Abstract: An elongated ramp is provided for longitudinal extension and retraction relative to a predetermined margin of a support structure therefor. The ramp includes a longitudinally short base end section and a considerably longer outer end section and the support and ramp include coacting guide structures for supporting and guiding the ramp during extension and retraction thereof, the outer end section of the ramp being automatically disengaged from the support and guide structure responsive to the ramp approaching its fully extended position. In a first form of ramp, a biasing structure is operatively connected between the sections yieldingly resisting downward swinging of the outer end section as it disengages from the support and guide structure during extension of the ramp and the biasing structure is operative to counteract a major portion, only, of the force of gravity acting upon the outer end section to swing the outer end thereof downwardly as the ramp moves to its fully extended position.