Hydraulic system for a work machine such as bull dozer, which has an ejector cylinder and a tailgate cylinder that moves through hydraulic action

摘要

A method of controlling movement of an ejector plate and a tailgate includes the step of supplying pressurized fluid via a fluid line (168) to an intake port (172) of a multi-stage cylinder (160), moving the ejector, and a second intake port (176, 178) of a single stage cylinder (150) moves the tailgate. During the first step, flow from the tailgate cylinder(S) is blocked by a locking valve (180), which is biased closed by a spring (185), is opened when the pressure in the line (186) is sufficient. A control assembly for a multistage cylinder, consists of a selector valve (170) having an eject, retract and lock modes. A bypass line (190) and valve (192) allows the flow to sump (162) when valve is in the retract mode.