Telescopic extension, for mobile crane, has inner casings extended in succession via hydraulic two-stage piston/cylinder system

摘要

The telescopic extension has an outer casing enclosing one or more inner casings, fitting coaxially within one another and extended in succession via a hydraulic 2-stage piston/cylinder system (10), fixed to the outer casing at one axial end and coupled to each inner casing via a securing and locking device (8,9). The piston/cylinder system has an outer cylinder (11) and an independently operated inner cylinder (12) acting as the piston of the outer cylinder, the outer cylinder and a piston rod (13) within the inner cylinder providing the extensible parts of the piston/cylinder system.