Transmissions incorporating eddy current braking

Abstract

Described herein is a transmission mechanism and an associated method of use for braking relative movement between members, movement and braking of the members being directed through one or more transmission elements.

1 - 30 . (canceled) 
     
     
         31 . A zipline trolley or carriage comprising a transmission mechanism,
 the transmission mechanism comprising:   at least one driving member; and   at least one driven member, movement of the at least one driven member urged via transmission of movement from the at least one driving member;   drag force inducing elements that move at different relative rates comprising at least one electrical conductor and at least one magnet, each inducing element integrally coupled with at least one driven member in a manner that allows the elements to interact on movement and generate eddy current drag forces, and   when a motive force occurs on the at least one driving member, that in turn applies a motive force on the driven members, an eddy current drag force is then induced on the driven members via interaction between the at least one electrical conductor and the at least one magnet that are integrally coupled to the at least one driven member, the drag force then retarding movement of the at least one driving member via the transmission and in turn retarding movement of the zipline trolley or carriage.   
     
     
         32 . The zipline trolley or carriage as claimed in  claim 31  wherein the at least one conductor is directly coupled to the at least one driving member and the at least one magnet is indirectly coupled to the at least one driving member via the transmission mechanism, and wherein:
 the transmission mechanism moves both elements rotationally; 
 a reaction torque induced by the elements is transferred into the driving member of the transmission mechanism. 
 
     
     
         33 . The zipline trolley or carriage as claimed in  claim 31  wherein the at least one magnet is directly coupled to the at least one driving member and the at least one conductor is indirectly coupled to the at least one driving member via the transmission mechanism, and wherein:
 the transmission mechanism moves both elements rotationally; 
 a reaction torque induced by the elements is transferred into the driving member of the transmission mechanism. 
 
     
     
         34 . The zipline trolley or carriage as claimed in  claim 31  wherein the at least one electrical conductor and the at least one magnet are independent to each other and coupled to the driven members. 
     
     
         35 . The zipline trolley or carriage as claimed in  claim 31  wherein rotational movement of the at least one driving member urges at least two driven members to rotate in opposite directions. 
     
     
         36 . The zipline trolley or carriage as claimed in  claim 31  wherein the transmission mechanism moves both members rotationally about a fixed axis. 
     
     
         37 . The zipline trolley or carriage as claimed in  claim 36  wherein the fixed axis is a common axis between the elements. 
     
     
         38 . The zipline trolley or carriage as claimed in  claim 31  wherein the rate of movement of the driving and driven members vary once eddy current drag forces are induced and continue to vary until a critical velocity is reached, the critical velocity being where the eddy current drag force does not increase with increased rotational velocity acting on the at least one driving member. 
     
     
         39 . The zipline trolley or carriage as claimed in  claim 31  wherein the transmission mechanism is a worm drive. 
     
     
         40 . The zipline trolley or carriage as claimed in  claim 39  wherein the transmission operates in the mode of providing a step up in velocity from the rotational velocity of the driving member to the rotational velocity of the eddy current inducing element or elements thereby providing a resisting force to the rotational velocity of the driving member. 
     
     
         41 . The zipline trolley or carriage as claimed in  claim 40  wherein the transmission ratio and/or coefficient of friction is selected such that the transmission operates with a prescribed level of mechanical efficiency. 
     
     
         42 . The zipline trolley or carriage as claimed in  claim 41  wherein the prescribed level of mechanical efficiency is sufficiently low to provide a supplementary retarding torque over that provided by the induced eddy current drag force and the numerical gear ratio alone. 
     
     
         43 . The zipline trolley or carriage as claimed in  claim 31  wherein a friction torque is held approximately in proportion to the eddy current element induced braking torque. 
     
     
         44 . The zipline trolley or carriage as claimed in  claim 31  wherein the transmission mechanism is configured to comprise:
 a tube including a wall and void defined therein; 
 a cylinder that fits into the tube void, the cylinder being a driven member linked to a driving member providing an input torque, the cylinder moving in response to an input torque on the driving member relative to the tube via axial translation of the cylinder relative to the tube so that the cylinder can pass at least partially into or out of the tube void; and rotation of the cylinder relative to the tube about a longitudinal axis, the axis passing through the tube void; 
 wherein, coupled to the tube and cylinder are one or more eddy current inducing elements and/or one or more magnetic attraction effects; and, 
 in use, the cylinder and tube have different relative speeds of rotation to each other such that, when the tube and/or cylinder is or are moved via axial translation caused by the driven member so that the cylinder at least partially enters the tube void, a braking reaction force on rotation of the driven member occurs due to induced eddy current drag force generation thereby slowing the velocity of rotation of the driving member. 
 
     
     
         45 . The zipline trolley or carriage as claimed in  claim 44  wherein the degree of overlap between the tube and cylinder determines the degree of eddy current induced drag force and/or magnetic attraction effect. 
     
     
         46 . The zipline trolley or carriage as claimed in  claim 44  wherein the axial force applied to the cylinder is imposed by the driven member, the degree of axial force applied being proportional to the torque acting on the driving member. 
     
     
         47 . The zipline trolley or carriage as claimed in  claim 44  wherein the transmission is a worm drive. 
     
     
         48 . The zipline trolley or carriage as claimed in  claim 47  wherein the eddy current elements are selectively coupled to the worm element, whereby the axial force applied to the worm gear is used to engage and disengage a coupling connecting the worm drive to the eddy current elements. 
     
     
         49 . The zipline trolley or carriage as claimed in  claim 48  wherein engagement occurs in response to a force threshold having been achieved. 
     
     
         50 . The zipline trolley or carriage as claimed in  claim 48  wherein disengagement occurs in response to a force threshold having been achieved.