HYDRAULIC CIRCUIT FOR ATTACHMENT

PURPOSE:To provide an attachment hydraulic circuit enabling the gentle start of a working device so as to attain the safety of work and prolong the life span of the whole device. CONSTITUTION:There are provided a direction switching valve 12 for operating the start and stop of a working device 1, and a flow control valve 31 for controlling the flow of pressure oil supplied to the working device 1. There is also provided an escape valve 32 operated in response to differential pressure between load pressure at the inlet of the working device 1 and the delivery pressure of pressure oil from a hydraulic source 21 so as to let pressure oil from a hydraulic pump 21 escape to a return circuit 3B in order to maintain the differential pressure to the specified value. There are further provided a pressure transmission delay means 37a, installed at pilot circuits 33, 34, 35 for leading load pressure at the inlet of the working device 1, for limiting the transmission of this load pressure so as to delay the response of the escape valve 32; and a pressure control valve for regulating the maximum pressure of the pilot circuits 33, 34.