SHOVEL AND CONTROL METHOD THEREFOR

摘要

A shovel (1) is provided with: a boom cylinder (7) and a bucket cylinder (9) that are driven by hydraulic oil that is discharged by a hydraulic pump (10R); a regenerated oil path that causes hydraulic oil that flows out from the bottom-side oil chamber of the boom cylinder (7) to flow into a rod-side oil chamber; a returning oil path (32R) that connects the bucket cylinder (9) and a hydraulic oil tank (22); a supplemental oil path (34) that makes it possible to connect the bottom-side oil chamber of the boom cylinder (7) and the returning oil path (32R); and a variable check valve (50) that is capable of blocking the connection between the hydraulic oil pump (10R) and the boom cylinder (7). The variable check valve (50) blocks the connection between the hydraulic oil pump (10R) and the boom cylinder (7) when a combined operation that includes a boom lowering operation and a bucket operation is performed. Hydraulic oil that flows out from the bottom-side oil chamber and the hydraulic oil from the returning oil path (32R) flow into the rod-side oil chamber.