HYDRAULIC ACTUATOR DRIVING CIRCUIT OF CONSTRUCTION MACHINE

摘要

PROBLEM TO BE SOLVED: To suppress cost-up and establish a space-saving arrangement by lessening piping leading to a low-pressure relief valve. SOLUTION: A low-pressure relief section 20 is integrally incorporated into a regular-reverse changeover valve for the motor rotation. The relief section 20 is equipped with a low-pressure relief changeover valve 21 connected with the regular-reverse changeover valve for motor rotation through a parallel circuit 25 and a relief valve 22 installed at one of the discharge ports of the changeover valve 21. The relief pressure of the relief valve 22 is set lower than the relief pressure of a main relief valve.