Abstract:
A cable in suspension (clear span) supports a trolley. At the upper end, a launch block fixed to the cable registers the trolley in all directions, including a safety release link holding the trolley near the launch block. After release and descent with a rider, the trolley strikes an attenuator of distributed springs and spacers. The spring stack absorbs momentum from the trolley, but a leash limits recoil “bounce” after reversing the trolley. A second, recoil, leash resists recoil by capturing a subset of the springs between respective ends of itself and the first leash. The doubly leashed trolley will oscillate to a stop in an equilibrium position.

Description:
BACKGROUND 
     1. Field of the Invention 
     This invention relates to amusement rides and, more particularly, to novel systems and methods for cable rides such as zip lines. 
     2. Background Art 
     Zip lines have existed for decades. In its most basic form, a zip line is a cable (wire rope) extending from an upper anchor to which it is fixed to a lower anchor to which a lower end of the cable is fixed. A rider suspends from a pulley traveling along the cable. The pulley may support a user holding on to a simple cross-bar handle, seated in a climbing harness, or seated on some other contrivance, such as a boatswain&#39;s (bo&#39;sun&#39;s) chair or the like. 
     Cable cars and various cable and transporting systems have existed for over a hundred years, many dating to mining technologies of the nineteenth century. Some rely on a rolling pulley connecting a vehicle traveling along a fixed cable. Some rely on a moving cable fixed to a vehicle. Yet others may rely on a cable to pull a vehicle along a track, road, path, or body of water. Meanwhile, various cable-supported chairs and gondolas exist in the ski industry as lifts for skiers, but they operate on a very different principle. 
     Cable rides are problematic in that an uncontrolled descent is dangerous, perhaps even fatal. Meanwhile, hand controlled brakes have been proposed by the inventor in U.S. Pat. No. 7,404,360, issued Jul. 29, 2008, U.S. Pat. No. 7,966,940, issued Jun. 28, 2011, U.S. Pat. No. 8,333,155, issued Dec. 18, 2012, and automatic braking systems as documented in U.S. Pat. No. 7,637,213, issued Dec. 29, 2009, U.S. Pat. No. 6,622,634, issued Sep. 23, 2003, and U.S. Pat. No. 6,666,773, issued Dec. 23, 2003, and retrieval systems in U.S. Pat. No. 7,299,752, issued Nov. 27, 2007, and U.S. Pat. No. 8,240,254, issued Aug. 14, 2012, all of which are hereby incorporated by reference in their entirety. They describe towers, cables suspended between the towers, and various trolleys, braking systems, retrieval systems, and the like. 
     What is needed is a system that will provide safe absorption of the kinetic energy of motion of a rider suspended under a trolley of any particular type. Also needed is a system for minimizing or eliminating recoil. Also needed is a system that will stop and position a user sufficiently gently to cause no injury to the rider, no damage to the system, and not risk leaving a rider spaced an inconvenient distance away from the cable termination point. Thus, what is needed is a system that can reliably stop a rider through an extended distance of space, and yet return the rider to the same predicable unloading station every time. A system is needed to return the rider to a predetermined, preferably consistently identical unloading station, typically at a deck proximate a lower end of a descending cable ride. 
     BRIEF SUMMARY OF THE INVENTION 
     A system in accordance with the invention includes one or more cables suspended between two towers (an upper and a lower). Multiple cables may also be suspended in sequence to form a canopy tour or other multiple-leg route. Typically, a trolley assembled with fasteners and one or more supporting axles will travel downward on a corresponding number of wheels or pulleys along the cable. Any suitable trolley may be handled by the systems, devices, apparatus, and methods described hereinbelow in accordance with the invention. Specifically, each and all of the trolleys disclosed in the documents incorporated hereinabove by reference, are contemplated as serving with at least one embodiment of a recoil attenuation apparatus and method in accordance with the invention. 
     In one embodiment, an apparatus may include a cable having a central axis defining a longitudinal direction and extending therealong between first and second ends and central to a diameter of the cable. The cable, being held in suspension may be a clear span extending unsupported between the first end and the second end, the second end being lower than the first end. A trolley, comprising at least one wheel rollable along the cable may interact with a launch block fixed to the cable proximate the first end. The trolley may include a hanger selectively removable from and securable in at least one hanger slot in the trolley to support a seat and rider below the trolley. 
     The launch block is typically shaped to register the trolley with respect to the cable, in all directions (axially along the cable, and circumferentially, while the cable itself secures both of them together radially). That is, the trolley may be shaped to register with the launch block in two dimensions, and simply be constrained by the cable to register in a third dimension distinct from the first and second dimensions. 
     A link registers the launch block with the trolley in the longitudinal direction at the upper end of the cable. That is, it holds the trolley against or in close proximity to the launch block, which is fixed to the cable. A key extends from at least one of the trolley and the launch block to register the trolley in a circumferential direction orthogonal to the longitudinal direction. Meanwhile, a receiving slot formed in the other of the trolley and the launch block has side surfaces registering with the key to resist relative rotation therebetween about the cable. 
     At the lower end of the cable an attenuator comprising springs arranged along the cable in a first set is arranged along the lower end of the cable. A latch block comprising a latch shaped to capture the trolley upon arrival thereof at or near the latch block is connected to a recoil leash that will restrain movement of the trolley and latch block away from the attenuator once the latch block and trolley engage one another. 
     Spacers, each comprising a spacer mass corresponding thereto and positioned between adjacent ones of the springs are sized and shaped to travel along the cable absorbing momentum from the trolley, at the end of its run down the cable, by at least one of acceleration of the spacer mass thereof and frictional drag with respect to the cable. An impact leash has a fixed end and a movable end, the movable end being connected to constrain the first set of springs against movement away from the second end more than a pre-selected first distance. A recoil leash connects to the latch block to constrain a second set (subset) of the springs to remain between the latch block and the movable end of the impact leash. The second set is typically a “proper subset” (less than all) of the first set. The impact leash and the recoil leash define an equilibrium position of the latch block for receiving the trolley repeatedly and repeatably. 
     The latch block is further provided with a release slot receiving the cable and sized to provide to the latch block a degree of freedom with respect to the cable in a vertical direction. The latch is operable to be removable from engagement with the trolley when the trolley stops stably at an equilibrium position proximate the second end. Thus, the trolley may be moved back up the cable or removed for transport in another way or to another location. Particularly, the “touring” type of trolley is sized and shaped to be readily removable from the cable at the equilibrium position without the use of tools. 
     A seat suspended from the trolley is shaped to support a user below the cable. It may be a climbing harness, fabric chair, rigid chair, or the like. From it, a release may be operable, by at least one of an operator proximate the seat or a rider in the seat, to free the trolley from the launch block. 
     Springs each have a spring constant corresponding thereto and defining a force per unit of deflection. Between springs may be placed spacers, each comprising a spacer mass corresponding thereto. They aborb momentum by virtue of acceleration of their mass. Spring absorb momentum by virtue of acceleration of their mass and compression of their length (spring force according to Hooke&#39;s law). 
     The recoil leash is connected to the latch block to capture the second set (the subset) of the springs to restrain travel of the latch block and trolley in recoil resulting from a tendency to launch the trolley and rider backwards by release of the force of compression among the first set of the springs stopping the trolley and its load. 
     Configured as an amusement ride, one embodiment may include a cable having a central axis defining a longitudinal direction and extending therealong between first and second ends and central to a diameter of the cable being held in suspension as a clear span extending unsupported between the first end and the second end, the second end being lower than the first end. A loading station comprising a space proximate the first end and therebelow and sized for receiving a rider may be matched by an unloading station comprising a space proximate the second end and therebelow and sized for admitting the rider. The trolley is shaped to register with the launch block in two dimensions, and constrained by the cable to register in a third dimension, distinct from and orthogonal to the first and second dimensions. 
     A link secures, and may register, the launch block with the trolley in the longitudinal direction. 
     In certain embodiments, a suspension system shaped to support a rider below the trolley may include a rod sized and shaped to fit between side plates of the trolley when oriented along the direction of the cable. The rod is selectively positionable between a first position oriented longitudinally parallel to the cable and movable up and down between the side plates, a second position transverse to the cable and extending through the window portion of the slot in each of the side plates, and a third position below the second position, with the rod captured by the well portion of the slot in each of the side plates. It is so positionable without the use of tools. Once in the well portion, the rod is pivotable (fore and aft 0  with respect to the side plates during the capture in the well portions. 
     A method of use may include providing an amusement ride comprising a cable having an upper end and a lower end, a trolley operable along the cable and supporting a seat sized to accommodate a rider, a launch block fixed to the cable proximate the upper end, an attenuator comprising springs proximate the lower end, and a latch block leashed to constrain the springs against movement more than a pre-selected distance from the lower end. Engaging, by the trolley, the cable will sustain the trolley thereon. Locking the trolley to the launch block may be done direction or with a link therebetween to fix the trolley to the block which is fixed to the cable. Thus the trolley is stable in all dimensions for loading a rider into the harness suspended therebelow. 
     The ride begins by releasing the trolley to travel from its position at or against the launch block near the upper end of the cable to an attenuator at or near the lower end. Impact of the trolley transfers the momentum of the trolley (with that of its rider) to the attenuator, which compresses springs. As the springs recoil, they transfer back to the trolley a portion of the momentum. The attenuator restrains recoil of the trolley from being flung back due to the recoil of that portion of the momentum. 
     In one embodiment of a method of attenuating recoil of a trolley on a cable, selecting a cable having an upper end proximate a first support and declining toward a lower end proximate a second support is followed by selecting a trolley. The trolley is securable to travel along the cable from proximate the upper end to proximate the lower end where a group of springs or other resilient members are distributed along a portion of the cable. 
     A first leash limits the distance from the second support to a first (first to see trolley impact) resilient member. A second leash does the same for a subset (less than all) of the springs selected in stiffness and number from those closest to the impact location of the trolley. The second leash limits recoil. Also, the first leash limits the entire set of springs (resilient members) from over shooting their initial positions from which they originally limited (absorbed momentum from) the forward motion of the trolley and rider. 
     a spacer, and thus a spring associated with it, is positioned intermediate the first spacer (and its corresponding resilient member) and the second support (e.g., lower tower). Typically, all the resilient members are distributed and separated from each other by spacers positioned between adjacent resilient members. This saves damage, tangling, drooping, buckling, and other failures of operation or materials. 
     In one alternative embodiment a system may include a trolley comprising a frame, at least one wheel positioned to carry the frame along a line suspended between an upper end and lower end thereof, and a first engagement mechanism secured to the frame. A recoil attenuation system comprising spacers and resilient members, each separated from adjacent ones by a spacer. A fixture riding between the trolley and the recoil attenuation system has a latch positioned and shaped to secure the trolley to the recoil attenuation system by selectively securing the engagement mechanism. 
     Recoil attenuation is accomplished by a first leash constraining the spacers against movement away from the lower end more than a pre-determined distance and a second leash constraining motion of the fixture and trolley away from the second end by engaging in compression at least one, but not typically all, of the resilient members. 
     The fixture has a first connector secured against traveling away from the lower end by the first leash. The fixture has a second connector securing the second leash to the midst of the spacers among the springs. the leashes may be threaded through apertures formed through the spacers and sized to receive them therethrough. 
     At or near the initiation or top of the descent path of a trolley along the cable, the trolley may be registered in a launch block and maintained in position by a link, which may have a pin and bail. For example, a snap shackle on a cable link may hold the trolley in close proximity to a launch block such that a key on the trolley or launch block will match and fit into a slot on the other. Thus, the snap shackle and the associated line or link may keep the trolley and the launch block in close enough proximity to maintain the key in the slot to maintain registration (position). Upon pulling a lanyard or handle, a pin in the snap shackle or other such release device may release a bail freeing the trolley from the launch block to roll down the cable. 
     The trolley may include a rider-operable braking system, an automatic braking system, or no braking system at all. Such systems are described in the above identified patent documents incorporated herein by reference. 
     After the trolley descends down the cable from the upper end to the lower end, an attenuator will absorb the kinetic energy of the trolley and rider. In certain embodiments, a latch block may connect to a first spacer or first mass terminating a stack of springs. The springs will be compressed by the kinetic energy of the trolley and rider. In certain embodiments, the latch block is free enough to ride up and down on the cable as well as sliding along it under the influence of the springs, the trolley, or both. 
     For example, a coupler may be formed to be positioned next to a termination spacer or block connected to the extreme uppermost end of a spring stack (stack of springs, typically compression coils, which may be graduated in stiffness). The coupler holds the latch block, but permits the latch block a degree of freedom vertically. Otherwise, the latch block travels with the coupler longitudinally along the cable. 
     As the rider and trolley arrive at the attenuator, the latch block captures a spur on the trolley as the trolley impacts a face of the latch block. Thus, a bumper portion of the trolley may strike the latch block, and the latch block may lift or otherwise move in order to engage a spur or barb on the trolley. Thus, the latch block and trolley are then fixed together with respect to an axial direction along the longitudinal direction of the cable. 
     As the momentum of the trolley and rider continue to compress the stack of springs, the momentum compresses a series of springs, separated by spacers therebetween. Eventually, the spring force overcomes the momentum, acting according to Hooke&#39;s law. That is, the force is equal to the distance traveled multiplied by the spring contact, and acting opposite to the direction of motion. 
     Once the trolley has come to a stop, the springs then begin to recoil, extending away from the lower tower and back upwardly or in the upward direction along the cable. Thus, the trolley and rider are accelerated in reverse of the direction that they traveled down the cable. However, leashes are connected between certain portions of the system. These leashes limit the amount of recoil and counter recoil that may occur. 
     For example, one leash is connected from proximate the lower tower, and extends out to the last or most distant spacer that forms the effectual end cap for the last or most distant spring. That terminal or impact spacer is the first affected by an arriving trolley. The latch block is not secured to that last impact spacer or end spacer. 
     Meanwhile, another leash extends from the latch block, passing through several of the spacers and eventually terminating by securement to one of the spacers that serves as a terminal spacer. We may refer to the impact spacer as the spacer closest to the latch block, and thus the first to feel the impact of the trolley. The recoil spacer is responsible to trap a subset of the springs and compress them against the impact spacer during recoil. Upon initial compression, the springs operate in a normal way, with each of the spacers acting as a friction producing element as well as a mass element absorbing momentum by their own acceleration. 
     During recoil, the springs all begin to expand again toward their original lengths. However, the momentum of the trolley and rider will be reversed from their original impact direction. That momentum backward may (and typically would) launch the rider and trolley out away from the spring stack. To resist this, the recoil leash captures between the recoil spacer and the impact spacer a certain number of intervening springs and spacers, preselected, and engineered as to their dimensions and spring constants. 
     Meanwhile, the impact leash does not permit any of the springs to extend past their initial positions where they were when initially engaged by the trolley. Thus, the impact spacer serves as a stop for the compression of the springs captured between it and the recoil spacer. 
     The recoil spacer is drawn by the momentum of recoil (reversed direction of the trolley) away from the end tower and back in the upper direction along the cable by the momentum of the recoil of the trolley and the rider. However, once again, the momentum of the trolley and rider must eventually be terminated by the continuing deflection of the springs, bringing the rider and the trolley to a stop from the recoil. Thus, the rider and trolley are again accelerated toward the entire spring stack, where they will impact and come to a halt. 
     Eventually, the two spring stacks, the one (full set) running from proximate the tower to the impact terminal spacer and the other (subset) extending between the recoil terminal spacer and the impact terminal spacer, will resist recoil. Eventually, the spring stack must come back to its initial equilibrium position because the impact leash terminates the attenuator at the impact spacer. 
     The rider is thus brought to a halt, at the same predictable location every time. The rider may exit the harness or seat suspended from the trolley. Thereafter, the latch on the latch block may be released to remove the trolley or to permit the trolley to be drawn back to the upper reaches of the cable for another run. 
     Thus, in general, the process begins by setting the trolley at a location on the cable, which may include setting the trolley on the cable. This may include securing the trolley to the cable so that it may not exit or jump off. This may be done previously or may be done subsequently depending on whether the ride is an amusement ride or whether it is a canopy tour where a rider may move a trolley from line to line (cable to cable) along a route. 
     Next, registering the trolley with the launch block involves securing the tongue or key in a slot after which they are shackled together. At this point one may secure the suspension system for the trolley, which may or may not be pre-secured to the trolley. Typically an operator will verify that the rigging is proper before loading or making ready a rider in the harness or seat suspended by the trolley. 
     Releasing the trolley from the launch block permits descending by the rider and the trolley either with a brake operated by the user, an automatic, self-controlling brake, or with no brake. The impacts are first the trolley against the latch and then against a face of the entire latch block. Then, the recoil is followed by again recompressing (to a lesser extent) the spring stack, and possibly additional recoil. 
     Meanwhile, the impact of the latch block against the trolley is matched by the oblique impact of the latch itself (part of the latch block) against a barb or spur on the trolley to latch the two together. 
     The mass and spring response then occurs with the trolley and rider being secured to the spring stacks since they may not separate from the latch block. 
     The system comes to a stop (which is only temporary), followed by recoil which is also temporary. Recoil moves the trolley and rider in the backward direction compared to that in which they were traveling in the descent. Again, counter-recoil then also occurs in conjunction with recoil until both spring stacks (impact or full, and recoil or subset) come to a halt, and the trolley and rider come to a full stop. At this point, unloading the rider and resetting the ride from the beginning or onto another cable may proceed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a side elevation view of one embodiment of a system in accordance with the invention illustrating a launch block, a trolley with a hanger for supporting a rider, a latch block, spacers, and the springs for end-of-ride momentum absorption, all foreshortened onto a single length of cable, notwithstanding it would normally be distributed between an upper end of a cable ride, and a lower or terminal end thereof; 
         FIG. 2  is a perspective view of certain details of a launch block, trolley, and latch block in accordance with the invention 
         FIG. 3  is a side elevation view of one embodiment of a trolley; 
         FIG. 4  is a perspective view of the system of  FIG. 2 , showing installation of one embodiment of a spreader bar for supporting a rider harness or seat, and showing the latch block separated from the trolley, with the coupler separated (exploded view) from its normal position of sliding up and down with respect to the latch block; 
         FIG. 5  is a side elevation view of the apparatus of  FIG. 4 ; 
         FIG. 6  is a perspective view of an alternative embodiment of a rider-controlled-braking trolley connected to a launch block by a gauge link, snap shackle, and so forth, and absent the harness, which would typically suspend from the attachment or bracket rail (frame or lever) toward the left side of the illustration; and 
         FIG. 7  is a schematic block diagram of one embodiment of a process for operating a system in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. 
     Referring to  FIG. 1 , while referring generally to  FIGS. 1 through 7 , an apparatus and method in accordance with the invention may include a system  10  suspended between two towers, one higher than the other, thus providing a declining route along a cable  12 . Typically, fasteners  13  may pull together the components that form a trolley  14 . The trolley  14  supports axles  15 . The actual axles  15  permit rotary motion of any particular type of friction reducing mechanism, whether slides, wheels, pulleys, or the like, including (as shown here) the pulleys  17  or wheels  17 . 
     In the illustrated embodiment, the trolley  14  registers near the upper end of the cable  12  typically near the launch tower or the launch platform that is supported at such a tower or the like. The launch block registers (fixes the position) of the trolley  14  at an upper end of the cable. Typically, the fasteners  13  on the launch block  16  also operate as clamps to hold the launch block  16  in rigid position with respect to the cable  12 . 
     Meanwhile, a latch block  18  is illustrated, but is illustrated next to the trolley  14  with which it will interact. In reality, the trolley  14  is launched from the launch block  16  at the upper end of the cable  12  and is captured by the latch block  18  at the lower end of the cable  12  near the lower tower, supporting tower. Thus, the launch block  16  and latch block  18  may be a quarter mile, a half mile, a mile, or more apart along the cable  12 . 
     The launch block  16  does not move with respect to the cable  12 . The latch block  18  does move with respect to the cable  12 . Meanwhile, the trolley  14  rolls along the cable  12  from the launch block  16  at the upper end of the cable  12  to the latch block  18  at the terminal end of the cable  12 . 
     One may see ports  19  that are basically apertures  19  formed in the trolley  14  in order to be able to see the inner workings thereof. Better seen in other illustrations is the pulley  17  or pulleys  17  that operate as the wheels  17  on the axles  15 . These provide the reduced rolling friction, as opposed to any sliding, along the cable  12  by the trolley  14 . 
     At the terminal end or near the terminal (downhill) tower supporting the cable  12  is situated an attenuator  20 . The attenuator  20  operates to provide both momentum absorption, and attenuation or dissipation of that momentum through several mechanisms including spring compression, spring extension, frictional movement, acceleration of distributed masses of springs, spacers, and other components, and so forth. 
     In the illustrated embodiment, a way  21  is formed in a coupler to receive a slide  23  within the way  21 . The significance of the way  21  and slide  23  is that the coupler  22  is responsible to guide the latch block  18  vertically. The coupler couples to the cable  12  and to a recoil leash that interacts with the system of spacers  24  and springs  25  interconnecting the spacers  24 . The coupler  22  is not connected directly to the springs  25  in the spring stack  27  of the attenuator  20 . 
     One will note that multiple springs  25  are separated from one another by intervening spacers  24 . The spacers  24  serve as masses  24 , and stabilizers  24  for the springs  25 , to assure that the springs do not tangle or damage one another. Spacers  24  also operate as friction producers  24 . 
     For example, each spacer  24  has a preselected weight or mass that will have to be accelerated in order for that particular spacer  24  to move. Similarly, each of the springs  25  has a spring constant, which spring constant will control the resistance of that spring to compression by the incoming momentum of a rider and trolley  14 . 
     Thus, the springs  25  and spacers  24  may be engineered to each have their own specific mechanical properties. For the springs  25 , there is a mass, and a spring constant that will be significant. For each of the spacers  24  there will be a mass, a coefficient of friction against the cable  12  and a connection to adjacent springs  25 . The connection to adjacent springs  25  assures that the springs  25  will not collapse, buckles fall, entangle with one another, or the like, but will stay centered about the cable  12 . 
     Any two spacers  24 , and any two springs  25  may thus be somewhat or entirely distinct from one another. Also, certain groups of each may be distinct from other groups thereof in their outermost diameters, their lengths, their masses, the wire diameter of which a spring  25  is formed, and so forth. In particular, different specific spacers  24  may provide distinct functionality as well. 
     For example, an impact spacer  26  or terminal impact spacer  26  may be the first spacer  24  contacted by the latch block  18  or its coupler  22 , and the first to feel the impact of the trolley  14 . Moreover, the spacer  26  or impact spacer  26  is also connected by a leash  30  to a fixed location near the terminal end or lower tower end of the cable  12 . The leash  30  leashes the impact spacer  26 , thereby maintaining or defining the maximum distance that the impact spacer  26  may move away from the lower tower or the lower end of the cable  12 . 
     In the typical embodiment, the springs  25  will all remain at all times subject to a slight amount of compression. By slight is meant not necessarily enough compression to dramatically effect the stopping of the trolley  14  without considerably more motion. Nevertheless, by maintaining each of the springs  25  in slight compression, the registration distance or length of the leash  30  positions the impact spacer  26  at the same location every time that the trolley  14  arrives. 
     One my also note a recoil spacer  28  or terminal recoil spacer  28 . The recoil spacer  28  is located at the end of another leash  32  or recoil leash  32 . The recoil leash  32 , connects the recoil spacer  28  back to the coupler  22 . The coupler  22  serves to register the latch block  18  along the cable  12 . Nevertheless, the way  21  in the coupler  22  allows the slide  23  of the latch block  18  to slide up and down (vertically, radially with respect to the cable). Accordingly, the latch block  18  my lift up with respect to the cable  12  in order to allow the trolley  14  to impact the latch block  18 . Thereafter, the latch block  18  drops down to capture the trolley  14 . 
     In operation, the momentum of a rider suspended from the trolley  14 , along with the weight of the trolley  14 , will strike the latch block  18 , causing the latch block  18  to first lift up and then settle back into a capture position. Therein, the coupler  22 , latch block  18 , and the trolley  14  are now connected in an axial direction (along the longitudinal direction of the cable  12 ). Axially, they move together in substantially rigid body motion, since they are coupled at least in that longitudinal direction. 
     As the various springs  25  are compressed due to the applied loads, and various spacers  24  are accelerated by absorbing momentum from the rider and trolley  14 , the spacers  26  all move to the right in the illustrated embodiment, as does each of the spacers  24 . When the momentum of the trolley  14  and rider have been completely absorbed, the trolley  14  and rider will come to a stop. 
     Then the springs  25  will all begin to re-expand to their original length, moving the spacers  24  toward the left in the illustrated embodiment. At some point, the trolley  14  and latch block  18  connected together will reach the location where the impact leash  30  stops the impact spacer  26 . Since momentum will not instantly change or will not instantly dissipate, the trolley  14 , rider, and latch block  18  will continue moving with the coupler  22  away (to the left in the illustration) from the impact spacer  26 . 
     This opens up a gap between the impact spacer  26  and the coupler  22 . However, the leash  32 , which is the recoil leash  32 , now begins to compress all of the springs  25  captured between the recoil spacer  28  (in the stack on the right) and the impact spacer  26  (on the left). Thus, a subset of the entire stack  27  is now being compressed by the recoil momentum of the trolley  14  and rider. This compression occurs because backward moment of the trolley  14 , latch block  18 , and rider are drawing the recoil spacer  28  toward the now fixed (by the impact leash  30 ) impact spacer  26 . This compresses any intervening springs therebetween. 
     One may see how the subset of springs  25  captured by the recoil spacer  28  will eventually bring the trolley  14  and rider to a stop some distance away from the impact spacer  26 . At that time, the trolley  15 , latch block  18 , and rider will come to a standstill with respect to the cable  12  for a moment before they all commence to return toward the impact spacer  26  again. 
     Arriving at the impact spacer  26 , the components and rider again compress the springs  25 , move the spacers  24 , and otherwise transfer momentum. One may see that the acceleration of the spacers  24  and springs  25 , and the forces applied by the springs  25 , resist the trolley  14  approaching the lower end of the cable  12 . The springs  25  push the trolley  14  and rider back in recoil. Then the subset of springs  25  draws the trolley again toward the impact spacer  26  and the lower end of the cable  12 . 
     Springs  25  may be advantageously made of metal in order to minimize their mass and consequent momentum. Typically, helical compression springs  25  have been found effective. However, other shapes may be selected, engineered, or otherwise employed, including blocks, tubes, cages, grids, plates, disks, and so forth. Likewise, any resilient material including polymers such as elastomeric polymers can serve as material for springs  25 , regardless of shapes of these spring elements  25 . For example springs  25  may be foamed, solid, or shaped (e.g., helical, oblate, polygonal, spherical, disk, cylinder, dished Bellville disks, hollow, filled, or the like, and so forth) in order to optimize their spring constants, masses, momentum transfer, energy absorption, and so forth. 
     For example, in certain embodiments, a spring may be an elastomeric foam ball, elastomeric foam egg, an elastomeric foam cylinder, polymeric Bellville washer/spring, plastic helical spring, “rubber” (any elastomeric material) block as a solid, matrix, foam, or the like. The selection of material may be based on absorption of energy, elastic and inelastic recovery, mass per unit length, total mass, and the like. Thus, mass, momentum, energy, elastic modulus, restitution (fraction of energy or momentum recovered on recoil), and other mechanical parameters may weigh in the decision. 
     The energy loss due to the force of cable friction of the various components, notably the spacers  24  and the latch block  18 , will result in an eventual total attenuation of the momentum originally introduced by the trolley  14  and rider. Thus, at that time and at that point in space, each of the leashes  30 ,  32  will typically be fully extended to establish the maximum lengths, thus positioning the coupler  22  next to the impact spacer  26 . 
     The actual locations of connections, the total lengths, and the enclosed number of springs  25  within the length of each leash  30 ,  32  may be engineered to obtain a desired performance. For example, stiffer springs  25  (higher spring constant) will result in a faster, more abrupt, more intense, braking and recoil force. Fewer enclosed springs  25  (captured by a leash  30 ,  32 ) may result in a softer response, but may risk “bottoming out” (fully collapsing) the springs  25  enclosed thereby. More springs  25  having a comparatively lower spring constant provide a longer and more gentle stop, with more intermediate spacers  24  absorbing momentum, for a more sluggish response to any loading (application of force; force is also mass times acceleration). This means a softer, slower acceleration and deceleration in both braking and recoil directions. 
     Moreover, as a general proposition, the number and location of “grouped” springs  25  captured by each leash  30 ,  32  is a matter of engineering design. Considerations may include and a certain amount of “rider preference” as to softness of the “stops” forward and backward. Likewise, other considerations are economical, such as optimizing throughput design, the speed of loading riders in and bringing riders off the ride. It is even conceivable to have separate stacks of springs  25  for a braking stage and a recoil stage, but that “complexifies” structures, and may even require parallel systems. The simplest arrangement is with a braking set of springs  25 , and recoil subset of springs  25 , all in series. 
     The trolley  14  and rider are both ultimately registered at the unloading station or unloading location. This occurs when the springs  25  and their capturing leashes  30 ,  32  come to equilibrium. Typically, this will be above a deck onto which the rider may step when released from the harness, seat, or other support system suspended from the trolley  14 . 
     At the upper end of the cable  12  a rider begins a descent from a position of registration of the trolley  14  with the launch block  16 . In the illustrated embodiment, a key  34  may be formed as part of the launch block  16  or the trolley  14 . In the illustrated embodiment, the key  34  happens to be connected as part of the trolley  14 . Accordingly, a slot  36  in the launch block  16  receives the key  34 , thus registering the trolley  14  against rotation about the cable  12 . Since the launch block  16  is fixed with respect to the cable  12 , the registration in an axial direction and a circumferential direction about the cable  12  is effected by the key  34  in the slot  36 . In some embodiments, a lock may secure the key  34  in the slot  36 . 
     Meanwhile, a slot  38  may alternatively be formed in the latch block  18 . Because the latch block  18  may need to rise with respect to the cable  12  in order to receive the trolley  14 , a long oval or elongated circular hole may provide a slot  38  for accommodating vertical motion by the latch block  18 . 
     Meanwhile, a rod  40  or hanger  40  may be secured into, or as part of, the trolley  14 . In the illustrated embodiment, side plates  39  of the trolley  14  may capture between them other structures secured by the fasteners  13  and axles  15 . However, near the bottom of the plates  39  may be positioned a gap between the side plates  39 . The side plates  39  may be perforated to form a window portion  41  of a slot  42 , and a well portion  43  below the window portion  41 . Thus, the slot  42  may be shaped as a “T” or as an “L.” Thus, the well  43  may be formed as the toe of the “T” or as the toe of the “L.” The rod  40  or hanger  40  may be secured to or be formed as part of a spreader bar  44 . 
     The rod may be turned such that it will slide upward between the side plates  39  until it is beside the window  41  or visible in the window  41  of each of the side plates  39 . At that point, the rod  40  may be rotated end for end by about 90 degrees. Thus, the rod  40  then may extend out through the windows  41  in the side plates  39 . A relief groove near each end of the rod  40  may then match the thicknesses of the side plates  39 , in order to capture the rod  40  as it slides down into the well portion  43  of the slot  42 . 
     At this point, the rod  40  becomes a pivot  40  by which the spreader bar  44  may be supported. Meanwhile, carabiners  46  may be inserted into the slot  42  in order to occupy the window  41  of the slot  42 . This prevents the rod  40  from jumping out of the well portion  43  of the slot  42 . In certain embodiments, a single carabiner  46  may suffice. In other embodiments, multiple carabiners  46  may be necessary. 
     Referring to  FIGS. 2 through 5 , while continuing to refer generally to  FIGS. 1 through 7 , the various components described hereinabove are illustrated in various embodiments. The trolley  14  may be provided with a bumper  48  or a bumper portion  48  that will collide or otherwise contact the face  49  of the latch block  18 . As the latch block  18  approaches the trolley  14 , the latch block  18  is riding (supported but slidable) the cable  12 . 
     The encounter between the latch  50  (of the latch block  18  contacting the trolley  14 ), and a spur  52  or barb  52  may force the latch  50  to rise, thus lifting the latch block  18  with respect to the cable  12 . Since the slot  38  in the latch block  18  is elongated, the vertical motion of the latch  50  is permitted. Thus, the latch  50  may tend to pitch  50  or lift  50 , and the slide  23  will assure that the latch block  18  lifts vertically through the ways  21  of the coupler  22 . 
     Thereafter, the sequence of momentum transfers between the trolley  14  and rider connected to the latch block  18  as they contact the impact spacer  26  will proceed as described hereinabove. 
     Referring to  FIG. 6 , while continuing to refer generally to  FIGS. 1 through 7 , at the launch block  16 , a trolley  14  may be registered by the key  34  in a slot  36 . However, this provides rotational stability or rotary stability with respect to the cable  12 . In the illustration of  FIG. 6 , the trolley  14  is of the rider-controlled brake type. As described in the references incorporated herein and by reference, a rider suspended from the trolley  14  may control the brake during descent. By contrast, the trolley  14  of  FIGS. 1 through 5  need not involve any braking except the terminal attenuation of momentum at the bottom end of the ride. 
     Referring to  FIG. 6 , a gauge link  54 , or simply a link  54  of pre-selected length, may connect the launch block  16  to the trolley  14 . The gauge link may include a line  56  or a line portion  56 , formed of a material, such as wire rope, cable, chain, or the like. The line  56  establishes the registration distance between the launch block  16  and the trolley  14 . A release pin  58  may be used, but serves particularly well if used to release the bail  58  of a snap shackle  60 . 
     A snap shackle  60  has the ability to hold a load, while transferring a very small fraction of that load (force) to the release pin  58 . Less load results in little or no binding (distortion, friction, etc.) of the pin. Thus, the snap shackle  60  holds a much larger load than is supported by the pin, due to the shape of the bail, which provides great leverage for the pin  58 . 
     During loading of a user supported by the trolley  14 , the gauge link  54  maintains the distance, and assures the safety of the system  10 . For example, the length of the gauge link  54  is selected to provide a precise fit, notwithstanding it may include a satisfactory tolerance allowing it to be easily connected to the trolley  14 . However, the length is selected to limit how far the trolley and its key  34  can move from the launch block. The length assures that the key  34  remains in the slot  36 , at which position the key  34  in the slot  36  of the launch block  16  resists rotation of the trolley  14  with respect to the cable  12 . The launch block  16 , secured to the cable  12  resists movement up the cable  12 , as does gravity. 
     Thus, the link  54 , including the line  56 , any attachment brackets, loops or the like, and connectors, such as the snap shackle  60 , acts as a gauge link  54  maintaining proximity of the trolley  14  to the launch block  16 . Moreover, the bail  58  has a thickness designed to fit between the head of its connector post on the trolley and the swing arm  69  locking the trolley  14  onto the cable  12 . One will note that the front pulley  17  in the illustrated embodiment is locked against jumping from or otherwise leaving the cable  12 . It is locked on by the swing arm  69  pivoted about the axle of the pulley  17  and engaging the latch bolt  55  on the trolley. This closes the load path as a carabiner does. 
     The snap shackle  60  secures by its bail  59  to the connector post  57 . If the connector post  57  is not sufficiently close to the launch block  16 , the snap shackle  60  cannot engage it. Thus, the snap shackle  60  as part of the gauge link  54  assures that the swing arm  69  is in place to lock the trolley  14  onto the cable. 
     Likewise, the rear pulley  17  or wheel  17  secures to the cable  12  by a **** 67  passing down parallel to the side plates  39  through a slot therewithin to protrude below. A carabiner  48  secures the slide  67  in place, assuring that the rear pulley  17  is secured to the cable  12 . Thus, securement is assured, loads are all secured, and a visual inspection verifies the readiness at a glance. Meanwhile, the foregoing features act as mechanical interlocks assuring safety of the equipment and readiness for use. 
     Once the rider is installed in the harness suspended from the trolley  14 , an operator or the rider may pull a lanyard, ring, chain, or the like and move a pin  58 , releasing a bail  59  in a snap shackle  60 . The bail  59  pivots with respect to the main structure of the snap shackle  60 , releasing its load, and releasing the trolley  14  to proceed downhill. 
     The snap shackle  60  is uniquely suited to support a load, such as the weight of a rider or the vector of rider and trolley weight along the direction of the cable  12 . However, the snap shackle  60  is configured such that it is capable of releasing its load, without undue binding. Thus, the shape of the bail  59  operates to easily sustain the load, and yet move, once free, and release without restraint the trolley  14  in due course. 
     A rider is thus released from the launch block  16 , leaving the gauge link  54  behind for the next rider. In  FIGS. 1 through 5 , the trolley  14  needs no brake.  FIG. 6  uses a rider-controlled brake. For example, by operating (pulling down on a handle of) a tether  62 , having a handle that will permit the rider to draw down the tether  62 . Thereby, the bracket  64  from which a rider is suspended will be moved closer toward the rear of the trolley  14 . This decreases the leverage that the rider&#39;s weight exerts on the lever  68  that is the rail  68  or frame  68  of the trolley  14 . 
     Meanwhile, the attachment  66  for a harness permits a rider to reduce force or even release the tether  62 . At that event, the bracket  64  will roll forward (left) thus increasing the leverage that the rider&#39;s weight has on a brake pad riding against the cable  12  and captured within the side plates  39  of the trolley  14 . 
     Referring to  FIG. 7 , a process for implementing an apparatus and method in accordance with the invention may include a procedure  70  or a process  70  that begins with a cable  12  in place between supporting towers. Typically, an entirely free span or catenary will be formed by the cable suspended from two suitable towers. The towers stand at significantly different elevations, thus providing a downhill or downward run of a trolley  14  along the cable  12 . 
     In the process  70 , setting  72  the trolley  14  may involve only returning a trolley  14  to the launch block  16 , or, alternatively, actually placing a trolley  14  on the cable  12 . 
     For example, in the embodiment of  FIG. 6 , the arm  69  may be rotated about its upper connection to free it from its lower connection and thus free it from its constraint to follow the cable  12 . Similarly, by removing the carabiner  46  of  FIG. 6 , the slide  67  may be withdrawn, thereby removing its wheel  17 . The trolley  14  may be removed from a cable  12  by rotating the arm  69 , thus exposing the cable  12 . Similarly, the slide  67  may be removed by drawing it upward. Thus removing the cable  12  from inside the trolley  14  permits the trolley  14  to remove from the cable  12 . 
     Setting the trolley  14  on the cable  12  may be done by opening up (rotating) the arm  69  (with the trolley  14  configured without the slide  67  and its corresponding wheels  17  in place). The trolley  14  may be placed with a single front wheel  17  associated with the arm  69  on the cable  12 . Thereafter, the slide  67  may be dropped into the trolley  14  and secured with a carabiner  46  to secure its respective wheel  17  to the cable  12 . In this embodiment, a brake shoe rides underneath and against the cable  12 , supported by the back end of the trolley  14 , between the sides of the slides  67 . 
     Setting  72  the trolley  14  by removal and replacement may be appropriate if the trolley  14  is readily removable, or is to be transported with the user who is traversing various legs of a canopy tour or the like. Otherwise, the trolley  14  may simply be set into place. 
     Securing  74  the embodiment of  FIG. 6  may involve closing the arm  69  and locking the slide  67  with the carabiner  46 . In the embodiment of  FIGS. 1 through 5 , the trolley  14  may be permanently attached, or may simply be removed upward once the spreader bar  44  and its locking rod  40  have been removed from the slot  42 . Thus, the side plates  39  may simply permit access to the cable  12  by the trolley  14  from underneath the trolley  14 . 
     Upon securing the trolley  74 , one may register  76  the trolley  14  with the launch block  16  by placing the key  34  in the slot  36 . One may then connect the snap shackle  60  of the gauge link  54  in order to secure the trolley  14  against rolling downhill away from the launch block  16  fixed to the cable  12 . This increases safety in loading and frees up hands and personnel for the task. 
     Securing  80  the suspension operates in different ways. For example, a harness may be attached to the connector  66  suspended by the bracket  64  from the lever  68  of the trolley  14  in  FIG. 6 . In contrast, the spreader bar  44  with its attached harness  66  may be locked into the slot  42  as described hereinabove. Ultimately, an operator should verify  82  the rigging to be assured that the wheels  17  are properly fitted onto the cable  12 , harnesses or seats are properly attached an open, that all securements such as the carabiners  46 , and side plates  39  are properly in place, and so forth. 
     At this point one may load  84  or ready a rider in a harness suspended from the trolley  14 , including re-checking rigging. Releasing  86  the snap shackle  60  or other suitable device  60  may be done once the rider is secured in the harness and comfortable that he or she is ready for a ride. Descending  88  occurs in different modes depending on the type of trolley  14  involved. For example, those trolleys  14  without a brake will simply come to some terminal velocity dictated by air drag and rolling friction. 
     Others such as the tour trolley  14  of  FIG. 6  will be controlled by application of the weight of a user to the lever  68  through the bracket  64  from which the user is suspended. In this way, the user pulling on the tether  62  may reduce the braking by pulling the bracket  64  (and thus the effective weight of the user) closer to the point of pivoting. This is described in great detail in the patents incorporated herein by reference. Likewise, those patents also describe in detail automatic braking mechanisms on a trolley  14  traveling down the cable  12 . 
     Ultimately, impacts occur between first the trolley  14  and the latch  50  of the latch block  18 . This is followed by impact of the bumper  48  of the trolley  14  against the face  49  of the latch block  18 . Promptly thereafter, the coupler  22  driven by the latch block  18  and the momentum of a rider suspended from the trolley  14  will impact the impact spacer  26 , if they are not already in contact. 
     The latch  50  will latch  92  onto the spur  52  of the trolley  14 , thus locking or latching  92  them together. Thus, the relative motion in the axial direction (along the cable  12 ) is extremely limited (approximately fixed, axially) between the trolley  14 , the latch block  18 , and the coupler  22 . 
     The response  94  of the spring stack  27 , including each of the spacers  24  and springs  25 , will occur in response to the momentum of the trolley  14  and rider imposed thereon. Ultimately, between the acceleration of the masses of the spacers  24  and springs  25 , and the elastic deflection (compression) of the springs  25 , all the momentum from the trolley  14  and latch block  18  in the downward direction along the cable  12  will be transferred into the spring stack  27 . The resulting stop  96  will be temporary, even momentary. 
     Thereafter, recoil  98  proceeds as the spring stack  27  begins to expand, reversing the direction of the trolley  14  and rider, and pushing them away from the lower end of the cable  12  and its lower suspension tower. Counter-recoil will occur as described hereinabove. The recoil leash  32  that compressed all the springs between the recoil spacer  28  and the impact spacer  26  during recoil will draw the trolley  14  toward the impact spacer again. Thus, momentum will continue to transfer as the entire spring stack  27 , and then the subset thereof located between the impact spacer  26  and the recoil spacer  28  continue to urge the trolley  14  to the equilibrium position. Properly sized and loaded, the spring stack will be at equilibrium at full extension of the impact leash  30 , and in most, typical circumstances, full extension of the recoil leash  32 . 
     Ultimately after cycling through recoil  98  and counter recoil  100 , the trolley  14  comes to a stop  102  after which unloading  104  may be safely done. Optionally, unloading  104  may involve resetting the trolley  14  or moving it to be set  72  on another cable  12 . 
     The present invention may be embodied in other specific forms without departing from its purposes, functions, structures, or operational 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.