SHOCKLESS LIFT CYLINDER FOR FULL FREE MAST AND TRIPLE MAST

摘要

PROBLEM TO BE SOLVED: To reduce vertical vibration of a mast also transmitted to an operator, which is enlarged as weight (its own weight) becomes heavy, caused by a transient change in an oil amount or pressure because a pressure reception area changes when changing over between a front cylinder and a rear cylinder in the conventional two-stage cylinder mast.;SOLUTION: This two-stage cylinder for the masts, i.e., the shockless lift cylinder for the full free mast and the triple mast, is provide with a front lift cylinder 1 including a gradually-narrowed flow passage; and a rear lift cylinder 2 with a cushion part 3, including a ball type poppet valve 4 for securing only one-way flow passage when ascending, and for controlling a flow passage when descending.;COPYRIGHT: (C)2002,JPO