| 摘要 |
Twin linkage assemblies shift a support platfom 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 (76) is connected at opposite ends to swivel members (86,88,94,96) and torque arms (102,104,110,112), the latter of which are connected to short links (64,70) which in turn are coupled to linkages (48,56) interconnecting a base (22) and the work supporting platform (24). The torque arms (102,104,110,112), in cooperation with the swivel members (86,88,94,96), facilitate swinging of the links (64,67) and linkages (48,56) to reduce the force necessary to separate the platform (24) and base (22) to a value smaller than would otherwise be required. In preferred embodiments, opposite end regions of the cylinder (78) and piston (80) are provided with trunnions (82,84) that carry the swivel members (86,88,94,96) and which engage stops (46,34) mounted to the platform (24) and base (22), to resist rotational urging of the piston and cylinder assembly (76) and to assist the torque arms (102,104,110,112) in swinging the links (64,70) and associated linkages (48,56) both when the assembly is collapsed and when the assembly is extended. |
