Method and apparatus for monitoring the effective load carried by a crane
First Claim
1. A method of monitoring the effective load carried by a crane having a luffing boom of variable effective radius, the method comprising generating a first signal corresponding to the magnitude of a load supported by the boom, generating a second signal corresponding to the effective boom radius, performing a calculation on the signals to calculate a load moment value, displaying the calculated load moment value, comparing the calculated load moment value with a predetermined maximum permissible load moment value, and generating a warning signal if the calculated load moment value exceeds said predetermined maximum permissible load moment value, the, effective boom radius being determined from a predetermined relationship between the luffing angle of the boom and the first signal, said boom being raised and lowered by means of a hydraulic ram, the luffing angle of the boom being measured by monitoring the displacement of hydraulic fluid in the ram as the boom is raised or lowered to a reference angle.
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Abstract
This is a method and apparatus for monitoring the effective load carried by a crane having a luffing boom of variable effective length. The method includes generating a first signal corresponding to the magnitude of the load supported by the boom and then a second signal corresponding to the effective radius. Calculations are made to calculate a moment value and displaying same. This is then compared with a predetermined maximum permissible moment value and a warning signal is generated it if differs from the maximum load moment value by less than a predetermined amount. The apparatus provides apparatus for carrying out the method by generating a first signal corresponding to the load supported by the boom and a second signal corresponding to the effective radius and includes processing means for performing calculation of the first and second signals to derive the load moment value and displaying same and memory means for storing a predetermined maximum permissible load moment value and comparative means for comparing the calculated load moment value with a predetermined maximum permissible load moment value.
25 Citations
15 Claims
- 1. A method of monitoring the effective load carried by a crane having a luffing boom of variable effective radius, the method comprising generating a first signal corresponding to the magnitude of a load supported by the boom, generating a second signal corresponding to the effective boom radius, performing a calculation on the signals to calculate a load moment value, displaying the calculated load moment value, comparing the calculated load moment value with a predetermined maximum permissible load moment value, and generating a warning signal if the calculated load moment value exceeds said predetermined maximum permissible load moment value, the, effective boom radius being determined from a predetermined relationship between the luffing angle of the boom and the first signal, said boom being raised and lowered by means of a hydraulic ram, the luffing angle of the boom being measured by monitoring the displacement of hydraulic fluid in the ram as the boom is raised or lowered to a reference angle.
- 9. Apparatus for monitoring the effective load carried by a crane having a luffing boom of variable effective radius which comprises means for generating a first signal corresponding to the magnitude of a load supported by the boom, means for generating a second signal corresponding to the effective boom radius from a predetermined relationship between the luffing angle of the boom and the first signal, processing means for performing a calculation on the signals to derive a load moment value, display means for displaying the load moment value, memory means for storing a predetermined maximum permissible load moment value, comparator means for comparing the calculated load moment value with the predetermined maximum permissible load moment value, and means for generating a warning signal if the calculated load moment value exceeds said predetermined maximum permissible load moment value, said boom being raised and lowered by means of a hydraulic ram, the luffing angle of the boom being measured by monitoring the displacement of hydraulic fluid in the ram as the boom is raised or lowered relative to a reference angle.
Specification