Hydraulic control system for work machine

A hydraulic control system for a work machine including:

• a hydraulic actuator;
• a first hydraulic pump and a second hydraulic pump capable of communicating with the hydraulic actuator;
• a first directional control valve that is disposed in a pump line communicating with a delivery port of the first hydraulic pump and communicates with the hydraulic actuator, the first directional control valve capable of interrupting a communication between the first hydraulic pump and the hydraulic actuator and returning a hydraulic fluid delivered by the first hydraulic pump to a tank;
• a second directional control valve that is disposed in a pump line communicating with a delivery port of the second hydraulic pump and communicates with the hydraulic actuator;
• and
• a first pressure sensor that detects a load on the hydraulic actuator, the hydraulic control system comprising:
• a pressure reducing valve that is provided in a pilot line connected with the first directional control valve and configured to limit or interrupt a pilot hydraulic fluid to be supplied to the first directional control value;
• a communication control section that takes in a detection signal detected by the first pressure sensor, outputs a command signal to the pressure reducing valve and drives the first directional control valve such that a communication area between the first hydraulic pump and the tank is enlarged corresponding to an increase in the load on the hydraulic actuator;
• and
• a flow rate control section that, during supply of the hydraulic fluid from the first hydraulic pump and the second hydraulic pump to the hydraulic actuator, takes in a detection signal detected by the first pressure sensor and controls to reduce a delivery flow rate of the first hydraulic pump corresponding to an increase in the load on the hydraulic actuator.