CA2984689C - Zipline trolley release and speed limiter - Google Patents

Abstract

A zipline system and components for the system. The system includes a trolley holder/launcher having an operator manipulable actuating arm requiring sequential linear movement and pivotal movement in order to launch the trolley. The system also includes a trolley with eddy current speed limiting provided by rare-earth magnets and enhanced- conductor sheaves.

Description

Y \ KDI01\5279 CA CIPONFtplernt 0esc171101.6pd ZIPLINE TROLLEY RELEASE AND SPEED LIMITER
Cross Reference to Related Application [0001] This application claims the benefit of US Provisional Patent Application No.
62/170,387, filed 3 June 2015.
Technical Field

[0002] The present invention relates to the field of ziplines. More particularly, the invention relates to holders and launching devices, and speed-limiting devices, for zipline trolleys.
Background Art

[0003] In simple terms, a zipline involves a suspended inclined cable and a sheave assembly free to move along the length of the cable. In most ziplines, the user is supported by a seat or harness that is secured to the sheave assembly.
Propelled by gravity, the user rides from the upper end of the cable towards the lower end of the cable.

[0004] In its simplest form, the sheave assembly may be a pulley with a single sheave. However, it is common for the sheave assembly to be a trolley with two or more sheaves, as multiple sheaves distribute the load over more than one spot on the cable (thus reducing cable bending stresses that may lead to metal fatigue and cable breakage).

[0005] Zipline cables can be very high, generally starting at a height of over 9 m (30 ft) and in some cases much higher, and traveling well over 460 m (1,510 ft). A
pivoting link, such as a carabiner, is used to secure the load to the trolley. Load carriers include enclosed cabins and gondolas, but more commonly the load carrier is a single-person harness or seat. It is of course very important to ensure that the rider is properly secured in the harness or seat before they are launch down the zipline cable.

[0006] The maximum velocity attained by a zipline rider and the rider's end velocity (i.e., the rider's velocity at the lower end of the cable), depend on a variety of factors, including the average incline (i.e., the rise over the run; that is, the difference in height between the cable upper end and the cable lower end, divided by the horizontal distance between the cable upper end and the cable lower end); and the cable tension.
As the cable ends are at different heights, an installed zipline cable assumes a skewed catenary curve under the force of gravity, such that the greatest downward incline (and thus greatest acceleration) is in the vicinity of the upper end of the cable, and the lower end of the cable has at least some upward incline (and thus at least some decelerating effect).
Thus, in some circumstances, to a certain extent, zipline velocity may be "tuned" by adjusting the cable tension, as, all other things being equal, higher tension produces lower initial acceleration and lower terminal deceleration.

[0007] However, "tuning" zipline velocity by adjusting cable tension is usually not completely effective in terms of producing a consistent desirable rider maximum velocity and end velocity. In many installations, cable tension is constrained by the terrain, for example a desired sag in terms of end velocity may bring the cable within an unsafe proximity to the ground, trees etc.. Further, the rider's weight affects velocity. It is understood that heavier rider's achieve higher velocities than lighter riders because force (mass times acceleration) increases more with rider weight than rider wind resistance (and any other weight-dependent decelerators, e.g., sheave friction etc.). As well, the rider's weight distorts the cable curve, such that, put simply, at the start of a zipline ride, the cable slope (and thus acceleration) is greater for a heavier person than for a lighter person. As well, the wind direction (e.g., tail wind or head wind) and strength affect velocity.

[0008] Various means of slowing and stopping a zipline rider have been used, including: thick purpose-built leather gloves; a mat or netting at the lower end of the incline; a passive arrester system composed of springs, pulleys, counterweights, bungee cord, tire or other devices, which slows and then stops the trolley's motion;
a "capture block" which is a block on the cable that is actuated by a rope held by an operator who can manually apply friction to slow a zipline rider; and rider-operated hand brakes.

[0009] US 8,336,463, Smith, ZIPLINE TROLLEY SYSTEM, 25 December 2012, discloses a trolley configured to engage with: a launcher fixed to the upper end of the cable, that in use is reversably pivoted roughly 90 degrees about the cable to secure and then launch the trolley; and a catch block fixed to the lower end of the cable, for catching and releasably securing the trolley.

Disclosure of Invention

[0010] In one aspect, the present invention provides a zipline system including a trolley holder/launcher and a speed-limited trolley intended to increase operational safety.

[0011] The trolley holder/launcher has a manipulable actuator requiring two distinct sequential movements by the operator in order to launch a trolley. In a preferred embodiment, the first movement is a linear movement of a hand grip to change the actuator from a locked to an unlocked position and the second movement is a pivotal movement of the grip to change the actuator from an engagement position to a disengaged position. The actuator includes a spring that resiliently biases the hand grip to maintain the actuator in the locked position and preferably includes a spring that resiliently biases the hand grip to maintain the actuator in the engagement position.

[0012] The speed-limited trolley includes eddy current speed limiting. Eddy current speed limiting occurs when a conductor is moved past (i.e., through) a magnetic field, producing a current in the conductor that in turn produces a magnetic field that resists the motion of the conductor. This resistive force is proportional to the speed at which the conductor moves past the magnet. Eddy current braking results in some by-product heat in the conductor because of the current flowing therein.

[0013] The speed-limited trolley embodiments of the present invention provide eddy current speed limiting through the interaction of rare-earth magnets and enhanced-conductor sheaves. Enhanced-conductor sheave embodiments have sheave sides having conductive material of a greater diameter and/or greater thickness, as compared to conventional sheaves. The conductive material (i.e., the conductor part of the eddy current speed limiter) is non-ferromagnetic. Suitable non-ferromagnetic conductor materials include aluminum containing metals and copper containing metals (e.g., copper and brass). Gold and silver containing metals would presumably also be suitable from a performance perspective but likely not from a cost perspective.

[0014] In preferred embodiments, the rare-earth magnets are mounted to the trolley side plates.

[0015] The positioning of the magnets relative to the sheave sides of the enhanced-conductor sheaves affects the speed-limiting effect. The inventor understands that in terms of magnet position and speed-limiting effect, the two most significant factors are:
the radial distance between the axis of rotation of the enhanced-conductor sheave and a magnet (which can also be thought of in terms of the radial distance between the magnet and the circumferential periphery of an enhanced-conductor disc portion of the sheave sides), and the proximity of the magnet to the sheave side (i.e., the gap between the magnet and the surface of the enhanced-conductor disc portion of the sheave side).
Increasing the radial distance between the axis of rotation of the enhanced-conductor sheave and a magnet, increases the speed-limiting effect of the magnet (so long as the magnet remains within the circumferential periphery of the enhanced-conductor disc portion of the sheave sides). Decreasing the gap between the magnet and the surface of the enhanced-conductor disc portion of the sheave side increases the speed-limiting effect of the magnet.

[0016] The number of magnets also affects the speed-limiting effect; in that, all other things being equal (e.g., magnet positioning and magnet strength), increasing the number of magnets increases the speed-limiting effect. However, adding magnets does not increase the speed-limiting effect in a linear manner. Although, two or more installed similar magnets will in use each induce a similar speed-limiting effect, to understand why speed limiting does not increase in a linear manner, it is useful to imagine a situation in which magnets are being added. The eddy current speed-limiting effect is proportional to the speed at which the conductor moves past the magnet(s). Thus, once one or more magnets are installed, they will have reduced the speed at which the conductor moves past the magnets. Thus, the maximum speed-limiting effect of each additional magnet will be reduced due to the reduction in maximum speed resulting from the magnets already in place. As a result, merely increasing the number of magnets results in diminishing returns in terms of speed-limiting effect.

[0017] In embodiments in which two or more magnets are mounted in proximity to each sheave side, it has been found that the spacing of the magnets relative to each other affects the speed-limiting effect. Spacing adjacent magnets apart by a distance no smaller than the magnets' diameter is desirable. In a preferred embodiments, adjacent magnets are spaced apart a distance equal to the magnets' diameter.

[0018] In embodiments in which two or more magnets are mounted in proximity to each sheave side and the magnets are spaced apart, one from the other, a distance equal to the magnets' diameter, the inventor has not found any appreciable difference in the speed limiting effect between magnets oriented to have the same polarity and magnets oriented to have opposite polarities. It is speculated that orienting adjacent to magnets to have opposite polarities could affect the speed limiting effect if the spacing of the magnets were different.

[0019] Magnet strength also affects the speed-limiting effect. However, it is understood that within the range of magnet strengths in the commercially readily available rare-earth magnets that are suitable in terms of their size for use in a zipline trolley, as a practical design consideration, magnet strength is less significant than magnet positioning.

[0020] In one aspect, the present invention provides devices for use with a zipline cable, the devices including: a speed-limiting zipline trolley comprising: two trolley sides in a spaced apart relationship; and one or more sheaves, each interposed between, and rotatably mounted to, the trolley sides and each sheave defining a sheave axis of rotation;
wherein the trolley sides comprise a plate eddy current speed-limiting component and at least one of the sheaves comprises a sheave eddy current speed-limiting component; and whereby, in use, the plate eddy current speed-limiting component and the sheave eddy current speed-limiting component interact to produce eddy current speed limiting.

[0021] The plate eddy current speed-limiting component may be a magnetic field source and the sheave eddy current speed-limiting component may be a conductor.

[0022] The at least one of the sheaves comprising the sheave eddy current speed-limiting component, may have a sheave side and the conductor may be a disc of conductive material at the sheave side; and the magnetic field source may include one or more magnets mounted in one of the trolley sides proximate to the disc of conductive material.

[0023] The at least one of the sheaves comprising the sheave eddy current speed-limiting component, may have two sheave sides and the conductor may be two discs of conductive material, wherein:one of the discs of conductive material may be at one of the sheave sides; and the other of the discs of conductive material may be at the other of the sheave sides; and the magnetic field source may include two magnet sets for each sheave, each magnet set including one or more magnets, wherein one of the magnet sets may be mounted in one of the trolley sides at a location proximate to one of the discs of conductive material; and the other of the magnet sets may be mounted in the other of the trolley sides at a location proximate to the other of the discs of conductive material.

[0024] Each disc of conductive material may be: an aluminum-containing disc integral to the sheave; a copper-containing disc affixed to the sheave; or an aluminum-containing disc affixed to the sheave.

[0025] Each disc of conductive material may be a circular disc having a planar surface and defining a disc circle substantially concentric with the sheave axis of rotation and defining a disc circle circumference; and for each magnet of each magnet set, the location proximate to the one of the discs of conductive material may be: at a distance from the planar surface no greater than about 1/16"; and within the disc circle circumference and at a distance from the disc circle circumference no greater than about 1/8". For each magnet of each magnet set, the location proximate to the one of the discs of conductive material may be: at a distance from the planar surface no greater than about 1/32"; and at a distance from the disc circle circumference no greater than about 1/16".

[0026] Each magnet may be a cylindrical neodymium rare-earth magnet. Each magnet may be a 3/4" by 1/4" magnet or a 3/4" by 5/16" magnet. Each magnet set may include three magnets and each magnet may be a cylindrical neodymium rare-earth magnet.

[0027] The at least one of the sheaves comprising the sheave eddy current speed-limiting component, may be two sheaves; each disc of conductive material may be a circular disc having a planar surface and defining a disc circle substantially concentric with the sheave axis of rotation and defining a disc circle circumference; and for each magnet of each magnet set, the location proximate to the one of the discs of conductive material may be: at a distance from the planar surface no greater than about 1/16"; and within the disc circle circumference and at a distance from the disc circle circumference no greater than about 1/8".

[0028] Each magnet set may include three magnets; each magnet may be a cylindrical neodymium rare-earth 3/4" by 5/16" magnet; each disc circle may have a diameter of about 4"; and for each magnet of each magnet set, the location proximate to the one of the discs of conductive material may be: at a distance from the planar surface no greater than about 1/32"; and within the disc circle circumference and at a distance from the disc circle circumference no greater than about 1/16".

[0029] Each magnet set may include one magnet; each magnet may be a cylindrical neodymium rare-earth 3/4" by 1/4" magnet; each disc circle may have a diameter of about 3"; and for each magnet of each magnet set, the location proximate to the one of the discs of conductive material may be: at a distance from the planar surface no greater than about 1/32"; and within the disc circle circumference and at a distance from the disc circle circumference no greater than about 1/8".

[0030] The devices may include a trolley holder device, including: fixing means for fixing the trolley holder device relative to a zipline cable; an actuating arm having: a bar, pivotally mounted to the fixing means for pivotal movement between an engagement position and a disengaged position, and the bar having a latch for engaging the trolley so as to impede movement of the trolley away from the trolley holder device when the bar is in the engagement position; and a grip, slidably engaged with the bar so as to be linearly manipulable between: a locked engagement position in which the grip abuts the fixing means so as to impede pivotal movement of the bar from the engagement position and an unlocked position in which pivotal movement of the bar from the engagement position is not impeded by abutment between the grip and the fixing means; and a lock biasing means for resiliently biasing the grip in the locked engagement position;
whereby, when the latch is engaged with the trolley and the grip is in the locked engagement position, disengaging the latch from the trolley requires sequential linear movement of the grip from the locked engagement position to the unlocked position and pivotal movement of the bar from the engagement position to the disengaged position.

[0031] The trolley holder may include a pivot biasing means for resiliently biasing the bar in the engagement position. The lock biasing means may be a first spring interposed between the bar and the grip; and the pivot biasing means may be a second spring interposed between the bar and the fixing means.

[0032] The trolley may include a tooth receptacle having an inner catch;
and the latch may include a tooth that fits within the tooth receptacle when the latch is engaged with the trolley, whereby the impeding of movement of the trolley away from the trolley holder device is provided by abutment between the tooth and the tooth receptacle inner catch.

[0033] In another aspect, the present invention provides a trolley holder for use in releasably holding a zipline trolley in a zipline installation including a zipline cable, the trolley holder including: fixing means for fixing the trolley holder relative to the zipline cable; an actuating arm having: a bar, pivotally mounted to the fixing means for pivotal movement between an engagement position and a disengaged position, and the bar having a latch for engaging a zipline trolley so as to impede movement of the trolley away from the trolley holder when the bar is in the engagement position; and a grip, slidably engaged with the bar so as to be linearly manipulable between: a locked engagement position in which the grip abuts the fixing means so as to impede pivotal movement of the bar from the engagement position and an unlocked position in which pivotal movement of the bar from the engagement position is not impeded by abutment between the grip and the fixing means; and a lock biasing means for resiliently biasing the grip in the locked engagement position; whereby, when the latch is engaged with the trolley and the grip is in the locked engagement position, disengaging the latch from the trolley requires sequential linear movement of the grip from the locked engagement position to the unlocked position and pivotal movement of the bar from the engagement position to the disengaged position.

[0034] The trolley holder may include a pivot biasing means for resiliently biasing the bar in the engagement position. The trolley may include a tooth receptacle having an inner catch; and the latch may include a tooth that fits within the tooth receptacle when the latch is engaged with the trolley, whereby the impeding of movement of the trolley away from the trolley holder device is provided by abutment between the tooth and the tooth receptacle inner catch.
Brief Description of Drawings

[0035] Fig. 1 is a side elevation partially transparent view of a zipline cable, a conventional zipline trolley (with two spreader-bar lanyards), and a trolley holder embodiment of the present invention, shown with the trolley holder in the locked position and engaged with the trolley.

[0036] Fig. 2 is a side elevation view of the cable, trolley and trolley holder embodiment of Figure 1, shown with the trolley holder in the release position and disengaged from the trolley.

[0037] Fig. 3 is side elevation exploded view of the actuating arm of the trolley holder embodiment shown in Fig. 1 and Fig. 2.

[0038] Fig. 4 is a side elevation view of a conventional trolley sheave.

[0039] Fig. 5 is sectional view of the conventional trolley sheave shown in Fig. 4.

[0040] Fig. 6 is a sectional view of a trolley sheave with a small brake disc attached on each side.

[0041] Fig. 7 is a side elevation view of one of the small brake discs of Fig. 6.

[0042] Fig. 8 is a side elevation partially transparent view of a zipline cable and a four-magnet small-brake-disc speed-limiter trolley (with two spreader-bar lanyards) embodiment of the present invention.

[0043] Fig. 9 is an end elevation partially transparent view of a trolley showing the spreader bar.

[0044] Fig. 10 is a side elevation transparent view of a large-brake-disc sheave embodiment of the present invention.

[0045] Fig. Ills a sectional view the large-brake-disc sheave embodiment of Fig.
10.

[0046] Fig. 12 is a side elevation view of an integral-brake-disc sheave embodiment of the present invention.

[0047] Fig. 13 is a sectional view of the integral-brake-disc sheave embodiment shown in Fig. 12.

[0048] Fig. 14 is a side elevation view of a zipline cable and a twelve-magnet speed-limiter trolley (with two spreader-bar lines) embodiment of the present invention.

[0049] Fig. 15 is a side elevation view of one of the three magnet retainers of the twelve-magnet speed-limiter trolley embodiment shown in Fig. 14.

[0050] Fig. 16 is an end elevation view of one of the cable-guide end spacers of the trolleys shown in the drawings.

[0051] Fig. 17 is a side elevation view of the cable-guide end spacer shown in Fig.
16.

[0052] Fig. 18 is a top plan view of the middle spacer of the trolleys shown in the drawings.

[0053] Fig. 19 is a side elevation view of the middle spacer shown in Fig.
18.
Detailed Description with Reference to the Drawings

[0054] Fig. 1 and Fig. 2 show a zipline cable 50, a conventional trolley 52, and a trolley holder 54 embodiment of the present invention.

[0055] The cable used for many ziplines is typically 1/2" - 7/8" galvanized or stainless steel cable. In this description and the drawings, the zipline cable 50 is 7/8"
galvanized steel cable and the dimensions for other components are understood to be suitable for use with such cable. If another cable size were used, the dimensions of other components would of course be modified accordingly.

[0056] The conventional trolley 52 has: two conventional trolley sheaves 60, two sheave axle pins 62, (each sheave axle pin 62 passing through two axle support holes 63), two conventional trolley side plates 64, two cable-guide end spacers 66 (shown in Fig. 16 and Fig. 17), and one middle spacer 68 (shown in Fig. 18 and Fig. 19).

[0057] The conventional trolley side plates 64 shown in the drawings each have a spreader-bar lanyard connector 70, which in use is attached a spreader-bar lanyard 72 extending to a spreader-bar end 74. Spreader bar 76 is shown in Fig. 9. Some trolleys have four spreader-bar lanyard connectors 70, with two spreader-bar lanyards extending to each spreader-bar end 74

[0058] As shown in Fig. 4 and Fig. 5, the conventional trolley sheave 60 includes a regular hub 80, typically made from metal, typically aluminum; a cable groove 82, being a grooved annular component affixed to the external circumference of the regular hub 80, for rotating along the zipline cable 50 during use. The cable groove 82 is made from a material selected to provide acceptable usable life while avoiding wear to the zipline cable 50, for example, urethane rubber.

[0059] All of the sheaves described herein, shown in the drawings and tested by the inventor, have an external diameter of 4" and a cable groove minimum diameter (i.e., the diameter measured between the deepest portion of the cable groove 82 and an opposite deepest portion of the cable groove 82). These sheaves are configured for 7/8"
zipline cable, and will accommodate smaller cables. The inventor has found that the sheaves provide acceptable performance with 3/8", 1/2", 5/8" and 3/4" cable.

[0060] The interior of the regular hub 80 includes: a bearing seat 84, in which a sheave axle pin bearing 86 is fitted; and a retainer ring seat 88 in which a retainer ring (not shown) is positioned to secure the sheave axle pin bearing 86 in the bearing seat 84.

[0061] The trolley holder 54 includes a clamp assembly 90 and an actuating arm 92 pivotally mounted to the clamp assembly 90.

[0062] The clamp assembly 90 shown in the drawings comprises an inner block and a clamp outer housing 96. The inner block 94 is slightly thinner than the diameter of the zipline cable 50, and includes a pivot spring recess 98 for containing the pivot spring 100. The clamp outer housing 96 is made from a piece of metal plate (preferably 1/8"
6061 aluminum), shaped (e.g., around a mandrel) to have a central 180 degree curve of a diameter no greater than the zipline cable 50. The inner block 94 and clamp outer housing 96 have three aligned clamp holes 102 for receiving clamp bolts 104, for installing and maintaining the clamp assembly 90 at a desired position on the zipline cable 50.

[0063] The inner block 94 and clamp outer housing 96 are preferably made from aluminum. To reduce the galvanic action that would otherwise result from the electrical contact between the dissimilar metals (i.e., steel and aluminum), an electrical insulating layer (e.g. conventional vinyl electrical tape) should be interposed between the cable 50, and the inner block 94 and clamp outer housing 96.

[0064] The inner block 94 and clamp outer housing 96 may be used with smaller sized cables by interposing a shim-spacer (not shown in the drawings) between the cable, and the inner block 94 and clamp outer housing 96. Preferably, the shim-spacer is curved and sized to substantially conform to the outer periphery of the cable. It is understood that a section of a pipe with a longitudinal slit such that the pipe may be sprung apart when being fitted on a cable, may be a suitable shim-spacer. Alternatively, a suitable pipe cut longitudinally to make two (or more) curved sections that may be slid between a cable, and the inner block 94 and clamp outer housing 96, may be a suitable shim-spacer. Non-metal materials, including materials with electrical insulation properties, may be suitable for the shim-spacer. If the shim-spacer is made from metal, to reduce galvanic action the metal should be the same as the metal of the inner block 94 and clamp outer housing 96.

[0065] The clamp outer housing 96 includes two aligned housing pivot holes =

for receiving the pivot bolt 108.

[0066] The actuating arm 92 includes: a pivot bar 110; a tooth 112 secured to the pivot bar 110 with a flat-head machine screw 114 threaded into a threaded tooth bore 116 in the pivot bar 110 and with a tooth retainer pin 118 (e.g., a slotted spring pin) to prevent rotation of the tooth 112 about the flat-head machine screw 114; a hollow cylindrical handle grip 120; a linear spring 122; a linear spring washer 124 and a linear spring bolt 126.

[0067] The pivot bar 110 includes a bar pivot hole 128 for receiving the pivot bolt 108. The handle grip 120 includes a linear spring washer seat 130. The pivot bar 110 includes a threaded linear spring bolt bore 132 for threadedly receiving the linear spring bolt 126 to secure the linear spring washer 124 against the linear spring 122, thus retaining the linear spring 122 within the linear spring washer seat 130. The portion of the pivot bar 110 that in use is within the handle grip 120 has chamfers 134 to reduce wear.

[0068] The clamp assembly 90 includes a handle grip seat 136 for engaging the proximal end of the handle grip 120. When the proximal end of the handle grip 120 is engaged with the handle grip seat 136, abutting of the proximal end of the handle grip 120 with the handle grip seat 136 prevents pivotal movement of the actuating arm 92 from a locked position. In the locked position, the trolley holder 54 may be in the engaged position, in which the trolley holder 54 is engaged with a trolley 52 as shown in Fig. 1 (more specifically, the tooth 112 is engaged with the upper end of the adjacent cable-guide end spacer 66).

[0069] The trolley holder 54 is maintained in the locked position (and the engaged position), by the linear spring 122, which biases the handle grip 120 towards engagement with the handle grip seat 136. To change the trolley holder 54 to the unlocked and disengaged position (so as to launch the zipline rider), the operator must move the handle grip 120 linearly away from engagement with the handle grip seat 136.
Once the handle grip 120 has been moved linearly sufficiently to clear the handle grip seat 136, trolley holder 54 is maintained in engagement with the trolley 52 by the biasing of the actuating arm 92 provided by the pivot spring 100. To disengage the trolley holder 54 from the trolley 52, the operator must pivot the actuating arm 92 against the pivot spring 100 bias so as to disengage the tooth 112 from the upper end of the adjacent cable-guide end spacer 68, as shown in Fig. 2.

[0070] Thus, the trolley holder 54 requires two distinct movements by the operator, linear movement of the handle grip 120 and pivotal movement of the actuating arm 92, in order to release a trolley 52, thus reducing the likelihood of inadvertent early release.

[0071] In the embodiments shown in the drawings, the trolley holder 54 is configured such that the conventional trolley 52 abuts (or is very close to) the clamp assembly 90, when the conventional trolley 52 is in the position in which the tooth 112 may be engaged with the upper end of the adjacent cable-guide end spacer 68.
This configuration is desirable because it prevents potentially damaging contact between the adjacent conventional trolley sheave 60, and the pivot bar 110 or tooth 112.
This configuration is also desirable because when the trolley holder 54 is engaged with the trolley 52 , the trolley 52 is essentially held in a fixed position, such that there is no discernable distracting "play" or noise associated with intermittent contact between components.

[0072] Most various known zipline trolleys include a feature analogous to the upper end of the adjacent cable-guide end spacer 68 (i.e., suitable for engaging a feature analogous to the tooth 112), but as compared to the upper end of the adjacent cable-guide end spacer 68, are different with respect to one or more of: the distance from the cable; the position relative to the adjacent end of the trolley (i.e., the end of the trolley closest to the trolley holder 54, in use); and the size and shape of the tooth receiving cavity. Thus, it is understood that configuring the trolley holder 54 for such known zipline trolleys would in most instances only require modification of the pivot bar 110 and/or tooth 112. It is understood that it would be possible to accommodate many such known zipline trolleys by having: different interchangeable pivot bar ends (including a tooth feature) each configured for a different trolley style; or a different pivot bar 110 and tooth 112 for each such different trolley style.

=

[0073] To provide a vivid visual indicator of whether the trolley holder 54 is in the locked or unlocked position, it may be desirable to permanently mark, e.g., with bright paint, that portion of the pivot bar 110 that is visible when the trolley holder 54 is in the unlocked and disengaged position but is not visible when the handle grip 120 is engaged with the handle grip seat 136.

[0074] If the designer considers it desirable, the handle grip seat 136 could be made longer than indicated in the drawings and other components could be modified accordingly, so as to require linear movement of the handle grip 120 to disengage it from the handle grip seat 136, greater than suggested by the drawings.

[0075] A possible variation (not show), which may not be desirable due to increased complexity, involves modifying the end of the pivot bar 110 having the tooth 112 so as to engage with a trolley 52 moved into contact with the trolley holder 54 without requiring the operator to manually move the handle grip 120. For example, the end of the pivot bar 110 having the tooth 112 could be separately pivotal, relative to the end of the pivot bar 110 supporting the handle grip 120. The end of the pivot bar 110 having the tooth 112 would be biased (e.g., by a spring) in straight position (i.e., essentially as shown in Fig.1). Responsive to contact between the sloped surfaces of the underside of the tooth 112 and the top of an approaching cable-guide end spacer 66, the end of the pivot bar 110 having the tooth 112 would initially move up so as to allow the cable-guide end spacer 66 to pass the tooth 112 and then, biased by the spring, the tooth 112 would drop in behind the cable-guide end spacer 66 (e.g., as indicated in Fig. 1).

[0076] Speed limiter embodiments of the present invention and components of same are shown in Fig. 6 to Fig. 15.

[0077] Fig. 7 shows a small brake disc 140 having three countersunk holes 142.
In the embodiments shown in the drawings, the small brake disc 140 is a 3/32"
thick copper washer, 3" in diameter, with a 1-1/2" diameter central hole. As shown in Fig. 8, in use, two small brake discs 140 are attached to a conventional trolley sheave 60, one small brake disc 140 on each side of the conventional trolley sheave 60, with stainless steel flat-head bolts (not shown) passing through the countersunk holes 142 into threaded bores (not shown) in the regular hub 80. The small brake discs 140 conventional trolley sheave 60 combination shown in Fig. 8 is at times referred to herein as a small brake sheave 144.

[0078] A four-magnet small-brake speed-limiter trolley 146 embodiment is shown in Fig. 8. The four-magnet small-brake speed-limiter trolley 146 is configured for use with small-brake sheaves 144.

[0079] The four-magnet small-brake speed-limiter trolley 146 includes: four 3/4"
by 1/4" magnets 148 (being cylindrical rare-earth (i.e., neodymium) magnets having a diameter of 3/4" and a thickness of 1/4"); four magnet receptacles 150 (being 3/4" holes in the sides of the four-magnet small-brake speed-limiter trolley 146); and four single magnet retainers 152. Each 3/4" by 1/4" magnet 148 is located within a magnet receptacle 150 and is held in place by magnetic attraction to an associated overlying single magnet retainer 152. Each single magnet retainer 152 is made from 1/32"

ferromagnetic sheet metal and is attached to the side of the four-magnet small-brake-disc speed-limiter trolley 146 with magnet retainer screws 154.

[0080] In the four-magnet small-brake speed-limiter trolley 146, the magnet receptacles 150 are positioned so that when used with small-brake sheaves 144, each 3/4" by 1/4" magnet 148 is proximate the adjacent surface of the small brake disc 140.
The four-magnet small-brake-disc speed-limiter trolley 146 is configured so that there is a 1/32" gap between each 3/4" by 1/4" magnet 148 and the adjacent portion of the small brake disc 140. In the four-magnet small-brake speed-limiter trolley 146, the distance between the sheave axis of rotation and the center of each magnet receptacle 150 is 1 3/16", such that the radial distance between the sheave axis of rotation and the side of each 3/4" by 1/4" magnet 148 furthest from the sheave axis of rotation, is 1/16" less than the radius of the small brake disc 140. That is, relative to the circumferential periphery of the small brake discs 140, each 3/4" by 1/4" magnet 148 is inset 1/16".

[0081] Fig. 10 and Fig. 11 show a large-brake-disc sheave 160 embodiment having: a large-brake hub 162 (having the same general configuration as the regular hub 80, but being narrower than the regular hub 80); and two large brake discs 164. In Fig.

10, the large brake disc 164 is represented as transparent such that the large-brake hub 162 is visible through the large brake disc 164. Each large brake disc 164 has three countersunk holes 142. The large brake discs 164 are attached to the large-brake hub 162, one large brake disc 164 on each side of large-brake hub 162, with stainless steel flat-head bolts (not shown) passing through the countersunk holes 142 into threaded bores (not shown) in the large-brake hub 162.

[0082] Fig. 12 and 13 show an integral-brake-disc sheave 170 embodiment having a brake hub 172, being a single integral component (i.e., a component not comprising sub-components fastened one to the other) combining hub and brake disc features. In the preferred embodiment, the brake hub 172 comprises a single piece of aluminum. The brake hub 172 has an annular channel 174 containing the cable groove 82, and casting vent holes 176 for use in casting a suitable cable-groove material (e.g., urethane rubber).

[0083] In the embodiments shown in the drawings, the general dimensions of the large-brake-disc sheaves 160 are the same as those of the integral-brake-disc sheaves 170, such that they may be interchangeably installed. In the embodiments shown in the drawings, the diameter of the large-brake-disc sheaves 160 and of the integral-brake-disc sheaves 170, is 4".

[0084] Fig. 14 and Fig. 15 show a twelve-magnet speed-limiter trolley 180 embodiment and components of same. The twelve-magnet speed-limiter trolley 180 is configured for use with large-brake-disc sheaves 160 or integral-brake-disc sheaves 170.
The twelve-magnet speed-limiter trolley 180 includes: twelve (i.e., four sets of three) 3/4"
by 5/16" magnets 182 (being cylindrical rare-earth (i.e., neodymium) magnets having a diameter of 3/4" and a thickness of 5/16"); twelve (i.e., four sets of three) magnet receptacles 150, each set of three in the vicinity of a respective axle support hole 63; and four triple magnet retainers 184. Each 3/4" by 5/16" magnet 182 is located within a magnet receptacle 150 and is held in place by magnetic attraction to an associated overlying triple magnet retainer 184. Each triple magnet retainer 184 is made from 1/32"
ferromagnetic sheet metal and is attached to the side of the twelve-magnet speed-limiter trolley 180 with magnet retainer screws 154.

[0085] In the twelve-magnet speed-limiter trolley 180, the magnet receptacles 150 are positioned so that when used with the large-brake-disc sheaves 160 or the integral-brake-disc sheaves 170, each 3/4" by 5/16" magnet 182 is proximate the adjacent surface of the large brake disc 164 or brake hub 172, as the case may be. The twelve-magnet speed-limiter trolley 180 is configured so that there is a 1/32" gap between each 3/4" by 5/16" magnet 182 and the adjacent surface of the large brake disc 164 or brake hub 172, as the case may be. In the twelve-magnet speed-limiter trolley 180, the distance between the sheave axis of rotation and the center of each magnet receptacle 150 is 1 1/2", such that the radial distance between the sheave axis of rotation and the side of each 3/4" by 5/16" magnet 182 furthest from the sheave axis of rotation, is 1/8"
less than the radius of the the large brake disc 164 and brake hub 172. That is, relative to the circumferential periphery of the large brake disc 164 or the brake hub 17, each 3/4"
by 5/16" magnet 182 is inset 1/8".

[0086] The four-magnet small-brake speed-limiter trolley 146 and twelve-magnet speed-limiter trolley 180 provide speed limiting by way of eddy current braking.

[0087] Applicant has run comparison tests of embodiments described herein and a trolley without magnets. The tests were run down the same zipline with the same rider, done close together, so weather conditions were reasonably consistent between the test runs. The tests were performed on a combination of zipline lengths and slopes.
The tests indicated that as compared to a trolley without magnets: a four-magnet small-brake speed-limiter trolley 146 with aluminum conventional trolley sheaves 60 produced an insignificant speed reduction (no more than about 1%); a four-magnet small-brake speed-limiter trolley 146 with small-brake sheaves 144 produced about a 10% speed reduction;
a twelve-magnet speed-limiter trolley 180 with large-brake-disc sheaves 160 produced about a 25% speed reduction; and a twelve-magnet speed-limitertrolley 180 with integral-brake-disc sheaves 170 produced about a 25% speed reduction.

[0088] The by-product heat generated in the tests was minimal, presumably in part due to the relatively high heat conductivity of copper and aluminum.

[0089] Applicant understands that different speed limiting for riders of different weights could be provided by: having different trolleys pre-configured (in terms of number and location of magnets) for different weight ranges; configuring the trolleys to facilitate operator effected changes to the number of magnets (including altering the magnet retainers to enable the operator to readily determine how many magnets are present in a particular trolley); etc.

[0090] As well, magnet mounts could be configured so as to adjust the position of the magnets relative to the conductor. For example, the gap between the magnet and conductor could be adjustable. It is assumed that very small changes in the gap would likely have significant effects on the speed-limiting effect and thus that this sort of movement (i.e. essentially parallel with the sheave axis of rotation), would probably only be of use in turning specific magnets between an "on" position (i.e., in sufficient proximity to the conductor to be effective in speed limiting) and an "off' position (Le., sufficiently distant from the conductor to be ineffective in speed limiting).

[0091] Alternatively, magnet mounts could be configured to provide operator controlled movement of the magnets radially relative to the sheave axis of rotation, so as to decrease or increase the relative speed at which the conductor passes the magnet.

[0092] As a further alternative, movement of the magnets could be effected by linear actuators or servo motors (or other suitable component) mounted to the relevant trolley. With such magnet moving components, speed-limiting effect could be adjusted during the zipline ride, for example, responsive to: velocity information received from a speed detector (e.g., a speed detector mounted to the trolley, a speed detection system including one or more speed detectors (e.g., radar) remote from and in radio communication with the magnet moving component, etc.); location information (e.g., proximity to the lower end of the cable) for example received from a sensor in radio communication with the magnet moving component; combinations of velocity and location information; etc.

[0093] As another alternative, the magnetic field source (i.e., one or more magnets) could be attached to each sheave. With such an arrangement, the trolley side plates (generally aluminum) would be the conductor component (and heat dissipater) of the eddy current braking system.

[0094] The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

[0095] The following reference numbers are used herein and in the drawings:
zipline cable 50; conventional trolley 52; trolley holder 54; conventional trolley sheave 60;
sheave axle pin 62; axle support holes 63; conventional trolley side plate 64;
cable-guide end spacer 66; middle spacer 68; spreader-bar lanyard connector 70; spreader-bar lanyard 72; spreader-bar end 74; spreader bar 76; regular hub 80; cable groove 82;
bearing seat 84; sheave axle pin bearing 86; retainer ring seat 88; clamp assembly 90;
actuating arm 92; inner block 94; clamp outer housing 96; pivot spring recess 98; pivot spring 100; clamp hole 102; clamp bolt 104; housing pivot hole 106; pivot bolt 108; pivot bar 110; tooth 112; flat-head machine screw 114; tooth bore 116; tooth retainer pin 118;
handle grip 120; linear spring 122; linear spring washer 124; linear spring bolt 126; bar pivot hole 128; linear spring washer seat 130; linear spring bolt bore 132;
chamfers 134;
handle grip seat 136; small brake disc 140; countersunk hole 142; small-brake sheave 144; four-magnet small-brake speed-limiter trolley 146:314" by 1/4" magnet 148; magnet receptacle 150; single magnet retainer 152; magnet retainer screw 154; large-brake-disc sheave 160; large-brake hub 162; large brake disc 164; integral-brake-disc sheave 170;
brake hub 172; annular channel 174; casting vent hole 176; twelve-magnet speed-limiter trolley 180; 3/4" by 5/16" magnet 182; and triple magnet retainer 184.

Claims (16)

WHAT IS CLAIMED IS:

1. Devices for use with a zipline cable, the devices comprising:
a speed-limiting zipline trolley comprising:
two trolley sides in a spaced apart relationship; and one or more sheaves, each interposed between, and rotatably mounted to, the trolley sides and each sheave defining a sheave axis of rotation;
wherein the trolley sides comprise a plate eddy current speed-limiting component and at least one of the sheaves comprises a sheave eddy current speed-limiting component; and whereby, in use, the plate eddy current speed-limiting component and the sheave eddy current speed-limiting component interact to produce eddy current speed limiting as between them; and a trolley holder device, comprising:
fixing means for fixing the trolley holder device relative to a zipline cable;

an actuating arm having:
a bar, pivotally mounted to the fixing means for pivotal movement between an engagement position and a disengaged position, and the bar having a latch for engaging the trolley so as to impede movement of the trolley away from the trolley holder device when the bar is in the engagement position; and a grip, slidably engaged with the bar so as to be linearly manipulable between: a locked engagement position in which the grip abuts the fixing means so as to impede pivotal movement of the bar from the engagement position and an unlocked position in which pivotal movement of the bar from the engagement position is not impeded by abutment between the grip and the fixing means; and a lock biasing means for resiliently biasing the grip in the locked engagement position;
whereby, when the latch is engaged with the trolley and the grip is in the locked engagement position, disengaging the latch from the trolley requires sequential linear movement of the grip from the locked engagement position to the unlocked position and pivotal movement of the bar from the engagement position to the disengaged position.

2. The devices of claim 1, wherein: the plate eddy current speed-limiting component comprises a magnetic field source and the sheave eddy current speed-limiting component comprises a conductor.

3. The devices of claim 2, wherein:
the at least one of the sheaves comprising the sheave eddy current speed-limiting component, has a sheave side and the conductor comprises a disc of conductive material at the sheave side; and the magnetic field source comprises one or more magnets mounted in one of the trolley sides proximate to the disc of conductive material.

4. The devices of claim 2, wherein:
the at least one of the sheaves comprising the sheave eddy current speed-limiting component, has two sheave sides and the conductor comprises two discs of conductive material, wherein:
one of the discs of conductive material is at one of the sheave sides; and the other of the discs of conductive material is at the other of the sheave sides; and the magnetic field source comprises two magnet sets for each sheave, each magnet set comprising one or more magnets, wherein one of the magnet sets is mounted in one of the trolley sides at a location proximate to one of the discs of conductive material; and the other of the magnet sets is mounted in the other of the trolley sides at a location proximate to the other of the discs of conductive material.

5. The devices of claim 4, wherein each disc of conductive material is: an aluminum-containing disc integral to the sheave; a copper-containing disc affixed to the sheave; or an aluminum-containing disc affixed to the sheave.

6. The devices of claim 4, wherein:
each disc of conductive material is a circular disc having a planar surface and defining a disc circle substantially concentric with the sheave axis of rotation and defining a disc circle circumference; and for each magnet of each magnet set, the location proximate to the one of the discs of conductive material is:
at a distance from the planar surface no greater than about 1/16"; and within the disc circle circumference and at a distance from the disc circle circumference no greater than about 1/8".

7. The devices of claim 6, wherein for each magnet of each magnet set, the location proximate to the one of the discs of conductive material is:
at a distance from the planar surface no greater than about 1/32"; and at a distance from the disc circle circumference no greater than about 1/16".

8. The devices of claim 4 wherein each magnet is a cylindrical neodymium rare-earth magnet.

9. The devices of claim 8, wherein each magnet is a 3/4" by 1/4" magnet or a 3/4" by 5/16" magnet.

10. The devices of claim 6, wherein each magnet set comprises three magnets and each magnet is a cylindrical neodymium rare-earth magnet.

11. The devices of claim 4, wherein:
the at least one of the sheaves comprising the sheave eddy current speed-limiting component, comprises two sheaves;
each disc of conductive material is a circular disc having a planar surface and defining a disc circle substantially concentric with the sheave axis of rotation and defining a disc circle circumference; and for each magnet of each magnet set, the location proximate to the one of the discs of conductive material is:
at a distance from the planar surface no greater than about 1/16"; and within the disc circle circumference and at a distance from the disc circle circumference no greater than about 1/8".

12. The devices of claim 11, wherein each magnet set comprises three magnets;
each magnet is a cylindrical neodymium rare-earth 3/4" by 5/16" magnet;
each disc circle has a diameter of about 4"; and for each magnet of each magnet set, the location proximate to the one of the discs of conductive material is:
at a distance from the planar surface no greater than about 1/32"; and at a distance from the disc circle circumference no greater than about 1/16".

13. The devices of claim 11, wherein each magnet set comprises one magnet;
each magnet is a cylindrical neodymium rare-earth 3/4" by 1/4" magnet;
each disc circle has a diameter of about 3"; and for each magnet of each magnet set, the location proximate to the one of the discs of conductive material is:
at a distance from the planar surface no greater than about 1/32"; and at a distance from the disc circle circumference no greater than about 1/8".

14. The devices of claim 1, further comprising a pivot biasing means for resiliently biasing the bar in the engagement position.

15. The devices of claim 14, wherein: the lock biasing means is a first spring interposed between the bar and the grip; and the pivot biasing means is a second spring interposed between the bar and the fixing means.

16. The devices of claim 1, wherein: the trolley comprises a tooth receptacle having an inner catch; and the latch comprises a tooth that fits within the tooth receptacle when the latch is engaged with the trolley, whereby the impeding of movement of the trolley away from the trolley holder device is provided by abutment between the tooth and the tooth receptacle inner catch.