piston rod 6 extends downwardly through a suitable opening in the lower end of the respective cylinders 13 and projections land is pivotally secured to "the central prortionsof a generally box-shaped leg 7.

Each of the legs 7 is formed of a pairof-side-plates;

8 which are joined together at their upper extremities by an upper plate 9. The upper plate 9 is provided with an elongated opening 10 through which the lower end of the corresponding piston rod 6 extends.

A pair of generally hemispherical-shaped bearings 11 are disposed on the lower end of each piston rod 6 on either side of the upper plate 9. The lower of the bearings 11 is retained on the corresponding rod by means of a nut 12.

The combination of the elongated opening 10 and the hemispherical bearings 11 permits the piston rod 6 to remain in engagement with the leg 7 even though the legs are pivoted and the axis of opening 10 is moved out of alignment with the axis of rod 6.

Each of the legs 7 is pivotally attached at its inner end to the base plate 2. This is accomplished by securing a plurality of blocks 13 to the lower surface of the base plate and the bifurcated inner ends of the legs 7 are pivotally secured to the corresponding blocks 13 by pins 14.

The side plates 8 of each of the legs 7 converge and are joined together at the outer end to provide a foot 15 which is adapted to contact the platform or deck onto which the load is to be deposited. Each foot 15 is enlarged and is provided with generally rounded outer corners 16. The rounded corners 16 are adapted to initially strike the deck, and as the load is lowered to rest on the deck, the point of contact between feet 15 and the deck moves or pivots to the central portion of the feet.

The basket 1 is raised and lowered by means of rods 17 which are pivotally attached to lugs 18 on feet 15. The upper end of each of the rods 17 is connected together by a ring 19. A series of cables 20 are attached to loops 21 on ring Iii and the cables in turn are connected to a crane, winch or other apparatus which can be used to raise and lower the structure. To guide the rods 17 in vertical movement, an arm 22 is attached to each of the cylinders 3 by means of brackets 23. Each of the arms 22 is formed with an elongated slot 24 through which the respective rod 17 extends. The rods 17 move vertically in accordance with movement of piston and the slots 24 serve to maintain the rods in alignment.

To supply fluid pressure to the cylinders 3, a pressure tank 25 is secured centrally within the basket 1. A compressor 26 is disposed on the top of the tank 25 and serves to compress the fluid, such as air-,and deliver the same to the pressure tank 25 through a conduit 27. A pressure regulator 28 is disposed in the conduit 27 and serves to regulate or control the pressure of the fluid within tank 25.

Fluid pressure is conducted from tank 25 to the upper end of each cylinder 3 by means of a conduit 29. A check valve 39 is disposed in each of the conduits 29 and serves to permit the free flow of fluid from the upper end of cylinder 3 into the tank 25 but prevents the flow of fluid from the tank to the cylinder.

In addition, a by-pass conduit 31 is connected around check valve 30, and a restricted opening control valve 32 is located in by-pass conduit 31. The valve 32 permits the slow passage of fluid 'between'the tank 25 and the cylinder 3. v

In operation of the apparatus, the pressure within the tank 25 and cylinders 3 is adjusted through pressure regulator 28 to a value just slightly higher than the Weight of the apparatus plus the maximum load to be carried so that the fluid pressure within the cylinders As the apparatus approaches the deck, one or more of the feet 15 contact the deck with the result that the corresponding leg 7 is pivoted upwardly causing piston 5 to move upwardly within the respective cylinder. This upward movement of piston 5 forces the fluid in the cylinder outwardly through conduit 29 and check valve 30 to the pressure tank 25.

Similarly, the other legs 7 contact the deck and are pivoted upwardly against the force of the fluid pressure in cylinders 3 and the apparatus thereby comes to rest on the deck with the base plate 2 disposed generally parallel to the deck. Leakage of fluid back through control valve 32 allows pressure from tank 25 to cause pistons 5 to return to their original lowermost position slowly enough so that the system reaches its final resting position without any bounce effect.

With this construction, the impact force of the feet contacting the deck is taken up by the fluid pressure within the cylinders. As the pressure fluid is displaced from the cylinders 3 to the tank 25, there is no tendency for the piston and leg to bounce when the feet strike the deck. This structure permits a heavy load to be landed on a moving platform without danger of the impact forces damaging either the loading apparatus or the platform.

A modified form ofthe invention is shown in FIG. 3. In this embodiment, the basket 33, which corresponds to basket 1 of the first embodiment, is mounted on a base plate 34 and the base plate supports three or more cylinders 35 which contain pistons 36. The lower end of the piston rods 37 are provided with generally hemispherical feet 38 which are adapted to contact the deck or platform.

As in the case of the first embodiment, the basket and other apparatus is raised and lowered through cables 39 which are attached to lugs 40 on cylinders 35. The cables in turn are connected to a crane, Winch or the like.

In this embodiment, a liquid, such as oil, is employed as the fluid pressure medium, and the oil is contained within a tank 41 which is supported by legs 42 above the base plate 34. The lower end of the tank 41 is disposed above the upper end of the cylinders 35 so that the oil can flow freely by gravity from the tank 41 to the cylinders 35.

The oil is conducted from the tank 41 to each cylinder 35 by a conduit 43. A check valve 44 is located in conduit 43 and permits the free flow of oil from the tank to V the cylinders but prevents the flow of oil in the opposite will support the same when the apparatus isrresting on I the deck or other platform.

With the basket loaded, the apparatus is picked up by the crane or winch and lowered over the deck onto direction.

In addition, a by-pass conduit 45 similar to by-pass conduit 31 of the first embodiment is connected across valve 44. A restricted opening control valve 46 is disposed within the by-pass conduit and permits the flow of oil between the tank and the respective cylinders.

The operation Olf this form of the apparatus is similar to that of the first embodiment. The pistons are at the lowermost portion of their stroke as the apparatus approaches the deck or other platform. As the feet 38 engage the deck, the pistons are moved upwardly within the cylinders forcing the oil through conduits 45 into the tank 41. This results in a damping action which takes up the impact force of the contact.

As the apparatus is lifted from the deck, the piston moves downwardly within the cylinders and the oil flows by gravity through conduit 43 into the corresponding to a piston rod 51. Each of the rods 51 extends through a suitable opening in the lower end of the respective cylinder, and the lower end of each rod is provided with a hemispherical foot 52, similar to feet 38 of the second embodiment.

The

cylinders

48 and 49 are closed and the pistons moving within the cylinders tend to compress and expand the air or other fluid in the upper end of the cylinder.

The apparatus is raised and lowered by means of cables 53 which are attached to lugs 54 on the cylinders 48.

With this construction, the major force is absorbed by the large central cylinder 49, and the outrigger cylinders 48 are constructed of a size so that they absorb only enough of the impact force to move the basket to a position essentially parallel with the deck but cannot develop enough force to cause the basket to tip over.

The present" invention provides a simple and inexpensive means for transferring a load to a moving deck or platform in which the'impact'forces are substantially absorbed and dissipated throughout a considerable distance. This results in the possibility of landing heavier loads without danger of damaging the deck or conversely, the deck or other platform can be constructed of materials of lesser strength.

Men can be transferred to a pitching deck without the necessity of considerable agility on their part to make the final phase of the transfer in safety. Rather, the men can remain in the basket and allow the piston mechanism to make all the adjustments necessary to conform to the change from stationary state to the state of moving With the deck.

While the above description is directed to a basket to contain the material to be transferred it is contemplated that any type of platform, container, or the like may be used and similarly, while the cylinders are described as being attached to the basket and the piston rods extending downwardly to engage the deck, it is contemplated that these elements can be reversed so that the piston rods are connected to the basket and the cylinders contact the deck.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. An apparatus for transferring a load to a moving platform which comprises, a support structure to support the load to be transferred, at least three vertically extending cylinders rigidly secured to the periphery of said support structure in spaced relation to each other, a piston slidably disposed in each cylinder and extending downwardly from said cylinder below the lower side of said support structure, contact means associated with the lower end of each of said pistons and terminating in a rounded foot member adapted to contact said platform, said cylinders being spaced in a manner such that the several contact means associated with the corresponding cylinder pistons form a tripod-like support for said support structure, and a fluid pressure medium contained in the upper end portion of each of said cylinders to oppose inward sliding movement of said pistons relatively of said cylinders to dampen the impact between said support structure and platform as the former is lowered onto the latter, said fluid pressure medium being contained in each of said cylinders under a uniform pressure and at a value which limits the maximum force developed in the piston-cylinder units as said pistons are moved inwardly of said cylinders to a value slightly higher than the total weight of said apparatus when containing a maximum load. a 1

2. An apparatus for transferring a load to a tilting platform which comprises, a basket to contain the load to be transferred, at least three vertically extending cylinders rigidly secured to the peripheral surface of said basket with said cylinders being spaced equally about said basket periphery, a piston slidably disposed in each of said cylinders and extending downwardly beneath the lower side of said basket, a tank supported on said basket and having a compressible fluid pressure medium contained therein, conduit means extending between said tank and the upper end portion of each of said cylinders for establishing a fluid pressure head in each of said cylinders, an elongated platform engaging member pivotally secured at its inner end to the lower side of said platform and extending outwardly and downwardly therefrom with an intermediate portion of said member being vertically aligned with each of said pistons and engageable with the lower end thereof, said member having a rounded foot member provided on its outer end adapted to contact said platform as said basket is lowered toward the platform, said platform engaging member being pivoted upwardly as said foot member contacts said platform to move said piston inwardly relative to said cylinder against the force of the fluid pressure medium within said cylinder to absorb the impact force between said platform and foot member, and control means on said tank for adjusting the static pressure head within said tank to a value which limits the maximum force developed in the piston-cylinder units during landing to a value just in excess of the total weight of said-apparatus when loaded with a maximum load to thereby limit the load-which may be sustained at any one particular piston-cylinder unit.

3. The apparatus of claim 2 wherein said conduit means is provided with a check valve adapted to permit the free flow of fluid medium from each of said cylinders to said tank while preventing the flow of fluid pressure medium in the opposite direction, and by-pass means connected to said conduit means around said check valve and having a restricted opening therein for restricting fluid pressure medium flow from said tank to said cylinder.

4. An apparatus for transferring a load to a rolling platform which comprises, a basket to contain the load to be transferred, at least three vertically extending cylinders rigidly secured to the periphery of said basket above the lower side thereof with said cylinders being spaced equally around said basket periphery, a piston slidably disposed in each of said cylinders and extending downwardly below the lower side of said basket, said piston terminating in a rounded foot member adapted to contact said platform as said basket is transferred thereto, a tank supported on said basket and above said cylinders and containing a predetermined height of a liquid medium, conduit means extending between the lower end of said tank and the upper end portion of each of said cylinders for permitting gravity flow of liquid medium from said tank to each of said cylinders to establish a pressure head within the latter, said liquid medium height in said tank having a value such that the corresponding total pressure head in each of said cylinders is at least equal to a value sufficient to maintain said pistons and cylinders relatively 5. The apparatus of claim 4 wherein said conduit means is provided with a check valve permitting free flow of liquid medium from each of said cylinders to said tank as said piston and cylinder are moved relatively together transferred, at least three vertically extending secondaryv cylinders rigidly secured to the peripheral edge of said basket andv disposed in equally spaced relation to other of said cylinders, a piston slidably disposed in each of said secondary cylinders and extending downwardly from the lower side of said basket, said pistons terminating in a rounded contact member adapted to contact said platform as said basket is lowered thereto, a vertically extending primary cylinder secured to a central portion of said basket, a piston slidably disposed in said primary cylinder and extending downwardly from the lower side of said basket, a-compressible fluid medium disposed in each of said secondary and primary cylinders and above said pistons, said compressible fluid medium adapted to establish a static pressure head within the secondary and primary cylinders when said basket is supported at rest on said foot members the sum of which at least equals the weight of said basket when containing a maximum load, and with the individual cylinder static pressure heads being sufiicient to maintain each of said pistons in a uniformly outwardly extended position relative to its corresponding cylinder to position the lower side of said basket parallel to the supporting platform and with the individual static pressures within said secondary cylinders being substantially smaller than the static pressure Within said main cylinder to prevent excessive loading at the secondary t 8 a cylinder positions during transfer of the basket to the platform.

References Cited in the file of this patent UNITED STATES PATENTS 875,787 Day Jan. 1, 1908 1,599,953 Clapp Sept. 4, 1926 1,647,518 H-awley Nov. 1, 1927 1,774,643 Fullerton Sept. 2, 1930 2,092,233 Warren Sept. 7, '1937 2,106,289 Wallace Jan. 25, 1938 2,185,802 De Port Jan. 2, 1940 2,359,961 Anthony Oct. 10, 1944 2,495,486 Stevenson Jan. 24, 1950 2,510,285 Heyerman June 6, 1950 2,628,118 Gunnels Feb. 10, 1953 2,633,811 Poage Apr. 7, 1953 2,683,576 Miller July 13, 1954 2,712,913 Stanley July 12, 1955 2,713,466 Fletcher et 'al July 19, 1955 2,750,204 Ohrmann June 12, 1956 2,774,560 Johnson Dec. 18, 1956 UNITED STATE CERTIFICATE OF CORRECTION January 9 Patent No,

Loerwood Co Wasson dthat error appears in the ab that the said Letters Paten It is hereby certiiie o've numbered patquiring correction an t should ,read as ent re corrected below.

Column 1, line 'ZO" after "The" insert present column 2 line 30 after "forces" insert of 1962.

Signed and sealed this 26th deyof June (SEAL) Attest:

- DAVID L. LADD Commissioner of Patents ERNE5T W. sWIDER Attesting Officer