Fire escape – ladder – or scaffold – Ladder – Flexible
Reexamination Certificate
1999-12-29
2002-03-19
Chin-Shue, Alvin (Department: 3634)
Fire escape, ladder, or scaffold
Ladder
Flexible
C182S190000
Reexamination Certificate
active
06357551
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to equipment for climbing and rescue, and more specifically to non-rigid ladders and sling assemblies.
2. Description of the Related Art
Various non-rigid, ladder-like structures are known for climbing, rescue and tactical use. Folding ladders of the type constructed with a pair of parallel lengths of rope, cable or chain with rigid rungs spanning the space therebetween are heavy, bulky, noisy and difficult to pack and transport. Further, unless used with extreme care, their rigid hardware damages adjacent objects and surfaces.
Ladders made entirely of rope are lighter and more flexible, thus being easier to pack into a stuff sack and transport. However, a ladder made entirely of rope normally needs at least two fixed, spaced-apart anchor points at the top of its length in order to permit a user to place a hand or foot on a rung without being obstructed by the sidelines. Even when the side-lines are so separated, placing weight on the center of a rope rung tends to draw the adjacent portions of the side-lines thereabove toward one another, thus giving the ladder an unwieldy V-shape. To combat this problem, fixed anchor points are required at the bottom ends of the side-lines, as well as at the top, which makes the use of such ladders all the more laborious in set-up, and limited in application.
One device that overcomes the dual side-line problem is a rope ladder having side-to-side alternating, i.e. staggered, loops. Such a device is shown in U.S. Pat. No. 4,405,034 issued to Dunne in 1983. Dunne's device hangs from a single fixed point. However, rope tangles easily, and is very uncomfortable for anything but very temporary use. Standing in rope loops in bare feet or soft-soled shoes gets painful very quickly. And, wrapping a wrist into a rope loop for a better grip soon chafes the skin on the back of the hand and wrist. Further, rope loops can act as a tourniquet, quickly cutting off circulation in a limb. Therefore, sliding a leg through a loop up to the thigh, or an arm to the armpit, to rest for any length time could be dangerous. Yet further, alternating, opposed loops such as Dunne discloses offer no comfortable resting position for a climber. One leg must always be straight, and one bent. Switching legs to alleviate fatigue requires moving a step up or down, which could be very inconvenient, for example, in rescue or tactical situations.
A ladder-like device known as an “etriet,” shaped very similarly to Dunne's rope ladder, is constructed of ½-inch to one-inch bar-tacked, flat, tubular nylon. This solves some of the problems of rope ladders, in that the material's flattened width spreads the pressure over a greater skin surface, making it a bit easier on the hands, wrists and feet. But, such etriets, having alternating, staggered loops similar to those in Dunne's rope ladder, fail to solve the problem of providing a way for a person to hang for long periods of time comfortably in one spot. Further, if an etriet is constructed of the limpest nylon fabric for maximum wrist-wrapping comfort, the loops thereof will be very difficult to step into without the aid of the climber's hands. That is, although the climber may be able to slide a hand easily through a very limp-hanging loop to achieve a secure wrist-wrapped grasp, poking the toe of a shoe or boot through a limp-material loop is nearly impossible, without holding the loop open by hand.
U.S. Pat. No. 4,577,726 issued to Wheeler in 1986 shows one method of keeping the loops open and foot-accessible in an etriet-type ladder, specifically, by adding an additional layer of strap material to the under-foot portion of each loop. Wheeler suggests this added layer helps a loop stand out, away from the central, weight-bearing strap assembly of the device. Presumably, this extra layer stiffens the loop, and/or weights its lower portion, thus helping keep it open. However, in most instances where an etriet-type ladder might be used, the convenience of Wheeler's multi-layered loop construction is likely a poor trade-off in that it appears to result in a weight increase of some fifty percent, or so, over that of a similar device with conventionally-constructed loops.
Rescue and tactical personnel also frequently need equipment able to function as a sling for feeble and injured persons. One simple sling construction commonly used merely comprises a loop of wide, flat nylon webbing material which can be wrapped around the pelvic and torso area of a person, and attached to the end of a length of line for raising or lowering the person. Alternatively, and most simply, the person may sit within the loop, grasping the upper portion of the loop with both hands, with the buttocks area supported by the lower end of the loop, while the upper end of the loop is attached to a line or other lifting device. Unfortunately, both such uses of single-loop slings of this type accommodate only one person. Further, a feeble person, such as an accident victim, may not balance well in the lower end of a single hanging loop; safety demands holding on tight with both hands. Otherwise, this risks additional injury. And, the wrap-around use of such a loop may be difficult to secure to a trapped or feeble user.
Thus, it appears that a need exists for a soft, flexible, quiet, light-weight ladder adapted for easy, comfortable and safe hand and foot placement, and for single anchor-point attachment. It would also be desirable if such ladder could accommodate a resting climber staying in one position for a long time, without causing hand or foot fatigue, or loss of circulation in a limb. Further, as it is advantageous for climbers, rescue and tactical personnel to have equipment which serves multiple functions, it would also be highly desirable if such a rescue ladder could serve the additional purpose of a safe and secure rescue sling.
SUMMARY OF THE INVENTION
The flexible ladder of the present invention is adapted to overcome the above-noted shortcomings and to fulfill the stated needs. One embodiment thereof is constructed of a primary weight-bearing strap, and a plurality of pairs of directly-opposed side loops depending therefrom, wherein at least one loop includes a half twist.
A second embodiment includes a primary weight-bearing strap, with a plurality of side loops depending from one side thereof, wherein at least one loop includes a half twist.
It is an object of the present invention to provide a flexible ladder constructed of limp, soft material which is very comfortable to grasp and hold, yet which, at once, includes hand and foot-hold loops which open very easily for the hand and foot.
It is another object of the present invention to provide a ladder at once useful to police personnel; firemen; spelunkers; swiftwater technicians; vertical rescue and escape technicians; helicopter rescue personnel; and, personnel involved in tactical and covert operations, as well as those in various other sports, activities and professions.
A further object of the present invention to provide a piece of equipment for climbing, rescue and tactical use which is light-weight, packs easily and serves multiple functions including that of ladder, a rescue sling and also a general-purpose tether and gear-hauling device.
Still further objects of the inventive flexible ladder disclosed herein will be apparent from the drawings and following detailed description thereof.
REFERENCES:
patent: 277389 (1883-05-01), Weed
patent: 686182 (1901-11-01), Wright
patent: 3216030 (1965-11-01), Garfield
patent: 3817351 (1974-06-01), Mikkelson
patent: 4405034 (1983-09-01), Dunne
patent: 4577726 (1986-03-01), Wheeler
patent: 5020633 (1991-06-01), Rangel
patent: 5628380 (1997-05-01), Matisi
patent: 5848667 (1998-12-01), Davidson
Chin-Shue Alvin
Heisler & Associates
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