Articulated jib torque limitation device - has pressure relief valve setting varied by angle of articulation

摘要

The torque-limitation safety device is for a hydraulically-operated articulated jib on a crane etc., slewing on a vertical axis, having a pressure relief valve permanently subjected to a pressure proportional to the torque about the slewing axis. The operating pressure of the relief valve is variable by an adjusting device, controlled by a value proportional to the angle of articulation (W) of the jib. This value can be derived from the ram (S2) derricking the outermost jib section (c). The equipment is partic. for cranes etc. whose jibs are likely to encounter obstructions when slewing or travelling.