Patent ID: 8392059

Claim:
A method for clocking cumulative operating time for a cargo-handling vehicle provided with a plurality of functional units, the functional units comprising at least a first functional unit and a second functional unit; whereby, each of the first functional unit having a first clocking device and the second functional unit having a second clocking device clocks the cumulative operating time of the cargo-handling vehicle, by use of each clocking device; the data information regarding the clocked cumulative operating time is stored in a memory device provided in each functional unit; the data information regarding cumulative operating time stored in each functional unit transmitted toward the other functional units, and the data regarding cumulative operating time over all the functional units are mutually transmitted one another, through a communication port provided in each functional unit for sending and receiving the data information; the differences among the data regarding the cumulative operating time over all the functional units are estimated so that the greatest cumulative operating time and the unit corresponding to the greatest cumulative operating time over all the functional units are identified; each of the functional units selects either of a synchronous mode under which the data regarding the greatest cumulative operating time stored in the functional unit corresponding to the greatest cumulative operating time is overwritten on the data regarding cumulative operating time stored in the remaining functional units so that all the differences among the data regarding cumulative operating time over all the functional units are cancelled, or a synchronization prohibition mode under which the process execution under the synchronous mode is prohibited; thereby each functional unit is placed under the synchronous mode in a case where the maximum value among the data regarding the cumulative operating time over all the functional units is less than or equal to a predetermined T, whereas each functional unit is placed under the synchronization prohibition mode in a case where the maximum value is greater than the predetermined time T.