Fire escape – ladder – or scaffold – Torso harness – Attached to strand wound on reel – and means for retarding...
Reexamination Certificate
2000-04-28
2001-02-13
Chin-Shue, Alvin (Department: 3634)
Fire escape, ladder, or scaffold
Torso harness
Attached to strand wound on reel, and means for retarding...
C182S007000
Reexamination Certificate
active
06186276
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to automatic belay apparatus and its use; and more particularly it concerns the provision of safe, easily used, simple and compact, fall protection/lowering apparatus which can be employed in many situations to save lives and also for recreational purposes.
There is a known phenomenon that when a rope is wrapped around a fixed cylinder an X tension is applied to one end of the rope, a reactive force less than X (we will call Y) will stop the rope from slipping. More wraps around the cylinder will reduce the required Y force necessary for equilibrium.
Once equilibrium is attained between X and Y, reducing Y force by some A amount will allow the rope to slip. The amount of reduction in Y is dependent upon, among other things, the elasticity of the rope, the number of wraps around the cylinder, the diameter of the cylinder, and the co-efficient of friction between the rope and the cylinder.
To belay in nautical terms, is to “make fast (a rope) by winding on a cleat or pin”.
If one is climbing, to be belayed is to be protected (by a rope) from falling. This is accomplished by wrapping a rope around the belayer, or some other object, so as to reduce the Y tension when a climber falls, creating X tension. The governing equation depicting this phenomenon is:
X
tension
=&thgr;
a
FY
tension
Where &thgr;
a
=Number of degrees, in radians, that the rope is in contact with a fixed cylinder
F=Coefficient of friction between the rope and the cylinder
a=Rope coefficient
Therefore, the greater number of wraps (radians), the lower Y is required for equilibrium.
And here is the paradox. If one wished Y to be minimal, multiple wraps are required; but, if one wishes to take up slack on the X rope when climbing by taking up Y tension, the weight of the rope X will be multiplied by the same factor (but in reverse) as when the climber falls which might make it impossible to take up slack, and hence a non-functional device. As one example:
For a wire rope, with 5½ wraps around a 3″ pipe (3.5 O.D.),
X=50# and Y=0.12#
Therefore, the amplification factor is 50#/0.12=400# Now, remove the 49# weight leaving a 1# rope and try to pull Y. Y=1#×400=400# to take up slack. This is not possible, or practicable.
Accordingly, there is need for improved apparatus to overcome the above problem so that slack can be automatically taken up while using the multiplying effect of multiple wraps; and there is need for apparatus which can be easily used for safe lowering of weights, as from great heights.
SUMMARY OF THE INVENTION
It is a major object of this invention to provide improved fall protection/lowering apparatus and methods, meeting the above needs. Basically, the apparatus of the invention is used for controlling vertical movement of a first weight (as for example a human being or other load), and comprises:
a) a first rotor rotatable in one direction about an axis and blocked against rotation in the opposite rotary direction,
b) a second rotor which is substantially freely rotatable in opposite rotary directions,
c) a control weight,
d) and lines supporting the first weight and control weight by the rotors, and including a first line wrapping about the first rotor and a second line entraining the second rotor, whereby changes in force exertion on the control weight determine alternative existence of a first mode of operation wherein line slippage relative to the first rotor allows the first weight to descend, and a second mode of operation wherein line non-slippage relative to the first rotor thereby blocks descending of the first weight.
Typically, the first line that wraps about the first rotor has line portions that extend downwardly to support loading imposed by the first weight and control weight, respectively; and the second line that entrains the second rotor also has line portions that extend downwardly to support loading imposed by the first weight and control weight respectively.
Another object is to provide the first rotor with an extended surface to engage multiple, non-interfering wraps of the first line. In this regard, the second rotor may typically comprise a pulley.
A further object is to provide the first rotor with two axially spaced generally conical portions, and a generally cylindrical portion intermediate those conical portions. Typically, the conical portions may have wrap engaging angularities characterized as maintaining the first line wraps free of sidewise interengagement or interference during operation of the apparatus to lower the first weight.
Accordingly, optimum operability and functioning of the first line and first rotor are maintained.
Yet another object is to provide the first rotor with an axial through passage, the second line passing through that passage, whereby a high degree of compactness of the equipment is achieved.
An additional object is to provide support structure for a human being who imposes the first weight in order to be lowered, such support structure defined by an upright strut connected to the line wrapped about the first rotor, and a seating ledge connected to the strut. That ledge may advantageously include at least one folding section having an up-folded position extending generally parallel to the upright stem, and a down-folded position extending generally laterally to seat the human being.
In use, the first rotor, i.e. a cylinder for example, is allowed to rotate freely in one direction (while taking up slack), and prevented from rotating in the opposite direction while resisting a fall. The taking up of slack is accomplished by hanging a weight on the Y reactive side of the cylinder greater than the weight of the rope on the X tension side of the cylinder; hence, in the above one example, Y need only be 1# to take up slack but it is strong enough to resist a 400# load during a fall.
If the device is to be used by a climber, once the climber has climbed he must be able to lower himself. This can be accomplished by attaching a separate control rope to the Y reactive weight, running this control rope over a freely rotating sheave, and then attaching the control rope to the X load. By shortening the control rope, the Y reactive force will be reduced until slippage occurs. Since X and Y will remain the same distance apart during slippage, slippage will continue unabated until the control rope is allowed to lengthen, for example lifted.
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patent: 662243 (1900-11-01), Nelson
patent: 1113369 (1914-10-01), Olson
patent: 1123776 (1915-01-01), Meyer
patent: 1766566 (1930-06-01), Tucker
patent: 1787651 (1931-01-01), Zwink
patent: 4039045 (1977-08-01), Hoger
patent: 4645034 (1987-02-01), Griffith
patent: 4679656 (1987-07-01), Lew et al.
patent: 4941548 (1990-07-01), Blanchard
patent: 4997064 (1991-03-01), Motte et al.
patent: 5186275 (1993-02-01), Bajin
Atoll Holdings Inc.
Chin-Shue Alvin
Haefliger William W.
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