Abstract:
A rappelling apparatus providing controlled constant speed to a cable unwinding from a rotating spool in frictional engagement with a stationary arcuate surface. Rotations of the spool are responded to by a centrifugal brake acting in inverse proportion to the rotations. An addition brake is provided for selective actuation by a person using the apparatus.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention, in general, relates to an apparatus for moving an object from an elevated position to a lower one and, more particularly, to an apparatus for moving an object from an elevated to a lower position at a controlled rate of speed. 
   2. The Prior Art 
   Apparatus of the kind here under consideration are well-known and are used, for instance, as emergency escape devices which permit persons in distressful situations to escape from high buildings, mountains and other elevated structures. One such apparatus has been disclosed by U.S. Pat. No. 4,623,038 issued 18 Nov. 1986 to Stancato. It uses two cascading or series-connected centrifugal brake mechanisms the effective braking rate of which must be determined and set manually by a person compelled to act under hazardous or dangerous circumstances when he is least likely to act rationally. Moreover, the brakes are actuated by a relatively complicated gear train of a plurality of gears any one of which may malfunction or jam in circumstances in which reliability is of the utmost importance. 
   OBJECTS OF THE INVENTION 
   It is an object of the instant invention to provide for a rappelling apparatus of simple and reliable construction. 
   A further object is to provide a rappelling apparatus which offers automatic speed control. 
   Another object of the invention relates to providing a rappelling apparatus the effective braking rate may be preset in proportion to the load to be lowered. 
   Still another object of the invention is to provide a rappelling apparatus provided with a brake mechanism the action of which is a function of friction between a rappelling cable and a stationary curved surface. 
   Yet another element is to provide a rappelling apparatus the braking action of which may be modified in accordance with conditions in which it is being used. 
   It is also an object of the invention to provide a rappelling apparatus equipped with a selectively actuable brake to provide for a complete stop. 
   Moreover, it is an object of the invention to provide a rappelling apparatus of compact structure by interesting its operating components. 
   Other objects will in part be obvious and will in part appear hereinafter. 
   SUMMARY OF THE INVENTION 
   In the accomplishment of these and other objects the invention, in a currently preferred embodiment thereof, provides for a rappelling apparatus including a spool for receiving a coiled cable and mounted for rotation in response to unwinding the cable, a curved surface of selectively variable length or angle of wrap to subject the cable to predetermined friction thereby to control the speed of the cable unwinding, and a braking mechanism for restricting the speed of the unwinding cable in proportion inversely of the speed. 

   
     DESCRIPTION OF THE SEVERAL DRAWINGS 
     The novel features which are considered to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, in respect of its structure, construction and lay-out as well as manufacturing techniques, together with other objects and advantages thereof, will be best understood from the following description of preferred embodiments when read with reference to the appended drawings, in which: 
       FIG. 1  is a perspective rear view of a first embodiment of a rappelling apparatus in accordance with the invention; 
       FIG. 2  is a perspective front view of the apparatus of  FIG. 1 ; 
       FIG. 3  is a top elevational rear view of the apparatus of  FIG. 2  on an enlarged scale; 
       FIG. 4  is a sectional view along line A-A of  FIG. 3 ; 
       FIG. 5  is an exploded view depicting the components of the apparatus of  FIG. 1 ; 
     and 
       FIG. 6  is an exploded view of an alternative embodiment of the apparatus in accordance with the invention; 
       FIG. 7  is an exploded view on an enlarged scale showing details of the apparatus of  FIG. 6 ; 
       FIG. 8  is a cross-section, on an enlarged scale, of the apparatus of  FIG. 6  in its assembled state; and 
       FIG. 9  is schematically depicts an apparatus in accordance with the invention strapped to a body harness. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2  schematically depict a portable rappelling apparatus  10  in accordance with the invention. The apparatus  10  is of the kind useful for lowering a person from an elevated position such as a high building or mountain in cases of emergency without requiring active intervention by such person to ensure safe operation of the apparatus. For that reason, the apparatus may also be referred to as an emergency escape apparatus. 
   As may be seen more particularly by reference to  FIGS. 5 and 6 , the apparatus  10  consists of a substantially cylindrical outer housing  12  consisting of a cylindrical wall  14  and a bottom plate  16  provided radial extensions  18 . The bottom plate  16  may be integral with the cylindrical wall  14 , or it may be affixed thereto by screws or the like as is well known in the art. As shown, the extensions  18  are provided with openings  20  suitably configured for securely attaching the apparatus  10 , as, for instance, by threaded bolts, hooks, straps, shackles or the like, either to a structure such as a building or mountain (not shown) from which an escape is to be made or to a harness  30  ( FIG. 9 ) to be connected to a person or article to be lowered from such structure. It will be appreciated that the function of the apparatus does not depend upon whether it is attached to a structure or to a person or article, although, if attached to a person, such person may control the operation of the apparatus in the manner to be described. The components of the housing are made of a strong, preferably heat-resistant light-weight material such, as for instance, aluminum alloy, stainless steel or suitable polymeric material; but those skilled in the art may be assumed to know other materials which are equally well suited for the intended purpose. 
   Radially extending from the cylindrical wall  14 , and affixed thereto, are two converging arms  22 ,  24  of a Y-shaped yoke  26 . For reasons to be described infra, the yoke  26  is of tubular construction and terminates in an open-ended leg  28 . 
   The exterior housing  12  forms a cylindrical chamber  34  for mounting therein an operating assembly of the apparatus. The operating assembly consists of an inner housing  36  constituted by a drum  38 , and, affixed thereto by threaded counter-sunk bolts  40 ,  42 , a front plate  44  and a rear plate  46 . While the angular disposition of the operating assembly within the chamber  34  relative to the exterior housing  12  is normally fixed by a releasable locking arrangement, such as a spring-loaded pawl or threaded bolt, schematically indicated at  48  ( FIG. 4 ), the assembly may be rotated relative to the exterior housing  12  for purposes to be described. A shaft  50  is journaled in friction-reducing sleeves or bearings  52 ,  54  coaxially mounted in front plate  44  and rear plate  46 , respectively. 
   A cylindrical brake housing  56  is coaxially mounted on the shaft  50  for rotation relative thereto and is affixed to the rear plate  46 . The rear plate  46  is releasably connected to the bottom plate  16  for selectively varying the angular disposition of the inner housing  36  relative to the exterior housing  12 . A rotary member  58  consisting of a hub  60  with three radially extending and evenly spaced arms  62  is affixed to the shaft  50  and is located within the brake housing  56 . Intermediate the arms  62 , brake shoes  64  (only one shown) are movably connected to the hub  60 . The brake shoes  64  are centripetally biased towards the hub  60  by springs (not shown) as is well-known in the art. The brake housing  56 , the hub  60  and the brake shoes  64  constitute a centrifugal brake of the kind well known in the art which serves to reduce the speed of rotation of the shaft  50  as will be described infra. 
   A circular brake disc  66  is affixed to the shaft  50  for rotation therewith and is provided with a peripheral surface  68 . A band  70  is wrapped around the surface  68  and is provided at its opposite ends with loops  72 ,  74  for receiving pins  76 ,  78  extending from an arm  80  in a direction substantially parallel to the shaft  50 . The arm  80  may be pivoted by a pin  82  connected to a lever  32  to increase or reduce friction between the peripheral surface  68  of the brake disc  66  and the band  70  for purposes to be described. The pin  82  extends through a bore in the front plate  44 , and the lever  32  is mounted for pivotal movement over the outer surface of the front plate  44 . 
   The drum  38  is coaxially disposed around the brake housing  56  as well as the disc  66  and is secured to the rear plate  46 . The axial ends of the drum  38  are formed by radial flanges  84 ,  86  which between them form a substantially cylindrical surface  88 . The cylindrical surface  88  has a slotted opening  90  therein which extends across the surface  88  and is bounded at at least one of its sides by a guide surface  92  extending tangentially from the surface  88  into the interior of the drum  38 . A spool  94  is rotatably mounted on the shaft  50  inside of the drum  38 , over the brake housing  56  and the disc  66 . The spool  94  is provided with end flanges  96 ,  98  and a cylindrical surface  100  for receiving a coiled cable  102  of predetermined length and tensile strength. To reduce friction between the spool  94  and the drum  38  the outer peripheral margin of the flanges  96 ,  98  may be cut out as exemplarily shown in  FIG. 4  to accommodate friction reducing means such as, for instance, ball bearings  104 ,  106 . The length of the cable  102  is, of course, a function of the height of the structure to be serviced by the apparatus of the invention and of the volume provided between the spool  94  and the interior of the drum  38 . Unwound from the coil, the length of the cable  102  may, for instance, be at least about 100 meters, and its tensile strength should advantageously be in excess of 1,300 lbs. 1×19 steel cables of 3/32″ diameter have been found to be satisfactory. However, those skilled in the art will know of other materials, including polymers of sufficient tensile strength and heat resistance, which may be used in compliance with stated safety standards. 
   One end of the cable  102  is securely connected to the spool  94 . The free end of the cable  102  is fed through the opening  90  over the guide surface  92  and the cylindrical surface  88  of the drum  38  and then through the tubular arm  22  out of the yoke  26 . The angle subtended by the length of the cable  102  wrapped over the cylindrical surface  88  of the drum  38  in intimate contact therewith and, hence, the friction generated therebetween, may be adjusted by rotating the drum  38  relative to the external housing  12 . To this end, the flange  86  of the inner housing  36  is provided with at least one axial bore or notch (not shown) which may be aligned with any of several equally spaced arresting features, such as, for example, a latch or, as shown in the drawings, bores  108  adjacent to the peripheral margin of the rear plate  46 . The position of the drum  38  may be arrested by a threaded bolt (not shown) extending through the axial bore in the flange  86  into the selected one of the bores  108  in the end plate  46 . Other arresting devices such as latches or pawls and notches may also be used to secure the angular disposition of the drum  38  within the external housing  12 . 
   In the assembled state of the apparatus  10  the free end of the cable  102  will be provided with appropriate fastening means, such as, for instance, a hook or shackle  110 . 
   An internally toothed annular gear  112  is coaxially connected to the spool  94  in the plane of the flange  96 , and forms part of a planetary transmission. The gear  112  meshes with a pair of planetary gears  114 ,  116  which, in turn, are in meshing engagement with a sun gear  118 . The sun gear  118  is affixed to the shaft  50  for transmitting rotary movement of the spool  94  to the rotary member  58  and to the brake disc  66  at a ratio of transmission dependent upon the gear ratios. At present the preferred ratio is such that one revolution of the spool  94  causes the rotary member  58  to rotate three or four times. Other ratios may, of course, be employed. 
   The front plate  44  closes the cylindrical chamber  34  and is provided with a central bore which may advantageously receive a friction reducing sleeve or ball bearing within which the other end of the shaft  50  is journalled. 
   Turning now to the alternative embodiment depicted in  FIGS. 6 ,  7  and  8 , the reference numerals used for identical components will be the same as those used supra, but primed. The alternative apparatus  10 ′ shown in  FIG. 6 and 7  differs from the one of  FIG. 5  by the band brake  66 ,  68  of the latter having been replaced by a disc brake. The disc brake consists of a disc  120  and a brake liner  122  on an axial face  124  of the spool  94 ′. The disc  120  is affixed by a key  126  on the shaft  50 ′ for rotation therewith and selective axial movement relative thereto. It will be noted that the rotation of the disc  120  is in a direction opposite the direction of rotation of the spool  94 ′, so that engagement between the disc  120  and the brake liner  122  will result in a braking action affecting the spool  94 ′. Axial movement may be selectively imparted to the disc  120  by a pin  128  seated in an axial recess  130  of the shaft  50 ′. One end of the pin  128  engages the key  126 . The other end of the pin  128  engages a camming surface  132  of a lever  134  pivotally mounted on the front plate  44 ′. The lever  134  is connected by a Bowden cable  136  or other suitable transmission to a handle  138 . Preferably, the lever  134  is biased by a spring (not shown) into a position away from the pin  128  in order to maintain the disc brake in a normal idle state. 
   Optionally, either or both ends of the shaft  50  may be provided with a key slot for connecting a crank or other mechanism for rewinding the cable  102  as may be particularly desirable if the apparatus  10  is intended for repeated use, for instance, as mountaineering equipment. 
   The function of the apparatus  10  is as follows: Prior to its first use, the rotational position of the drum  38  or inner housing  36  with respect to the rear plate  46  or external housing  12  will have been set in accordance with the amount of friction to be generated between the cable  102  and the curved guide surface  88 . The friction will desirably be related to the weight of the person to whom the apparatus  10  is assigned. Persons of greater weight would mandate a greater angle subtended by the cable  102  on the curved surface  88  of the drum  38  than would persons of lesser weight. Advantageously, the drum  38  will be provided, for instance along its flange  86 , with an index scale (not shown) to facilitate its weight-related setting. 
   A person compelled to evacuate a tall structure will attach the apparatus  10  or the hook  110  either to himself by means of a harness  30  or to a structure. It will hereinafter be assumed that the apparatus  10  is attached to the harness. 
   The person then climbs out of, or away from, the structure and lowers himself as the cable  102  unwinds from the spool  94  which is thus caused to rotate. As it unwinds, the cable  102  will move through the opening  90 , slip over the guide surface  92  and over an arcuate section of the surface  88  of the drum  38 . Desirably, the length of the arcuate section or the angle subtended by the cable will have been previously set in the manner described. 
   As the spool  94  is rotating its movement is transmitted by way of the planetary gear transmission, to the centrifugal brake arrangement housed in the brake housing  56 . The rotary member  58  is thus set into rotary motion, and, as a result of centrifugal force thus generated, the brake shoes  64  will be radially moved into engagement with the internal cylindrical surface of the brake housing  56  to generate a braking force in proportion to the speed of rotation of the rotary member  58 . The force of the brake shoes  64  acting radially against the brake housing  56  is the square of the speed of rotation of the rotary member  58 . This results in a self-balancing brake force and, accordingly, in a controlled constant speed at which the cable  102  is unwinding and the person is descending. 
   If the person becomes aware of an obstacle in the path of his descent he may move the lever  32  to engage the band brake  68 ,  70 , or he may move the handle  136  to engage the disc brake  120 ,  122 , in order to slow or to stop his descent. Once he has maneuvered himself by the obstacle, he may release the brake and continue his descent.