Abstract: Twin linkage assemblies shift a support platform between a low profile, fully collapsed position and a fully extended position of a height suitable for supporting a workman underneath an aircraft or for supporting, for instance, an engine at a comfortable working position. A hydraulic cylinder and piston assembly is connected at opposite ends to swivel members and torque arms, the latter of which are connected to short links which in turn are coupled to linkages interconnecting a base and the work supporting platform. The torque arms, in cooperation with the swivel members, facilitate swinging of the links and linkages to reduce the force necessary to separate the platform and base to a value smaller than would otherwise be required.