HYDRAULIC DRIVE APPRARATUS FOR CONSTRUCTION MACHINE

摘要

Provided is a hydraulic drive apparatus for a construction machine capable of achieving both of cavitation prevention and improvement of regeneration efficiency. The apparatus includes a regenerative motor (47) configured to regenerate energy of hydraulic fluid discharged from a slewing motor (33), a first regeneration tank line (61) for returning regeneration discharge fluid from the regenerative motor (47) to a tank (T) through a back pressure valve (45) which is provided in a makeup line (44), a second regeneration tank line (62) for returning the regeneration discharge fluid directly to the tank (T) so as to bypass the back pressure valve (45), a regeneration-tank-line selector valve (63), and a regeneration-tank-line-selection control section (51) configured to shift the regeneration-tank-line selector valve (63) to pass the regeneration discharge fluid through the first regeneration tank line (61) during slewing deceleration and otherwise through the second regeneration tank line (62).