U.S. patent application number 16/971748 was filed with the patent office on 2020-12-17 for tug with an all around towing installation.
The applicant listed for this patent is IMC CORPORATE LICENSING B.V.. Invention is credited to Markus VAN DER LAAN.
Application Number | 20200391835 16/971748 |
Document ID | / |
Family ID | 1000005061665 |
Filed Date | 2020-12-17 |
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United States Patent
Application |
20200391835 |
Kind Code |
A1 |
VAN DER LAAN; Markus |
December 17, 2020 |
TUG WITH AN ALL AROUND TOWING INSTALLATION
Abstract
An all around towing system (33) for a tug (31) comprising a
heavy plate (40) mounted on a deck of the tug, an upper rail
segment (42) and a lower rail segment (44) disposed on the upper
and lower surfaces of an outer edge of the heavy plate,
respectively, a carriage (46) movable along the upper and lower
rail segments, a set of bearing wheels (47, 48) arranged for
guiding the carriage along the upper and lower rail segments,
characterized in that the heavy plate further comprises respective
upper and lower grooves (43, 45) on the upper and lower surfaces of
the heavy plate, and in that the upper and lower rail segments are
respectively mounted in the upper and lower grooves of the heavy
plate.
Inventors: |
VAN DER LAAN; Markus; (CP,
Oegstgeest, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IMC CORPORATE LICENSING B.V. |
Ijssel |
|
NL |
|
|
Family ID: |
1000005061665 |
Appl. No.: |
16/971748 |
Filed: |
February 11, 2019 |
PCT Filed: |
February 11, 2019 |
PCT NO: |
PCT/IB2019/051068 |
371 Date: |
August 21, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B63B 21/60 20130101;
B63B 35/68 20130101 |
International
Class: |
B63B 35/68 20060101
B63B035/68; B63B 21/60 20060101 B63B021/60 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2018 |
MY |
PI 2018700682 |
Claims
1. An all around towing system (33) for a tug (31) comprising: a
heavy plate (40) mounted on a deck (32) of the tug; an upper rail
segment (42) and a lower rail segment (44) disposed on the upper
and lower surfaces towards an outer edge of the heavy plate,
respectively; a carriage (46) movable along the upper and lower
rail segments; and a set of bearing wheels (47, 48) arranged for
guiding the carriage along the upper and lower rail segments;
characterized in that the heavy plate further comprises respective
upper and lower grooves (43, 45) on the upper and lower surfaces of
the heavy plate and in that the upper and lower rail segments are
respectively mounted in the upper and lower grooves of the heavy
plate; wherein a plurality of bolt connections formed between the
upper and lower rail segments and the heavy plate is positioned
along the upper and lower rail segments.
2. The all around towing system (33) according to claim 1, wherein
the upper and lower rail segments (42, 44) are bolted in the upper
and lower grooves (43, 45), respectively.
3. The all around towing system (33) according to claim 1, wherein
the upper and lower rail segments (42, 44) are bolted through holes
in the heavy plate (40) to the rail segments on the opposing top
and bottom surfaces.
4. The all around towing system (33) according to claim 1, wherein
the plurality of bolt connections formed between the upper and
lower rail segments and the heavy plate are positioned at between
15% to 40% of the width of the upper and lower rail segments
measured from the inner curvature of the upper and lower rail
segments (42, 44).
5. The all around towing system (33) according to claim 1, wherein
the carriage (46) has at least two rigid parts (61, 62) connected
to each other.
6. The all around towing system (33) according to claim 5, wherein
the carriage (46) has at least two guiding structures (59) suitably
disposed on the two rigid parts (61, 62) of the carriage (46) for
connection to a split towline (60) and a towline (35) for towing an
object.
7. The all around towing system (33) according to claim 6, wherein
the guiding structures (59) are arranged and disposed on the
carriage at a distance of at least 20% of the carriage length
measured from half length of the carriage (46).
8. The all around towing system (33) according to claim 6, wherein
the towline (35) is connected to the split towline (60) which forms
a triangle connection (34) with a maximum split angle of
60.degree..
9. The all around towing system (33) according to claim 6, wherein
the split towline (60) has two ends passing through the guiding
structures (59) and the ends are connected to each other at half
length of the carriage (46) forming a closed loop triangle.
10. The all around towing system (33) according to claim 6, wherein
the split towline (60) has two ends passing through the guiding
structures (59) and the ends are connected by means of a release
system.
11. The all around towing system (33) according to claim 6, wherein
the guiding structures (59) have a fixed curved smooth surface.
12. The all around towing system (33) according to claim 6, wherein
the guiding structures (59) have a rolling surface.
13. The all around towing system (33) according to claim 5, wherein
the carriage (46) has two rigid parts (61, 62) which are connected
by a marginally flexible structure (63).
14. The all around towing system (33) according to claim 5, wherein
the carriage (46) has two rigid parts (61, 62) with a plurality of
flexible blocks (65) mounted between the rigid parts.
15. The all around towing system (33) according to claim 1, wherein
the set of bearing wheels comprises: at least two upper main
bearing wheels (47) arranged and disposed on the upper surfaces of
the carriage for guiding the carriage along the upper rail segment
(42); and at least two lower main bearing wheels (48) arranged and
disposed on the lower surfaces of the carriage for guiding the
carriage along the lower rail segment (44).
16. The all around towing system (33), according to claim 15,
wherein the upper main bearing wheels (47) are arranged and
disposed on the upper and inner half surface of the carriage for
guiding the carriage (46) along the inner side of the upper rail
segment (42) and the lower main bearing wheels (48) are arranged
and disposed on the lower and inner half surface of the carriage
for guiding the carriage along the inner side of the lower rail
segment.
17. (canceled)
18. The all around towing system (33) according to claim 15,
wherein each of the upper main bearing wheels (47) is provided with
a flange (49) and each of the lower main bearing wheels (48) is
provided with a flange (50).
19. (canceled)
20. The all around towing system (33) according to claim 15,
further comprising at least two upper wheels (53) arranged and
disposed on the upper and outer half surface of the carriage (46)
for guiding the carriage along the outer side of the upper rail
segment (42); and at least two lower wheels (54) arranged and
disposed on the lower and outer half surface of the carriage (46)
for guiding the carriage along the outer side of the lower rail
segment.
21. (canceled)
22. The all around towing system according to claim 20, wherein the
additional upper wheel (53) is provided with a flange (55) and the
additional lower wheel (54) is provided with a flange (56).
23. (canceled)
24. The all around towing system (33) according to claim 20,
wherein the additional upper and lower wheels (53, 54) are fitted
with an eccentric bushing.
25. The all around towing system (33) according to claim 15,
wherein the upper main bearing wheels (47) and lower main bearing
wheels (48) have a vertical rotation axis of 90 degrees
perpendicular to the heavy plate (40).
26. The all around towing system (33) according to claim 15,
wherein each upper main bearing wheel (47) is arranged with its
flange (49) on the upper side of the upper main bearing wheel
aligning with the upper side of the upper rail segment (42) and
each lower main bearing wheel (48) is arranged with its flange (50)
on the lower side of the lower main bearing wheel aligning with the
lower side of the lower rail segment (44).
27. (canceled)
28. The all around towing system (33) according to claim 15,
wherein the upper main bearing wheels (47, 51) and lower main
bearing wheels (48) are distributed evenly along the upper and
lower surfaces of the carriage (46).
29. The all around towing system (33) according to claim 1, wherein
the heavy plate (40) has either a circular shape or an oval or
elliptical shape.
30. (canceled)
31. The all around towing system (33) according to claim 29,
wherein the upper and lower rail segments (42, 44) have either a
circular profile or an oval or elliptical profile.
32. (canceled)
33. The all around towing system (33) according to claim 1, wherein
both inner and outer diameters of the circumference of the upper
rail segment (42) and lower rail segments (44) are equivalent in
that the upper and lower rail segments are laterally aligned to
each other.
34. The all around towing system (33) according to claim 1, wherein
the upper groove (43) has a smaller diameter than the lower groove
(45).
35. The all around towing system (33) according to claim 1, wherein
the length of the carriage is at least 5% of the outer
circumference of the rail segments (42, 44).
36. The all around towing system (33) according to claim 1, wherein
the length of the carriage is in the range of 10% to 20% of the
outer circumference of the rail segments (42, 44).
37. The all around towing system (33) according to claim 1, wherein
the outer edge of the upper groove (43) has a smaller diameter than
the inner edge of the lower groove (45).
Description
FIELD OF INVENTION
[0001] The invention relates to a tug. More specifically, the
invention concerns a tug having an all around towing system.
BACKGROUND OF THE INVENTION
[0002] In harbours and restricted sailing areas, ships are usually
assisted by one or more tugs. The ship and tug are connected by a
towline and the tug manoeuvres in the required position to pull the
ship. In addition to towing, the tug can also perform pushing
operations.
[0003] Tugs in general have a fixed towing hook or towing winch on
deck and the towline is connected to this equipment. Further an
accommodation and wheelhouse are mounted on deck, thereby hindering
the towline to rotate freely around.
[0004] A solution to enable free rotating all around in the
horizontal plane is offered by various rotating towing
installations. Examples include DE881312 (Schlepper fur Schiffe by
Buff 1951), NL1012977 (Ontwerp van sleepboot by M. van der Laan
1999) and NL1027414 (Sleepboot met verplaatsbare sleepinstallatie
by Mampaeij 2006). These patents describe a 360.degree. rotatable
towing installation on either a circular track or an oval track,
running on the outer side of the accommodation/wheelhouse. On this
towing installation a towing hook or winch is fitted where the
towline to the assisted ship is connected. Typical diameter or
width of the towing installation is in the range of 66-100% of the
tug's width. By moving the towing point to the ship's side, the
heeling moment is reduced and capsizing risk minimized.
[0005] All around towing systems offer interesting functionality
with regards to towing operations, but the design of the rail
construction, the production, installation, repairs and maintenance
involve high cost and also the design of the carriage involves high
production cost. Further the whole installation is mounted on the
deck of the tug and is subjected to the highly corrosive
environment. The so-called carrousel tug (according to NL1012977)
involves all around rail segments welded into the supporting
structure, followed by machining to achieve a circular shape. The
carriage is formed by a full circular outer ring with a large
number of supporting wheels distributed over the whole
circumference. The DOT tug (according to NL1027414) involves all
around horizontal rail structure with two parallel supporting
plates combining a large welding length and a solid structure
without possibilities to easily modify, repair or exchange. The
carriage is formed by two separate carriages with a complex stool
and double hinge structure.
[0006] The object of the present invention is to provide an
improved all around towing system on a tug which does not have the
drawbacks described above, i.e. easy manufacturing of the rail and
supporting construction, reduction of welding length, easy mounting
and replacement of the rail construction, a simplified carriage
construction without hinges and internal moving parts.
SUMMARY OF THE INVENTION
[0007] In one aspect, the invention provides an all around towing
system for a tug comprising:
[0008] a heavy plate mounted on a deck of the tug;
[0009] an upper rail segment and a lower rail segment disposed on
the upper and lower surfaces of an outer edge of the heavy plate,
respectively;
[0010] a carriage movable along the upper and lower rail
segments;
[0011] a set of bearing wheels arranged for guiding the carriage
along the upper and lower rail segments;
[0012] characterized in that the heavy plate further comprises
respective upper and lower grooves on the upper and lower surfaces
of the heavy plate, and in that the upper and lower rail segments
are respectively mounted in the upper and lower grooves of the
heavy plate.
[0013] This object is achieved by the design of the rails and the
carriage. The rails consist of separate segments mounted partially
inside a groove in a heavy plate which is a thick steel plate. The
heavy plate is mounted on the deck of the tug in a primarily
horizontal arrangement and extends all around outside the
supporting structure. In this heavy plate on both the upper side
and the lower side grooves are machined, wherein the rail segments
can be fitted. To transfer the sideward towing force, the grooves
only require relative small depth. As example a groove in range of
10-20 mm can be used for a 80 mm thick rail. Larger and smaller
sized rails will scale in similar ratio. The carriage is formed by
an `U`-shaped structure around the edge of the heavy plate and
equipped with bearing wheels on both upper and lower surfaces of
the carriage. These bearing wheels are in contact with the upper
and lower rail segments and are positioned on the inner surface of
the carriage to transfer the outward force from the towline. The
towline from the assisted ship is connected to the carriage by any
suitable means. This can be for example a towing hook or a towing
winch.
[0014] According to further advantageous design, the outer
circumferences of the upper and lower rail segments have the same
outer and inner diameter in that the upper and lower rail segments
are laterally aligned to each other. The grooves are mirrored
around the centre line of the heavy plate. For ease of mounting and
strength support, the upper and lower rail segments are fitted with
bolt or threaded construction to connect to each other through the
heavy plate in the grooved section.
[0015] According to another advantageous design, the rails on the
upper and lower side are moved along the circumference to produce
an overlapping structure in order to increase the bending strength
and structural stability. The upper rail segment can for example
extend halfway above the lower rail segment and similarly the lower
rail segment extends halfway below the adjacent upper rail
segment.
[0016] According to another advantageous design, the bolted
connections formed between the upper and lower rail segments and
the heavy plate are positioned along the inner curvature of the
rail segments to prevent the rail segments from rotating out of the
groove by the outward load. As example the bolted connection is at
approximately 15-40% of the rail width measured from the inner
curvature of the rail segments.
[0017] According to another advantageous design, the upper groove
has a smaller diameter than the lower groove, preferably the outer
edge of the upper groove has a smaller diameter than the inner edge
of the lower groove. Hereby the thickness of the heavy plate can be
reduced. In case of significant difference between the groove
diameters, the lever between upper and lower rail increases and
counters up and down rotation around the outer edge of the heavy
plate. This can be advantageous when installing larger towing
components on the carriage.
[0018] According to another advantageous design, the carriage has
two rigid parts.
[0019] Preferably each rigid part of the carriage includes one
connecting or guiding structure for connection to the towline or
the separate cable structure. The marginally flexible construction
can be a connection steel structure allowing small deformation in
the range of a few mm, thereby allowing each rigid part to flex
marginally from the other rigid part and to follow small
deformations of the rails. These deformations can have various
reasons, e.g. production tolerances, small plastic deformations,
wear on rail surface.
[0020] According to another advantageous design, the carriage is
fitted with two connection or guiding structures positioned at a
distance of at least 20% of the carriage length measured from half
length of the carriage. The towline from the towed ship divides at
certain distance from the carriage (e.g. forming a triangle shape
with each angle 60.degree.) into two parts and both parts extend to
either connection structures and thereby distribute the load
(evenly) over the circumference of the contacting rail
segments.
[0021] According to another advantageous design, the connection
structures are replaced by guiding structures, the split towline
runs on the outer side of the guiding structures and around the
guiding structures towards the centre. These guiding structures can
consist of a fixed curved smooth surface or a rolling surface. At
the centre of the carriage both cable ends can be connected to each
other or fixed to the carriage. Further the connection can also
involve a release system to allow both ends to part and move
outward around the guiding structures.
[0022] According to another advantageous design, the towline is
connected to a separate cable structure running through or around
the guiding structures.
[0023] According to another advantageous design, the carriage
consists of two rigid parts which are connected to each other with
a marginally flexible construction. Each rigid part consists of two
main upper bearing wheels on the upper surface of the carriage and
two lower main bearing on the lower surface of the carriage.
[0024] According to another advantageous design, the carriage
consists of two rigid parts, which are connected to each other with
a flexible construction. The rigid parts are similar to the
previous design, but the connecting structure allow significant
flexing in the range of a few cm or more. This construction can be
composed of all kind of flexing structures, hinges, sliding parts.
Hereby each rigid part can flex compared to the other rigid part
and thereby follow various significant changes in the radius of the
rails. This will not only allow for small deformations of a few mm,
but also allows to move along an oval/elliptical rail shape. In
case of the towline or separate cable structure is connected to a
connection structure on each rigid part, the resultant force pushes
the rigid parts together. In case the towline or separate cable
structure runs through the guiding structures on each rigid part
towards the centreline, the resultant force again pushes both rigid
parts together. In both cases a significant push force is generated
by the towline load and the connection does not need to generate
pull forces. A simple flexible buffer like structure between both
rigid parts is sufficient.
[0025] According to another advantageous design, the main bearing
wheels consist of at least four wheels on the upper and inner half
surface of the carriage and at least four wheels on the lower and
inner half surface of the carriage. Also five, six, seven or even
eight wheels on either sides can be applied. The bearing wheels are
preferably equally distributed over the carriage length to
distribute the force properly to the upper and lower rail
segments.
[0026] According to another advantageous design, the main bearing
wheels have a rotating axis rectangular to the heavy plate. These
bearing wheels are positioned on the inner surface of the carriage
to transfer the outward pull from the carriage to both the force
from the upper bearing wheels to the upper rail segment and
simultaneously from the lower bearing wheels to the lower rail
segment.
[0027] According to another advantageous design, the main bearing
wheels are fitted with a flange, the upper main bearing wheel has
the flange on the upper side corresponding to the upper level of
the rail segment. The same arrangement applies to the lower side of
the lower main bearing wheel. Hereby the carriage is positioned not
only in radial outward direction by the bearing wheels, but also in
vertical direction by the flanges.
[0028] According to another advantageous design, the main bearing
wheels are fitted with flanges whereby the main bearing wheels take
the radial load and the flanges take the load parallel to the
rotating axis.
[0029] According to another advantageous design, in addition to the
main bearing wheels, the additional supporting wheels are mounted
on the carriage to position the carriage properly on the upper and
lower rail segments, both in radial inward direction and against up
and down rotation around the outer edge of the heavy plate. As a
practical example a number of additional wheels are positioned on
the outer side of the upper and lower rail segments with the
rotating axis rectangular to the heavy plate. Hereby the upper and
lower rail segments are enclosed between the main bearing wheels
and the additional wheels on the inner and on the outer side
ensuring proper guidance. By mounting these additional wheels both
on the upper side against the outer side of the upper rail segment
and on the lower side against the outer side of the lower rail
segment the carriage moves smoothly along the rail segments with
little up and down rotation. To facilitate mounting and adjustment,
the additional bearing wheels on the outside of the rail segment
may be fitted with an eccentric bush around the shaft. By turning
the eccentric bush, the wheel may be positioned accurately near the
rail segment surface. The additional bearing wheels positioned on
the outside of the rail segment may be fitted with flanges, the
upper main bearing wheel with flanges on the upper side and the
lower main bearing wheel with flanges on the lower side. In case of
a towline at a large upward angle (e.g. in case of a ship with a
high deck or in case of the tug heeling sideward with a large
angle), the flanges of the lower outer wheels will assist the
flanges of the lower inner wheels in sharing the vertical load.
[0030] According to another advantageous design, additional wheels
are mounted on the upper and outer half surface of the carriage in
contact with the outer side of the upper rail segment to take the
vertical downward load. This load consists of a combination of
gravity load of the carriage and towline load.
[0031] According to another advantageous design, additional wheels
are mounted on the lower and outer half surface of the carriage in
contact with the outer side of the lower rail segment to take the
vertical upward load. This load consists of a combination of
gravity load of the carriage and towline load.
[0032] According to another advantageous design, the carriage
consists of a certain length around the outer circumference of the
rail segments to distribute the local towline load over part of the
rail length. The length of the carriage will be in the range of at
least 5% preferably in range of 10-20% of the outer circumference
of the rail segments. Along the upper part and the lower part
wheels are mounted along the circumference to transfer the load
from the carriage to the rail segments.
[0033] According to another advantageous design, the production
process of the rail segments can be done by cold rolling a straight
bar over a number of rollers in a heavy hydraulic press to form the
bar into the requested curvature by plastic deformation. This
allows easy production with little material losses and a high
accuracy of the rail width to match the width of the groove and the
distance between the rollers on the inside and the outside of the
rail. Also, other similar mechanical presses can be considered to
shape the straight rail into the requested curvature. In case of
large rail segments additional heating of the rail material may be
used to perform part heated rolling.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The present invention will become more clearly understood
from the following description of the embodiments thereof, when
taken in conjunction with the accompanying drawings. However, the
embodiment and the drawings are given only for the purpose of
illustration and explanation, and are not to be taken as limiting
the scope of the present invention, the scope of which is to be
determined by the set of appended claims.
[0035] FIG. 1 shows a conventional all around towing system on a
tug in perspective view with main components;
[0036] FIG. 2 shows a conventional carrousel towing system in
section view at a set of wheels;
[0037] FIG. 3 shows a conventional DOT towing system in section
view at a set of wheels;
[0038] FIG. 4 shows an all around towing system according to an
embodiment of the invention;
[0039] FIG. 5 shows a sectional view of the all around towing
system;
[0040] FIG. 6 shows the all around towing system in a perspective
view from an angle from above; and
[0041] FIG. 7 consisting of FIGS. 7a and 7b shows the carriages
with two rigid parts with flexible connection structures.
DETAILED DESCRIPTION OF THE EMBODIMENT
[0042] The tug 1 represented in FIG. 1 is provided with a central
deck 2, a circular towing installation 3, a towing hook 4 and a
towline 5 to the ship towed (not shown). Inside the towing ring is
the accommodation 6 and on top of the accommodation the wheelhouse
7 and funnels 8. The towing installation can for example consists
of a circular rotating ring extending all around the circular fixed
structure by means of rollers/bearings.
[0043] FIG. 2 represents a cross section of the carrousel towing
system with the steel structure of the tug's hull 11, the lower
rail 12 and the upper rail 13, the box shaped rotating circular
carrousel ring structure 14 and the upper load bearing wheel 15 and
the lower load bearing wheel 16. The upper load bearing wheel has a
flange 17 on the lower edge to prevent the carrousel structure from
moving upward. The same applies to the lower load bearing wheel
with flange 18. The arrow 19 indicates the direction of the outward
towing force. Since the carrousel forms a ring structure all
around, there is no need for additional wheels to prevent the ring
structure to move outward. The rotating axis 20 of the load bearing
wheels is positioned vertically.
[0044] FIG. 3 represents a cross section of the DOT system with the
steel structure of the tug's hull 21, the single horizontally
mounted rail structure 22, supported by two girders 23. The
rotating structure is formed by two carriages, one of them shown
simplified in section with a heavy plate 24 fitted with again load
bearing wheels on the outer side 25 and on the inner side 26. The
load bearing wheels are equipped with flange 27 on wheel 25 and
flange 28 on wheel 26 to prevent the rotating structure from moving
upward. The arrow 29 indicates again the outward towing force and
the rotating axis 30 of the wheels is again vertically. Further a
number of smaller supporting wheels are fitted to counter the
gravity force (not shown).
[0045] The tug 31 represented in FIG. 4 is according to an
embodiment of the present invention. It is provided with a central
deck 32, a circular towing installation 33, a triangular connection
34 and a towline 35 to the ship towed (not shown). Inside the
towing ring is the accommodation 36 and on top of the
accommodation, the wheelhouse 37 and funnels 38. The towing
installation 33 includes a fixed heavy plate 40, a fixed circular
support 41 and a rotating outer carriage which is rotatable 360
degrees with respect to the tug 31 about the central deck 32.
[0046] FIG. 5 represents a sectional view of the towing system 33
according to the invention, with the ship's structure formed by a
heavy thick horizontal plate 40, a circular support 41, an upper
rail segment 42 positioned in the upper groove 43 in the heavy
plate and a lower rail segment 44 positioned in the lower groove
45. Further, the carriage frame 46 with an U-shaped form fitted
with two upper main bearing wheels 47 and lower main bearing wheels
48. The upper main bearing wheels are arranged and positioned on
the upper and inner half surface of the carriage 46 for guiding the
carriage 46 along the inner side of the upper rail segment 42. The
lower main bearing wheels 48 are arranged and positioned on the
lower and inner half surface of the carriage 46 for guiding the
carriage 46 along the inner side of the lower rail segment 44. The
upper and lower main bearing wheels 47, 48 are each equipped with a
flange 49 of upper wheel 47 and flange 50 of lower wheel 48,
respectively to prevent the carriage 46 from moving up and
downward. The upper and lower main bearing wheels 47, 48 have a
vertically rotating axis 51. The arrow 52 indicating the outward
towing force and the rotating axis 51 is again vertically.
[0047] Further, a set of additional outer wheels 53, 54 are
provided on the upper and lower surfaces of the carriage 46. The
carriage frame 46 is fitted with additional upper wheels 53 and
additional lower wheel 54. The additional upper wheels 53 are
arranged and positioned on the upper and outer half surface of the
carriage 46 in contact with the outer side of the upper rail
segment 42. The additional lower wheels 54 arranged and positioned
on the lower and outer half surface of the carriage 46 in contact
with the outer side of the lower rail segment 44. The additional
upper and lower wheels 53, 54 are each equipped with a flange 55 of
upper wheel 53 and the flange 56 of lower wheel 54, respectively.
Also, the additional upper and lower wheels 53, 54 have a
vertically rotating axis 57.
[0048] FIG. 6 represents the towing system in perspective view with
the ship's structure 58, the heavy thick plate 40, the upper rail
segment 42, the towing system 33, the two guiding structures 59 and
the towline 35 from the assisted ship. The carriage 46 is formed by
two rigid parts 61, 62 connected to each other. Each of the guiding
structures 59 is mounted on the surface of each rigid part 61, 62
of the carriage. The towline divides into two line parts 60 with
internal angle .alpha., which are connected to the guiding
structures 59 or are guided through the guiding structures 59 and
run from the outside towards the centreline of the carriage 46.
Preferably the angle .alpha. is between 45.degree. and 75.degree..
The two line parts 60 can have a circular section or a flat
rectangular section. The flat rectangular section can be used with
smaller diameter guiding structures, because the minimal bending
ratio is defined by radius of the guiding structure divided by the
radius of the line. The two lines can also consist of standard
lifting slings with flat sections and integrated connection eyes on
both ends.
[0049] The right part 61 of the carriage 46 is shown transparent
with internals and showing the main upper bearing wheels 47, the
additional upper wheel 53 and the additional lower wheel 54. The
left rigid part 62 of the carriage 46 is shown solid with main
upper bearing axle 66 and an additional upper axle 67.
[0050] FIG. 7 represents the carriages in the same perspective view
as in FIG. 6, but without surrounding structures for clarity. The
carriage in FIG. 7a consists of two guiding structures 59, a rigid
right carriage part 61 and a rigid left carriage part 62 connected
by a marginally flexible structure 63. This can be a flexible steel
plate bolted or welded to the rigid parts. The carriage in FIG. 7b
consists of two guiding structures 64, composed of either a fixed
or rotating roller, a rigid right part 61 and a rigid left part 62.
Between both parts a flexible structure is fitted, in this drawing
shown as two rubber fender blocks 65 with only take compressive
forces. Also, other structures with hinges and sliding faces can be
considered.
[0051] Although the invention has been described above with
reference to a preferred embodiment, numerous modifications may be
made without departing from the scope of the present application.
The all around towing installation may be constructed in all kind
of different arrangements of rails, wheels and rollers both on
fully circular shapes and on oval or non-circular shapes. The
design is intended for unrestricted all around operation, but the
design may be used for only part rotation, e.g. rails over a half
circle from one side to the other over the aft deck.
[0052] Instead of upper and/or lower rail segments, the heavy plate
(groove) surface may also be treated to increase the hardness (or
by adding material) and thereby allowing to operate the bearing
wheels directly on the heavy plate without the need for additional
rails.
* * * * *