Hydraulic device of a simple tipper cylinder

The hydraulic control unit (H) has seat valve (S) which is provided between pressure line (1) and working duct (32) of tipper cylinder (Z), attached with pressure source (P). The pilot-operated check valve (R) is provided in the unlocking terminals (17,17') for unlocking the circulation-seat valve (U) based on operating situation of the tipper cylinder. A pressure relief valve (D) is provided in bypass pipe (19) between the pressure line and tank line (2). The seat valve, circulating-seat valve, check valve and pressure relief valve are accommodated in a common block.