HYDRAULIC CONTROL DEVICE FOR AUTOMATIC TRANSMISSION

摘要

PROBLEM TO BE SOLVED: To provide a hydraulic control device for an automatic transmission stable against variation and capable of sharing an excellent controllability during transient period of speed change by fine hydraulic control and assurance of torque capacity holding an engagement after completing a speed change. SOLUTION: A selector valve (d) leaving an output pressure PO from a pressure-reducing control valve (c) at a tightening element pressure PC until the output pressure PO from the pressure-reducing control valve (c) reaches a set switching pressure PCO and, when the output pressure PO from the pressure-reducing control valve (c) is increased over the set switching pressure PCO, switching the to the side for feeding a line pressure PL to the tightening element (a) is provided between the pressure-reducing control valve (c) and the tightening element (a). Also a gain at the pressure-reducing control valve (c) is set smaller than that at the pressure-reducing control valve obtained when the tightening element pressure is controlled directly only by the pressure- reducing control valve.