Articulated aerial device including an upper boom compensation unit

摘要

An aerial lift apparatus unit includes at least a lower boom pivotally interconnected to a transport unit for raising and lowering of the lower boom. An upper boom is pivotally connected to the outer end of the lower boom for raising and lowering of the upper boom with respect to the lower boom. A single integrated lifting and compensating cylinder unit includes an elongated cylinder with a piston and piston rod journaled in the one end and operable to extend outwardly therefrom. The cylinder defines a dual operating cylinder with a base end from which the piston rod extends and an inner base end extending from the base end and defining an upper boom/compensating unit. A hydraulic control system includes a first hydraulic gated control system for raising and positioning of the upper boom relative to the lower boom. A hydraulic unit and control system for raising and lowering of the lower boom includes a control module connected to the upper boom/compensating unit and an interrelated positioning module to the lower boom and connected to the hydraulic system for raising and lowering of the lower boom. The control module and lower boom module are connected to each other in response to the flow of hydraulic fluid for lowering and raising of the lower boom and simultaneously provide for direct transfer of fluid from the rod end and the base end of the upper boom positioning unit with the fluid flow and control of the lower boom to position the upper boom to maintain its preset orientation with respect to the ground. The compensating module includes valves connected to the opposite sides of the upper boom for establishing an interrelated flow between the boom/compensating unit and thereby the upper cylinder and the lower cylinder during movement of the lower boom.