Patent attributes
The present invention provides a safety device against crane overturning which operates in a crawler crane comprising at least four outriggers in a frame, the safety device comprising a load detector 2 that detects a ground reaction to each of the outriggers, and an alarm output section 4 which calculates sums of detected values for ground reactions to every two adjacent outriggers to find a minimum value of the sums. The alarm output section then compares the minimum value obtained with a preset preliminary reference value and a preset limit reference value and outputs a preliminary alarm signal when the minimum value is smaller than the preliminary reference value or outputs a limit alarm signal when the minimum value is smaller than the limit reference value. This prevents safety from being degraded as a result of a change in the working radius of the crane. Further, calculation processes are simplified.
