An adjustable support apparatus for a recreational vehicle permits rapid height adjustment with a spring mechanism of a handle-nut assembly on a threaded rod. A portion of the threaded rod is inserted into the hollow portion of a jackscrew assembly. A tab on the handle-nut assembly includes an over-sized hole intersecting a threaded hole for engaging the threaded rod. An approximate desired height of the support apparatus is accomplished by pushing a tab inward and sliding the handle-nut assembly to a desired position on the threaded rod. A fine adjustment to the desired height, if required, is made by turning the handle nut assembly so that it travels with respect to the threaded rod.