Abstract: A load lifting device includes a lower structure, an upper structure movable with respect to the lower structure between a lowered position and a raised position, a scissors-like pantograph, including at least two arms mutually articulated according to an X-shape, connecting the upper structure to the lower structure, and an actuator device controlling the position of a connecting element which connects the actuator to one arm of the pantograph and having a cam-following element cooperating with a fixed cam. The actuator is articulated to the connecting element around an axis which is located below the articulation axis of the connecting element to the arm of the pantograph, in such a way that, when the actuator is activated to cause the lifting movement of the device, the connecting element acts as a pushing strut subjected substantially to compression between the cam and the articulated arm. Preferably the actuator includes a hoist device with a belt, cord, or chain engaging a number of pulleys.

Abstract: A load lifting device includes a lower structure, an upper structure movable with respect to the lower structure between a lowered position and a raised position, a scissors-like pantograph, including at least two arms mutually articulated according to an X-shape, connecting the upper structure to the lower structure, and an actuator device controlling the position of a connecting element which connects the actuator to one arm of the pantograph and having a cam-following element cooperating with a fixed cam. The actuator is articulated to the connecting element around an axis which is located below the articulation axis of the connecting element to the arm of the pantograph, in such a way that, when the actuator is activated to cause the lifting movement of the device, the connecting element acts as a pushing strut subjected substantially to compression between the cam and the articulated arm. Preferably the actuator includes a hoist device with a belt, cord, or chain engaging a number of pulleys.

Abstract: A unidirectional valve (7) forms a reduced meatus which extends in the direction of the obturator (23) movement, which meatus is to be passed through by possible microleaks in case of losses in the actuator branch (3); a considerable run of the obturator (23) in the presence of microleaks and of consequent pressure losses is thus obtained; a sensor (47) detects the obturator displacements.

Abstract: The actuator of rapid linear variable motion comprises: a linear member--fixed or sliding--having a concave cylindrical surface with generatrices parallel to the direction of motion of said member, on which variable-pitch helix-like and shaped channels are formed; and a rotating member with its axis parallel to the linear member and provided with pegs angularly distributed and capable of coming in contact, one after the other, with limited contemporaneousness, with the channels of the linear member.