REVOLUTION CONTROL DEVICE

摘要

A swivel control apparatus according to the present invention , includes: a hydraulic pump; a hydraulic motor for swiveling which is driven by hydraulic oil emitted from the hydraulic pump; a control valve which controls a flow of hydraulic oil which is supplied from the hydraulic pump to the hydraulic motor for swiveling, and at a neutral position of the control valve cuts off from one another a pair of ports which communicate to input and output ports of the hydraulic motor; a valve device which communicates and cuts off from one another a pair of conduits which are respectively connected to the input and output ports of the hydraulic motor for swiveling; a pressure detection device which detects respective pressures in the two conduits and outputs pressure signals; a rotational speed detection device which detects a physical quantity based upon a rotational speed of the hydraulic motor for swiveling and outputs a rotational speed signal; a mode selection device which selects a neutral brake mode and a neutral free mode; and a control device which controls driving of the valve device so as to cut off the two conduits from one another when the neutral brake mode is selected, and so as to communicate the two conduits based upon the pressure signals and the rotational speed signal when the neutral free mode is selected. <IMAGE>