CONTROLLER FOR QUANTITY OF DISCHARGE OF PUMP OF HYDRAULIC CLOSED CIRCUIT

摘要

PURPOSE:To prevent the sudden change of speed in case of the falling of one- rod cylinder by comparing the magnitude of the pressure of two ducts of the hydraulic closed circuit and regulating the acceleration of the one rod cylinder in case of the falling of an activator. CONSTITUTION:A first pressure detector 15 detects the internal pressure of the duct 4, and outputs the output value as signals. A second pressure detector 16 similarly outputs signals concerning the duct 5. A controller 17 is subject to said signals, and electrically operates a control mechanism 13 for the quantity of discharge of the variable-capacity pump by an output device 21. The sudden change of speed in case of the falling of the one-rod cylinder is prevented because the maximum quantity of variation in aptitude which can change the quantity of operation command of the control mechanism 13 for the quantity of discharge of the pump 3 is set lest the acceleration of a boom cylinder 2 should exceed acceleration by the gravity of a boom 1.