Rotation control device and construction machine including rotation control device

A rotation control device comprising:

• a slewing motor driving a slewing body to rotate;
• a hydraulic pump serving as a hydraulic pressure source of the slewing motor;
• a pair of rotation hydraulic fluid paths connected to ports on both sides of the slewing motor for driving the slewing body in two directions;
• a control valve provided between the respective rotation hydraulic fluid paths and the hydraulic pump and switching a supply destination of a hydraulic fluid, which is discharged from the hydraulic pump, between the respective rotation hydraulic fluid paths;
• a pair of relief valves serving as brake valves respectively connected to the rotation hydraulic fluid paths;
• rotation operating means for operating the control valve;
• an operation detector detecting an operating direction and an operating amount of the rotation operating means;
• a rotation direction detector for detecting a rotating direction of the slewing body;
• and
• a controller controlling a discharge amount of the hydraulic pump such that in a forward direction operation in which the operating direction detected by the operation detector and the rotating direction detected by the rotation direction detector coincide with each other, the discharge amount of the hydraulic pump is increased in accordance with an increase in the operating amount detected by the operation detector, on the other hand, in a backward direction operation in which the operating direction detected by the operation detector and the rotating direction detected by the rotation direction detector are reverse to each other, the discharge amount of the hydraulic pump is restricted more than the discharge amount in the forward direction operation.