Crane load computer

Claim 1

Device for checking the loading state of a lifting applicance including a crane having a telescopic jib provided with a hook from which a load is adapted to be suspended, comprising: a calculation member for determining the weight of the suspended load on the hook of the crane; memory means including memories storing information derived from diagrams previously prepared, the diagrams providing values of various admissible loads which depend on various values of at least one parameter defining the geometric state of said applicance; a central unit coupled with said calculation member and said memory means for receiving information relating to the parameters of said crane for determining the maximum admissible load for each of the values stored in said memory means; said unit producing as an output a value desired for the load by a process of incrementation which consists of dividing the intervals between two maximum admissible load values corresponding to two values of a parameter defining the geometric state of the crane, in which: C 1 is a lower value for one of said maximum admissible load values from the previously prepared diagrams, C 2 is a higher value for another of said maximum admissible load values from the previously prepared diagrams, N is the number of increments in which the values C 2 -C 1 is divided. C i is a maximum admissible load value falling between said load values C 1 and C 2 for which there is no previously prepared diagram and information stored in said memory, the value of the maximum admissible load C i is determined according to the expression: ##EQU5## in which K is the grade of the increment corresponding to the parameter and whose expression is ##EQU6## in which: l i is the length of said jib for the load C i , l 1 is the length of said jib for the load C 1 , and l 2 is the length of said jib for the load C 2 ; said central unit including a comparison means to compare the value of the maximum admissible load of said lifting appliance with the value of the actual suspended load as determined by said calculation member; and, a testing device for checking that the loading state is operating correctly, said testing device comprising a member for introducing into the calculation chain a perfectly calibrated voltage of a load raised of greater value than any value inserted into said memory from the previously prepared diagrams and being easily identifiable, whereby to enable the checking of the correct operation of the checking device before it is used.