EXPANDING/CONTRACTING DEVICE OF SPREADER

摘要

PROBLEM TO BE SOLVED: To provide an expanding/contracting device of spreader whose value as a product is heightened by raising the cylinder speed in expansion to the same degree as at contraction while contriving to make the diameter of the piping for the cylinder smaller. ;SOLUTION: An expanding/contracting device of a spreader is equipped with an expansion/contraction cylinder 6 for adjusting the gap of a twist lock 3 and a control valve 8 to control the expanding and contracting motions of the cylinder 6, wherein the bottom side oil chamber 6a of the cylinder 6 is connected to a rod side oil chamber 6b through a bypass line 13. The bypass line 13 is furnished with a solenoid operated selector valve 14 which is held in the close position at normal times and changed over to the open position when the control valve 8 is turned to the elongate position in which the working oil from a hydraulic pump 7 is fed to the bottom side oil chamber 6a. When the control valve 8 is in the elongate position, the rod side oil chamber 6b of the cylinder 6 should be kept free of connection with a tank port.;COPYRIGHT: (C)1999,JPO