Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to an improved rope ladder and to a novel
step therefor, as well as to assembly of the ladder.
Rope ladders, which are especially useful as pilot's ladders by which
a local pilot boards or leaves a ship, have heretofore been made with wooden
or metal steps. The present invention incorporates a molded elastomer step of
hard rubber-like material.
In my United States Patent No. 4,177,878, dated December 11th, 1979,
I disclosed a rope ladder of the type in which there are two ropes on each side
of each step and in which a novel wedging device is used to make the attachment
secure. In the present invention, I am able to incorporate into the molded
step, part of a similar but significantly different wedging system, thereby
giving even surer and more reliant structure, since part of it is integral with
the step itself. This new wedging system more tightly holds the ropes even when
they are elongated.
The breakage and non-uniformity of wooden steps has long been a
problem, and the use of molded elastomer greatly reduces breakage and gives
improved quality control. Also, the elastomer has more resilience and so better
receives strong impacts. It will not flex or bend under average work load, but
on the other hand can yield to very strong loads or impacts without actually
breaking.
Furthermore, the rope ladder of the present invention is simpler to
make and to assemble than were previous wooden-step ladders, and the invention
lends itself to a novel form of assembly that also places elongating force on
the rope and secures the rope more securely as a result.
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Summary of the Invention
The invention provides a rope ladder of the type having a series of
ladder steps, each with an upper surface and a lower surface, two longitudinal
edges and two end edges, and two spaced-apart pairs of ropes, the improvement
wherein:
each said step is a molded one-piece hard elastomer member having
two spaced-apart vertical through openings, one spaced in from each said edge,
each said through opening being narrow at its upper end for closely confining
said ropes and being much wider than that where it emerges from said lower
surface, each through opening tapering inwardly from bottom to top, each said
step having vertical bolt openings therethrough adjacent each said through open-
ing,
a pair of separate wedge collars for each said step, one at each end
of and below said step and bearing up against it, each said wedge collar having
a single elongated through opening whose upper end is approximately the same
width as said step's through opening where it emerges from its lower surface,
said elongated through opening tapering inwardly therefrom down to a narrow
portion at the lower end for closely confining the two ropes, each said wedge
collar having vertical bolt passages therethrough aligned with the bolt open-
ings through said step,
a generally diamond-shaped wedge heart in between the said ropes of
each pair of ropes, a said heart lying in each through opening of each step and
extending into each said elongated through opening of said wedge collar, said
wedge heart having an upper vertex adjacent said upper end of said step's
through opening and a lower vertex adjacent the bottom of the elongated through
opening of said wedge collar, and providing two rope-engaging side grooves
extending between and ending at said vertices, so that these rope-engaging
grooves, when said wedge heart is fully wedged in place, lock the pair of ropes
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in place and prevent relative movement between them and said step, said wedge
collar and said wedge heart, and
fastening means extending through the bolt passages of each wedge
collar and the bolt openings of each step and tightened in place to hold said
wedge collar and wedge heart in place and lock said ropes in fixed position
relative to said wedge heart, said step, and said wedge collar.
The ladder steps are preferably provided with a non-slip surface and
with strengthening structure.
The invention also includes a method for assembly of a rope ladder
of the type having a series of ladder steps, each having two spaced~apart
vertical through openings, one spaced in from each end, and each tapering
inwardly from bottom to top, and a pair of separate wedge collars for each step
with opening aligned with those of the step,
threading two pairs of ropes alternately through the steps and wedge
collars,
bringing a wedge collar up close to the bottom of each step at each
end,
inserting a generally diamond shaped wedge heart in between each pair
of ropes and in between each collar and its step,
holding said step in place against an anvil on its upper surface, and
hydraulically forcing both said wedge collars for that step upwardly
until the upper surface of the wedge collar engages the lower surface of said
step.
The invention also provides a step for a rope ladder, comprising
a molded one-piece hard elastomer member with an upper surface and a
lower surface, two longitudinal edges, two end edges, and two spaced-apart,
vertical rope-receiving, through openings, one spaced in from each said end
edge,
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said member having at the upper end of each through opening an
integral wedging portion surrounding said opening on and above said upper
surface,
each said through opening having a narrow outlet from said wedging
portion approximately twice the diameter of the rope it is to receive, for the
reception of two such ropes, and being much wider than that where it emerges
from said lower surface, each opening tapering inwardly from bottom to top and
arcurate at each end,
each said step having a pair of vertical bolt openings therethrough
adjacent each said through opening.
Brief Description of the Drawings
In the drawings:
Figure 1 is a view in front elevation of a portion of a rope ladder
embodying the principles of the invention and showing an elongated step in
between several normal steps.
Figure 2 is a fragmentary isometric view of one of the steps of the
ladder, showing the ropes and other parts of the assembly.
Figure 3 is a bottom plan view of one of the steps, viewed in the
direction of the arrows 3-3 in Figure 2.
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1 Fig, 4 is an enlarged isometric view of one end of
2 a step, with the remainder of the step broken off to conserve
3 space.
Fig. 5 is an end view taken along the line 5-5 in
6 Fig. 4, at a slightly reduced scale.
8 Fig. 6 is an isometric view of a wedge heart used
9 in the invention.
11 Fig. 7 is an isometric view from below of one of
12 the wedge collars used in conjunction with the step and the
13 wedge heart to secure the ropes in place.
14
Fig. 8 is a top plan view of the wedge collar of
16 Fig. 7.
17
18 Fig. 9 is an enlarged fragmentary view in section
19 taken along the line 9-9 in Fig. 2, showing the combination
of a pair of ropes with the step and its integral wedge
21 portion and with a separate wedge collar at the bottom, and
22 with the wedge heart, which is broken away to show the bottom
23 of its groove on one side as well as the outer wall of its
24 groove on the other side.
26 Fig. 10 is an enlarged fragmentary view in section
27 of a portion of the molded step.
28
29 Fig. 11 is a fragmentary top plan view of approxi-
mately half of one of the elongated steps.
31
32 Fig. 12 is a view in front elevation showing a
33 stage in the assembly of one step with the ropes and collar,
34 the installing apparatus being at its beginning position, not
yet tightened.
36
37 Fig. 13 is a somewhat enlarged view in side
38 elevation of a portion of Fig. 12.
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1 Fig. 14 is a view similar to Fig. 12 showing the
2 assembly tightened together, the bottom portions being
3 broken off to conserve space.
De ailed_Descri~on of the Invention
6 Fig. 1 shows a portion of a rope ladder 10 embodying
7 the invention. The ladder 10 is especially useful as a
8 pilot's ladder for boarding and leaving ships and comprises
9 four ropes distributed as two pairs of ropes 11,12 and 13,14,
one pair at each side of the ladder 10. The ladder 10 further
11 comprises a series of regular steps 15 and, at intervals
12 usually as prescribed by the United States Coast Guard, a
13 series of elongated steps 16, which extend out well beyond
14 the rope pairs 11,12 and 13,14, and help to keep the ladder
10 from turning or twisting relative to the side of a ship.
16 In addition, the invention comprises two wedge collars 17
17 and two wedge hearts 1~ for each step 15 or 16.
18
19 The step 15, as shown in Figs. 2 through 5, 9,
and 10, is a unitary one-piece molded member made from a
21 sui~able hard elastomer, such as a hard synthetic rubber
22 composition. It has some flexibility but is not readily
23 bent or flexed by hand. The step 15 has an upper tread
24 surface 20 which is shaped to reduce the liklihood of skidding
or sliding thereon. The step 15 also has a lower surface
26 21, which preferably includes a pair of streng~hening ribs
27 22 and 23. The step 15 has vertical front and rear edges
28 24 J 25 and end edges 26 and 27.
29
~oreover, the step 15 has near or at each end
31 26,27 an integral, upwardly extending, rope-engaging portion
32 30,31 which is molded out with the step 15 of the same
33 elastomer and at the same time, so that the portions 30
34 and 31 are simply parts of the step 15. Down through each
portion 30,31 is a through opening 32 or 33. Along the lower
36 surface 21 and at each end of the step 15 is an entry opening
37 34 for each through opening 32,33. This entry 34 is wide
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and cooperates with the wedge heart 18 in a manner as will be seen later.
At the upper end of each portion 30,31 is an outlet 35 from the opening 32,33
which is narrow, preferably barely wide enough for the two ropes 11,12 or 13,14
to pass out, so that they are fairly snug there. The inside surface 36 in
between the entry 34 and outlet 35 is tapered and, being curved, acts like a
groove to receive the round ropes.
In addition to the vertical through openings 32,33~ each end of each
step 15 has a pair of vertical bolt openings 37,38 extending down through the
portion 30,31 and through the entire step. At the top, recesses 39 (See
Figure 4) are provided to help receive a bolt 40 and to provide a bearing
surface 41 for its head 42 (See Figure 9).
As shown in Figure 10, the non-skid aspect of the upper surface 20
may be enhanced by first spraying a suitable paint 43 of a type which will
adhere to that surface, then adding to it grit 44 and then coating with paint
45 again so as to bond the grit 44 to the paint 43,45 and through it to the
step 15.
The elongated steps 16 are like the steps 15 except that they have
outward outboard portions 46 and 47 which may comprise hard rubber rims 48
with openings 49 therethrough to save material and lighten the step while not
decreasing its effectiveness for the purpose.
A wedge collar 17 is shown in Figures 7 and 8 as well as in Figure 9,
and comprises a metal member basically like that disclosed in United States
4,177,878. Each wedge collar 17 has an upper surface 50 and a lower surface 51
and a through opening 52 which is generally like the openings 32,33, but invert-
ed7 with a wide opening 54 at the top 50 to a narrower opening 55 at the bottom
51 and a tapered as well as curved
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l surface 56 in between. The wide opening 54 is preferably
2 exactly the same in dimension as the entry opening 34 of the
3 step since it will mate against it. The wedge collar 17 also
4 has bolt openings 57,58 through which the bolt openings 37,38
S align and through which the bolts 40 are inserted, preferably
6 from the top, with nuts 60 on the bottom that are tightened
7 against a ledge 61, for which a recess 62 is provided, to
8 hold the collar 17 in place against the step 15 or 16.
The wedge heart 18 (Fig. 6) is of generally diamond
11 shape, having a vertex 63 at the top and a vertex 64 at the
12 bottom and with concave rope guides or grooves 65 and 66
13 along its two opposite edges; it has flat side faces 67 and
14 68 as shown in Figs. 6 and 9. Each wedge heart 18 is
inserted between the two ropes 11,12 or 13,14 and lies with
16 its widest portion 69 at about the plane where the lower
17 surface 21 of the step 15 and the upper surface 50 of the
18 wedge collar meet; its upper apex 63 lies at about the upper
19 face of the portion 30 in the outlet 35, while its lower
apex 64 lies at about the lower outlet 55 from the wedge
21 collar 17. When fully wedged in place, the grooves 65
22 and 66 are parallel to the curved end walls ~of the openings
23 37 and 38 of the step 15 or 16 and to the curved end
24 walls of the openings 52 of the wedge collar 17. The heart
18 then locks the step 15 (or 16), the wedge collar 17~ and
26 itself to the ropes 11,12 or 13,14, so that relative movement
27 between them cannot take place.
28
29 Since the completed wedging is so tight and since
slippage is not permitted, installation of the device is
31 preferably accomplished as shown in Figs. 12-14. The rope
32 ladder 10 is preferably assembled from the bottom up, the
33 bottommost step 15 being assembled first; and the parts
34 15, 16, and 17 are threaded on the rope 11,12 and 13,14 in
advance. Assembly of an intermediate step 15 is shown. A
36 rigid anvil member 70 is secured to a pair of vertical
37 supports 71,72 which are secured firmly to a suitable rigid
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1 vertical support or wall 73. The upper edge 20 of a next
2 upper step 15 is brought up against the lower surface of the
3 anvil 70. Below the anvil 70 and below that step 15 is
4 a pair of hydraulic cylinders 74,75, secured to the supports
S 71,72 and resting on a base plate 75a, which is placed on
6 the next-below step 15a, which has already been secured in
7 place, as by a previous use of the assembly de~ice. Each
8 cylinder 74,75 has a rod 76,77 connected to its piston (not
9 shown). The rods 76 and 77 support a crosshead 78. A wedge
collar 17, after having been threaded through lts ropes, is
11 inserted on an end shelf 79 at each end of the crosshead 78,
12 and a wedge heart 18 is inserted in between each pair of
13 ropes 11,12 and 13,14. Then, hydraulic pressure is exerted
14 to raise the crosshead 78 as shown in Fig. 13, finally
lS bringing it up to the position shown in Fig. 14, in which
16 both wedge collars 17,17 have their upper surfaces 50 bearing
17 against the bottom surface 21 of the step 15 and the wedge
18 hearts 18,18 in the position where they lock the assembly
19 together, all as shown in enlarged form in Fig. 9. This
2Q action of the cylinders 74,75 also acts to exert a strong
21 stretching force on the ropes 11,12 and 13,14 in between
22 the steps 15 and 15a, helping to assure tautness and to
23 secure the wedging action simultaneously. Then, the bolts
24 40 are inserted and the nuts 60 tightened on them to hold
the assembly together. Then, the next step 15 and its
26 associated elements are extended in the same manner.
27
28 For a pilot's ladder 10, the steps 15 are about
29 twenty inches long, about five inches wide, and about an
inch thick at the tread. The elongated steps 16 are typically
31 about seventy inches long, and the openings 49 about two
32 inches by eight inches, there being two openings 49 on each
33 side of each step 16. For a forty-foot ladder, there are
34 usually four of the elongated or spreader steps 16.
36 In addition to serving their usual functions,
37 the spreader steps 16 of this invention solve several
38 problems. Conventional wooden spreaders tend to catch
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1 the wind, and when they do, they tend to cause the ladder
2 to twist or spin, thereby making ascent or descent danger-
3 ous, if not impossible. The openings 49 let the wind pass
4 through the outboard positions 46 and 47 and greatly reduce
5 the wind resistance, thereby significantly increasing the
6 ladder's safety. Furthermore, the rims 48, due to the
7 openings 49, serve as hand holds when needed, as on windy
8 days and nights, thereby adding another safety feature.
9 Beyond all this, the openings 49 lighten the weight of
10 the ladder 10 considerably, and weight is always a con-
11 sideration for pilot ladders. On a forty-foot ladder 10
12 with four spreader steps 16, the open area is about 2" x
13 8" x 4 x 4 = 256 square inches, and at one inch thick,
14 this open area is equivalent to reducing the weight by the
15 weight of a 4" x 1" board about five and one-half feet
16 long.
17 .`
18 The molded one-piece hard elastomer polymer
19 composition RIM (reaction injection molding) may have a
20 reinforcement by means of a tubular material completely
21 imbedded or concealed in the body of the step to add
22 additional strength and prevent flexing. The tubular
23 reinforcing is preferably connected on the ends of the
24 tubular reinforcements by bolts through the bottom collar
25 to form a perîpheral framework. The tubular reinforcement
26 also acts as a buoyancy factor.
27
28 To those skilled in the art to which this inven-
29 tion relates, many changes in construction and widely -~
30 differing embodiments and applications of the invention
31 will suggest themselves without departing from the spirit
32 and scope of the invention. The disclosures and the de-
33 scription herein are purely illustrative and are not
34 intended to be in any sense limiting.
36
37
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