AXLE LOCKING CYLINDER STRUCTURE FOR HEAVY CONSTRUCTION EQUIPMENT

摘要

An axle locking cylinder structure for heavy construction equipment is provided to discharge high pressure working oil from a cylinder chamber effectively and to extend a cylinder rod quickly by supplying working oil to a locking cylinder sufficiently. The axle locking cylinder structure for heavy construction equipment includes a primary pilot passage(12) getting a supply of working oil from a supply passage and discharging pilot pressure, a valve poppet(14) moved vertically by the pilot pressure to open and close a main passage(13) connected to a cylinder chamber(4) selectively, extended from a poppet seat(14a) to the front end and provided with a poppet end projection(19), a pressure chamber(15) formed between the valve poppet and the main passage, a valve spring(16) supporting the valve poppet elastically in the downward direction to keep the main passage closed, a secondary pilot passage(17) connecting working oil discharged from the cylinder chamber to a return passage when the main passage is opened, a branch passage(21) formed between the cylinder chamber and the supply passage and connected parallel to a pilot valve to supply working oil to the cylinder chamber when the cylinder rod is extended, a control plug(18) coupled to the upper part of a locking cylinder(10) to control the elastic force of the valve spring, and a check valve(20) installed to one side of the branch passage, supplied with pilot pressure through a third pilot passage(20) connected with the pressure chamber and provided with a valve plunger(23) to open and close the branch passage selectively.