end walls 26 are clamped or affixed to the rung of a ladder by means of outer tube 22 as the end walls of the rung connector are pushed toward each in order to fit them over separate vertical supports of the ladder the two segments of the outer tube slide toward each other when no further inward movement is possible the segments are immobilized by means of locking pin 24 the end walls of the rung connector are then locked into engagement with the ladder the outer tube and locking pin accordingly function to clamp the rung connector to the ladder since the inner tube can be inserted into any of the rungs of the ladder the elevation of the rung connector is adjustable the ladder support is accordingly adjustable on the ladder at preselected locations thereon i e wherever this is a rung with reference to fig5 6 and 7 each link 20 is composed of a channel 50 to which a circular toothed coupling 52 is welded or otherwise attached to its inner end the teeth of the coupling and the spaces between them mate with the teeth and spaces of each of the couplings 30 of the rung connector the two couplings 52 30 are outer and inner of each other respectively and are interconnected by a bolt not illustrated which extends through the end walls 26 of the rung connector through the two couplings 30 52 and terminates at a threaded outer end to which a knurled knob 56 is threadably attached loosening of knob 56 allows the links which are slidable on outer arm 16 to be separated from the rung connector so.