the skate 10 , shown in fig1 ( a ) and 1 ( b ), is composed of a series of interconnected skate units in aligned , sequential relationship , each unit comprising a pair of parallel rails 13 , each having a pair of rollers 12 which extend laterally outward . the rollers are rotatable on pins fixed to the rails , and the diameters of the cylindrical parts of the rollers are greater than the height of the rails . the rollers are provided with flanges at their outer ends , which keep the skate units aligned with the cable guide . the skate is sandwiched between opposed portions of a folded cable guide as depicted in fig5 . as the cable guide flexes during use , it flexes in a simple curve . that is , an imaginary centerline , extending longitudinally through the center of cable - accommodating channel within the guide , remains substantially in one imaginary plane , defined by the portions of the centerline in which the opposed portions of the cable guide lie . connecting blocks 15 , maintain a predetermined spacing between the parallel rails 13 , and also connect the skate units to one another . each of the connecting blocks 15 of the skate 10 shown in fig1 ( a ) is a steel plate having a u - shaped cross section , as shown in fig1 ( b ). connecting pins 14 are inserted through insertion holes provided in the rails 13 and in the connecting blocks 15 . the connecting pins are secured to the skate units and connecting blocks by screws 17 , which are threaded into the ends of the connecting pins as shown in the enlargement in fig1 ( a ), and washers 16 underneath the heads of the screws 17 engage the outer surfaces of the rails 13 . as an alternative to the screws and washers , the connecting pins can be secured to the skate units and blocks by cotter pins , wire hoops , or other suitable devices . the length of each of the pins 14 is preferably slightly greater than the sum of the width of the connecting block and the widths of the two opposite rails 13 . moreover , the diameters of the insertion holes in the connecting blocks or in the side rails is slightly greater than the diameters of the pins 14 on both end portions of the connecting pin 14 . as a result , the skate units of each pair of adjacent skate units are freely articulable relative to the connecting blocks and relative to each other about the pin axes through washers 16 , and are thus freely articulable in the plane defined by the portions of the guide centerline within the opposed portions of the guide . the second embodiment , depicted in fig2 ( a ) and 2 ( b ), is similar to the embodiment of fig1 ( a ) and 1 ( b ), and corresponding parts are identified by reference numbers that exceed , by 10 , the reference numbers in fig1 ( a ) and 1 ( b ). the rails 23 , forming the skate units of skate 20 , are held at a predetermined spacing by connecting blocks 25 . these connecting blocks , unlike the u - shaped blocks of the first embodiment , are rectangular prism - shaped blocks , having elongated insertion holes 28 , through which connecting pins 24 extend . the connecting pins 24 are secured in place by cotter pins 26 , and extend through the insertion holes 28 with a clearance , so that the individual skate units can articulate about the pin axes relative to the connecting blocks and relative to one another . in this embodiment , instead of using cotter pins , the connecting pins 24 can be held in place by wire hoops , or by means of screws and washers as in the first embodiment . in the third embodiment , depicted in fig3 , parts corresponding to parts in fig1 ( a ) are identified by reference numbers that exceed , by twenty , the reference numbers in fig1 ( a ). in fig3 each of the connecting blocks 35 in skate 30 is in the shape of a hollow rectangular frame , having side walls but lacking top and bottom walls . short connecting pins 34 extend through insertion holes in the rails 33 and insertion holes formed in walls of the connecting block 35 . cotter pins are provided at both ends of each of the short pins 34 . the adjacent skate units 30 are freely articulable about the pin axes relative to the connecting blocks and relative to one another . the connecting pins can be held in place by wire hoops , or other suitable securing means , instead of by cotter pins . in the fourth embodiment , depicted in fig4 , parts corresponding to parts in fig1 ( a ) are identified by reference numbers that exceed , by thirty , the reference numbers in fig1 ( a ). the units of skate 40 , shown in fig4 are composed of rails 43 having rollers 42 . the rails of each skate unit are maintained at a predetermined spacing from each other by rectangular prism - shaped connecting blocks 45 , and stepped bolts 44 threaded into screw holes in the connecting block 45 . each stepped bolt 44 comprises a head 44 a , a cylindrical portion 44 b , and a threaded portion 44 c as shown in the enlargement . insertion holes in the rails 43 are of a size such that they can receive the cylindrical portions 44 b of the stepped bolts 44 with a small radial clearance . the length of the cylindrical portion 44 b of each bolt is slightly greater than the thickness of the rail though which it extends . thus , when a rail 43 is bolted to the connecting block 45 , the rail is freely pivotable relative to the connecting block at least about the bolt axis so that the skate units are freely articulable relative to the connecting blocks and relative to one another . in each of the four embodiments , the connecting pins or bolts allow the adjacent skate units to articulate freely at least about the axes of the pins or bolts . thus , the skate units are free to articulate at least in a plane defined by the portions of a centerline of the guide within the opposed , facing parts of the guide . because the units articulate freely , even where both facing parts of the guide bend during use , the skate can be made sufficiently long to protect all parts of the guide that might otherwise come into frictional engagement with one another .