WESTERMARK, Henrik (Höjdlyckevägen 3, Stenungsund, S-444 55, SE)
| CLAIMS 1. Device (1) in connection with a ship ramp which consists of two articulately interconnected ramp parts (3, 4) in order to allow adjustment of the angle (X; X1) between the ramp parts (3, 4) in the extended position (I, II) of the ramp at a quay (6) or another installation part, characterized in that a common actuation system (7), which normally is arranged to fold the parts (3, 4) of the ramp (2) from a double-folded stored raised position (III) into a lowered unfolded position (I, II) at a quay, etc., (6) and in the reverse order, is arranged for angular adjustment of the ramp parts (3, 4) in the extended position (I, II) thereof by the co-operation between the winch (8) of the actuation system (7) and an actuation arm (9), that the arm (9), which, in addition to controlling the unfolding/folding of the ramp parts (3, 4), also controls the buttressing of the ramp parts (3, 4), i.e., changes the angle (X, X1...) between the ramp parts (3, 4) when the ramp (2) is in the unfolded position, also forms a buttspread arm, and that the same, by direct action, forces the ramp parts (3, 4) to turn in relation to each other, whereby the angle (X, X1...) between the ramp parts (3, 4) is varied by the driving action of the winch in the desired direction (11, 12) . 2. Device according to claim 1, characterized in that a wire (10) driven by the winch (8) is connected with said actuation arm (9) via tackles (13) for the wire (10) . 3. Device according to any one of the preceding claims, characterized in that the winch (8) preferably is electrically driven. 4. Device according to any one of the preceding claims, characterized in that the actuation arm (9) is formed of the existing spreading arm of the ramp, i.e., the arm (9) by which the ramp parts (3, 4) are unfolded from the folded up raised vertical storage position (III) into the essentially extended unfolded horizontal loading and unloading position (I, ID - 5. Device according to any one of the preceding claims, characterized in that said arm (9) is pivotably mounted and is, by the co-operation with a counter-pressure arm part (14), arranged to force the ramp parts (3, 4) to change the angle (X, X1...) between them by means of a lever function. 6. Device according to claim 5, characterized in that, in order to decrease the angle (X, X1...) between the ramp parts (3, 4), the winch (8) is arranged to pull in wire (10), whereby the wire (10) pulls the formed buttspread arm (9) so that the same is turned and thereby presses apart the ramp parts (3, 4) from each other and decreases the angle (X, X1...) between the ramp parts (3, 4) . 7. Device according to any one of claims 5-6, characterized in that, in order to increase the angle (X, X1...) between the ramp parts (3, 4), the winch (8) is arranged to let out the wire (10) from the winch (8), whereby the formed buttspread arm (9) is allowed to turn back and thereby allow the ramp parts (3, 4) to level out and increase the angle (X, X1...) between the same. 8. Device according to any one of claims 5-7, characterized in that said arm 9 is provided with a pressure part (15) in its bearing end at the common bearing joint (5) of the ramp parts (3, 4), and that the counter-pressure arm part (14) is supported by the opposite ramp part (4), a link (100) being arranged to act between said pressure part (15) and counter-pressure arm part (14). 9. Device according to claim 8, characterized in that, in one end of the link (100) , there is a journalled shaft (18), while in the opposite end of the link, there is a bearing part (101) that meets a fork (102) on the counter-pressure arm part (14) and where the transfer of force occurs. 10. Device according to claim 9, characterized in that the spring-loaded link (100) is arranged in such a way that, when said bearing part (101) on the free end of the link approaches the fork (102), it is directed into and fixed in the seat of the fork that is formed to, on one hand, distribute the contact pressure over a larger semi-cylindrical area corresponding to the contact/hole edge pressure in a bolt joint that is loaded by shearing forces, and on the other hand hold the link (100) in place. 11. Device according to claim 10, characterized in that the bearing part (101) formed as a shaft is arranged so that, when said bearing part (101) has fixed itself in the seat of the fork (102), a certain rotation/turning of the link (100) occurs because the arm (9) moves, and that rotation occurs in the bearings at small friction losses and at a small angle between the ramp parts (3, 4). 12. Device according to claim 11, characterized in that the link (100) is arranged so that it can turn along the operating range of the arm (9) and the angular change that occurs geometrically, and that the spring is then compressed during this movement, but that, in docking out, the spring is entirely out and the contact link (100) is spring-loaded into abutment against a mechanical stop. 13. Device according to any one of the preceding claims 8-12, characterized in that the arm (9) is connected with the inner ramp part (3) of the ramp via a pivot joint (16) . 14. Device according to any one of the preceding claims, characterized in that a link (200), chain or wire forms a preventing member for the arm (9) in order to hold said arm (9) in the desired correct position. 15. Device according to claim 14, characterized in that a said link (200) is journalled with a bearing part (201) movable in an elongate bearing hole (202). |
The present invention relates to a device in connection with a ship ramp, which consists of two articulately interconnected ramp parts in order to allow adjustment of the angle between the ramp parts in the extended position of the ramp at a quay or another installation part.
Such an angular adjustment of ramp parts is normally termed buttressing, and such an angular adjustment is required to, among other things, be able to use the ramp at as great differences of height as possible between ship and quay or another object such as another ship, loading platform, etc.
Conventionally, there are two main types of buttressing :
Manual buttressing:
Here, the angle between the ramp parts is changed by simply putting in a wedge of the size that is required to achieve the desired angle between the ramp parts. It is a simple solution and implies that there is no need to change the ramp angles during the course of the
loading/unloading .
Manual systems are just manual, and will not do if an automatic/adjustable solution is wanted. It is required that a person walks out on the ramp and makes adjustments, something that can be avoided with automated systems.
Buttressing with hydraulic cylinders:
Here, a solution is used that in principle is based on the fact that the hydraulic cylinder is made to form the wedge between the ramp parts, which then can be adjusted during loading and unloading, to achieve the desired angles. There are other solutions, but all are based on pressing by a hydraulic cylinder or other pressure devices in order to change the ramp angles.
A separate buttressing system consisting of hydraulic cylinders, hydraulic pipes, etc., has to be installed in the ramp. This may give rise to leakage and is also costly.
The compressive force in the hydraulic
cylinders used to press apart the ramp parts tend to become great, which requires large and in many cases expensive cylinders.
The line of trade tends to increasingly request all-electric solutions, and then hydraulic cylinders are not possible .
Neither JP 55136684A nor JP 2125493 U relates to a device that is constructed in such a way that they solve the problem in question desired to be achieved, to be able, by means of a spreading system, to buttress, i.e., change the angle between a first and a second ramp part when the ramp is in an unfolded horizontal position at a quay. The only thing accomplishable with said devices is ordinary spreading, i.e., to unfold/fold the ramp.
Therefore, the main object of the present invention is primarily to solve, among others, the problems mentioned above by reliable and cost-effective means.
Said object is achieved by means of a device according to the present invention that essentially is
characterized in that a common actuation system, which normally is arranged to fold the parts of the ramp from a double-folded stored raised position into a lowered unfolded position at a quay, etc., and in the reverse order, is arranged for angular adjustment of the ramp parts in the extended position thereof by the co-operation between the winch of the actuation system and an actuation arm, that the arm, which, in addition to controlling the unfolding/folding of the ramp parts, also controls the buttressing of the ramp parts, i.e., changes the angle between the ramp parts when the ramp is in the unfolded position, also forms a buttspread arm, and that the same, by direct action, forces the ramp parts to turn in relation to each other, whereby the angle between the ramp parts is varied by the driving action of the winch in the desired direction.
The new device, by which the buttressing operation now is solved, is based on the use of the existing spreading system of the ramp. Spreading means to unfold the ramp from a double-folded essentially vertical position, into an unfolded essentially horizontal position at a quay.
Together with the existing spreading system, which in this case consists of an electric winch and a wire tackle, a so-called buttspread arm is used, which is the core of the invention.
Together with wire and winch, said buttspread arm acts in order to, like a pinch bar/jemmy, force the ramp parts to change the angle between them.
In order to increase the angle between the ramp parts, wire is pulled in by the winch. In doing so, the wire pulls the buttspread arm so that the same rotates and in such a way presses apart the ramp parts. The ramp parts rotate apart, i.e., the angle increases.
In order to decrease the angle between the ramp parts (level the ramp), some wire is simply let out. Then, the buttspread arm is allowed to rotate back, which in turn allows the ramp to level out, foremost by virtue of the dead weight and possible carried cargo.
The advantages of the invention are that existing equipment is usable for undertaking an additional operation, in those cases the spreading winch is utilized that, besides in spreading, now proves useful in buttressing. Hydraulic cylinders can be avoided, which is an important environmental aspect.
When the ramp is in the stowed position, the buttspread arm will be foldable to decrease the total height of the stowed ramp.
During the entire loading/unloading operation, the spreading wire will be subjected to a tensile force, in contrast to utilizing a separate buttressing system, wherein the spreading wire is at rest during the entire
loading/unloading process. If necessary, it could be possible to utilize a ratchet that automatically or manually is engaged in different load positions if it is desired not to load the spreading wire continuously.
The invention is described below in the form of a preferred embodiment example, reference being made to the accompanying drawings, in which
Fig. 1 schematically shows a collapsible folding ramp on a ship, as seen from the side,
Fig. 2 shows the different motion patterns of the ramp in a common picture,
Fig. 3 shows the ramp in the extended position as seen from above,
Figs. 4-5 show the ramp as seen from the side during its unfolding sequence,
Figs. 6-8 show in side views the ramp in the extended loading/unloading position with the device according to the invention in an active state, however there being only shown one buttressing arm of the ramp situated on one side of the ramp,
Fig. 9 shows the device according to the invention as seen from above in the unfolded position of the ramp, however without any wire shown, and Figs. 10-12 show an example of the actuation arm and its bearing mounting.
Specifically, the invention, which consists of a device 1 in connection with a ship ramp 2 that consists of two ramp parts 3, 4 articulately interconnected by a pivot joint 5 and that is provided with means for allowing adjustment of the angle X, X 1 between the ramp parts 3, 4 in the extended position I, II of the ramp at a quay 6 or some other
installation part, can be said to consist of a common actuation system 7. Said common actuation system 7 is normally arranged to cause said folding ramp parts 3, 4 to be folded from a double-folded stored raised position III into a lowered
unfolded position I, II at a quay 6, etc., and in the reverse order. According to the present invention, said actuation system 7 is also arranged for angular adjustment of the ramp parts 3, 4 in the extended position I, II thereof. This is enabled by the co-operation between the arranged winch 8 and actuation arm 9 of the actuation system 7, whereby the angle X, X 1 ... between the ramp parts 3, 4 is varied by the driving action of the winch on the wire 10 thereof in the desired direction 11, 12.
The wire 10 driven by the winch 8 is connected with said actuation arm 9 via suitable tackles 13 for the wire 10, and said winch 8 is electrically driven to achieve all advantages thereby. The arm 9 is formed of the existing
spreading arm 9 of the ramp, i.e., the arm by which the ramp parts 3, 4 are unfolded from the folded up essentially vertical storage position III into the unfolded essentially horizontal loading position I, II and vice versa upon reverse folding.
The arm 9, which, in addition to controlling the unfolding/folding of the ramp parts 3, 4, also controls the buttressing of the ramp parts 3, 4, i.e., changes the angle X, X 1 ... between the ramp parts 3, 4 when the ramp 2 is in the unfolded position, also forms a buttspread arm, and the same forces, by direct action, the ramp parts 3, 4 to turn in relation to each other, whereby the angle X, X 1 ... between the ramp parts 3, 4 is varied by the driving action of the winch in the desired direction 11, 12.
Said arm 9 is pivotably mounted and is, by the co-operation with a counter-pressure part 14, arranged to force the ramp parts 3, 4 to change the angle X, X 1 ... between them by means of a lever function like the function of a pinch bar or jemmy.
By the system 7 and arm 9 thereof, the device 1 according to the present invention is made so that it, in order to decrease the angle X, X 1 ... between the ramp parts 3, 4, pulls in wire 10 by the winch 8, whereby the wire 10 pulls the buttspread arm 9 so that the same is turned and thereby presses apart the ramp parts 3, 4 from each other and decreases the angle X, X 1 ... between the ramp parts 3, 4.
In order to increase the angle X, X 1 between the ramp parts 3, 4, the wire 10 is let out from the winch 8, whereby the buttspread arm 9 is allowed to turn back and thereby allow the ramp parts 3, 4 to level out and increase the angle X, X 1 ... between the same.
Furthermore, said arm 9 is provided with a pressure part 15 in its bearing end at the common bearing joint 5 of the ramp parts, and an arm part 14 of the outer ramp part 4 forms a counter-pressure part for the pressure part 15. The counter-pressure arm part 14 and the buttspread arm 9 is connected with each other via a link 100, and the buttspread arm 9 is connected with the inner ramp part 3 of the ramp via a pivot joint 16.
Main operation
This system consists of one or two winches, usually mounted on the upper deck of the ship, the winches have a number of pulleys on the deck so as to then deflect up to what are called kingposts. On top of these, there is the pulley housing. Around this pulley housing and the one mounted down on the ramp, the main operation arrangement of the ramp is
arranged consisting of 12-14 wire strands per side. The winches on the deck may be hydraulic, electric or consist of a jigger winch, however the latter alternative is nothing that is practicable on larger ramps. This arrangement affects the angle of the ramp part 3 in relation to the basically vertical stern of the ship.
The arrangement disclosed in the patent text affects the angles of the ramp part 3 and 4 in relation to each other. Both spreading and buttressing. The ramp part that is attached to the ship is the first ramp part and is indicated by the numeral 3 in the text and drawings. The second ramp part is indicated by the numeral .
Preventer link
This link 200 works as a stay and holds the buttspread arm 9 at the correct angle in relation to the ramp part 1. The function is such that the stay-forming link 200 slides in an oval hole 202, a slot, and reaches an end
position, wherein it is loaded depending on how the buttspread arm 9 is loaded. Basically, this part is active when the ramp is spread, that is when the ramp part 4 is folded out and in before the quay 6 is reached. When the ramp 2 is lying on the quay 6, the angle between the ramp parts 3, 4 is close to 180°. A shaft 201 is entirely unloaded and slides in the oval hole 202 if the ramp 2 levels out and the buttress arm 9 rises, that is when wire 10 is let out from the spreading winch 8. This link 200 could also consist of a shorter wire/chain of about 2 m with a fixed length, since it only would carry cargo in one position and prevent the buttspreading arm 9 from rotating when it is loaded in a spreading operation. Contact link
When the ramp part 4 has been spread
sufficiently before the ramp is to be put down on the quay 6 or another platform, the ramp part 4 meets the buttspreading arm 9 in a point, wherein the entire structure can be prestressed if the wire 10 is tightened harder. It is in this contact point the force from the buttspread arm 9 and the ramp part 4 is transferred or vice versa, depending on how to look at it.
Since the buttspread arm 9 is hinged around a centre 16 of the ramp part 3, and the ramp part 4 is hinged in the hinge 5 between the ramp parts 3 and 4 and these have not the same centre, there will occur a certain sliding in the contact point, which is solved by a link 100. The design of the link 100 depends on geometrical conditions. There is an aim to have as short a link as possible. In one end of the link, there is a journalled shaft 18, this may be fixed. In the opposite end of the link, there is said bearing part 101 that meets a "fork" 102 on the part 2, where the transfer of force occurs. When said bearing part 101 on the free end of the link approaches the fork and the oval hole 202 thereof, it is directed into and then fixed in the seat of the fork that is formed to, on one hand, distribute the contact pressure over a larger semi- cylindrical area corresponding to the contact/hole edge
pressure in a bolt joint that is loaded by shearing forces, and on the other hand hold the link in place. When the shaft 101 has fixed itself in the seat of the fork, a certain
rotation/turning of the link 100 occurs because the buttressing arm 9 moves. The rotation occurs in the bearings at the
smallest possible friction losses and angle between the ramp parts 3, 4. The link 100 is spring-loaded so that it always is placed in the correct position when the parts meet. It can then move (rotate) a little, by virtue of the operating range of the buttressing arm and the small angular change that occurs geometrically. During this movement, the spring is then compressed. In docking out, the spring is entirely out and the contact link is spring-loaded against a mechanical stop. 1 Device
2 Ship ramp
3 Ramp part (inner)
4 Ramp part (outer)
5 Pivot joint, Hinge, Bearing joint
6 Quay
7 Actuation system
8 Winch
9 Actuation arm (buttspread arm)
10 Wire
11 Direction
12 Direction
13 Tackle
14 Counter-pressure arm part
15 Pressure part
16 Pivot joint, centre
18 Shaft
X Angle
X I Angle
I, II Extended unfolded position (horizontal)
III Raised storage position (vertical)
100 Link
101 Bearing part, Shaft
200 Link
201 Shaft
202 Oval hole
102 Fork In the following, the invention and its
function are described more generally although with reference to the drawings in general terms:
The buttspread arm mechanism is hinged to the outer part of the ramp part 1. The hinge is preferably made with a shaft and ear bracket arrangement, but other hinge types are feasible as long as it is possible to rotate in a supported position .
The general function is to act as a crowbar between the part 1 and part 2 of the ramp between a ship and a quay, platform, linkspan or floating pontoon. The buttspread arm works as a crowbar, and with its lever it is possible to separate the hinged ramp parts by being able to rotate and change the geometry of the hinge/push/pull-points, this to be able to increase the knuckle of an articulated ramp when bearing load. The innovation involves using the existing wire tackle or actuator arrangement /setup, which is employed to unfold this articulated ramp (in our terminology to spread the ramp) , in order to work as a buttressing arrangement as well as a spreading arrangement .
The motion of the buttspread arm is restricted to occur between a pre-defined and designed interval. It is mechanically hindered or supported in its end positions, and the structure has the strength to bear the loads/torques applied on the buttspread arm, from the dead weight of the ramp, the load on the ramp, and the counter force from driving systems, which may be a winch, cylinder or an electric screw. In this case, it is shown to be a winch having a wire
arrangement, since this is commonly used with this typical design. Benefits :
• Possible to use the spreading winch/actuator also for making the buttressing manoeuvre.
• This means that, in the common setup, we can make a buttressing manoeuvre without large hydraulic cylinders or electric screws.
• In the fully electric alternative, we can easily use the electric spreading winch tackle to hold the crossbar in position and allow retaining/moving the ramp into a new desired position.
• When the whole ramp is in the stowed position, the
buttspread arm can be folded forward or backward to decrease the total air draught of the ramp arrangement. This is an advantage when the air draught is an issue. It will also be easier to get access to the sheaves and inspect/service parts of the mechanism, sheaves, shafts, bearings and wires, actuators, etc.
How it works, this text will guide you through the different steps of the ramp operation from stowed position to lowered position and back to stowed position.
A. The ramp is in the stowed position and the buttspread arm is folded. The spreading winch starts to rotate, which means that it is spooling up wire. The wire tackle is arranged so that it will raise the folded buttressing arm into an almost vertical position. The end position is reached
(preventer link or fixed support, could be wires or a link) and the pressure/torque is increasing. Wires are tensioned and the winch stops, either by an angle sensor, position sensor or by pressure or torque control, depending if it is a hydraulic or electric operated winch. B. The main manoeuvre of ramp can now be started. The ramp is pushed out by launching cylinders and the main manoeuvring winch (es) lets out more and more wire from the drums. The ramp starts to move by gravity, and this operation is continued until the ramp is inclined about 70° from the horizontal position. This means the ramp has been moved from the stowed position, almost 90° (vertical) to 70°, approx. 20°.
C. In this position, the part 2 (or the second main part of the ramp structure) has been hanging in the hinges only supported by a "light" force acting in the wire tackle, a force only strong enough to keep the buttspread arm in its outer position but not strong enough to prevent the part 2 from rotating freely by the force of gravity. During the ramp operation of about 20°, the force of the wire tackle changed state from acting as a closing force to an opening force
(spreading) , since it passed over the hinge between the part 1 and part 2. The spreading winch that has been torque controlled now starts to generate tension in the spreading wire tackle. The buttspread arm aims to rotate around its fulcrum/point of rotation, but is prevented or supported mechanically (could be a preventer link or wire) from this movement in this direction, and the force increases until the part 2 starts to rotate. The spreading operation is visible to the operator.
D. Both spreading and lowering of the ramp is carefully made simultaneously in order to prevent the ramp from interfering with the quay. When the spreading operation reaches its end position, this innovation achieves its purpose. The part 2 has been spread almost 180° and the gap between the part 1 and part 2 is closing, however now the buttspread arm is in the way (blocking this phase) . The part 2 is rotating to close the gap between the structure parts, and it rotates due to the drum that spools up wire until it hits the buttspread arm. The pressure or torque increases and the contact pressure between the buttspread arm and mechanical surfaces increases. The whole structure is tightened and "jammed" when the torque/pressure has reached its maximum on the winch/actuator. This since the lever of the wire tackle via the buttspread arm to the contact point is stronger (5:1), nothing moves. The lever of the part 2 from the sheave housing/force point to the hinge and up/down to the contact point is (5:2) . The torque is weaker and this means that the part 2 has "nowhere to go", only to be pretensioned to the pre-set position that is the most inclined buttressing position, about 12-15° knuckle over the drive way on the ramp.
E. The now stiff ramp is lowered to the quay. The outer part of the ramp reaches the quay and a reaction force is acting on the structure. The ramp is lowered until the main operation wires are slacking. The reaction force from the quay is now at its maximum for an unloaded static ramp and about 40- 50 % of the dead weight of the ramp. Meanwhile, the spreading system is kept in the same position. The wire length is
maintained .
F. Now, the ramp rests safely on the quay, and, depending on the draught of the ship and the height of the quay, the operator could find it favourable for a loading operation to straighten the ramp into a less inclined/knuckled driveway. The reaction force and the "Laws of Newton" (gravity) make this automatically. What is preventing this from happening is that the buttspread arm acts as a crowbar between the parts and that the wire tackle has a fixed length, and due to the geometry of the buttspread arm, the hinge position and the contact position, this is not possible unless the buttspread arm is raised. This raising of the buttspread arm can only be achieved by letting out more wire from the winch drum. The operator checks the distance to the quay, and should it be possible to straighten the ramp, the operator lets out more wire from the winch drum and the gravity does the work. The contact pressure of the buttspread arm is decreased, and when the position of equilibrium of the arm, via a possible link to prevent friction/scratching between the surfaces and the arm, begins to rotate, the ramp is released into a straighter position, which is advantageous to the loading operation.
G. When the correct position has been reached, the operator stops the drum motion/rotation, and the brake of the drum is actuated. The buttspread arm has now rotated slightly into a new position. The ramp is now ready to carry load/cargo in/out from the ship.
H. The loading operation starts, and when a heavy load wagon or a similar type of cargo is on the ramp, the wire tension in the tackle of the spreading/buttressing arrangement increases depending on the weight of the cargo. Since the wire length of the system is constant, the ramp cannot change inclination due to the buttspread arm preventing the ramp parts from moving, like a crow bar between the parts. When the maximum safe working load SWL is placed on the ramp, the wire tension is kept below the maximum allowed tension of the used wire, usually around 4-5 times below the minimum breaking load BL. The wires may tend to become longer/elongate during loading operation, which may change the angle of the drive way a little, but may also be seen as a shock absorber/spring of the system.
I. When the loading operation continues and the tide or the draught of the ship changes, the operator may find it necessary to change the inclination of the part 2 to prevent the ramp from interfering with the quay or any obstacle under the ramp. The buttspread arm needs to change position/rotate in order to press/bend apart the two ramp structures, like a crow bar, and this can be done simultaneously with the loading operation if necessary. The operator actuates the winch and starts to increase the pressure/torque in order to wind up more wire on the drum with the purpose of changing the position of the buttspread arm. The wire tension is increased, and when passing the point of equilibrium, the drum starts to rotate and the wire of the system is wound up on the drum. The buttspread arm starts to rotate and presses on the contact point via the "possible link" of the part 2. This makes the ramp structures to separate and the inclination between them changes. The operation continues until an adequate clear distance is achieved between the ramp and the quay/obstacle. When the winch is stopped and the brakes are actuated, the buttressing operation is finished. J. The loading operation is finished and the ramp is to be raised, closed and secured for sea voyage. Before the main operation of the ramp can start, the ramp may be
buttressed to a maximum inclination of 12-15°, or just be where it is :
A) If the buttressing is in an intermediate position when main ramp operation starts, the part 2 and the buttspread arm will change position until the buttspread arm reaches its support position, and then, when the wires of the buttspread tackle get tensioned again, the whole ramp including the part 2 will be lifted from the quay.
B) If the ramp is maximally buttressed before the main ramp operation starts, the whole ramp will be lifted from the quay and the structure is jammed as described above. This is described as a more controlled way of making the main ramp operation.
K. The main operation of the ramp continues and the ramp is lifted safely from the quay. When a safe distance is reached, the spreading winch releases its pressure/torque and starts to feed out wire to the wire system of the spreading arrangement (now folded) . This means that the ramp part 2 starts to move in a controlled way by gravity. This anti spreading/folding manoeuvre of the part 2 and the main ramp operation continues until the part 1 is oriented at an angle of about 70° to the horizontal state and the part 2 is hanging almost vertically in the hinges. The spreading winches are now set to the pre-tension mode in order to keep away possible wire slack from the wire tackle and keep the buttspread arm raised.
L. The final part of the closing operation starts and the main ramp (part 1) operation continues. The spreading winch is torque controlled and the ramp part 1 is actuated into the closed, almost vertical position. During this operation, the part 2 has been hanging in the hinges, and the wire tackle has geometrically changed position since it has passed the hinge between the part 1 and 2 (what we call over centre geometry) and now works as a closing force if actuated.
M. The part 1 is now in an almost vertical
position. The cleat hooks in the hull or in the ramp. The part 1 is now engaged and the ramp part 1 is being pulled in the last bit, and the sealing around the hull opening is
compressed, if there is any. The part 1 can now be locked by wedges to the hull. While the spreading winches have been in the pre-tension mode, the operator or the control system
(automatic) now increases the pressure/torque on the winches, and by the force generated, the part 2 can rotate and close itself closer to the part 1 until mechanically stopped. It can now safely be locked to the part 1 or the hull. N. When both the part 1 and part 2 are safely locked to the ship, the wire tension of the spreading winch can now be released, and depending on the design geometry, the buttressing arms can be folded in order to reduce the air draught and lock them in a safe position. Folding of the buttspread arms can either be done by design geometry and gravity, or by an electric or hydraulic actuator. It is also feasible to have the buttspread arms forced to rest/fold by a spring system or a similar mechanical system. If the air draught is not an issue, an alternative is just to leave the buttspread arms as they are after having pulled in the part 2 into the stowed/locked position.
Some further explanatory information The buttspread arm obtains its torque by tensioning of the wires. This torque can be transferred to the part 2 when the part 2 and the buttspread arm are in mechanical contact with each other. This is what we call the contact point. This contact point could be a smooth surface where the surface of the buttspread arm meets the surface of the part 2. The contact pressure is high, for a standard ramp, the force interval will range between 100-400 t per side. Hence, we have an alternative to use the link. The terminology preferred for this link could be: push link.
The link could be attached to the buttspread arm or on the part 2 of the ramp structure. The contact point of the link could be a fork of the open fitting type that "wedges in" the link and keeps it in position. It is also feasible that the link has a fork in one end and meets a shaft or the like in order to "wedge it in" and keep it in position. The link can have bearings or be without depending on force and size. For the smoothest operation, a link with greased sliding brass bearings can be recommended.
This link becomes activated/loaded when the ramp is spread so much that the part 2 and the fork merge into this link. They will stay connected during lowering of the ramp to the quay, during cargo loading and buttressing operation, i.e., angular change between the part 1 and part 2 of the ramp (main structures) , and until the ramp is folded again and the ship is set to sail. The link and the fork will always dock in the same position every time, and the link will, depending on length, rotate slightly during the entire operation. Most efficient is to have the link to dock the fork, for example, at -7° and over the full range rotate to +7°. The longer the link, the narrower the angle interval, however it is a geometrical iteration to find the optimal length. If it is too short and rotates too much between the contact point and the attachment to the buttspread arm, the force will have to change direction and we get unwanted tensions/forces in the structure and in the fork fitting, which we need to absorb somehow. The link may have a spring-loaded base position, where it is during all inactive periods of time. When docked, it will compress this spring during its rotating motion, and when undocked again, it will be in a base position again.
The buttspread arm is hinged to the part 1, but could also be hinged to the part 4.
The spreading winch can be positioned on either the part 3 or part 4. Most common is that it is positioned on the part 1, but with the possibility of being positioned anywhere, since the wire routing can be made in all possible ways. The winch could be both electric and hydraulic and pull a wire, rope or a chain. It could also be possible to have some kind of screw actuator or hydraulic cylinder instead of a winch and wire tackle between the buttspread arm and the part 4. Since the stroke is very long, ramps are heavy steel structures, and the part 4 has an operation range of 180°, it is uncertain if this will be a cost effective solution, however possible. The hydraulic cylinder needs to be telescopic or designers need to figure out an extreme link structure, which will be a
challenge .
The nature and function of the invention should have been clear from what has been mentioned above and shown in the drawings .
Naturally, the invention is not limited to the embodiments described above and shown in the accompanying drawings. Modifications are feasible, particularly as for the nature of the different parts, or by using an equivalent technique, without departing from the protection area of the invention, such as it is defined in the claims.