Abstract:
Apparatus for use in controlling vertical movement of a first weight, comprises a first element rotatable in one direction about an axis and blocked against rotation in the opposite rotary direction; a second element acting as a guide; a control weight; and lines supporting the first weight and control weight by the elements, and including a first line wrapping about the first element and a second line entraining the second element, 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 element allows the first weight to descend, and a second mode of operation wherein line non-slippage relative to the first element thereby blocks descending of the first weight. In addition, the control weight is usable to exert force acting to remove slack from the second line, which is important for safety reasons, where the apparatus is used for climbing.

Description:
This application is a continuation of Ser. No. 09/126,652 filed Jul. 31, 1998. 
    
    
     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 =θ a   FY   tension   
       
     
     Where θ 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. 
    
    
     These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: 
     DRAWING DESCRIPTION 
     FIG. 1 is a perspective view of apparatus incorporating the invention; 
     FIG. 2 is an elevation showing modified apparatus incorporating the invention; and 
     FIG. 3 shows a folding seat type support for a human who may wish to climb onto the seat as from a building window, and lower himself, safely, from a height, at the outer side of a building, using the apparatus as described; and 
     FIG. 4 is a view like FIG. 2, but showing further modified apparatus, which is preferred. 
    
    
     DETAILED DESCRIPTION 
     In FIG. 1, a first load bearing rotor  10  such as a cylinder, is rotatable in one direction (clockwise, for example) but is blocked against rotation in the opposite rotary direction (counter-clockwise, as shown). Suitable bearing supports are shown at  11  and  12 , to support the axle  13  supporting the rotor, and extending in the axial direction indicated at  14 . A device to block counter-clockwise rotation may take the form of a ratchet arm  15  engaging ratchet teeth on the rotor. A suitable frame  19  supports  11 ,  12  and  15 . Frame  19  may for example be attached to the outer side of a building. 
     A second rotor  16 , such as a sheave or pulley, is supported to be freely rotatable in opposite directions about an axis. In the example, the rotor  16  may be carried by axle  13  to be freely rotatable about axis  14 . 
     Two weights are supported by the two rotors. These include a first weight  20  and a control or reaction weight  21 , the weights in this example hanging from the rotors, as via supporting lines. These include a first line  22  supporting first weight  20  and wrapping about the rotor at wrap locations  22   a  at which each turn of the wrap engages the rotor surface, line  22  then extending downwardly at  22   b  to assist in supporting the control weight  21 . The lines also include a second line  23  extending downwardly toward the first weight  20 , and also extraining the sheave at location  23   a ; line  23  then extends downwardly at  23   b  to assist in supporting the control weight  21 . 
     Changes in force exertion 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. 
     By “shortening” the line  23  (for example by manually lifting line  23   b ) reactive force is reduced, until slippage of line  22  occurs at the wrap locations  22   a , and slippage will continue, accompanied by lowering of first weight  20 , until line  23   b  is allowed to “lengthen”, i.e. eliminating or reducing manual lifting of line  23 . Note that lines  22  and  23 , near the weight  20 , travel downwardly together during such slippage. Slippage at the wrap locations is prevented by friction, when the line  23  is “lengthened”. 
     Table A below indicates that, depending upon the type of line (such as rope) and, the amount of weight “removed” as by lifting line  23   b  to allow slippage is affected by the number of wraps. (These results are results obtained for a selected set of rotors.) 
     
       
         
               
             
               
               
               
               
               
               
             
           
               
                 TABLE A 
               
             
             
               
                   
               
               
                 Auto-Belayer Test 
               
             
          
           
               
                 Wraps 
                 Material 
                 X 
                 Y 
                 {circumflex over ( )} 
                 T 
               
               
                   
               
               
                 Wraps = 5 ½ 
                   
                   
                   
                   
                   
               
               
                   
                 Wire Rope 
                 50 
                 .12 
                 .12 
                 1.31 sec. 
               
               
                   
                 Sisal 
                 50 
                 .36 
                 .24 
                 4.37 sec. 
               
               
                   
                 Nylon 
                 50 
                 .98 
                 .48 
                 9.50 sec. 
               
               
                 Wraps = 4 ½ 
               
               
                   
                 Wire Rope 
                 50 
                 .96 
                 .48 
                  .90 sec. 
               
               
                   
                 Sisal 
                 50 
                 .96 
                 .24 
                 3.00 sec. 
               
               
                   
                 Nylon 
                 50 
                 1.20 
                 .24 
                 1.38 sec. 
               
               
                 Wraps = 3 ½ 
               
               
                   
                 Wire Rope 
                 50 
                 1.44 
                 .48 
                  .40 sec. 
               
               
                   
                 Sisal 
                 50 
                 2.28 
                 .84 
                 1.55 sec. 
               
               
                   
                 Nylon 
                 50 
                 3.41 
                 .48 
                  .38 sec. 
               
               
                 Wraps = 2 ½ 
               
               
                   
                 Wire Rope 
                 50 
                 4.18 
                 1.5 
                 Fast 
               
               
                   
                 Sisal 
                 50 
                 6.0 
                 2.3 
                 Fast 
               
               
                   
                 Nylon 
                 50 
                 7.11 
                 .50 
                 Fast 
               
               
                 Wraps = 1 ½ 
               
               
                   
                 Wire Rope 
                 50 
                 13.82 
                 5.00 
                 Fast 
               
               
                   
                 Sisal 
                 50 
                 11.8 
                 3.5 
                 Fast 
               
               
                   
                 Nylon 
                 50 
                 16.22 
                 2.00 
                 Fast 
               
               
                 Wraps = ½ 
               
               
                   
                 Wire Rope 
                 50 
                 33.13 
                 7.00 
                 Fast 
               
               
                   
                 Sisal 
                 50 
                 22.09 
                 3.5 
                 Fast 
               
               
                   
                 Nylon 
                 50 
                 33.51 
                 3.00 
                 Fast 
               
               
                 Wraps = 5 ½ 
               
               
                   
                 Nylon 
                 50 
                 .48 
                 .48 
                 very slow movement 
               
               
                 Wraps = 4 ½ 
               
               
                   
                 Nylon 
                 50 
                 1.20 
                 .24 
                 very slow movement 
               
               
                   
                 Nylon 
                 50 
                 1.20 
                 1.08 
                 5 seconds per foot 
               
               
                   
                 Nylon 
                 50 
                 1.20 
                 1.20 
                 1 second per foot 
               
               
                   
               
               
                 3.5″ Steel Shaft  
               
               
                 {fraction (3/32)}″ Wire Rope (1000 lb. cap.) weighing 0.015 lbs per foot.  
               
               
                 ¼″ Twisted Sisal Rope (45 lb. Working load Limit) weighing 0.015 lbs. per foot.  
               
               
                 ¼″ Twisted Nylon Rope (124 lb. Working Load Limit) weighing 0.012 lbs. per foot.  
               
               
                 X = 50 lb. load.  
               
               
                 Y = Weight to just Balance Load.  
               
               
                 {circumflex over ( )} = Amount of Weight removed from Y to allow slippage.  
               
               
                 Wraps = Number of times the Material is around the Steel Shaft.  
               
               
                 T = Time to fall 20″ when Y made 0.0 lbs.  
               
             
          
         
       
     
     The following are four important features: 
     1. Increasing wraps around a cylinder will non-linearly increase the force amplification until it eventually reaches an asymptotic limit. 
     2. To take up slack, the cylinder must rotate in one direction while, acting as a force amplifier, it cannot be allowed to rotate in the opposite direction. 
     3. The type of rope combined with the number of wraps affects the lowering sensitivity. 
     4. A deadweight in series with the device on the Y reactive side can act to both protect the climber from a fall and control the rate of his descent. 
     Referring now to FIG. 2, showing modified and preferred apparatus  100 , it includes a modified first rotor  110  about which a cable or line  111  is wrapped via multiple turns, at  111   a . Line  111  extends downwardly to support a first weight  112  and may be operatively connected to the weight. The rotor  110  is shown as rotatable about a horizontal axis  113 . The rotor has a through bore  110   a  through which a cylindrical duct  114  extends. The duct projects at opposite ends of the rotor and which may be supported by bearings  115  and  116  to allow free rotation of the rotor and duct about axis  113 . Those bearings are carried by fixed walls  115   a  and  116   a.    
     The opposite end extent  111   b  of line or cable  111  extends downwardly to a freely hanging control weight  120 . The line  111   b  is shown as turned by pulleys or idlers  117  and  118 , as shown, whereby control weight  120  may be located remotely from the weight  112 . Fixed structure  117   a  and  118   a  supports the idlers. 
     A second rotor or rotors  121  is or are shown, as at the end or ends of the duct  114 . A second cable or line  123  entrains the rotor or rotors  121 . One end portion  123   a  of line  123  extends to control weight  120 , and is turned via idlers  124  and  125  as shown. The opposite end portion  123   b  of the line  123  extends downwardly toward weight  112 . Since the line  123  slidably extends through the interior  114   b  of the duct  114 , and therefore through windings  111   a , a very compact and simple assembly is provided, with lines  111  and  123   b  extending close to one another and almost directly downwardly toward the weight  112 ; also line extents  123   a  and  111   b  may extend close together toward the remotely located control weight, and within a protective duct  140 , to shield lines  111  and  123   b  from the weather. 
     Raising or lowering of the line extent  123   b , as via a control sleeve  126  extending about line  111  in proximity to weight  112 , controls the rate of descent of the weight  112 , as via control of control weight application to line extent  111   b . Such control variations control the friction forces exerted by the multiple wraps at  111   a  on the surface of the rotor  110 , which in turn controls the slippage rate. A ratchet is indicated at  160 , for preventing reverse rotation of the rotor  110 . 
     For enhanced control of such slippage, the first rotor  110  may be provided with two axially spaced generally conical surface portions  110   b  and  110   c , and a generally cylindrical surface portion  110   d  intermediate the conical portions. The conical portions are interrupted by short cylindrical lands shown at  110   e  and  110   f . It is found that such configurations serve to maintain the multiple wraps axially separated sufficiently as to avoid development of side-by-side rubbing of the multiple wraps. Such rubbing would otherwise interfere with accurate control of slippage of the wraps on the rotor. A means may be provided to urge line  111  leftwardly, to additionally assist in keeping the turns from side-by-side rubbing. Such means may comprise an idler  130  urged leftwardly as by a spring  131 . Raising of weight  112  is associated with take-up of slack in line  123   b , the importance of which is explained later, especially for safe climbing purposes. 
     A support may be provided for the weight  112  referred to, that support connected to at least one of the first and second lines. FIG. 3 shows the support in the form of a ledge  140  to seat a weight such as a human being. An upright strut  141  is connected to the ledge, and line  111  is shown connected to the strut. Ledge  140  is shown as including left and right sections  140   a  and  140   b  pivoted to the strut at  142 , as by hinges. Accordingly, the seating sections  140   a  and  140   b  may be swung down to the section position  140   b  shown at such time as a human is to step onto the support to controllably and safely descend from a height, as at the outer side of a building, to escape from fire. 
     The rotors  121  may be non-rotary guides for line  123 ; and the bore of tube  114  may also or alternatively act as a line guide. 
     In the preferred apparatus of FIG. 4, the elements that remain the same as those in FIG. 2 carry the same identifying numerals. The rotor  210  (like rotor  110 ) has annular flanges  215  and  216  at its opposite ends, and which are received in annular grooves  215   a  and  216   b  in the fixed walls  217  and  218  of the frame  219 . Those flanges or tongues rotate in the grooves about axis  113  as the rotor rotates, with loading transferred from rotor  210  to walls  217  and  218  via annular bearing surfaces provided at  215  and  215   a , and at  216  and  216   a . Surfaces  110   b ,  110   c ,  110   d  and  110   e  are the same as in FIG. 2, as are the line  111 , wrappings at  111   a , and line extent  111   b.    
     Duct  214  is non-rotatable, and has its opposite ends clamped, via nuts  221  and  222  to the fixed walls  217  and  218 . Those nuts have screw threaded attachment at  221   a  and  222   a  to the duct. Duct  214  serves as a guide or guide duct for the line  223  passing through the duct, i.e. through windings  111   a . The opposite end interior surfaces  214   a  and  214   b  are flared or turned, as shown, to act as slide guides for the line  223 , to turn that line as shown, thereby eliminating need for the pulleys  121  as seen in FIG.  2 . See also fixed, non rotary guides for the lines, at  224 ,  227 ,  228 , and  225 . 
     Protective duct  240  shields lines  123   b  and  111   b  from the weather. Pulleys  240  and  241  are carried by the control weight  220 , to turn lines  123   a  and  111   b , as shown, the ends of those lines being attached to  240 . Therefore, weight  120  need only travel one half the vertical distance at it travels in FIG. 2, as weight  112  is lowered; and as it is raised. Raising of weight  112  is associated with lowering of control weight  120 , which serves to take up slack in control line portions  123 ,  123   a  and  123   b . This is important for example where the weight  112  is a human climber, climbing a wall or rock face, whereby he may use non-slack line  123   b  to control or stop a fall, immediately.