Safety mechanism for telescopic boom crane

摘要

The hydraulic jack includes cylinder inside which slides a tightly sealed piston linked to a stem extending out of the cylinder. It has a constraint detector to detect all load in the axial direction of the hydraulic jack, corresponding to the load on the stem. A strain-gauge rigidly fixed to the jack will detect all load and emit an electrical signal. As a preferred addition to this claim at least one gauge is lodged between the cylinder's bottom and its supporting axis or on the periphery of the piston's stem