Pressure control system for lock-up clutch in automotive automatic power transmission with compensation of fluid pressure in low engine speed range

摘要

A pressure control system for a lock-up clutch includes a variable flow restriction orifice disposed in a lubricating circuit. The variable flow restriction orifice is operated depending upon a discharge rate of an oil pump so that working fluid flow through the lubricating circuit is restricted when the discharge rate of the oil pump is smaller than a predetermined value.