Abstract: This invention provides for a spring-balanced loading arm with a positive lock-down device use in a material handling system. It includes a swivel arm which is pivotally connected at one end to a support structure for swivel movement both in horizontal and vertical planes relative to the support structure. There is also provided an extendable lock-down device for positively locking the swivel arm. One end of the lock-down device is pivotally connected to the support structural and the other end is fixedly connected to the swivel arm. The lock-down device is adapted to be locked in position at several predetermined lengths. When the lock-down device is locked in a given position, it also positively locks the swivel arm and prevents any vertical movement of the loading arm.

Abstract: This invention provides for a loading arm for use with material handling systems and includes a support structure and an arm pivotally attached to the support structure for swivel movement in both the horizontal and vertical plane relative to the support structure.

Abstract: An extensible cantilever boom assembly, for a mobile crane, has telescopically interfitting box-like boom sections, that include web or side plates of uniform thickness. These plates are shaped to provide increased stiffness, and openings are provided within some of the plates to reduce the plate weight, so that the load carrying capacity of the boom is increased. A plurality of shaped portions are formed within the plates, at locations intermediate the top edges and the bottom edges of the plates. These plate portions are spaced laterally from the parallel planes that define the side surfaces of the plates, at the junctures of the side surfaces with the top and bottom edges. The shaped portions, located at longitudinally spaced intervals, are aligned in a row that extends longitudinally of the plate. Each shaped portion has a regular geometrical pattern that forms a laterally projecting protuberance on one side of the plate and a corresponding depression on the opposite side of the plate.