Patent Publication Number: US-2020282841-A1

Title: Eddy current braking device for rotary systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/831,358, filed Aug. 20, 2015, which claims priority to and the benefit of U.S. Provisional Patent Application No. 62/039,731, filed Aug. 20, 2014, the disclosures of which are hereby incorporated by reference herein in their entireties. 
    
    
     INTRODUCTION 
     Eddy current braking systems may use centrifugal force to cause rotors to expand into a magnetic field. Centrifugal eddy current devices require significant support structure in the rotating rotor assembly to support the centrifugally deploying electrically conductive members, and to ensure that they remain in plane during deployment so that they don&#39;t make contact with magnets. Because of the complexity, structure, part count, and mass of incorporating the biasing mechanism(s) into a rotating assembly in which the electrically conductive members deploy centrifugally, the systems contain a significant amount of rotational inertia. Because of this, the initiation of eddy-current braking can be delayed during deployment, and/or completion of braking can be delayed once the load motion has ceased. Furthermore, this delay is intrinsic to the design and cannot be controlled or adjusted without redesigning the unit. 
     Even with such extensive support structure, such devices still require very exacting tolerances to allow the peripherally mounted conductive members to reliably move on the same plane into the magnetic field. If a conductive member&#39;s pivot is out of tolerance even by very slight amounts (something that can occur due to material defect or if a device has been dropped or suffered an impact) the conductive member can make contact with a magnet during braking, thereby damaging the device and preventing correct rotor deployment. 
     Heat dissipation is also an issue. Because eddy current braking systems convert kinetic (e.g., rotational) energy into heat, effectively removing the heat before the various components of the braking system are damaged is a design criteria. Centrifugal devices rely on smooth sided, low-friction conductive members to centrifugally deploy into the magnetic field while sliding against a constraining structure. Because of this, conductive member heat dissipation (an important factor in eddy current braking) is extremely limited. 
     For eddy current braking systems that include a retraction spring, such as self-retracting lifelines, auto belay devices and recreational self-retracting descent devices, a device with a heavier rotor assembly retracts more slowly and requires a larger and more robust retraction spring to perform the same work. Because of the limitations of acceptable device size, a larger retraction spring may not be an option, resulting in a device that cannot handle high cyclic usage (e.g., the retraction spring fatigues and fails rapidly). 
     Centrifugal eddy current devices often include multiple biasing elements, one for each deploying rotor. This both increases the complexity of the device and makes bias adjustment more difficult. Indeed, most centrifugal systems are not provided with adjustable biasing which would allow a device to be used in different applications. Rather, centrifugal systems are provided with a manufacturer-selected fixed bias that is determined based on the average load conditions expected for the end-use of the device. In addition, the sheer complexity of the centrifugal design contributes to a high manufacturing cost and a high servicing cost. 
     SUMMARY 
     The eddy current braking systems described herein utilize a direct mechanical linkage activated by an applied load to move a conductor closer to a magnetic field generated by a magnet assembly (either by moving the conductor, moving the magnet assembly, or both). Through the mechanical linkage, the amount of load applied dictates the distance between the conductor and magnet assembly, thereby causing the braking force to vary with the applied load. The applied load causes a rotation of the device proximate a magnetic field to generate the braking force. Most of the examples described herein will be described in terms of a line dispensing device such as an autobelay or descending device in which the load is applied by the payload being lowered by the device. The reader, however, will understand that the load controlled braking devices described herein could be adapted to any number of devices and uses beyond those presented in the drawings. 
     In one aspect, the technology relates to: an apparatus having: a rotatable first portion of a magnetic braking system having a first element disposed thereon, wherein the first portion is rotatable about a rotatable first axis, and wherein a position of the first element is disposed a fixed distance from the rotatable first axis; a second portion of the magnetic braking system having a second element disposed thereon, wherein at least one of the first element and the second element generates a magnetic field; and a spring for biasing the rotatable first portion a first distance from the second portion, wherein upon application of a force to at least one of the rotatable first portion and the second portion, a relative position of the rotatable first portion to the second portion is reduced to a second distance less than the first distance. In an embodiment, the second portion is rotatable about a second axis. In another embodiment, a position of the second element is disposed a fixed distance from the second axis. In yet another embodiment, the first element includes a plurality of magnets and the second element includes a conductor. In still another embodiment, the first element has a conductor and the second element has a plurality of magnets. 
     In another embodiment of the above aspect, the apparatus further includes: a rotatable drum; a length of material wound about the drum; and wherein the force is applied to at least one of the rotatable first portion and the second portion by a weight applied to the length of material. In an embodiment, the length of material includes a length of at least one of a webbing, a cable, a rope, and a chain. In another embodiment, a rotation of the rotatable drum causes a corresponding rotation of the rotatable first portion. In yet another embodiment, the apparatus further includes a plurality of gears disposed between the rotatable drum and the rotatable first portion. 
     In another aspect, the technology relates to an apparatus having: a first portion of a magnetic braking system having a first element, wherein the first element is arranged in an array, wherein the first element is a first fixed distance from a first datum; a second portion of the magnetic braking system having a second element, wherein the second element is a second fixed distance from a second datum, wherein at least one of the first element and the second element generates a magnetic field; a linkage connecting the first portion and the second portion, wherein an application of a force to the linkage changes a position of the first datum relative to the second datum. In an embodiment, the first portion is rotatable about the first datum. In another embodiment, the second portion is rotatable about the second datum. In yet another embodiment, the linkage has a biasing element configured to bias the first datum a first distance away from the second datum, and wherein the application of the force moves the first datum relative to the second datum. In still another embodiment, the application of the force moves the first portion to a second distance relative to the second datum, wherein the second distance is less than the first distance. 
     In another embodiment of the above aspect, the apparatus further includes: a rotatable drum; a length of material wound about the drum; and wherein a rotation of the rotatable drum generates a corresponding rotation of at least one of the first portion and the second portion. In an embodiment, a weight applied to the length of material generates the force applied to the linkage. In another embodiment, the array includes a plurality of first elements. In yet another embodiment, the array defines: a first subset of first elements disposed a first subset distance from the first datum; and a second subset of first elements disposed a second subset distance from the first datum. In still another embodiment, the first subset includes a first number of first elements and wherein the second subset includes a second number of first elements, and wherein the second subset is different than the first subset. 
     In another embodiment of the above aspect, the first subset includes a first density per a fixed unit area of first elements and wherein the second subset includes a second density per the fixed unit area of first elements, and wherein the second subset is different than the first subset. In an embodiment, the first subset includes a first area of first elements and wherein the second subset includes a second area of first elements, and wherein the second subset is different than the first subset. 
     In another aspect, the technology relates to a method including: positioning a first portion at a first distance to a second portion, wherein: the first portion has a first element of a magnetic braking system, and wherein the first element is a first fixed distance from a first datum; and the second portion has a second element of the magnetic braking system, wherein the second element is a second fixed distance from a second datum, and wherein at least one of the first element and the second element generates a magnetic field; and applying a force to a linkage connecting the first portion and the second portion, wherein the application of the force to the linkage changes a position of the first datum relative to the second datum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       There are shown in the drawings, examples which are presently preferred, it being understood, however, that the technology is not limited to the precise arrangements and instrumentalities shown. 
         FIGS. 1A-1H  depict schematic views of first and second portions of eddy current braking systems in accordance with examples of the technology. 
         FIGS. 2A and 2B  depict perspective and side views, respectively, of an eddy current braking system in accordance with an example of the technology. 
         FIG. 3  depicts a perspective view of an eddy current braking system in accordance with another example of the technology. 
         FIGS. 4A and 4B  depict perspective and side views, respectively, of an eddy current braking system in accordance with an example of the technology. 
         FIGS. 5A and 5B  depict end views of eddy current braking systems in accordance with examples of the technology. 
         FIGS. 6A and 6B  depict perspective and side views, respectively, of an eddy current braking system in accordance with an example of the technology. 
         FIGS. 7A and 7B  depict side views of an eddy current braking system in accordance with an example of the technology, in a first position and a second position, respectively. 
         FIGS. 8A and 8B  depict perspective and end views, respectively, of an eddy current braking system in accordance with an example of the technology. 
         FIG. 9  depicts a side view of an eddy current braking system in accordance with another example of the technology. 
         FIG. 10  depicts a side view of an eddy current braking system in accordance with another example of the technology. 
         FIG. 11  depicts a method of operating an eddy current braking system in accordance with an example of the technology. 
     
    
    
     DETAILED DESCRIPTION 
     Several configurations of eddy braking systems are contemplated and depicted in the following figures.  FIGS. 1A-1H  depict schematic views of first and second portions of eddy current braking systems  100  in accordance with examples of the technology. The various examples are described generally below, with regard to shared aspects, structures, and functions. Components common to systems  100  described in  FIGS. 1A-1H  are identified only by root numbers (e.g., “first datum  100 ”), without regard to suffix (e.g., A-H). With regard to specific examples of the eddy current braking systems  100 A-H of  FIGS. 1A-1H , specifics of the various examples are described following in this general presentation. In general, each braking system  100  includes first portion  102  and a second portion  104 . In various examples, each portion  102 ,  104  can include (or be manufactured from) one or more electrically conductive elements  106  and/or magnetic elements  108 . The electrically conductive element is also referred to herein as a conductor, conductor element, or conductive element. The magnetic element is also referred to herein as a magnet. The first portion  102  includes a datum  110 , and the second portion  104  includes a datum  112 . The location of the datums  110 ,  112  on their respective first and second portions  102 ,  104  may be defined as required or desired for a particular application. For example, datums for rotating elements may be defined as an axis A about which that element rotates. Datums for non-rotational elements may be defined as a fixed point P on that element. 
     The datums  110 ,  112  define points by which to measure the spacing between the first portion  102  and the second portion  104 . For example, in one condition of the braking system  100 , the datums  110 ,  112  are separated by a first distance D. In a second condition, the datums  110 ,  112  are separated by a second distance D′ that is less than the first distance D. As the distance D between the datums  110 ,  112  is reduced, the conductor elements  106  and magnetic elements  108  overlap, thereby causing the braking force to vary with an applied load force F. Additionally or alternatively, the second condition can contemplate a closer proximity or shorter distance between the conductor elements  106  and magnetic elements can also generate a higher braking force. In general, the farther the conductor  106  penetrates the magnetic field generated by the magnets  108 , the greater the braking force applied. Each of the datums  110 ,  112  serve as reference points for the conductor elements  106  and/or magnetic elements  108 . For example, in the example depicted in  FIG. 1A , the conductor element  106 A is a fixed, constant distance from the datum  110 A, in that the entire first portion  102 A is made from the conductor element  106 A. In other words, the conductor element  106 A does not move relevant to its datum. Similarly, the magnetic element  108 A is a fixed, constant distance from the datum  112 A, in that the entire second portion  104 A is made from the magnetic element  108 A. Again, the magnetic element  108 A does not move relative to its datum  112 A. 
     As the distance D between datums  110 ,  112  is reduced to the shorter distance D′, the conductor element  106 A moves into a magnetic field generated by the magnetic element  108 A. Movement of the datums  110 ,  112  can be caused by the application of a force, as described in various examples below. If one of the portions  102 ,  104  is rotating R, a magnetic force generated on the conductor element  106  by the magnetic element  108  begins to slow rotation R of that portion  102 ,  104 . As the datums  110 ,  102  move closer together, the conductor element  106  further overlaps the magnetic element, such that a greater magnetic force is applied, further slowing the rotation R. This helps apply a braking force that is directly related to, e.g., a weight force acting upon the system  100 , as described below. It is desirable that the portions  102 ,  104  do not contact each other, as this may cause damage and failure of the system  100 . As such, the portions  102 ,  104  may be disposed in different planes such that facing edges  114 ,  116  may overlap as the datums  110 ,  112  move closer together. 
     With regard to specific examples depicted in the figures,  FIG. 1A  depicts a braking system  100 A including a first portion  102 A manufactured substantially of an conductor element  106 A that rotates R. The second portion  104 A is manufactured substantially of a magnetic element  108 A. As the distance D between datums  110 A,  112 A is reduced to shorter distance D′, rotation R of the first portion  102 A is slowed as the conductor element  106 A overlaps further with the magnetic field generated by the magnetic element  108 A. In  FIG. 1B , a braking system  100 B includes a first portion  102 B manufactured substantially of an conductor element  106 B that rotates R. The second portion  104 B includes a plurality of magnetic elements  108 B, that are disposed substantially parallel to a leading edge  116 B of the second portion  104 B. As such, as the distance D between datums  110 B,  112 B is shortened, the rotating first portion  102 B encounters a stronger magnetic field as the conductor element  106 B overlaps with the plurality of magnets  108 B. That is, the conductive element  106 B encounters magnetic field generated by a greater number of magnetic elements  108 B as the datums  110 B,  112 B are moved closer together. As such, heavier loads that are being applied to either the first portion  102 B or the second portion  104 B are subject to a higher braking force since the heavier loads bring the datums  110 B,  112 B closer together. 
     In  FIG. 1C , a braking system  100 C includes a first portion  102 C that includes a plurality of magnetic elements  108 C, and is configured for rotation R. The second portion  104 C is manufactured of a conductive material  106 C. As the datums  110 C,  112 C are moved closer together, a larger portion of the conductive element  106 C encounters the magnetic fields generated by the magnetic elements  108 C and braking force is increased. In  FIG. 1D , a braking system  100 D includes a first portion  102 D manufactured substantially of an electrically conductive element  106 D that rotates R. The second portion  104 D includes a plurality of magnetic elements  108 D that are disposed substantially parallel to a leading edge  116 D of the second portion  104 D, in a number of arrays  118 D. As the distance D between datums  110 D,  112 D is shortened, the conductive element  106 D encounters magnetic fields formed by a first array  118 D′, which applies a first braking force to slow the rotation R. Heavier loads applied to either of the first portion  102 D or the second portion  104 D will cause the datums  110 D,  112 D to move even closer together. As such, a heavier load will cause the conductive element  106 D to encounter magnetic fields formed by both the first array  118 D′, as well a second array  118 D″. Even heavier loads will cause the conductive element  106 D to encounter magnetic fields formed by the first array  118 D′, the second array  118 D″, and a third array  118 D′″. By encountering magnetic fields generated by all arrays  118 D, the strongest braking force is applied to the rotating first portion  102 D, thus applying greater braking forces to the system  100 D when under a heaviest load. 
     In  FIG. 1E , a braking system  100 E includes a first portion  102 E manufactured substantially of an electrically conductive element  106 E that rotates R. The second portion  104 E includes a plurality of magnetic elements  108 E that are disposed substantially parallel to a leading edge  116 E of the second portion  104 E, in a number of arrays  118 E, wherein the arrays  118 E contain a subset of the total number of magnetic elements  108 E. Each array has a density per unit area of magnets  108 E, where the area is identified by the total area of the second portion  108 E bounded by the magnets  108 E in the particular array  118 E. As the distance D between datums  110 E,  112 E is decreased, the conductive element  106 E encounters magnetic fields formed by a first array  118 E′, which applies a first braking force to slow the rotation R. Heavier loads applied to either of the first portion  102 E or the second portion  104 E will cause the datums  110 E,  112 E to move even closer. As such, a heavier load will cause the conductive element  106 E to encounter magnetic fields formed by both the first array  118 E′, as well a second array  118 E″. The second array  118 E″ has a higher density per unit area of the second portion  104 E, as apparent by the greater number of magnets  108 E in the first array  118 ′ than in the second array  118 ″. Even heavier loads will cause the conductive element  106 E to encounter magnetic fields formed by the first array  118 E′, the second array  118 E″, and a third array  118 E′″, which has an even greater array density. Moreover, a fourth, supplemental array  118 E″″ disposed adjacent the third array  118 E′″ provides even further braking force to slow rotation R for very heavy loads. Each array  118 E is defined by an array distance or subset distance from the datum  112 E. Although the arrays  118 E are described with regard to derivatives thereof, the arrays may also be described with regard to a number of magnetic elements  108 E per array  118 E, or the total area of magnets in a particular array. 
       FIG. 1F  depicts a braking system  100 F including a first portion  102 F manufactured substantially of an electrically conductive element  106 F that rotates R. The second portion  104 F is manufactured substantially of a magnetic element  108 F. As the distance D between datums  110 F,  112 F is reduced to shorter distance D′, rotation R of the first portion  102 F is slowed as the electrically conductive element  106 F is moved further into the magnetic field generated by the magnetic element  108 F. Notably, a leading edge  114 F is serrated or otherwise non-smooth, with a number of cut-outs  120 F depicted. The cutouts  120 F result in a first portion  102 F having a smaller amount of conductive element  106 F proximate the leading edge  114 F. As such, a smaller amount of conductive element  106 F enters the magnetic field generated by the magnetic element  108 F under smaller loads, while heavier loads cause a greater amount of the conductive element  106 F to enter the field. This controls braking force applied based on the load. 
       FIG. 1G  depicts a braking system  100 G including a first portion  102 G manufactured substantially of an electrically conductive element  106 G that rotates R. The second portion  104 G includes a plurality of magnetic elements  108 G having a shape that defines a smaller area closer to a leading edge  116 G of the second portion  104 G, and a greater area as the distance from the leading edge  116 G increases. As the distance D between datums  110 G,  112 G is reduced, the conductive element  106 G encounters a greater area of magnet elements  108 G and, as such, a higher force produced by the magnetic fields generated therefrom. Thus, heavier loads are subject to higher braking forces. 
       FIGS. 1A-1G  depict braking systems  100  having a first portion  102  that rotates and a second portion  104  that is generally non-rotational. The technologies described herein may also be leveraged with braking systems  100 H that have two rotating portions  102 H,  104 H, as depicted in  FIG. 1H . Here, the first and second portions  102 H,  104 H rotate in opposite directions. The first rotating portion  102 H includes a plurality of conductive elements  106 H arranged in arrays  122 F. The second portion  104 H includes a plurality of magnetic elements  108 H, having shapes that define a smaller area closer to a leading edge  116 H of the second portion  104 H, and a greater area as the distance from the leading edge  116 H increases. As the distance D between datums  110 H,  112 H is reduced, the conductive elements  106 H encounter a greater area of magnet elements  108 H and, as such, a higher force produced by the magnetic fields generated therefrom. Thus, heavier loads are subject to higher braking forces. Some of the conductive elements  106 H and the magnet elements  108 H are configured such that they have smaller areas proximate the leading edges of their respective portions. As such, smaller braking forces are encountered at those smaller areas. Other shapes of such elements are contemplated. This can help further alter the dynamic range of the braking system. 
     The following figures depict generally eddy current braking systems that incorporate these and other examples of configurations of magnetic and electrically-conductive elements. These non-limiting examples may be further modified as will be apparent to a person of skill in the art upon reading the specification. As such, other eddy current braking systems including different magnetic element and conductive element configurations are contemplated. For example, although the following examples depict auto-belay and other fall-protection systems, other applications of the braking systems described herein are contemplated. The braking systems may be used to provide a braking force a car such as a roller coaster or train. That is, the systems can be integrated into the wheels of the car and braking systems that apply a braking force to those wheels. Vertical configurations (e.g., for elevator systems) are also contemplated. Additionally, the cable or webbing being unrolled from the drums described below can be unrolled in a horizontal configuration (e.g., on a zipline system, or other substantially linear conveyance system). Such systems can include loading and unloading systems for the movement of goods from cargo vessels, and so on. 
       FIGS. 2A and 2B  depict perspective and side views, respectively, of an eddy current braking system  200  in accordance with an example of the technology.  FIGS. 2A and 2B  are described simultaneously. The eddy current braking system  200  may be utilized in any system that requires braking forces, e.g., to slow and/or stop the fall of a weight or load. For example, the eddy current braking system  200  may be utilized in an autobelay device that is used for climbing, fall-protection, or other systems. Such an autobelay device is depicted generally in  FIGS. 2A and 2B  as dashed box AB. The device AB includes a drum (hidden in  FIGS. 2A and 2B ) having wrapped there around a webbing, cable, or other elongate element  202 . A weight W (e.g., a climber) applies a force F on the webbing  202 . The force F unwraps the webbing  202  by rotating the drum. A drum gear  204  fixed to the drum rotates R, and that rotation R is transferred via a chain and gear, cable and pulley, or other transmission  206  to a corresponding first portion  208  manufactured of a conductive element  210 , which also rotates R. The first portion  208  and the drum gear  204  (as well as the drum) are connected via a linkage  212  that has a fixed pivot point  214 . 
     A biasing element  216  is fixed at an anchor  218  and connected at an opposite end to the linkage  212  and drum gear  204  so as to bias the drum gear  204  (upward in the depicted  FIGS. 2A and 2B ). As described herein, biasing elements may include compression springs, torsion springs, extension springs, gas cylinders, electromagnetic devices, and so on. Additionally, a biasing force B provided by the biasing elements in the various examples depicted herein may be adjustable. In that regard, a user could further tune the biasing force B for an autobelay device based at least in part on a weight of the user, a desired fall rate, and other factors. As the weight W applies a force F to the webbing  202 , the linkage pivots P about the fixed pivot point  214 . This, in turn, moves the first portion  208  proximate a second portion  220  having a fixed position, which includes a plurality of magnets  222  disposed in an array  224  thereon. Lighter weights W that generate lower forces F may only move the first portion  208  proximate a first portion  224 ′ of the magnet array  224 . Each of the first portion  208  and the second portion  220  include a datum  226 ,  228 , respectively. Datum  226  is an axle around which the first portion  208  rotates. Heavier weights may generate forces further reduce the distance between the first datum  226  and the second datum  228 , thus moving the conductive material  210  closer to the second  224 ″ and third portions  224 ′″ of the array  224 . As such, heavier weights W are subjected to stronger braking forces to more effectively slow the weight W. 
       FIG. 3  depicts a perspective view of an eddy current braking system  300  in accordance with another example of the technology. The eddy current braking system  300  may be utilized in any system that requires braking forces, e.g., an autobelay device as described above, but not depicted in  FIG. 3 . The system  300  used in the autobelay device includes a drum  301  having wrapped there around a webbing, cable, or other elongate element  302 . A weight W applies a force F on the webbing  302 , which unwraps the webbing  302  by rotating the drum  301 . A drum gear  304  fixed to the drum  301  rotates R, and that rotation R is transferred via a transmission  306  to a corresponding first portion  308 . Here, the first portion  308  includes a plurality of discrete disks  308 A,  308 B,  308 C, each configured to rotate R together. Each disk  308 A,  308 B,  308 C is manufactured of a conductive element  310 . The first portion  308  and the drum  301  are connected via a linkage  312  that has a fixed pivot point  314 . A biasing element  316  is fixed at an anchor  318 , and connected at an opposite end to the linkage  312  and drum  301  so as to bias the drum  301  upward. As the weight W applies a force F to the webbing  302 , the linkage pivots P about the fixed pivot point  314 . This, in turn, moves the first portion  308  proximate a second portion  320  having a fixed position. The second portion  320  defines a plurality of channels  320 A,  320 B,  320 C. Each channel  320 A,  320 B,  320 C includes a plurality of magnets  322  disposed on either side of the respective channel  320 A,  320 B,  320 C. The channels  320 A,  320 B,  320 C are configured to receive a respective one of the discrete disks  308 A,  308 B,  308 C as the first portion  308  moves proximate the second portion  320 . While three channels and disks are depicted, other examples may utilize only a single channel or more than three channels. Lighter weights W that generate lower forces F may only move the first portion  308  proximate a first distance D into the second portion  320 . Each of the first portion  308  and the second portion  320  include a datum  326 ,  328 , respectively. Datum  326  is an axle around which the first portion  308  rotates. Heavier weights may generate forces that further reduce the distance between the first datum  326  and the second datum  328 , thus moving the conductive material  310  further into the second portion  320 . As such, heavier weights W are subjected to stronger braking forces to more effectively slow the weight W. Heavier weights may generate forces to move the disks  308 A,  308 B,  308 C deeper into the channels  320 A,  320 B,  320 C, so as to subject the conductive element  310  to more magnetic fields generated by the magnets  322 . As such, heavier weights W are subjected to stronger braking forces to more effectively slow the weight W. 
       FIGS. 4A and 4B  depict perspective and side views, respectively, of an eddy current braking system  400  in accordance with an example of the technology.  FIGS. 4A and 4B  are described simultaneously. The eddy current braking system  400  may be utilized in any system that requires braking forces, e.g., an autobelay device, which is not depicted in  FIGS. 4A and 4B . The system  400  includes a drum  401  having wrapped there around a webbing  402 . A weight W applies a force F on the webbing  402 , which unwraps the webbing  402  by rotating the drum  401 . A drum gear  404  fixed to the drum rotates R, and that rotation R is transferred via a transmission  406  to a corresponding first portion  408  that includes thereon a number of magnets  422  and also rotates R. The drum  401  and drum gear  404  are connected via a linkage  412  to a second portion  420 , which is manufactured of a conductive element  410 . Upon movement of the linkage  412 , the second portion  420  pivots P about a fixed pivot point  414 . A biasing element  416  is fixed at an anchor  418  and connected at an opposite end to the linkage  412  and drum gear  404 , so as to bias the drum gear  404  (upward in the depicted  FIGS. 4A and 4B ). As the weight W applies a force F to the webbing  402 , the linkage  412  pivots P the second portion  420  about the fixed pivot point  414 . This, in turn, moves the second portion  420  further from the first portion  408  having a fixed position. Lighter weights W that generate lower forces F may only move the second portion  420  slightly away from the first portion  408 . Each of the first portion  408  and the second portion  420  include a datum  426 ,  428 , respectively. Datum  426  is an axle around which the first portion  408  rotates. Heavier weights may generate forces that further increase the distance between the first datum  426  and the second datum  428 , thus moving the conductive material  410  further from a greater number of magnets  422 . As such, heavier weights W are subjected to lesser braking forces to less effectively slow the weight W. A knurled knob  430  that is rotatable on a threaded rod that attaches to the anchor and is disposed proximate the anchor  418  for adjusting a biasing force of the spring  416 . 
       FIGS. 5A and 5B  depict end views of eddy current braking systems  500  in accordance with examples of the technology.  FIGS. 5A and 5B  are described simultaneously, although specific structural differences are noted. Each eddy current braking system  500  may be utilized in any system that requires braking forces. A weight W applies a force F on a linkage  512  that includes a plurality of bars  512 ′ that pivot about a fixed pivot point  514 . A first portion  508  is manufactured of a conductive element  510  and configured for rotation R about a datum  526 . A biasing element  516  is connected to the linkage  512  so as to bias a second portion  520 , which includes a plurality of magnets  522 . As the weight W applies a force F to the linkage  512 , the linkage arms  512  pivot P about the fixed pivot points  514 . This, in turn, moves the second portion  520  proximate the first portion  508 . Each of the first portion  508  and the second portion  520  include a datum  526 ,  528 , respectively. Datum  526  is an axle around which the first portion  508  rotates. Heavier weights may generate forces further reduce the distance between the first datum  526  and the second datum  528 , thus moving the magnets  522  closer to the conductive material  510 . As such, heavier weights W are subjected to stronger braking forces to more effectively slow the weight W.  FIG. 5A  depicts a conductive element  510  disposed substantially parallel to parallel magnet elements  522 .  FIG. 5B , on the other hand, depicts a conductive element  510  having a tapered outer edge  508 A configured to interact with substantially curved magnets  522 A. 
       FIGS. 6A and 6B  depict perspective and side views, respectively, of an eddy current braking system  600  in accordance with an example of the technology.  FIGS. 6A and 6B  are described simultaneously and depict a system  600  having two rotating elements. The eddy current braking system  600  may be utilized in any system that requires braking forces, e.g., an autobelay device as described above, but not depicted in  FIGS. 6A and 6B . The system  600  used in the autobelay device includes a drum  601  having wrapped there around a webbing  602 . A weight W applies a force F on the webbing  602 , which unwraps the webbing  602  by rotating the drum  601 . A drum gear  604  fixed to the drum  601  rotates R, and that rotation R is transferred via a transmission  606 , which includes a plurality of gears  606 A,  606 B, as depicted, to a corresponding first portion  608 . Here, the first portion  608  includes a plurality of discrete disks  608 A,  608 B, each configured to rotate R together. Each disk  608 A,  608 B is includes a number of magnets  622 . The first portion  608  and the drum  601  are connected via a linkage  612  that has a fixed pivot point  614 , which is an axle about which the drum  601  rotates. Rotation of the drum  601  also transfers rotation R via a transmission  630 , which includes a plurality of gears  630 A,  630 B, as depicted, to a corresponding second portion  620 . The second portion  620  is manufactured of a conductive material  610  and is configured to rotate R. The second portion  620  and the drum  601  are connected via a linkage  632  that shares the fixed pivot point  614 . Each of the first portion  608  and the second portion  620  include a datum  626 ,  628 , respectively. 
     A biasing element  616  is fixed at an anchor  618  to the first linkage  612  and fixed at an anchor  634  to the second linkage  632 , so as to bias the datums  626 ,  628  away from each other. As the weight W applies a force F to the webbing  602 , the linkages  612 ,  632  pivot about the fixed pivot point  614 . This, in turn, compresses the biasing element  616  so as to move the datums  626 ,  628  closer to each other. As such, the second portion  620  moves between the disks  608 A,  608 B of the first portion  608 . Heavier weights may generate forces that further reduce the distance between the first datum  626  and the second datum  628 , thus moving the conductive material  610  deeper into the magnetic field created by the magnets  622 . As such, heavier weights W are subjected to stronger braking forces to more effectively slow the weight W. A positive stop mechanism formed as a bar  636  extending from the linkage  612  controls the overlap of the magnetic field and the conductor element  610  and prevents contact between the first portion  608  and the second portion  620 . 
       FIGS. 7A and 7B  depict side views of an eddy current braking system  700  in accordance with an example of the technology, in a first position and a second position, respectively.  FIGS. 7A and 7B  are described simultaneously and depict a system  700  having two rotating elements. The eddy current braking system  700  may be utilized in any system that requires braking forces, e.g., an autobelay device as described above, but not depicted in  FIGS. 7A and 7B . The system  700  used in the autobelay device includes a drum  701  having wrapped there around a webbing  702 . A weight W applies a force F on the webbing  702 , which unwraps the webbing  702  by rotating R the drum  701 . A drum gear (hidden in  FIGS. 7A and 7B ) fixed to the drum  701  rotates, and that rotation R is transferred via a transmission  706 , to a corresponding first portion  708 . Here, the transmission  706  includes a first chain  706 A which rotates R a first gear  706 B. The first gear  706 B transfers rotation to a second gear  706 C, which in turn drives a second chain  706 D that turns the first portion  708 . Here, the first portion  708  is configured to rotate R and includes a number of magnets  722 . Rotation of the drum  701  also rotates a second portion  720  that is manufactured of a conductive material  710 . In a first position (as depicted in  FIG. 7A ) the second portion  720  has a datum  728  substantially aligned with a datum  726  of the first portion  708 . 
     The second portion  720  and the drum  701  are connected via a linkage  712  to a biasing element  716  that is fixed at an anchor  718 . The linkage  712  has a fixed pivot point  714 . The biasing force B biases datums  726 ,  728  into the position of  FIG. 7A  where they are substantially aligned. As the weight W applies a force F to the webbing  702 , the linkage  712  pivots about the fixed pivot point  714 . This force F opposes the biasing force B of the biasing element  716  so as to move the datums  726 ,  728  away from each other, as depicted in  FIG. 7B . As such, the second portion  720  moves closer to the magnets  722  disposed on the first portion  708 . Heavier weights may generate forces that further increase the distance between the first datum  726  and the second datum  728 , thus moving the conductive material  710  closer to the magnetic field created by the magnets  722 . As such, heavier weights W are subjected to stronger braking forces to more effectively slow the weight W. 
       FIGS. 8A and 8B  depict perspective and end views, respectively, of an eddy current braking system  800  in accordance with an example of the technology. More specifically, the eddy current braking system  800  is used in conjunction with a windlass  800 A. The windlass  800 A includes a drum  801  having wrapped there around an elongate element such as a rope  802 . Upon exiting the drum  801 , the rope  802  is wound around a capstan  840 . A weight W applies a force F on the rope  802 , which unwraps the rope  802  by rotating both the capstan  840  and the drum  801 . A capstan gear  804  fixed to the capstan  840  rotates R, and that rotation R is transferred via a transmission  806  and first element gear  842 . Rotation of the first element gear  842  rotates a first portion  808 . Here, the first portion  808  is manufactured of a conductive element  810 . The first portion  808  and the capstan  840  are connected via a linkage  812 . A biasing element  816  is fixed at an anchor  818  and connected at an opposite end to the linkage  812 , so as to bias the capstan  840  and first portion  808  upward. As the weight W applies a force F to the rope  802 , the biasing element  816  is compressed. This, in turn, moves the first portion  808  proximate a second portion  820  that has a fixed position. The second portion  820  defines a channels  820 A that includes a plurality of magnets  822  disposed on either side of the channel  820 A. The channel  820 A is configured to receive the first portion  808  as it moves proximate the second portion  820 . Each of the first portion  808  and the second portion  820  include a datum  826 ,  828 , respectively. Datum  826  is an axle around which the first portion  808  rotates. Heavier weights may generate forces that further reduce the distance between the first datum  826  and the second datum  828 , thus moving the conductive material  810  deeper into the channel  820 A, so as to subject the conductive element  810  to more magnetic fields generated by the magnets  822 . As such, heavier weights W are subjected to stronger braking forces to more effectively slow the weight W. 
       FIG. 9  depicts a side view of an eddy current braking system  900  in accordance with another example of the technology. The eddy current braking system  900  may be utilized in any system that requires braking forces, e.g., an autobelay device. The system  900  includes a drum  901  having wrapped there around a webbing  902 . A weight W applies a force F on the webbing  902 . The force F unwraps the webbing  902  by rotating the drum  901 . A drum gear  904  fixed to the drum  901  rotates R, and that rotation R is transferred via a transmission  906  to a corresponding first portion  908  manufactured of a conductive element  910 , which also rotates R. A linkage  912  connects the drum  901  to a second portion  920 , which includes a plurality of magnets  922 . The linkage  912  is depicted includes a cam  912 A, but gears, levers, or other structure may be utilized, as would be apparent to a person of skill in the art. 
     A biasing element  916  is fixed at an anchor  918  and connected at an opposite end to the linkage  912  so as to position the second portion  920  such that the magnets  922  are oriented in a first orientation. As the weight W applies a force F to the webbing  902 , the linkage  912  changes a position of the second portion  920  (more specifically, changes an orientation of the magnets  922  by rotating R a shaft  920 A). When unloaded by weight W, the magnets  922  may be in an orientation such that the magnetic field generated thereby does not form a braking force on the conductive element  910 . Lighter weights W that generate lower forces F may only rotate the shaft  920 A and magnets  922  slightly, so a lower magnetic force is applied to the rotating conductive element  910 . Heavier weights may generate forces that further rotate the shaft  920 A and magnets  922 , so a higher magnetic force is applied to the rotating conductive element  910 . As such, heavier weights W are subjected to stronger braking forces to more effectively slow the weight W. 
       FIG. 10  depicts a side view of an eddy current braking system  1000  in accordance with another example of the technology. Here, the system  1000  is incorporated into a centrifugal governor  1000 A. A weight W applies a force F that opposes a biasing force B that keeps counterweights closer to a shaft  1052  of the governor  1000 A. Thus, as a rotation R is applied to the shaft  1052 , e.g., by paying out webbing disposed about a drum (not shown), a first portion  1008  including a plurality of magnetic elements  1022  rotates about the shaft  1052 . A second portion  1020  including a number of discrete conductive materials  1010  provides a braking force to counter the rotation R. 
       FIG. 11  depicts a method  1100  of operating an eddy current braking system in accordance with an example of the technology. The method begins with operation  1102 , where a first portion is positioned at a first distance from a second portion. The portions can be as described above in the various examples, or as otherwise configured as would be apparent to a person of skill in the art. The portions generally include respective datums that can be used to quantify the distance therebetween. In operation  1004 , a weight force is applied to a linkage connecting the first and second portions. This weight force changes a position of one of the datums relative to the other. As such, the positions of the two portions change, thereby adjusting a braking force applied to the weight. 
     It is to be understood that this disclosure is not limited to the particular structures, process steps, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular examples only and is not intended to be limiting. It must be noted that, as used in this specification, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. 
     It will be clear that the systems and methods described herein are well adapted to attain the ends and advantages mentioned as well as those inherent therein. Those skilled in the art will recognize that the methods, devices, and systems within this specification may be implemented in many manners and as such is not to be limited by the foregoing exemplified examples and examples. In this regard, any number of the features of the different examples described herein may be combined into one single example and alternate examples having fewer than or more than all of the features herein described are possible. 
     This disclosure described some examples of the present technology with reference to the accompanying drawings, in which only some of the possible examples were shown. Other aspects may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein. Rather, these examples were provided so that this disclosure was thorough and complete and fully conveyed the scope of the possible examples to those skilled in the art. 
     Although specific examples were described herein, the scope of the technology is not limited to those specific examples. One skilled in the art will recognize other examples or improvements that are within the scope and spirit of the present technology. Therefore, the specific structure, acts, or media are disclosed only as illustrative examples. The scope of the technology is defined by the following claims and any equivalents therein.