fig1 illustrates an on - rope work positioning device 100 for ascending and descending on a rope , in neutral or collapsed position on a rope 115 . device 100 comprises an upper assembly 111 , a spine assembly 112 , a lower assembly 113 , and a pin / bollard assembly 114 . upper assembly 111 comprises two generally parallel side plates 101 and 102 . these side plates are elongate in shape , generally flat in cross section , are constructed of a rigid material appropriate for high wear and stress applications and comprise each a first , second , and third aperture arranged sequentially along the length , patterned such that the apertures of side plate 101 and 102 match . both side plates 101 and 102 comprise a pivot end and a control end . the distal aperture of the control end of side plate 101 is formed as a slot sized to mate an end portion of eccentric pin 108 a , which is bolt 119 a , and is formed such that said bolt may pass out of said slot by means of rotation of either side plate 101 or 102 relative to the other side plate . bolt 119 a additionally constrains eccentric pin 108 a laterally within said slot when in closed position , spacing the side plates . the distal aperture of the control end of side plate 102 is formed as ( but not limited to ) a round hole in some embodiments and as a lobed star - shaped hole in some other embodiments patterned to mate a matching pattern in an extended portion of eccentric pin 108 a , ( see fig5 below ). roller element 107 is affixed between side plates 101 and 102 by bolt 118 a through the center aperture of said side plates , providing a pivot axis for roller 107 , such that a rope 115 may pass within the aperture formed by the side plates 101 and 102 , the roller 107 and eccentric pin 108 a . the pivot end aperture of side plate 102 is joined pivotally to the upper aperture of link 106 by bolt 116 c . the pivot end of side plate 101 is similarly joined pivotally to the upper aperture of link 105 by bolt 116 a ( see fig2 ). lower assembly 113 comprises two generally parallel side plates 103 and 104 . these side plates are elongate in shape , generally flat in cross section , and are constructed of a rigid material appropriate for high wear and stress applications , just as are the side plates of the upper assembly . lower side plate 103 comprises a first , second , and third aperture arranged sequentially along the length . lower side plate 104 comprises a first , second , third and fourth aperture arranged sequentially along the length ( see fig5 ) patterned such that the first , second , and third apertures of side plate 103 and 104 align . both side plates 103 and 104 comprise a pivot end and a pin / bollard end . the distal ( third ) aperture at the pin / bollard end of side plate 103 is formed as a slot sized to mate the end portion of eccentric pin 108 b , which is bolt 119 b , and is formed such that said bolt may pass out of said slot by means of relative rotation between side plates 103 and 104 . bolt 119 b additionally constrains eccentric pin 108 b laterally within said slot when in closed position . a fourth aperture of the pin / bollard end of side plate 104 is formed as ( but not limited to ) a slot which has a long axis generally parallel to the long axis of lower side plate 104 ( see fig5 below ). the third aperture of the pin / bollard end of lower side plate 104 comprises , but is not limited to , a round hole in some embodiments , or a lobed star - shaped hole patterned to mate a matching pattern milled or cast in an end portion of eccentric pin 108 b , ( see fig5 below ). cam / anchor element 110 is pivotally joined between side plates 103 and 104 by bolt 118 b through the center aperture of said side plates , such that it may rotate freely about the major axis of said bolt , and such that a rope 115 passing through the upper assembly 111 may then pass within the aperture formed by side plates 103 and 104 , the cam / anchor 110 and eccentric pin 108 b without interference . cam / anchor 110 comprises a first and second aperture and a concave cam / friction face . the first aperture of cam / anchor 110 is sized such that a standard climbing carabineer may easily pass through said aperture for the purpose of attaching a climber to the device 100 . the second aperture of cam / anchor 110 mates pivotally to the second aperture of lower side plates 103 and 104 by means of bolt 118 b and functions as a pivot fulcrum for the cam action of cam / anchor 110 . pin / bollard assembly 114 serves as an adjustable counter face upon which cam / anchor 110 compresses rope 115 ( see fig4 below ) and comprises eccentric pin 108 b , bollard 109 , and bolts 119 b , 119 d and 501 . eccentric pins 108 a and 108 b are identical and are constructed of a hard - wearing material such as steel and have a central portion with a width that matches that of the space between upper side plates 101 and 102 and lower side plates 103 and 104 . at each end of the central portion there are extensions , both of which are centered about a common long axis , which is in turn parallel to and offset from the long axis of the central portion of the pin . thus when eccentric pins 108 a and 108 b are rotated about the long axis ( rotational axis ) of the smaller end extensions the central portion rotates about said axis in an eccentric fashion . eccentric pins 108 a and 108 b are drilled and tapped through the rotational axis to receive bolts 119 a - c . further , one end of each of eccentric pins 108 a and 108 b may be milled and / or shaped to a pattern matching that cut / milled into the third aperture of upper side plate 102 and lower side plate 104 , thus providing a mechanism for indexing the position of rotation of the eccentric pin ( see fig5 below ). in this manner overall size of the rope aperture may be adjusted to accommodate various rope sizes and constructions . bollard 109 is constructed of a wear - resistant and lightweight material such as aluminum and comprises a circular barrel of the same width as the central barrel of eccentric pin 108 a and 108 b . bollard 109 comprises a first and second aperture . the first aperture of bollard 109 is offset from center and parallel to the centerline such that the first aperture overlaps the edge of the barrel forming thereby a semicircular cutout ( see fig2 - 5 below ). the diameter of the semicircular cutout is the same as the diameter of the central portion of eccentric pin 108 b . the second aperture comprises a tapped hole offset from and parallel to the center axis of bollard 109 , and mates to the slot ( fourth aperture ) of lower side plate 104 by means of bolt 501 such that bolt 501 may move freely within said slot and bolt 501 further constrains the outer face of bollard 109 to be flush with the inner face of lower side plate 104 ( see fig5 ). the central portion of eccentric pin 108 b fits within the first aperture of bollard 109 and rotates freely therein . as eccentric pin 108 b is rotated to different positions , the eccentric position of the center barrel consequently moves bollard 109 in a reciprocal fashion constrained by bolt 501 within the slot ( fourth aperture ) in lower side plate 104 ( see fig5 below ). bolt 119 d is loosened to make such adjustment , and tightened again to hold bollard 109 in a new position . upper assembly 111 and lower assembly 113 are joined by means of spine assembly 112 . spine assembly 112 comprises link 105 and link 106 which are mirror images of one another , each having an upper and a lower end . both links 105 and 106 are elongate in shape , generally flat in cross section , are constructed of a rigid material appropriate for high wear and stress applications , and comprise each a first , second , and third aperture arranged sequentially along the length . both links 105 and 106 are affixed to one another pivotally by bolt 117 through their centermost ( second ) apertures in such a way that they may freely rotate about the major axis of said bolt . the uppermost ( first ) aperture of links 105 and 106 are affixed to the pivot ends ( first ) apertures of upper side plates 101 and 102 respectively by bolts 116 a and 116 c ( see fig2 ). bolts 116 a - c are identical and comprise a flat head countersunk into link 105 such that link 105 may lay flush to , and move freely past link 106 without interference from said bolt head , and such that upper side plate 101 may additionally rotate about the major axis of bolt 116 a . bolt 116 c ( see fig2 ), link 106 , and upper side plate 102 mirror the arrangement of bolt 116 a , link 105 and upper side plate 101 . the lower ( third ) aperture of link 105 and 106 mate with the first aperture of the pivot end of lower side plates 103 and 104 respectively in the same fashion as the upper ( first ) aperture of link link 105 and 106 mate the pivot end ( first ) apertures of upper side plates 101 and 102 . as shown in neutral position in fig1 , device 100 moves freely along the length of rope 115 until the climbers weight is applied to the cam / anchor element 110 , which moves the friction face of element 110 to compress the rope between the friction face and bollard 108 b , at which time the device becomes configured in the locked position as seen in fig4 . fig4 shows device 100 in locked or stationary position with upper side plate 101 and lower side plate 103 removed for clarity . in this position the device 100 holds the climber &# 39 ; s weight and remains stationary on the rope 115 until such time as the device is unlocked by application of downward force upon upper assembly 111 , to return the device to the freely - sliding position shown in fig1 . when a climber &# 39 ; s weight is applied the force is transmitted from the cam / anchor 110 through the lower side plates 103 and 104 , through links 105 and 106 , to upper side plates 101 and 102 where friction between rope 115 and eccentric pin 108 a cause side plates 101 and 102 to rotate roughly about the major axis of bolt 118 a . this in turn causes the rope to bend in a roughly “ s ” shaped curve about roller 107 and eccentric pin 108 a thus increasing the friction generated at eccentric pin 108 a and imparting a dragging force on the upper assembly 111 . this force is transmitted down the spine assembly 112 to the connected ends of the lower side plates 103 and 104 , which causes said side plates to pivot about the major axis of bolt 118 b forcing the pin / bollard assembly 114 downwards and pushing the rope into the face of cam / anchor 110 . it is the combination of friction forces acting in concert at the upper and lower assemblies , which allow the climber &# 39 ; s position to be held on the rope . fig5 shows an exploded view of pin / bollard assembly 114 and the mating of eccentric pin 108 a to upper side plate 102 to illustrate an indexing function of these elements . the pattern manufactured into the end portion of eccentric pin 108 a mates to the pattern manufactured in the third aperture of the upper side plate 102 for the purpose of indexing the rotational position of eccentric pin 108 a . by withdrawing bolt 119 c from eccentric pin 108 a , said pin can be pulled out of its mating aperture and rotated to a new position . it is then reinserted and bolt 119 c is tightened to hold eccentric pin 108 a in place during use . eccentric pin 108 b mates with the third aperture of lower side plate 104 in the same fashion as above with the addition of bollard 109 . bollard 109 comprises a first and a second aperture . the first aperture of bollard 109 is offset from center and parallel to the centerline such that the first aperture overlaps the edge of the barrel forming thereby a semicircular cutout the diameter of which is the same as the diameter of the central barrel of eccentric pin 108 b . the second aperture comprises a tapped hole offset from and parallel to the center axis of bollard 109 and mates to the slot ( fourth aperture ) of lower side plate 104 by means of bolt 501 such that bolt 501 may move freely within said slot and bolt 501 further constrains the outer face of bollard 109 to be flush with the inner face of lower side plate 104 . the central barrel of eccentric pin 108 b fits within the first aperture of bollard 109 and rotates freely therein . as eccentric pin 108 b is rotated to different positions , the eccentric position of the center barrel consequently moves bollard 109 in a reciprocal fashion constrained by bolt 501 within the slot ( fourth aperture ) in lower side plate 104 . fig2 shows device 100 in open position preparatory to engaging the device to or disengaging the device from a rope . to open the device from neutral position , the upper assembly 111 , spine assembly 112 , and lower assembly 113 must be aligned in such a way that bolts 118 a , 116 a , 117 , 116 b and 118 b align in a straight line one to the other . upper side plates 101 and 102 may then rotate in opposing directions about the major axis of bolt 118 a , links 105 and 106 may rotate in opposing directions about the major axis of bolt 117 , and lower side plates 103 and 104 may rotate in opposing directions about the major axis of bolt 118 b . this results in a scissors - like action which moves upper side plate 101 and lower side plate 103 away from eccentric pins 108 a and 108 b respectively and allows the rope to be inserted between the roller 107 and the eccentric pin 108 a of the upper assembly 111 and the cam / anchor 110 and pin / bollard assembly 114 of the lower assembly 113 . if any of the five pivot points is not in the straight line with the other four , then the device cannot open . fig3 shows the device 100 in the open position with the rope path 115 illustrated , upper side plate 101 removed for clarity . the rope is passed between eccentric pin 108 a and roller 107 as shown , then down and between eccentric pin 108 b and the concave friction face of cam / anchor element 110 . the device may then be closed , and weight may be applied to cam / anchor element 110 , which will cause the device to seize the rope and bear the weight . the skilled person will understand that the descriptions made above are exemplary , and that there are a considerable range of variability in dimensions , material , fasteners , pivots and the like that may be made within the scope of the invention . consequently the scope of the invention is limited only by the claims that follow .
a rope - climbing device has an upper assembly with planar side plates spaced apart by a roller , such that the side plates rotate relative to one another about the roller axis , a spine unit comprising planar links of common width each of half the plate spacing , the links pivoted at a central point , and a lower assembly comprising third and fourth side plates spaced apart by a clamp element such that the third and fourth side plates are enabled to rotate relative to one another about the clamp axis , and the clamp element is enabled to clamp a rope between the plates . the device may be opened by aligning pivot points , a rope inserted , and closed on the rope . engaged on the rope the device may be set to slide on the rope , ar clamp to the rope by action of a user .