A mechanism for facilitating the storage of ladders in the upper area on the outside of an emergency vehicle which includes the capability of moving of the ladder to a lower deployed position to facilitate immediate access thereto by emergency workers such as firemen and the like. The construction includes an inner housing attached to the vehicle and an outer housing movable by an arm assembly relative thereto to urge the ladder between the storage and deployed positions. An adjustment mechanism including a yoke is included for varying the position of the powering drive cylinder which operatively moves the outer housing relative to the inner housing.