Synchronism control manner and device null of lifting jack

摘要

PROBLEM TO BE SOLVED: To easily and synchronously control jack groups by finding deviation to minimum displacement by detecting stroke displacement of respective jacks, and making it coincide with stroke displacement of a jack to show minimum displacement by reducing output of a jack whose deviation becomes equal to or larger than a preset value. ;SOLUTION: When an ascent-descent of a lifting-up material 56 is started, the same output operation such as operating respective lifting-up jacks 60 in a rated value is performed. When a difference is caused in stroke displacement between the respective jacks 60, output of the other jack 60 is reduced with a jack 60 minimum in stroke displacement as a reference, and the stroke displacement of the respective jacks 60 is equalized. That is, a jack 60 whose stroke displacement is minimum is found up, and when deviation between stroke displacement of the other jack 60 and stroke displacement of a reference jack 60 becomes equal to or larger than a preset value, output of the other jack 60 is reduced. Therefore, jack groups can be easily and synchronously controlled, and the lifting up material 56 can be raised and lowered almost in parallel.;COPYRIGHT: (C)1997,JPO