Hydraulic circuit of excavating and slewing working vehicle

A hydraulic circuit of a excavating-and-slewing working vehicle, comprising:

• actuators for a boom, a bucket, stewing and an arm;
• directional control valves for the respective actuators;
• a pair of first and second hydraulic pumps for supplying pressure oil to the actuators through the respective directional control valves;
• a delivery oil passage of the first hydraulic pump tandem-connecting the boom directional control valve for boom to the bucket directional control valve for bucket on the downstream side of the boom directional control valve;
• a delivery oil passage of the second hydraulic pump tandem-connecting the stewing directional control valve for stewing to the arm directional control valve for arm;
• a check valve, wherein the delivery oil passage of the first hydraulic pump passes the bucket directional control valve and is connected to a portion of the delivery oil passage of the second hydraulic pump between the stewing directional control valve and the arm directional control valve through the check valve;
• and
• a bleed circuit branching from the delivery oil passage of the first hydraulic pump on the upstream side of the check valve so as to be opened and closed in association with switching of a further upstream located one of the stewing directional control valve and the arm directional control valve.