CIRCUIT PRESSURE CONTROL DEVICE, HYDRAULIC CONTROL CIRCUIT USING CIRCUIT PRESSURE CONTROL UNIT, AND HYDRAULIC CONTROL CIRCUIT OF CONSTRUCTION MACHINE

摘要

A circuit pressure control unit includes a relief valve and a variable throttle valve. The relief valve is connected to a connecting passage communicating with an actuator upstream. The variable throttle valve is disposed upstream of the relief valve and is configured to change an opening degree thereof according to a control signal from a controller.