Hydraulic circuit for boom cylinder combination has two inner paths formed on one side of cylinder to connect operation oil from hydraulic pump to hydraulic tank, and to connect oils from chambers to tank, respectively

摘要

The circuit has an inner path (3a) formed on a side of a boom cylinder (6) combining a spool (5), and connecting a hydraulic pump (1) and a cylinder large chamber (6b) in a switching mode. Two inner paths (3b, 3c) are formed on other side of cylinder to connect operation oil from pump to a hydraulic tank (18) in a switching mode, and to connect the oils from a small chamber and large chamber to tank, respectively.