Abstract:
A system comprising a cable held in suspension and a trolley traveling along the cable relies on a brake to control velocity and net downhill acceleration of the trolley. The trolley may include a brake pad positioned to contact the cable. At the downhill end of the ride, the lever actuating the brake is caught and lifted by a capture ring, thus relieving the braking load on the trolley. Also, the trolley engages a comparatively modest, second resistance mechanism, such as, for example, a system of springs, that gradually increases in resistance with distance of motion of the trolley thereagainst, bringing the trolley to a gradual halt.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of co-pending U.S. patent application Ser. No. 13/151,197, filed Jun. 1, 2011, entitled LOAD-MINIMIZING, TROLLEY ARRESTER APPARATUS AND METHOD, to be issued as U.S. Pat. No. 8,191,482, which is a continuation of U.S. patent Ser. No. 12/233,270, filed Sep. 18, 2008, which is a continuation-in-part of U.S. Pat. No. 7,637,213, issued Dec. 29, 2009, entitled UNIVERSAL BRAKE ASSEMBLY, which is a continuation-in-part of U.S. patent application Ser. No. 11/168,101, filed Jun. 28, 2005, now abandoned, all of which are hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. The Field of the Invention 
         [0003]    This invention relates to suspended cable systems and, more particularly, to novel systems and methods for braking and retrieving trolleys traveling on suspended cable systems. 
         [0004]    2. The Background Art 
         [0005]    Weather conditions such as temperature and wetness affect the performance of typical trolleys configured to slide or roll along suspended cables. For example, rain on a cable may significantly change the coefficient of fiction between a trolley brake and the cable. Accordingly, a trolley brake that is acceptable for dry conditions, may be unacceptable for wet conditions. Thus, operators must closely monitor weather conditions when using current trolleys. What is needed is a trolley brake providing acceptable performance across a greater range of weather conditions. 
         [0006]    Many trolley systems, sometimes called Ziplines, provide no braking. They simply use a cable declining at a shallow angle in which a rise at the lower end slows a user. Others may have a brake set at a fixed parameter. Also, current trolleys do not provide a user control “on-the-fly” over the magnitude of a braking force or friction force generated by the trolley as it travels along a cable. That is, to one degree or another, a user or knowledgeable operator must preselect the braking force or the range of braking force to be provided by the trolley. Once selected, the arrangement is not easily or safely changed without stopping the trolley and relieving the trolley of the user&#39;s weight. In certain embodiments, legal liability and user inexperience may favor such inflexibility. However, in other embodiments, greater user control may be desirable. Accordingly, what is needed is a trolley providing safe, “on-the-fly” adjustment between minimum braking and maximum braking. 
         [0007]    Furthermore, when using a trolley as the basis for an amusement ride, revenue may largely depend on the number operators employed to operate the ride and throughputs the number of users served within a given period of time. Currently, to a large degree, safety concerns dictate the numbers for both. For example, one of the potential hazards of an amusement ride employing a trolley is the possibility of collision. A first rider may ride a first trolley to some location along a cable. Assuming that the first rider has reached the bottom and exited the ride, a second rider may ride a second trolley down the same cable. Accordingly, if the first rider did not actually reach the lower end due to over-braking, serious injury may occur when the second rider collides with the first rider. What is needed is a trolley retrieval system configured to maximize user throughput, minimize operator interaction, and reduce or eliminate the risk of collision. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    In view of the foregoing, in accordance with the invention as embodied and broadly described herein, a method and apparatus are disclosed in one embodiment of the present invention as including a trolley comprising a frame, a brake assembly, and a sheave mount. In selected embodiments, a brake assembly in accordance with the present invention may provide significant adjustability. For example, a brake assembly may include a brake pad that may be removed and replaced, should wear so dictate. Additionally, a brake pad may itself be readily adjustable to provide a desired or customized braking effect to suit conditions. 
         [0009]    Various material properties and characteristics may be considered when selecting a material for a brake pad in accordance with the present invention. Often a material that has certain advantageous characteristics may have others that are disadvantageous. For example, one material may have excellent wear resistance, but its coefficient of friction against a cable may vary greatly depending on whether the cable is dry. Accordingly, the material may be suitable for dry conditions, yet be hazardous for wet conditions. 
         [0010]    In certain embodiments, it may be advantageous to provide a brake pad having repeatable and consistent performance with respect to wear, coefficient of friction, or the like regardless of temperature, wetness, etc. To provide the advantages of a brake pad in accordance with the present invention, a brake pad may be formed of various segments, typically positioned in series. So positioned, the width of each segment may control the contact area between each segment and the cable. The contact area may vary between segments. For example, in certain embodiments, one segment may have a width greater than the width of another segment. Accordingly, the former segment may provide a greater contribution to the overall performance of the brake pad than the latter segment. 
         [0011]    By controlling the composition of the segments, the contact area of the segments, and the gaps between the segments, the performance of a brake pad may be optimized to a given trolley application. For example, in selected embodiments, it may be desirable for a brake pad in accordance with the present invention to slide along a cable. That is, the brake pad may reduce the speed of the trolley along the cable  12 , but not overly slow or stop it. 
         [0012]    Accordingly, in one embodiment, certain segments may be formed of a first, substantially inelastic material (e.g., high density polyethylene (HDPE), ultra high molecular weight (UHMW) polyethylene, or the like). The rest of the segments may be formed a second, elastic material (e.g., multi-rubber or elastomeric materials such as are used for the caliper brake pads of a bicycle). Elastomers may strip water from a surface, but typically do not wear as well as other polymers. Accordingly, overall, the brake pad may have both acceptable wear and frictional engagement even when applied to a wet cable. By adjusting the number of segments corresponding to the first and second materials and the contact areas associated with those segments, a proper balance of characteristics may be achieved. 
         [0013]    In selected embodiments, a trolley in accordance with the present invention may provide a user (e.g. operator, or rider in some circumstances) “on-the-fly” control over the magnitude of a braking force generated by the trolley as it travels along a cable. For example, by adjusting the moment arm (e.g. leverage) at which the weight of a user is applied to the frame of a trolley, the magnitude of the resulting moment may be controlled. The magnitude of the moment may then dictate the magnitude of the normal force against the cable generating the frictional braking force. Accordingly, by adjusting the moment arm at which the weight of a user is applied to the frame of a trolley, a user may control, within a particular range, the speed of the trolley for a particular catenary, or naturally hanging cable. 
         [0014]    In selected embodiments, a trolley may include a carriage configured to secure to, operate with, and be adjusted with respect to a frame or portion of a frame throughout a range of motion bounded by a first position of the carriage and a second position of the carriage with respect to the frame. A carriage may move along the frame through the range of motion without compromising the connection between a user and the cable. Accordingly, adjustment of the position of the carriage with respect to the frame, and the resulting adjustment to the braking force, may safely be accomplished in any suitable manner while the trolley including the carriage and frame is in motion along the cable. 
         [0015]    In certain embodiments, absent contrary inputs or forces, a carriage may, under the impetus of gravitational acceleration, move toward the second position. At the second position, the braking force may be at a maximum. Accordingly, a trolley in accordance with the present invention may have a default configuration corresponding to maximum braking, which, given typical cable declination, is sufficient to bring the trolley to a halt, such as in the event of any failure of the trolley. 
         [0016]    Trolleys in accordance with the present invention may be used as the basis for an amusement ride. For such rides, revenue may largely depend on the number of operators employed to operate the ride and the number of users served within a given period of time. Accordingly, a trolley retrieval system in accordance with the present invention may be configured to maximize user throughput, minimize operator interaction, and increase safety. 
         [0017]    In selected embodiments, a trolley retrieval system may include multiple cables held in suspension between first and second supports. A retrieval line may be suspended in an open line or in a closed loop extending from proximate a start area to proximate a finish area. A closed loop is more readily controllable and less likely to tangle or fail to deploy properly. A motivator (e.g. motor) may selectively circulate the retrieval line back and forth or around the loop. A controller may control operation of the motivator. 
         [0018]    In certain embodiments, a controller may include a processor and one or more sensors. The sensors may be operably connected to the processor to pass thereto a stop signal informing the processor that one or more of trolleys is sufficiently near the start area. The processor may be programmed to issue, in response to the stop signal, a stop command causing the motivator to cease circulation or other operation of the retrieval line. The processor may be further programmed to issue, in further response to the stop signal, a reverse command causing the motivator to reel in or circulate the retrieval line in an opposite direction when it resumes circulation of the retrieval line. For example, a motive source may comprise an electric motor. In such an embodiment, the controller of such a motivator may include a polarity switch switching, in response to the reverse command, the polarity of the current supplied to the electric motor. A controller may further include a retrieval switch operably connected to cause, when activated, the motivator to resume circulation of the retrieval line. 
         [0019]    In operation, an amusement ride in accordance with the present invention may begin with selection of a system comprising one or more cables held in suspension between first and second supports and a trolley positioned to travel along each cable. A user may then be connected to the trolley. Following securement of a user into a harness or possibly of a harness or seat of a user thereto, the trolley may be released to travel along the cable from proximate the start area to proximate the finish area. At the finish area, the user may be disconnected from the trolley. The trolley may then be connected to a retrieval line. Safety will usually favor fastening a user into a harness already connected to the main support cable rather than connecting and disconnecting harnesses and trolleys from a main support cable. 
         [0020]    Once a trolley is connected to a retrieval line, the motivator may be activated to draw the trolley along the cable from proximate the finish area to proximate the start area. When one or more of the trolleys connected to a retrieval line activates a sensor, the motivator may stop the retrieval line. The trolley or trolleys may then be disconnected from the retrieval line and secured for future use. 
         [0021]    As stated hereinabove, in selected embodiments, a processor may be programmed to issue, in response to a stop signal, a reverse command causing the motivator to circulate the retrieval line in an opposite direction when it resumes circulation of the retrieval line. So configured, the engagement locations between a retrieval line and a trolley may travel in a cycle from the starting (e.g. loading, launching) area to the finishing (e.g. end, unloading) area and back. Moreover, while one engagement location is stopped at the starting area, another may be stopped at the finish area. 
         [0022]    Accordingly, while one or more trolleys are being loaded with users, other trolleys may be connected to a retrieval line. Also, while one or more trolleys are towed or pulled back up from the finish area to the start area, other engagement locations on the retrieval line may be returning to the finish to continue the cyclical pattern. So configured, a trolley retrieval system in accordance with the present invention may provide a substantially continuous throughput, minimize operator interaction, and increase safety. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The foregoing features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which: 
           [0024]      FIG. 1  is a perspective view of one embodiment of a trolley and cable in accordance with the present invention; 
           [0025]      FIG. 2  is a perspective view of one embodiment of a sheave mount from a trolley in accordance with the present invention; 
           [0026]      FIG. 3  is a perspective view of one embodiment of a frame from a trolley in accordance with the present invention; 
           [0027]      FIG. 4  is a perspective view of a brake assembly from a trolley in accordance with the present invention; 
           [0028]      FIG. 5  is an exploded view of the brake assembly of  FIG. 4 ; 
           [0029]      FIG. 6  is a perspective view of the trolley of  FIG. 1 , omitting a cheek plate and brake shoe of the brake assembly; 
           [0030]      FIG. 7  is a top, plan, cross-sectional view of one embodiment of a brake pad and brake shoes in accordance with the present invention; 
           [0031]      FIG. 8  is a top, plan, cross-sectional view of an alternative embodiment of a brake pad and brake shoes in accordance with the present invention; 
           [0032]      FIG. 9  is a top, plan, cross-sectional view of another alternative embodiment of a brake pad and brake shoes in accordance with the present invention; 
           [0033]      FIG. 10  is a top, plan, cross-sectional view of another alternative embodiment of a brake pad and brake shoes in accordance with the present invention; 
           [0034]      FIG. 11  is a side, elevation view of an alternative embodiment of a trolley applying to a cable minimum braking in accordance with the present invention; 
           [0035]      FIG. 12  is a side, elevation view of the trolley of  FIG. 11  applying to a cable maximum braking in accordance with the present invention; 
           [0036]      FIG. 13  is a perspective view of the trolley of  FIG. 11 ; 
           [0037]      FIG. 14  is another perspective view of the trolley of  FIG. 11 ; 
           [0038]      FIG. 15  is a perspective view of an alternative embodiment of a capture in accordance with the present invention; 
           [0039]      FIG. 16  is a partial, top, plan view of a trolley retrieval system in accordance with the present invention; 
           [0040]      FIG. 17  is a partial, perspective view of a line engagement system from a trolley retrieval system in accordance with the present invention; 
           [0041]      FIG. 18  is a schematic block diagram of a method for operating a trolley retrieval system in accordance with the present invention; 
           [0042]      FIG. 19  is a partial, top, plan view of an alternative embodiment of a trolley retrieval system in accordance with the present invention; 
           [0043]      FIG. 20  is a side, elevation view of a cable support in accordance with the present invention; 
           [0044]      FIG. 21  is a perspective view of a cable anchoring assembly in a slack-take-up mode in accordance with the present invention; and 
           [0045]      FIG. 22  is a perspective view of a cable anchoring assembly in a tied-off configuration in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0046]    It will be readily understood that the components of the present invention, as generally described and illustrated in the drawings herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in the drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of various embodiments of the invention. The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. 
         [0047]    Referring to  FIG. 1 , in discussing a trolley  10  in accordance with the present invention, it may be advantageous to establish a coordinate system  11 . Accordingly, a trolley  10  may be defined in terms of a longitudinal direction  11   a,  a lateral direction  11   b,  and a transverse direction  11   c,  substantially orthogonal to one another. 
         [0048]    A trolley  10  in accordance with the present invention may be configured for travel along a cable  12  in the longitudinal direction  11   a . In general, a trolley  10  of the present invention may be applied to a cable  12  held in suspension by two or more supports. For example, as disclosed in U.S. Pat. No. 6,622,634 issued Sep. 23, 2003 and entitled AMUSEMENT RIDE EMPLOYING A SUSPENDED TENSIONED STATIC CABLE, which is incorporated herein by reference, a cable  12  may be supported between two supports (e.g., towers, platforms). A first support may hold one end of the cable  12  at a higher elevation than a second support holds the other end of the cable  12 . Accordingly, a trolley  10  secured to roll along the cable  12  may tend to travel from the first, upper support toward the second, lower support. 
         [0049]    While a suspended cable  12  may provide the basis for an amusement ride, other uses are also contemplated. For example, a suspended cable  12  may be used as part of a lift system transporting persons or goods over or up certain geologic obstacles. Suspended cables  12  are commonly used on ski lifts, gondolas, aerial trams, and the like. Similarly, suspended cables  12  have been incorporated into evacuation systems (e.g., oil derrick evacuation systems). Whether for repair, evacuation, or as part of the system itself, such suspended cable  12  systems often require a trolley  10  in accordance with the present invention. 
         [0050]    In selected embodiments, a frame  14  may provide the main structure of the trolley  10  or a base to which other components may secure. A frame  14  may be formed of any suitable material or combination of materials. Characteristics that may be considered when selecting the material for the frame  14  may include cost, formability, machineability, strength, rigidity, durability, corrosion resistance, density, etc. In certain embodiments, aluminum has been found to be a suitable material for a frame  14 . 
         [0051]    A frame  14  may extend from a first end  16  to a second end  18 . In certain embodiments, a brake assembly  20  may connect to the frame  14  proximate the first end  16  thereof. Proximate the second end  18 , a bumper assembly  22  may connect to the frame  14 . In one embodiment, a bumper assembly  22  may include a bumper  24  held between two cheek plates  26 . In selected embodiments, a bumper  24  may be formed of a friction-reducing polymeric material (e.g., HDPE, UHMWPE, PTFE). In other embodiments, a bumper  24  may be formed of an elastomeric (e.g. rubber compound) material. 
         [0052]    A sheave mount  28  may connect to the frame  14  at a location between the brake assembly  20  and the second end  18 . A sheave mount  28  may support one or more sheaves  30  positioned to roll along the cable  12 . In selected embodiments, the portion  32  of the frame  14  between the sheave mount  28  and the second end  18  may be characterized as the user-suspension-portion  32 . That is, the weight of a user may be directed to, and supported by, this portion  32  of the frame  14 . 
         [0053]    In certain embodiments, the frame  14  of a trolley  10  in accordance with the present invention may be suspended below a cable  12  in the transverse direction  11   c.  A sheave mount  28  may extend upwardly from the frame  14 , positioning a sheave  30  to roll on an upper surface of the cable  12 . A brake assembly  20  may extend upwardly from the frame  12  to contact a lower surface of the cable  12 . With the brake assembly  20  and user-suspension portion  32  on opposite sides of the sheave mount  28 , the weight  34  of a user applied to the user-suspension portion  32  may generate a torque  36  or moment  36  urging the brake assembly  20  to “pitch” against the underside of the cable  12  (i.e., generate or urge rotation about an axis extending in the lateral direction  11   b ). The greater the moment  36  generated, the greater the braking force or friction force produced by the brake assembly  20 . 
         [0054]    A carriage  38  may provide the primary interface between a user and a trolley  10  in accordance with the present invention. That is, while other locations, apertures, connection, structures, and the like may be used for redundant, fail-safe systems, in normal use, the majority of user weight  34  may be applied to the carriage  38 . The carriage  38 , in turn, may communicate that load to the frame  14 . 
         [0055]    The position of the carriage  38  with respect to the frame  14  may be adjusted to provided a desired braking force. For example, the greater the distance  40  between the sheave mount  28  and the carriage  38 , the greater the moment  36  and resulting braking force. The opposite may also be true. That is, the braking force may be minimized by minimizing the moment arm  40  over which the weight  34  of a user may act. 
         [0056]    Adjustability and securement between a carriage  38  and a frame  14  may be provided by any suitable structures. In selected embodiments, an array of apertures  42  may provide an array of positions at which a carriage  38  may be secured to a frame  14 . A pin  44  or bolt  44  may pass through a carriage  38  and a selected aperture of the array  42  to lock the carriage  38  at a desired moment arm  40 . Accordingly, a trolley  10  in accordance with the present invention may be tuned to a particular cable  12  arrangement. That is, a trolley  10  may be formed according to a single design, yet be flexible within that design to provide braking appropriate for a wide range of cable  12  arrangements. 
         [0057]    For example, given a first cable  12  arrangement involving a comparatively larger change in elevation, a trolley  10  traveling on such a cable  12  may tend to reach excessive speeds. Thus, the carriage  38  may be secured to the frame  14  at an aperture  46  in the array of apertures  40  providing a corresponding, comparatively larger moment arm  40 . This greater moment arm  40  may increase the braking force and keep the trolley  10  within acceptable speed ranges. 
         [0058]    Conversely, consider a second cable  12  arrangement involving a minimal change in elevation. For such an arrangement, a carriage  38  secured at certain apertures (e.g., aperture  46 ) may provided excessive braking. For example, the resultant braking may cause the trolley  10  to stop without reaching the unloading area at the bottom of the cable  12 . According, for such arrangements, a carriage  38  may be secured to the frame  14  at an aperture  48  in the array of apertures  40  providing a minimal moment arm  40 . By so positioning the carriage  38 , the trolley  38  may provide greater speed along the cable  12 . 
         [0059]    While the weights of different users may vary, a trolley  10  in accordance with the present invention may automatically compensate for such variations. For example, the braking force required to regulate the speed of a trolley  10  carrying a user weighing 200 lbs. may be significantly greater than the braking force required to regulate the speed of a trolley  10  carrying a user weighing 100 lbs. However, with a single setting of the carriage  38  (i.e., a single moment arm  40 ), at trolley  10  may appropriately regulate the speed of both users. 
         [0060]    The braking force generated by a trolley  10  is equal to the coefficient of friction between the brake assembly  20  and the cable  12  multiplied by the normal force urging the braking assembly  20  against the cable  12 . For a single moment arm  40 , the only variable becomes the weight  34  of the user. Accordingly, the normal force urging the braking assembly  20  against the cable  12 , which is result of the moment  36  applied by the weight  34  of a user to the frame  14 , controls the braking force. Thus, without adjusting the position of the carriage  38 , the braking force generated for a user weighing 200 lbs. user will automatically be roughly twice that generated for a user weighing 100 lbs. That is, a trolley  10  may be tuned to a particular cable  12  arrangement, but need not be tuned for each user. 
         [0061]    A trolley  10  in accordance with the present invention may include any desirable redundant or fail-safe systems. For example, in selected embodiments, a frame  14  may include a slot  50  within or along which the carriage  38  may travel. Accordingly, if the pin  44  holding the carriage  38  in a particular location were to fail, the carriage  38  would not be free to separate from the frame  14 . Additionally, the orientation of the slot  50  with respect to the weight  34  of a user may urge an unpinned carriage  38  toward the end of the slot  50  corresponding to the second end  18  of the frame  14 . At such a location, the moment arm  40  and corresponding braking force may be at a maximum. Accordingly, if a pin  44  were to fail, the link between the user and the cable  12  would not be lost and the trolley  10  would quickly be brought to a halt. 
         [0062]    Referring to  FIG. 2 , in selected embodiments, a sheave mount  28  in accordance with the present invention may be pivotably secured to a frame  14 . For example, in certain embodiments, a bolt  52  may extend through the frame  14 . If desired, a collar  54  may be positioned over the bolt  52  to improve wear resistance, increase the rigidity of the bolt  52 , or the like. 
         [0063]    In certain embodiments, to increase safety, a sheave mount  28  may provide an enclosure capturing a cable  12  therewithin. That is, once the sheave mount  28  has received a cable  12  therewithin, it may resist inadvertent removal of that cable  12 . For example, in one embodiment, a sheave mount  28  may include a first side  56  extending from the bolt  52  to an aperture  58  for supporting a sheave  30 . This first side  56  may include one or more ribs  60  to increase the rigidity and strength thereof. A top  62  of the sheave mount  28  may connect the first side  56  to a second side  64  of the sheave mount  28 . In selected embodiments, the second side  64  may control admittance and release of a cable  12  from within the sheave mount  28 . 
         [0064]    In selected embodiments, the second side  64  of a sheave mount  28  may be separated into a hook portion  66  and a bail assembly  68 . In one embodiment, the hook portion  66  may be connected to the top  62  and include an aperture  70  that, in combination with another aperture  58 , may pivotably connect a sheave  30  to the sheave mount  28 . A hook portion  66  may also include a hook  72 . 
         [0065]    A bail assembly  68  may include a bail  74  and a bail mount  76 . A bail mount  76  may connect to the bolt  52  or collar  54  extending through the frame  14  from the first side  56  of the sheave mount  28 . A bail  74  may, in turn, extend from the bail mount  76  to engage the hook  72  of the hook portion  66 . In selected embodiments, a bail  74  may be biased toward a closed position with respect to the hook  72 . Accordingly, in certain embodiments, a bail  74  may be moved (e.g., pivoted) to permit entry of a cable  12  into the sheave mount  28 . Once the cable  12  is captured with the sheave mount  28 , the bail  74  may be released to return automatically to its preferred (biased), closed position. 
         [0066]    In selected embodiments, the interface between a bail  74  and a hook  72  may be such that the bail  74  is configured to open only toward the interior of the sheave mount  28 . Thus, the bail  74  may be biased to permit entry of a cable  12  into the sheave mount  28  but resist inadvertent removal of that cable  12 . As an additional safety feature, in certain embodiments, a bail mount  76  may include a slotted aperture  78  extending therethrough to receive the bolt  52 , collar  54 , or some combination thereof. A tensioner  80  may control the position of the bolt  52 , collar  54 , etc. within the slotted aperture  78 . 
         [0067]    Accordingly, once a cable  12  has been received within a sheave mount  28  and the bail  74  has returned to a closed position, the tensioner  80  may be adjusted to move the bail assembly  68  with respect to the bolt  52 , collar  54 , etc. Thus, the bail  74  may be pulled  82  firmly into engagement with the hook  72 . In such an arrangement, the hook  72  may resist opening of the bail  74 . Additionally, the bail assembly  68  may assist in transferring loads from a sheave  30  to the frame  14  of the trolley  10 . That is, the first side  56  of the sheave mount  28  need not act alone, thereby increasing the load-bearing capacity, and corresponding safety factor, associated with the sheave mount  28 . 
         [0068]    Referring to  FIG. 3 , in selected embodiments, a trolley  10  in accordance with the present invention may include a brake assembly  20  that is pivotably secured to the frame  14 . A pivotable connection between a brake assembly  20  and a frame  14  may support a more controlled and even wear on the break assembly  20 . 
         [0069]    In certain embodiments, to provide a pivoting securement between a brake assembly  20  and a frame  14 , the frame  14  may include various apertures  84 ,  86 . A pivot aperture  84  may be sized and shaped to receive a pivot bolt (i.e., a bolt about which the brake assembly  20  may pivot). A limiting aperture  86  may be sized and shaped to receive a limiting bolt (i.e., a bolt moving with the brake assembly  20  and abutting the extremes of the limiting aperture  86  when the brake assembly  20  reaches a desired limit to its pivoting). 
         [0070]    In selected embodiments, a frame  14  may include multiple pivoting apertures  84   a ,  84   b,    84   c.  For example, a first pivoting aperture  84   a  may provide a pivot point (e.g., central pivot point) for a brake assembly  20  of a first size. A second pivoting aperture  84   b  may provide a pivot point for a brake assembly  20  of a second, smaller size. A third pivoting aperture  84   c  may provide a pivot point for a brake assembly  20  of a third, even smaller size. If desired, multiple limiting apertures  86  may be provided. In one embodiment, however, a single limiting aperture  86  may be sized and shaped to providing a limiting effect to brake assemblies  20  pivoting in any of the various pivoting apertures  84 . 
         [0071]    Referring to  FIGS. 4 and 5 , a brake assembly  20  in accordance with the present invention may provide significant adjustability. For example, a brake assembly  20  may include a brake pad  88  that may be removed and replaced, as wear so dictates. Additionally, a brake pad  88  may itself be adjustable to provide a desired or customized braking effect. In selected embodiments, a brake pad  88  may comprise a plurality of interchangeable brake pad segments  89 . Thus, the sequence, composition, gaps, and the like of the various segments  89  may be selected to provide a desired resistance to wear, frictional coefficient, all-weather braking, and the like. 
         [0072]    In certain embodiments, the various segments  89  of a brake pad  88  may be held in place by one or more brake shoes  90 . For example, in one embodiment, a first brake shoe  90   a  may engage one side of the brake pad  88 , while a second brake shoe  90   b  may engage the other side of the brake pad  88 . Accordingly, in such an embodiment, the brake shoes  90  may securely hold the brake pad  88  therebetween. 
         [0073]    In selected embodiments, the brake pad  88  and one or more brake shoes  90  may be configured to facilitate mutual engagement. For example, in one embodiment, the various segments  89  of a brake pad  88  may include one or more extensions  92 . The brake shoes  90  may include one or more recesses  94  shaped and sized to receive the extensions  92 . Accordingly, when assembled, the brake shoes  90  may secure the brake pad  88  in all three dimensions  11   a,    11   b,    11   c.    
         [0074]    If desired or necessary, a brake assembly  20  may include various structural members providing additional strength, rigidity, safety, or the like. For example, in selected embodiments, a brake assembly  20  may include one or more cheek plates  96 . In one embodiment, a brake assembly  20  may include a first cheek plate  96   a  positioned to reinforce a first brake shoe  90   a  and a second cheek plate  96   b  positioned to reinforce a second brake shoe  90   b.    
         [0075]    In certain embodiments, a cheek plate  96  may include various apertures to support desired functionality. For example, a cheek plate  96   a  may include an aperture  98  sized and positioned to receive a limiting bolt, one or more apertures  100  sized and positioned to receive a pivot bolt, and one or more apertures  102  sized and positioned to receive assembly bolts or bolts securing the brake assembly  20  together. In selected embodiments, corresponding apertures  98 ,  100 ,  102  may be formed in other cheek plates  96   b,  as well as the various brake shoes  90 . 
         [0076]    In selected embodiments, a brake assembly  20  may include a groove  104  or slot  104  sized and positioned to accommodate a portion of the frame  14  therewithin. Accordingly, in such embodiments, a brake assembly  20  may effectively straddle the frame  14 , permitting various fasteners (e.g., pivot bolts, limiting bolts, etc.) to pass through both the brake assembly  20  and the frame  14 . If desired or necessary, a slot  104  may extend some distance less than the entire length of the brake assembly  20 . For example, in one embodiment, opposing brake shoes  90   a,    90   b  may each include a shoulder  106  extending to meet the other. The shoulders  106  may effectively close the slot  104 . Accordingly, any fastener (e.g., assembly bolt) passing through the area of the shoulder  106  may be tightened without clamping the frame  14  and reducing the ability of the brake assembly  20  to pivot with respect to the frame  14 . 
         [0077]    A brake assembly  20  in accordance with the present invention may include a capture  108 . A capture  108  may secure a cable  12  therewithin. That is, once a trolley  10  is applied to a cable  12 , the capture  108  may secure the brake assembly  20  to the cable  12 . Accordingly, the capture  108  may provide a redundant safety mechanism and, should there be a catastrophic failure of the sheave mount  28 , the trolley  10  may be secured to the cable  12  via the brake assembly  20  and capture  108 . 
         [0078]    If desired, a capture  108  may include a slide  110 . In certain embodiments, a slide  110  may provide an interface between a capture  108  and a cable  12 . For example, a capture  108  may in certain situations slide along a cable  12 . In such situations, a slide  110  may prevent abrasion or grinding that may reduce the structural integrity of the capture  108 . In one embodiment, a slide  110  may include a groove  112  or slot  112  providing a preferred or default location of engagement between a slide  110  and a cable  12 , should contact occur therebetween. 
         [0079]    Referring to  FIG. 6 , a capture  108  in accordance with the present invention may have any suitable shape or configuration. Additionally, a capture  108  may secure to the rest of the brake assembly  20  in any suitable manner. For example, in one embodiment, a capture  108  may be positioned and secured to bracket the rest of the brake assembly  20 . Such bracketing may improve the structural integrity of the brake assembly  20  without requiring additional fasteners (e.g., bolts), which may interfere with the adjustability or functionality of the brake assembly  20 . Portions of the capture  108  may be held in place by one or more bolts extending in the lateral direction  11   b  through the brake assembly  20 . For example, in one embodiment, a capture  108  may be held in place by a limiting bolt  114  and an assembly bolt  116 . 
         [0080]    Referring to  FIG. 7 , various material properties and characteristics may be considered when selecting a material for a brake pad  88  in accordance with the present invention. Properties and characteristics that may be considered include cost, availability, machineability, wear resistance, toughness, all weather performance (e.g., characteristics at various conditions of humidity, moisture, corrosion, temperature, and the like), coefficient of friction against a cable  12  in various weather conditions (e.g., temperature and wetness levels), and the like. Often a material that has certain advantageous characteristics may have others that are disadvantageous. For example, one material may have excellent wear resistance, but its coefficient of friction against a cable  12  may vary greatly depending on whether the cable is dry. Accordingly, the material may be suitable for dry conditions, yet be hazardous for wet conditions. 
         [0081]    In certain embodiments of a trolley  10  in accordance with the present invention, it may be advantageous to provide a brake pad  88  having repeatable and consistent performance with respect to wear, coefficient of friction, or the like regardless of temperature, wetness, etc. For example, by providing a brake pad  88  with consistent wear, fixed maintenance schedules may be determined and executed. The resulting decrease in subjectivity may be accompanied by an increase in consistency and safety. Similarly, by providing a brake pad  88  with a consistent coefficient of friction regardless of the wetness of the cable  12 , rain need not concern an operator of a trolley  10  in accordance with the present invention. Again, the resulting decrease in subjectivity and weather dependence may be accompanied by an increase in consistency and safety. 
         [0082]    In selected embodiments, a brake pad  88  may be configured to operate within a specific range. For example, a brake pad  88  may perform within a range, regardless of environmental temperature and the wetness or dryness of a cable  12 . A brake pad  88  may deliver a rider to the bottom end of a cable  12  at a first speed in a dry environment at 90 degrees Fahrenheit. That same brake pad  88  may deliver a rider to the bottom end of a cable  12  at a second speed, different from the first speed, in a wet (e.g., saturated cable  12 ) environment at 65 degrees Fahrenheit. However, the difference between the first and second speeds may be such that both are within an acceptable range. For example, while the first may be 20 miles per hour and the second may be 27 miles per hour, both speeds may be below a hypothetical safety cutoff of 35 miles per hour. 
         [0083]    To provide the advantages of a brake pad  88  in accordance with the present invention, a brake pad  88  may be formed of various segments  89  The various segments  89  may be formed in various shapes and of various materials. As stated hereinabove, the shape of the various segments  89  may support engagement with the rest of the brake assembly  20  (e.g., the brake shoes  90 ). The shape of the various segments  89  may also control the contact area between a segment  89  and a cable  12 . 
         [0084]    In selected embodiments, a brake pad  88  may include a plurality of segments  89  positioned in series. So positioned, the width of each segment  89  in the longitudinal direction  11   a  may control the contact area between each segment  89  and the cable  12 . The contact area may vary between segments  89 . For example, in certain embodiments, one segment  89   a  may have a width  118  greater than the width  120  of another segment  89   b . Accordingly, the former segment  89   a  may provide a greater contribution to the overall performance of the brake pad  88  than the latter segment  89   b.  Although friction forces are independent from the area engaged, wear is not. 
         [0085]    If desired, gaps  122  may be included between various segments  89  of a brake pad  88 . In certain embodiments, gaps  122  may improve the all weather performance of a brake pad  88 . For example, when a cable  12  is saturated with water, the gaps  122  may provide locations for the water to escape from between the cable  12  and a segment  89  being pressed thereagainst. The size  124  or width  124  of the gaps  122  in a brake pad  88  may vary from a minimum of direct abutment between adjacent segments (e.g., segment  89   a  and segment  89   b ) to some maximum. 
         [0086]    By controlling the composition of the segments  89 , the contact area of the segments  89 , and the gaps  122  between the segments  89 , the performance of a brake pad  88  may be optimized to a given trolley  10  application. For example, in selected embodiments, it may be desirable for a brake pad  88  in accordance with the present invention to slide along a cable  12 . That is, the brake pad  88  may lower the speed of the trolley  10  along the cable  12 , but not overly slow or stop it. Accordingly, in one embodiment, certain segments  89   a,    89   c,    89   e ,  89   g  may be formed of a first, substantially inelastic material (e.g., high density polyethylene (HDPE) or ultra high molecular weight polyethylene (UHMWPE)). The rest of the segments  89   b,    89   d,    89   f,    89   h  may be formed a second, elastic material (e.g., multi-rubber or other natural or synthetic elastomeric materials such as those used for the caliper brake pads of a bicycle). 
         [0087]    So arranged, the first material may provide the desired wear resistance and a suitable (e.g., limited) frictional engagement with a dry cable  12 . The second material may not wear as well as the first material, yet provide a suitable water stripping or frictional engagement with a wet cable  12 . Accordingly, overall, the brake pad  88  may have both acceptable wear and frictional engagement even when applied to a wet cable  12 . By adjusting the number of segments  89  corresponding to the first and second materials and the contact areas associated with those segments  89 , a proper balance of characteristics may be achieved. 
         [0088]    Referring to  FIG. 8 , in selected embodiments, two materials and two larger gaps  122  may be all that is required to provide a satisfactory brake pad  88 . Additionally, for optimum performance, the contact area between the two materials may only slightly favor one material over the other. In such an embodiment, a first plurality of segments  89   a,    89   c ,  89   e,    89   g,    89   i  may be formed of a first material. A second plurality of segments  89   b,    89   d ,  89   f,    89   h  may be formed of a second material. If desired, the segments  89  may be positioned in an alternating pattern. Accordingly, each segment  89  of the second material may be positioned between segments  89  corresponding to the first material. 
         [0089]    Alternatively, the segments  89   a,    89   c,    89   e,    89   g,    89   i  comprising the first material may be positioned adjacent one another, and the segments  89   b,    89   d,    89   f,    89   h  comprising the second material may be positioned adjacent one another. In such an embodiment, the segment  89   a,    89   c,    89   e,    89   g,    89   i  comprising the first material may be consolidated into a single monolithic (i.e., seamless) unit. Similarly, the segments  89   b,    89   d,    89   f,    89   h  comprising the second material may be consolidated into a single monolithic unit. 
         [0090]    Referring to  FIG. 9 , in selected embodiments, two materials and minimal gaps  122  may be all that is required to provide a satisfactory brake pad  88 . Additionally, for optimum performance, the contact area between the two materials may favor one material over the other (e.g., 75 percent one material, 25 percent another). In such an embodiment, a first plurality of segments  89   a,    89   c,    89   e,    89   g,    89   i  may comprise a first material. A second plurality of segments  89   b,    89   d,    89   f,    89   h  may comprise a second material. Again, the segments  89  may be positioned in an alternating pattern. Alternatively, the segments  89   a ,  89   c,    89   e,    89   g,    89   i  comprising the first material may be positioned adjacent one another and the segments  89   b,    89   d,    89   f,    89   h  comprising the second material may be positioned adjacent one another. Adjacent segments  89  of common material may be consolidated as desired. 
         [0091]    Referring to  FIG. 10 , in selected embodiments, more than two materials  122  may be required to provide an optimal brake pad  88 . For example, for optimum performance, three materials may be needed in varying degrees (e.g., contact area comprising 45 percent of a first material, 30 percent of a second material, and 25 percent of the last material). In such an embodiment, a first plurality of segments  89   a,    89   e,    89   i  may comprise a first material. A second plurality of segments  89   c,    89   g  may comprise a second material. A third plurality of segments  89   b,    89   d,    89   f,    89   h  may comprise a third material. Again, the segments  89  may be positioned in an alternating or distributed (e.g., balanced) pattern. Alternatively, the segments  89  may be separated and arranged by material type, and, if desired, consolidated into a minimum number of segments  89  (e.g., only one segment  89  for each type of material). 
         [0092]    Referring to  FIGS. 11 and 12 , in selected embodiments, a trolley  10  in accordance with the present invention may provide a user readily adjustable, or even “on-the-fly,” control over the magnitude of a braking force  126  or friction force  126  generated by the trolley  10  as it travels along a cable  12 . The braking force  126  may be equal to the normal force  128  urging the brake assembly  20  against the cable  12  multiplied by the friction coefficient for the brake pad  88  against the cable  12 . With the friction coefficient for the brake pad  88  against the cable  12  being substantially constant, the braking force  126  may perhaps most easily be manipulated by manipulations of the normal force  128 . 
         [0093]    For example, by adjusting the moment arm  40  at which the weight  34  of a user is applied to the frame  14  of a trolley  10 , the magnitude of the resulting moment  36  may be controlled. The magnitude of the moment  36  may then dictate the magnitude of the normal force  128 . Accordingly, by adjusting the moment arm  40  at which the weight  34  of a user is applied to the frame  14  of a trolley  10 , a user may control, within a particular range, the braking force  126  generated by the trolley  10 . 
         [0094]    In selected embodiments, a trolley  10  in accordance with the present invention may include a carriage  38  configured to travel along a frame  14  or portion of a frame  14  through a range (e.g., continuous range) of motion bounded by a first position of the carriage  38  proximate the sheave mount  28  (e.g., the position of the carriage  38  in  FIG. 11 ) and a second position of the carriage  38  proximate a second end  18  of the frame  14  (e.g., the position of the carriage  38  in  FIG. 12 ). 
         [0095]    In certain embodiments, a carriage  38  may travel along the frame  14  through the range of motion bounded by the first and second positions without compromising the connection between a user and the cable  12 . Accordingly, adjustment of the position of the carriage  38 , and the resulting adjustment to the braking force  126 , may safely be accomplished in any suitable manner while the trolley  10  is in motion along the cable  12 . That is, in selected embodiments, neither a stopped trolley  10  nor any change in the connection between a user and a cable  12  may be necessary to transition from minimum leverage and braking to maximum leverage and braking. 
         [0096]    In selected embodiments, the default position of a carriage  38  with respect to the frame  14  may be the second position (e.g., the position of the carriage  38  in  FIG. 12 ). That is, absent contrary inputs or forces, a carriage  38  may, under the impetus of gravitational acceleration, move toward the second position. At the second position, the braking force  126  may be at a maximum. Accordingly, a trolley  10  in accordance with the present invention may have a default configuration corresponding to maximum braking, which, given typical cable  12  declination, is sufficient to bring the trolley  10  to a halt. 
         [0097]    Referring to  FIGS. 13 and 14 , in selected embodiments, a trolley  10  in accordance with the present invention may be configured to facilitate travel of the carriage  38  along the user-suspension portion  32  of the frame  14 . For example, in selected embodiments, a frame  14  may include a rail  130  to provide a suitable surface over which a carriage  38  may travel. In certain embodiments, a rail  130  may provide a substantially planar surface. If desired, a rail  130  may be formed of a material dissimilar from the rest of the frame  14 . For example, in embodiments where the frame  14  may be formed of aluminum, a rail  130  formed of steel may be connected to the frame  14  to provide a more durable surface over which a carriage  38  may travel. 
         [0098]    A trolley  10  may be configured to resist removal of a carriage  38  from the frame  14 . For example, in selected embodiments, a sheave mount  28  may prevent a carriage  38  from passing therebeyond (e.g., beyond the first position). Similarly, the second end  18  of the frame  14  may be configured to prevent a carriage  38  from passing therebeyond (e.g., beyond the second position). For example, in certain embodiments, the second end  18  of the frame  14  may be shaped to include a rise  132  extending transversely  11   c  from the frame to resist passage of the carriage  38  thereover. Also, in some embodiments, the second end  18  of a frame  14  may include a stop  134  (e.g. bolt, pin, etc.) extending laterally  11   b  from the frame to block passage of the carriage  38 . 
         [0099]    In certain embodiments, a carriage  38  may include two cheek plates  136  bracketing the frame  14 . Various fasteners  138 ,  140 , and  142  may extend between the cheek plates  136  to connect the plates  136  together. Such fasteners  138 ,  140 ,  142  may also support various functions of a carriage  38 . For example, one fastener  138  may provide a user mount  144  or a location  144  at which a user may connect to or tie into the carriage  38  and transfer his or her weight  34  thereto. Another fastener  140  may support a roller  146 , bushing  146 , or bearing  146  facilitating travel of the carriage  38  along the rail  130 . Yet another fastener  142  may provide a structure supporting manipulation of the carriage  38  along the rail  130 . 
         [0100]    For example, in selected embodiments, a fastener  142  may provide a location for a tether  148  to engage the carriage  38 . If desired, a tether  148  may extend from the carriage  38 , over the pivot  52 , bolt  52 , or fastener securing the sheave mount  28 , and down toward a user. Thus, by pulling  150  down on the tether  148 , a user may pull  152  the carriage  38  toward the first position and the minimum braking corresponding thereto. Conversely, by releasing the tether  148  or sufficiently lowering the downward force  150  applied to the tether  148 , the carriage  38  may travel toward the second position and the maximum braking corresponding thereto. 
         [0101]    A user may engage or manipulate a tether  148  in any suitable manner. For example, in one embodiment, a tether  148  may be connected to a handle suspended at an appropriate height for the user. Accordingly, the user may simply grab the handle and pull  150  down on the tether. Alternatively, a tether may extend to engage the foot of a user. For example, a user may position a foot within a loop connected to the tether  148 . Thus, by weighting the foot (e.g., shifting some of the weight  34  of the user from the carriage to the tether  148 ), the tether  148  may be pulled  150  downward. 
         [0102]    Accordingly, while a carriage  34  may be the primary suspension point for the weight  34  of the user, portions of that weight  34  may be diverted as necessary to adjust the position of the carriage  38  or to otherwise increase the safety of a trolley  10 . For example, in selected embodiments, various apertures  154  may be provided in a frame  14 . Such apertures  154  may support redundant user support systems taking a portion of the weight  34  of a user in normal use and a substantial portion of the weight  34  of a user in compromised use. Additionally, such apertures  154  may provide locations for supporting other loads or persons not directly responsible for the operation of the trolley  10  (e.g., a rescuee being lowered from a stalled chair lift). 
         [0103]    In selected embodiments, a trolley  10  in accordance with the present invention may be configured for rapid engagement with and disengagement from a cable  12 . In such embodiments, a capture  108  may be omitted. Alternatively, a capture  108  providing rapid release may be employed. For example, in one embodiment, a capture  108  may comprise a flexible cable. So configured, the capture  108  may extend from a first mount  156  positioned on one side of a brake assembly  20  to a second mount  158  positioned on the other side of the brake assembly  20 . The engagement between the capture  108  and one mount  156  may be substantially permanent, while a release mechanism  160  (e.g., quick release hook, carabiner, or the like) may provide selective engagement between the capture  108  and the other mount  158 . 
         [0104]    In certain embodiments, a brake pad  88  may be formed as a monolithic and homogeneous unit. For example, a brake pad  88  may be formed as a single, seamless piece of a non-elastic material (e.g., UHMWPE). Alternatively, a brake pad  88  may include various other segments  89  or inserts  89  selectively providing additional control over braking characteristics. A pivot bolt  162  may pivotably secure the brake pad  88  to the frame  14 . If desired or necessary, a brake assembly  20  in accordance with the present invention may include an adjustable stop  164 . In some embodiments, the adjustable stop  164  may provide a selectively adjustable limit on the pivoting of the brake pad  88 . In other embodiments, the adjustable stop  164  may dictate the angle at which the brake pad  88  may contact a cable  12 . 
         [0105]    Referring to  FIG. 15 , in selected embodiments, one or more captures  108  may be used to secure a brake assembly  20  to a cable  12 . If desired, one or more captures  108  may be positioned to maintain a brake assembly  20  in abutment with the cable  12 . For example, a capture  108  may be positioned such that the brake pad  88  and one or more slides  110  simultaneously contact a cable  12 . The various slides  110  may be formed of various materials (e.g., materials such as those used in a brake pad  88 ) to provide a desired composite sliding or braking effect. Such an arrangement may provide additional control over the motion of the trolley  10  with respect to the cable  12 . 
         [0106]    In certain embodiments, a capture  108  may be formed of an elastic material to provide a degree of control over the normal force  128  applied thereby. In one embodiment, a capture  1087  may be formed of an elastic band material formed with various apertures  165 . Mounts  158  may be configured as extensions or posts extending (e.g., in a lateral direction  11   b ) from the cheek plates  96 . Accordingly, the apertures  165  in the capture  108  may be placed over the mounts  158  to secure the capture  108  to the rest of the brake assembly  20 . 
         [0107]    Additionally, by selecting which aperture  165  is applied to which mount  158 , a user may control the slack between the slides  110  and the cable or, alternatively, the tension in the capture  108  pulling the slides  110  into contact with the cable  12 . The normal force  128  may thus be increased sufficiently to hold the trolley  10  in place on the cable  12  both during application of the trolley  10  the cable  12  and securement of a user to the trolley  10 . The effect of the capture  108  may thus bias the cable  12  against the brake pad  88 , hold the trolley  10  in place, provide additional braking effect in operation, or some combination thereof. In practice, ten to twenty pounds of braking force is readily achieved by manually tensioning a pair of captures  108 . On portions of a cable  12  having little declination, the captures  108  may be loosened or released to eliminate their braking effect. 
         [0108]    Moreover, by tensioning the capture  108  sufficiently to prevent motion of the trolley  10  along the cable  12 , a user may not have to contend with the trolley  10  sliding along the cable  12  as the user is attempting to properly apply weight  34  to the frame  14 . This may provide more precise control of movement of the trolley  10  at all times, particularly on portions of the cable  12  at steep angles (e.g., greater than 30 degrees) or in close quarters near suspended chairs or gondolas being serviced. 
         [0109]    Referring to  FIG. 16 , trolleys  10  in accordance with the present invention may be used as the basis for an amusement or thrill ride. One of the potential hazards of a ride employing trolleys  10  in accordance with the present invention is the possibility of collision. For example, a first rider may ride a first trolley  10  to some location along a cable  12 . Assuming that the first rider has reached the bottom and exited the ride, a second rider may ride a second trolley  10  down the same cable  12 . Accordingly, if the first rider did not actually reach the bottom, serious injury may occur when the second rider collides with the first rider. While communication between finish area operators, or sensors thereat, and start area operators, or sensors thereat, may reduce the risk of such collisions, the possibility of miscommunication or malfunction permits some risk of collision to remain. 
         [0110]    Also, for amusement rides, revenue may largely depend on the number operators employed to operate the ride and the number of users served within a given period of time. Accordingly, revenue may be increased in various ways. For example, a plurality of cables  12  may be employed. Additionally, the rate at which each cable is utilized may be increased. That is, the method for circulating trolleys  10  (i.e., transporting trolleys  10  from the finish area back to the start area) may be optimized. Also, the number of operators may be minimized. 
         [0111]    In view of the foregoing, a trolley retrieval system  166  in accordance with the present invention may be configured to maximize user throughput, minimize operator interaction, and eliminate the risk of collision. In selected embodiments, a system  166  may include multiple (e.g., four) cables  12  held in suspension between first and second supports. A retrieval line  168  may be suspended in a closed loop extending from proximate a start area  170  to proximate a finish area  172 . In general, the start area  170  may correspond to the first or upper support, while the finish area  172  may correspond to the second or lower support. A motivator  174  may selectively circulating the retrieval line  168  around the loop. A controller  176  may control operation of the motivator  174 . 
         [0112]    In selected embodiments, a controller  176  may include a processor  178  and one or more end-of-travel sensors  180  sensing when a trolley  10  nears the start area  170 . The sensors  180  may be operably connected to the processor  176  to appropriately pass thereto a stop signal informing the processor  176  that one or more of trolleys  10  is sufficiently near the start area  170 . The processor  176  may be programmed to issue, in response to the stop signal, a stop command causing the motivator  174  to cease circulation of the retrieval line  168 . The processor  176  may be further programmed to issue, in further response to the stop signal, a reverse command causing the motivator  176  to circulate the retrieval line  168  in an opposite direction when it resumes circulation the retrieval line  168 . A controller  176  may further include a retrieval switch  182  operably connected to cause, when activated, the motivator  174  to resume circulation of the retrieval line  168 . The retrieval line  168  may travel down with a user or simply disconnect to be reconnected only when retrieval is needed. Thus, movement of the retrieval line  168  may be continuous in a loop of a constant sense of direction. 
         [0113]    At the finish area  172 , each cable  12  may include arresting equipment  184 . Arresting equipment  167  may include whatever structures are necessary to safety slow a trolley  10  and associated user to a stop. In selected embodiments, the arresting equipment  184  may include terminal brake acceptors (e.g. receiver or actuator), springs, and weights as disclosed in U.S. Pat. No. 6,622,634. 
         [0114]    In certain embodiments, a retrieval system  166  may include a plurality of sheaves  186  cooperating to hold the retrieval line  168  in suspension. If desired, each sheave  186   a,    186   b ,  186   c,  and  186   d  of the plurality of sheaves  186  may be connected to one of the first and second supports. Accordingly, the retrieval line  168  may be suspended in the same catenary form or angle as that of the various cables  12 . Also, the sheaves  186  may define the loop about which the retrieval line  168  may circulate or travel. In selected embodiments, different legs or portions  188  of the retrieval line  168  may serve different cables  12  during operation. For example, in a four cable embodiment, a first leg  188   a  of a retrieval line  168  may be positioned to serve two cables  12   a,    12   b,  while a second leg  188   b  of the retrieval line  168  may be positioned to serve the other cables  12   c,    12   d.    
         [0115]    In certain embodiments, a retrieval line  168  may be formed of any suitable material. In one embodiment, a retrieval line  168  may be formed of a relatively lightweight, synthetic polymer rope. If desired or necessary, a retrieval line  168  may include one or more swivels  190  relieving twisting imposed thereon or generated therein. Various interface mechanisms  192  (e.g., carabiners, loop reinforcements, or the like) may provide the interface between the line  168  and the swivels  190 . In selected embodiments, the swivels  190  or interface mechanisms  192  may provide a location at which a trolley  10  may connect to or engage the retrieval line  168 . Additionally, the swivels  190  and interface mechanisms  192  may provide break points supporting replacement of certain portions of the retrieval line  168  should wear so dictate. 
         [0116]    In selected embodiments, a motivator  174  may include a motive source  194  coupled to a line engagement system  196 . In certain embodiment, a motive source  194  may provide rotation to the line engagement system  196 , which, in turn, may induce movement (e.g., circulation) of the retrieval line  168 . In one embodiment, a motive source  194  may comprise an electric motor. In such an embodiment, the motivator  174  may further include a polarity switch switching, in response to the reverse command, the polarity of the current supplied to the electric motor. The motive source  194  may operate in a single direction such that the retrieval line  168  loops continuously. Thus, the upward leg of the retrieval line  168  corresponds to retrieval of a harness or seat unit, and the downward leg “deadheads” back to the finishing location for a new pickup. In such an arrangement, links for connecting to harnesses or seats may be removable from the line  168 . 
         [0117]    Referring to  FIG. 17 , a line engagement system  196  may include any structures effectively translating motion of the motive source  192  into motion of the retrieval line  168 . In certain embodiments, a line engagement system  196  may include a first bank of sheaves  198  rotating about a first axis  200  and a second bank of sheaves  202  rotating about a second axis  204 , spaced from and parallel to the first axis  200 . The retrieval line  168  may be reeved between the first and second banks of sheaves  198 ,  202 . The motive source  194  may provide rotation (directly or appropriately “geared”) to the first bank  198 , the second bank  202 , or both. In such an arrangement, the surface area between the line  168  and the sheaves may be selected to be sufficient to provide adequate frictional engagement therebetween. 
         [0118]    Referring to  FIG. 18 , in operation, a method  206  in accordance with the present invention may begin with the selection  208  of a system  166  comprising one or more cables  12  held in suspension between first and second supports and a trolley  10  positioned to travel along each cable  12 . In selected embodiments, one trolley  10  may be assigned to each cable  12  and remain secured thereto. So configured, the possibility of collision is eliminated as only one trolley  10  is ever applied to a cable  12  in such a system. Thus, unless and until a trolley  10  is retrieved (circulated from the finish area  172  bak to the start area  170 ), no new riders will be sent down that cable  12 . 
         [0119]    Once an appropriate system  166  has been selected  208 , a user may be connected  210  to the trolley  10 . In selected embodiments, connecting  210  a user to a trolley  10  may include positioning and securing a user within a harness or seat suspended from the trolley  10 . Following securement  210  of a user in the harness, the trolley  10  may be released  212  to travel along the cable from proximate the first support (i.e., the start area  170 ) to proximate the second support (i.e., the finish area  172 ). At the finish area  170 , the user may be disconnected  214  from the harness. The trolley  10  and harness may then be connected  216  to a retrieval line  168  for the return trip. 
         [0120]    A trolley  10  may be connected  216  to a retrieval line  168  by any suitable method using any suitable structures. In one embodiment, a trolley  10  may include a tether connected thereto. A first end of the tether may connect to the harness suspended from the trolley  10 . A second end of the tether may include a quick-release hook (e.g., carabiner) providing rapid engagement with a swivel  190  or interface mechanism  192  of a retrieval line  168 . When the first end of a tether is pulled (e.g., by the retrieval line  168 ), the tether may lift the harness up toward the trolley  10 . Once the harness cannot be lifted further, additional pulling of the tether may induce travel of the trolley  10  along the cable  12 . By cinching or lifting the harness, the tether may reduce air drag as the trolley  10  is circulated back to the start area  170 . Also, lifting the harness may reduce flopping and whipping of the harness during travel. Furthermore, lifting the harness may facilitate passage of the harness over obstacles such as a starting gate positioned at the start area  170 . 
         [0121]    Once a trolley  10  connected  216  to a retrieval line  168 , the motivator  174  may be activated  218  to draw the trolley  10  along the cable  12  from proximate the second support (i.e., the finish area  172 ) to proximate the first support (i.e., the start area  170 ). When one or more of the trolleys  10  connected  216  to a retrieval line  168  activates an end-of-travel sensor  180 , the motivator  174  may stop the retrieval line  168 . The trolley  10  or trolleys  10  may then be disconnected  220  from the retrieval line  168  and secured or prepared for future use  210 . 
         [0122]    As stated hereinabove, in selected embodiments, a processor  176  may be programmed to issue, in response to a stop signal, a reverse command causing the motivator  176  to circulate the retrieval line  168  in an opposite direction when it resumes circulation the retrieval line  168 . So configured, the engagement locations (e.g., swivels  190 , interface mechanisms  192 ) between a retrieval line  168  and a trolley  10  may be securely or even permanently attached and travel in a cycle from the starting area  170  to the finishing area  172  and back. Alternatively, interface mechanisms may be clamped and removed readily so the line  168  may travel with only a loop of one “sense” of direction only. 
         [0123]    Moreover, while one engagement location is stopped at the starting area  170 , another may be stopped at the finish area  172 . Accordingly, in selected embodiments, while one or more trolleys  10  are being loaded  210  with users, other trolleys  10  may be connected to a retrieval line  168 . Also, while one or more trolleys  10  are pulled from the finish area  172  to the start area  170 , other engagement locations on the retrieval line  168  may be returned to the finish are  172  to continue the cyclical pattern. So configured, a trolley retrieval system  166  in accordance with the present invention may provide a substantially continuous throughput, minimize operator interaction, and eliminating the risk of collisions. 
         [0124]    Referring to  FIG. 19 , a retrieval system  166  in accordance with the present invention may be configured to service any number of cables  12 . Scaling of such a system  116  may occur in at least one of two ways. First, multiple loops may be created in a single retrieval line  186 . Accordingly, for a system  166  serving six or eight cables  12 , a retrieval line  168  may include four legs  188  or portions  188 . Each such leg  188  may be positioned to service at least one cable  12 . For example, certain legs  188   a,    188   d  may service two cables  12   a,    12   b  and  12   e,    12   f,  respectively, while other legs  188   b,    188   c  may service one cable  12   c ,  12   d,  each, respectively. Second, a retrieval system  166  may include various subsystems, each in itself being an independent yet cooperative retrieval system  166 . 
         [0125]    Referring to  FIGS. 20-22 , an upper or lower support  224  for suspending a cable  12  may be configured in any suitable manner. In selected embodiments, a support  224  may perform at least three functions, namely anchoring, positioning, and tensioning a cable  12 . In one embodiment a support  224  may include a tower  226  positioning a cable  12  at a desired height  228  above the ground  230  or other supporting surface  230 . A tower  226  may include a sheave  232  suspended from a sheave mount  234  to engage and support the cable  12 . The height  228  of the cable  12  may be controlled by altering the height of the tower  226 , by altering the length of the sheave mount  234 , or by some combination thereof. 
         [0126]    After passing over the sheave  232  of a tower  226 , a cable  12  may extend to an anchor assembly  236 . In selected embodiments, an anchor assembly  236  may include one or more sheaves  238  to redirect the cable  12 , one or more cable clamps  240 , and a wrapping post  242 . In one embodiments, an anchor assembly  236  may be arranged such that a cable  12  may pass under a sheave  238   a,  through a cable clamp  240 , and wrap around a wrapping post  242 . 
         [0127]    In certain embodiments, a tension assembly  244  may be positioned between a tower  226  and an anchor assembly  236 . A tension assembly  244  may deflect the cable  12  to cause relatively fine adjustments to the tension or suspension shape of a cable  12 . In one embodiment, a tension assembly  244  may include a sheave  246  positioned to capture the cable  12 . The sheave  246  may be connected to an adjuster  248 . Accordingly, changes in the length of the adjuster  248  (e.g., decreases in the length of the adjuster  248 ) may deflect the cable  12  from its path otherwise. The greater the deflection of the cable  12 , the greater the increase in tension, the flatter the suspension shape of the cable (e.g., less sag between supports  226 ), or both. 
         [0128]    In selected embodiments, changes in length of an adjuster  248  may be manually induced. Alternatively, changes in length of the adjuster  248  may be automatically calculated and applied to periodically or continuously adjust cable tension (e.g., to compensate for changes in length of the cable  12  due to changes in temperature and the like). In certain embodiments, an adjuster  248  may be a hydraulic ram. 
         [0129]    If desired or necessary, one or more supports  250  may extend between a tower  226  and an anchor assembly  236 . Such supports  250  may increase the strength and rigidity of the support  224 . Additionally, such supports  250  may facilitate the transfer of loads imposed on the various structures  226 ,  236  to underlying foundation. 
         [0130]    A support  224  in accordance with the present invention may be positioned at either end of the cable  12 . In certain embodiments, a tension assembly  244  may be positioned at only one end of a cable  12 . Alternatively, when greater adjustment capacity is desired, a tension assembly  244  may be positioned at each end of a cable  12 . 
         [0131]    During installation and initial suspension of a cable  12 , significant slack of the cable  12  must be appropriately consumed before the cable  12  may be secured or “tied off.” In selected embodiments, an anchor assembly  236  may support rapid consumption of slack cable  12 . For example, in selected embodiments, an anchor assembly  236  may include a first sheave  238   a  receiving cable from a tower  226 . The cable  12  may pass from the first sheave  238   a,  through a cable clamp  240 , past a wrapping post  242 , to a second sheave  238   b.  In one embodiment, the various components  238   a,    238   b,    240 ,  242  of the anchoring assembly  236  may be secured to an anchor plate  252 , which, in turn, may secure to an appropriate foundation. 
         [0132]    After passing through the second sheave  238   b,  a cable  12  may be pulled  254  in a variety of directions. If desired, the slack of a cable  12  may be pulled  254  through an anchoring assembly  236  by a tractor. Thus, the variety of directions at which the cable  12  may be pulled  254  may allow the tractor to selected the best route for accomplishing the task. 
         [0133]    Moreover, once a cable  12  achieves a desired suspension shape, pulling  254  of the cable may cease and the cable clamp  240  may be tightened. Once the clamp  240  is secured, the cable  12  may be appropriately cut and wrapped around the wrapping post  242 . Once the cable  12  is tied off, the clamp  240  released. The cable  12  will remain in the desired configuration, as transitioning from clamp  240  to wrapping post  242  requires no guess work or estimates as to how the shape of the cable  12  will change once the temporary securement is released. 
         [0134]    In selected embodiments, a tractor or the like may not provide sufficiently fine adjustment of the suspension position of a cable  12 . In such embodiments, a tractor or the like may draw or “consume” the bulk of the slack, while leaving the fine tuning of the suspension to an adjuster  248 . That is, before an adjuster  248  is fully incorporated into a tension assembly  244 , the adjuster  248  may be fitted with a clamp to engage a cable  12 . The adjuster  248  may then incrementally, and with significant precision, pull  254  the cable  12  to a desired suspension shape. Alternating engagement between the cable clamp  240  of the anchor assembly  236  and the clamp associated with the adjuster  248 , the adjuster  248  may take multiple “bites” or pulls at the cable  12 . Again, once the cable  12  is properly positioned, pulling  254  of the cable may cease. The cable clamp  240  may be tightened and the cable  12  may be appropriately cut and wrapped around the wrapping post  242 . 
         [0135]    In selected embodiments, once installation of a cable  12  is complete, the second sheave  238   b  and cable clamp  240  may be removed (e.g., unbolted). If desired, the components  238   b,    240  may be re-used on other anchoring assemblies  236  to facilitate installation and initial suspension of other cables  12 . 
         [0136]    Referring to  FIGS. 23-25 , in selected embodiments, a bumper assembly  22  in accordance with the present invention may be configured as a guide  22 . For example, a bumper assembly  22  may be formed as a guide  22  or yolk  22  having two extension  256 ,  258  angling away from one another to form a central vertex  260  therebetween. A guide  22  may facilitate engagement with an engagement mechanism  262 . 
         [0137]    In selected embodiments, an engagement mechanism  262  may be configured to slide along a cable  12 . An engagement mechanism  262  may provide the interface between a trolley  10  and a deflecting element. Accordingly, momentum may be transferred from a moving trolley  10 , through an engagement mechanism  262 , and into a deflecting element. In certain embodiments, a deflecting element may comprise the terminal brake  50  disclosed in U.S. Pat. No. 6,622,634. In other embodiment, a deflecting element may comprise the terminal brake  50  disclosed in U.S. Pat. No. 6,622,634, minus the weights  60 . In still other embodiments, a deflecting element may comprise the terminal brake  50  disclosed in U.S. Pat. No. 6,622,634, with the weights  60  replaced by light weight interfaces aligning the various springs  58  with respect to one another and the cable  14 . 
         [0138]    In certain embodiments, an engagement mechanism  262  may include a carriage  264  and a capture element  266 . In one embodiment, a capture element  266  may be formed as a ring pivotally suspended from a carriage  264 . A capture element  266  may be positioned to capture or engage the guide  22  of an approaching trolley  10 . In selected embodiments, the extensions  256 ,  258  of a guide  22  may direct the capture element  266  toward the vertex  260  thereof. With additional movement  268  of a trolley  10  toward an engagement mechanism  262 , the capture element  266  may pivot with respect to the carriage  264 . 
         [0139]    In selected embodiments, a capture element  266  may pivot with respect to a carriage  264  about a single point. Accordingly, a capture element  266  may pivot in an arc, lifting  270  one end  16  of a trolley  10  in the process. This lifting  270  may continue until a guide  22  or a portion thereof contacts the engagement mechanism  262 . 
         [0140]    For example, a guide  22  may include a top bumper  272  extending upward therefrom. A top bumper  272  may be positioned to contact an underside of an engagement mechanism  262 . Such contact may define an upper limit for the lifting  270 . Upon reaching this upper limit, a rigid connection between a trolley  10  and an engagement mechanism  262  may be formed and substantially all momentum associated with a trolley  10  may be directed through the engagement mechanism  262  and into a deflecting element in accordance with the present invention. 
         [0141]    The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.