US3008537A - Rope ladder - Google Patents

Description

Nov. 14, 1961 e. G. ROBERTS ETAL 3,008,537

ROPE LADDER Filed Nov. 14, 1958 2 Sheets-Sheet 1 [NVENTORS GEORGE G. ROBERTS N B. SHAW WMM ATTORNEY.

Nov. 14, 1961 G. G. ROBERTS ETAL ROPE LADDER 2 Sheets-Sheet 2 Filed Nov. 14, 1958 3% a w u INVENTORS GEORGE 6. ROBERTS JOHN B. HAW W Q ATTORNEY.

United States Patent 3,008,537 ROPE LADDER George G. Roberts, 4152 Jefferson St., Redwood City, Calif., and John B. Shaw, Redwood City, Calif. (447 Eleanor Drive, Woodside, Calif.)

Filed Nov. 14, 1958, Ser. No. 773,867 8 Claims. (Cl. 182196) This invention relates to improvements in rope ladders and also to a novel clamp member for use in fastening ladder rungs or other parts to stranded ropes. I

Rope ladders are very old but heretofore they have been considered dangerous, and no rope ladder was approved by the United States Coast Guard for ships pilots uses. The ladder of this invention is the first rope ladder to receive approval from the Coast Guard, and it obtained this approval by solving many problems heretofore unsolved with rope ladders.

An important object of the invention is to provide a safe rope ladder. This safety is achieved not merely by using strong enough materials, but by uniting them in a novel manner, using some novel elements in the combination. The rope is protected from chafing; steel ears provide handholds and connect the steps or rungs to the rope stiles while lying flush against the side of a ship or building to hold the steps steady, to give climbing stability, and to protect the hands from being banged against a wall.

Another object of the invention is to provide a rope ladder which is easy to inspect and to detect wear or faults in the ladder.

Another object of the invention is to provide a fully adjustable rope ladder, by providing ears that can be used as lashing rings for safe, easy adjustment of the length of the ladder.

Another object of the invention is to provide a rope ladder in which all the parts are separately replaceable and to enable quick, economical insertion of new parts for old ones.

Another object of the invention is to provide a rope ladder that folds together and stows compactly so as to save space.

Another object of the invention is to provide a relatively lightweight rope ladder with an open design that gives superior strength while reducing the weight.

Another object of the invention is to provide a novel clamp means for providing a hole through a rope or, in other words, a clamp that can be used for securing rungs or other kind-s of members to a rope. It protects the rope from being chafed by the threads of the bolts or securing members and at the same time is readily removable, instead of having to be molded in place. Moreover, it is easily applied to fiber ropes as well as wire ropes.

Another object of the invention is to provide a rope ladder wherein a broad (double) step is attached to a pair of single ropes.

Other objects and advantages of the invention will appear from the following description of a preferred embodiment thereof.

In the drawings:

FIG. 1 is a view in front elevation of a rope ladder embodying the principles of the present invention. To save space, the ladder has been broken and only two steps shown.

FIG. 2 is a view in side elevation of the ladder of FIG. 1 with an additional portion broken to conserve space.

FIG. 3 is an enlarged perspective view of a portion of one end of one step of the ladder showing the attachment of the rung to the ears and of the ears and rung to the rope.

FIG. 4 is a further enlarged view in elevation and in section through one of the clamps showing how the rope fits into the clamp.

FIG. 5 is a view taken along the line 55 of FIG. 4.

FIG. 6 is a view in elevation and in section taken along the line 66 in FIG. 5 but showing only the clamp and omitting the rope strands.

FIG. 7 is an elevation View looking at the interior of the male half of the clamp of FIGS. 46.

FIG. 8 is an elevation view looking at the interior of the female half of the clamp of FIGS. 46.

FIG. 9 is a view in section taken along the line 99 in FIG. 4.

The ladder 10 shown in FIGS. 1 and 2 has two rope stiles 11 and 12. Wire rope may be used sometimes, but generally fiber rope or its equivalent is employed. For example, first grade four-strand manila rope is a preferred material, and is shown in FIG. 5 with four strands 13, 14, 15, 16. However, the rope 11, 12 may have more or fewer strands. At its upper end each rope 11, 12 is fastened to lashing rings 17 by any suitable means, such as that illustrated, which is conventional in the art and employs a three-tuck splice 18 with a galvanized thimble 19. The lower ends of the ropes 17 and 18 may be terminated similarly in accordance with the best practice.

Each ladder step 20 comprises a pair of rungs 21, 22 secured to a pair of ears 23, 24 that lie opposite and symmetric to each other. Each ear 23, 24 (as shown in FIG. 3) comprises an uppermost portion 25 that extends parallel to the axis of the rope 11 or 12, a U-shaped handhold portion 26, and a lowermost reverse-U portion 27. The uppermost portion 25 has a bolt opening 28 therethrough. The U-shaped handhold and rope-spacing portion 26 may be made in various configurations but preferably comprises an upper generally horizontally extending portion 30, a generally. vertical portion 31 high enough to serve as a hand grasp and spacer, and a lower horizontal portion 32 that extends in toward the rope 11 or 12. The lowermost reverse-U portion 27 includes the portion 32, an axially extending portion 33 with a bolt opening 34 therethrough and a bottom portion 35 which extends horizontally outward from the lower end of the axial portion 33.

When hardwood rungs 21, 22 are used, it is preferable to proportion them to fit into the nest provided by the lower portion 27, with a lower supporting portion 35 helping to prevent splintering. However, in particular if metal rungs are to be employed, this lower horizontal portion 35 may be omitted.

A vitally important part of this invention is the clamp 40 by which the attachment to the ropes 11 and 12 is made. Each clamp 40 (see FIGS. 46) comprises two similar pieces 41 and 42, the piece 41 being male and the piece 42 female. The clamp 40 provides a rope passage 43, through which the rope 11 or 12 extends, and a bolt passage 44 through which a bolt 45 or 46 extends. In this clamp 40 the bolt 45 or 46 is isolated from the rope 11 or 12 by a sleeve-like portion 47, which comprises a tubular stud formed as part of the male member 41. In accordance with this preferred construction, the female member is provided with a socket 48 in which the tubular stud 47 fits, the socket 48 being tubular and completing the bolt opening 44 when the two pieces are joined together. Thus, the stud 47 comprises, in effect, a tubular member separating the threaded bolt 45 or 46 from the rope passage 43 and from the rope 11 or 12.

The two end portions 50, 51 of the rope passage 43 are narrower than the central portion 52, so that the rope 11 or 12 is securely clamped at the ends 50, 51 and space is provided for the rope strands to pass around the stud 47. In the four-strand rope 11, for example,

two strands 13, 14 pass on one side of the stud 47 and two strands 15, '16 pass on the other side.

The interior surface of the rope passage 43 is preferably provided with projections 53, 54 which serve as guiding means for the strands A particularly large projection 53 lies adjacent the stud 47 to guide the strands around the stud, and the projection '54 fills in the void between each pair of strands -13, 14 and 15, 16 and thereby prevents collection of water, etc., within the clamp 40. The interior surface of the rope passage 43 is also preferably provided with a series of parallel generally horizontal ribs 55 which provide a grasping or clamping surface for concentrating clamping force and thereby holding the clamp 40 to the rope securely against sliding action.

In assembly, the short bolt 45 is used at the upper end and the long bolt 46 at the lower end of each pair of ears 23, 24. The short bolt 45 passes through the opening 28 in the ear 24, the bolt passage 44 of the clamp 40, and thereby through the rope 11 between its strand pairs 13, 14 and 15, 16 but isolated from them by the stud 47, and through the opening 28 of the ear 23. A nut 60 is then used and tightened into place. A vertical planar exterior portion 61 of the clamp 40 around the bolt opening 44 forms bearing surfaces that engage against the uppermost axial portions 25. The long bolt 46 passes through a rung 22, opening 34 of ear 24, bolt opening 47 of clamp 40, opening 34 of ear 23, and rung 21 and is secured by a nut 62. The bearing portion 61 engages the axial ear portion 33.

The clamps 40 are put in place first on the ropes 11, 12 at spaced intervals and are then fastened to the ears 23, 24. In attaching the clamp 40 to the rope, the strands are separated and laid into the male member 41 and then the female member 42 is fitted therearound. Preferably, the male stud 47 fits into the socket 48 in a tight pressed fit'to help hold the clamp together even before the bolt 45 is inserted.

It will be noted that four bolts 45, 46 suffice to carry each step 20, two on each stile 11, 12, and that the bottom bolts 46 not only hold the rungs 21, 22 to the stile 11, 12 and to the ears 23, 24 but also hold the ears 23, 24 to the stile 11, 12. By this combination the minimum number of parts can be used.

It will be apparent from the foregoing that it is easy to replace any part that may be damaged or worn out, for all that need be done is to take off the appropriate nuts and withdraw the needed bolts.

The ladder parts are readily standardized; for example, the rungs 21, 22 may be identical, all the ears 23, 24 are identical, all the clamps 40 are identical, and only two different kinds of bolts 45, 46 are used. So considering the stiles, rungs, ears, clamps, bolts, nuts, thimbles, and lashing rings, there are only 9 different parts for the ladder and only the ears and clamps are not standard articles of commerce.

The ladder described above has been tested by the United States Coast Guard. The rope side members easily support 2,000 pounds and the center of each step 700 pounds. The ropes are protected from chafing by being secured through the center of the metal ear assembly '23, 24 which automatically absorbs the majority of wear. They are also protected against chafing by the bolts 45, 46 due to the stud 47 construction. The steps 21, 22 do not tend to chip because the safety steel ears 23, 24 lie flush against the side of the ship or building and therefore hold the steps steady.

The ears 23, 24 may be used as lashing rings to shorten the length of the ladder if desired. The open construction of the cars 23, 24 makes it easy to spot wear and simplifies inspection, thereby assuring constant safety. Their open design also keeps the weight equal to or less than the old-style Jacobs ladders. The open design of the ears 23, 24 also makes it easy to insert Wooden outriggers to prevent the ladder from twisting as it is being climbed. Such outriggers are normally placed about two feet apart and comprise wooden two-by-fours extending about two or three feet on each side of the step. The ladder is readily folded together into approximately half the space of comparable ladders.

The clamp 40 may be made of metal, if desired, but it also may be, and preferably is, made of plastic such as polyethylene, for example, what is known as Marlex-SO, a strong form of polyethyl. Other plastics are also suitable so long as they have sufiicient strength and elasticity. Clamps 40 made from such plastic have been tested; dropping one 10 feet onto concrete caused only slight dents on the edge. When mounted on a rope and submitted to blows of 45 pounds or dropped from a height of 16 inches and hitting on its side at right angles to the bolt, the only damage was slight denting and scratching. Another clamp 40, when mounted on the rope, was subjected to a force of a falling one-pound steel ball dropped from a height of 24 feet. The ball made a dent about /8 deep in the plastic clip 40 but did not break it. Another clip 40 was put together with a bolt without any rope inserted and was subjected to compressive force from end to end. The plastic did not start to yield by bending until a load of approximately 2,000 pounds had been applied. Even at 2,100 pounds, when the sample slowly collapsed, it did not break. The use of the plastic clamp further reduces wear by being very smooth, and makes it easy to provide lightweight, inexpensive members instead of having to use the heavy metal members.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

We claim:

1. A rope ladder, comprising a pair of stranded ropes; a series of symmetric handhold, spacing, and step-supporting ears opposite each other, each ear having an upper end portion with a bolt opening therethrough, a handhold portion, and a lower portion with a bolt opening therethrough; a pair of rungs joining each pair of ears on one rope to a pair of ears on the other rope at said lower portions; a rope clamp between said upper end portions of each pair of ears; another rope clamp between said lower portions of each pair of ears, each said clamp comprising a sleeve-like member with a rope passage therethrough and having a bolt passage perpendicular to said rope passage and passing between strands of said rope; a bolt extending through said upper ear portions, a said clamp, and said rope; and a bolt extending through said pair of rungs, said lower portions, 3. said clamp, and said rope.

2. A rope ladder, comprising a pair of stranded ropes; a series of symmetric handhold, spacing, and step-supporting ears opposite each other, each ear having an upper vertical end portion with a bolt opening therethrough, a generally U-shaped portion, and a lower vertical portion with a bolt opening therethrough; a pair of rungs joining each pair of ears on one rope to a pair of ears on the other rope; a rope clamp between said upper end portions of each pair of ears; another rope clamp between said lower portions of each pair of ears, each said clamp comprising a sleeve-like member with a rope passage therethrough and having a tubular member perpendicular to said rope passage and passing between strands of said rope; bolt means securing said upper ear portions to a said clamp and said clamp to its rope; and bolt means securing said rungs, said lower portions, and a said clamp to said rope and to each other.

3. A rope ladder, comprising a pair of stranded ropes; a series of handhold, spacing, and rung supporting ears, each ear comprising an uppermost vertical portion lying generally axial of a said rope with a bolt opening therethrough, a generally U-shaped portion connected to said 1IPPWIIOSt portion and a lowermost reverse U-portion having a vertical portion with a bolt opening therethrough, said ears being arranged in symmetric pairs on the opposite sides of each rope; a pair of rungs connected in the reverse U-portion of each ear; pairs of clamps secured to said rope, one between a pair of said uppermost portions of each pair of ears, the other between said lowermost Vertical portion of each pair of ears, each clamp comprising a sleeve-like member surrounding said rope and having a rope passage therethrough and having a tubular member perpendicular to said rope passage and passing between strands of said rope; bolt means'passing through the bolt opening of the uppermost portion of one ear, said tubular member, and the bolt opening of said uppermost portion of the other said ear to anchor the upper ends of said ears on said rope; and bolt means passing horizontally through one said rung, said lowermost vertical portion of one ear, said tubular portion of a clamp, said lowermost portion of the other ear, and the other said rung, to secure the lower end of said ear and said rungs to said rope and to anchor said rungs to said ears.

4. A rope ladder, comprising a pair of stranded ropes; a series of handhold, spacing, and stile-supporting ears, each ear comprising an uppermost portion lying generally parallel to a said rope with a bolt opening therethrough, a generally U-shaped portion connected to said uppermost portion and a lowermost section having an axial portion parallel to said rope with a bolt opening therethrough and a horizontal supporting portion extending out away from said rope at the lower end of said axial portion, said ears being arranged in pairs arranged symmetrically on opposite sides of each rope, one said pair on each rope horizontally on the same level; a pair of rungs joining each pair of ears to another pair and resting on said supporting portion; a pair of clamps, one between said uppermost portions of each pair of ears, the other between said lowermost portions of each pair of cars, said clamps comprising a sleeve-like member surrounding said rope to provide a rope passage therethrough and having a tubular member perpendicular to said rope passage and passing between strands of said rope; bolt means passing through the uppermost portion of one car, a said tubular member, and the uppermost portion of the other said ear to anchor the upper end of said ear and said clamp to said rope; and bolt means passing horizontally through one said rung, said lowermost portion of one ear, a said tubular portion of another clamp, said lowermost portion of the other ear, and the other said rung, to secure the lower end of said ea-r, said other clamp, and said rungs to said rope and to anchor said rungs to said ear.

5. The rope ladder of claim 4 wherein said clamp is made in two parts, a male part including said tubular member as a tubular stud projecting across said rope passage, said stud passing between strands of said rope and isolating the bolt from direct contact with said rope, and a female part having a socket in which said stud fits and forming an opening for said bolt in alignment with said stud.

6. The rope ladder of claim 4 wherein said clamp has narrow end portions for tightly grasping said rope and a wider central portion to accommodate some strands on one side of said tubular member and some on the other side.

7. The rope ladder of claim 4 wherein said clamp has guide means in said rope passage for separating and guiding said strands around said tubular member, thereby filling space between said strands and preventing their deformation.

8. The rope ladder of claim 4 wherein the inner surface of said clamp defining said rope passage has a plurality of parallel ribs transverse to the axis of said rope for gripping the surface of said rope.

References Cited in the file of this patent UNITED STATES PATENTS 287,560 Miller Oct. 30, 1883 1,349,125 Full Aug. 10, 1920 1,976,533 Afileck Oct. 9, 1934 2,638,260 Skolmen May 12, 1953 2,698,471 Peirce Jan. 4, 1955 2,834,529 Dahlander May 13, 1958 2,862,270 Fox Dec. 2, 1958 2,877,527 Bond Mar. 17, 1959 FOREIGN PATENTS 271,613 Great Britain June 2, 1927 469,877 Germany Dec. 28, 1928

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