DUST SEAL OF MULTI-STAGE HYDRAULIC JACK

摘要

PROBLEM TO BE SOLVED: To prevent pressurized oil in a back pressure chamber of a lower piston from being ejected from a cylinder of an upper piston in a multi-stage hydraulic jack in which the upper piston is inserted in the lower piston in a vertically movable manner and the back pressure chamber of the lower piston is communicated with a positive pressure chamber of the upper piston and pressurized oil is filled in each back pressure chamber. SOLUTION: An oil seal and a dust seal are internally fitted to a lower portion and an upper portion of an upper end ring provided on the upper end of a rod cylinder of a lower piston to slidably hold a rod cylinder of an upper piston, and at least one portion on the circumference of the dust seal is radially cut. COPYRIGHT: (C)2004,JPO&NCIPI