HYDRAULIC DRIVE SYSTEM

摘要

A hydraulic drive system (1A) having first and second multi-control valves (4A, 4B) connected to first and second hydraulic pumps (21, 22). A first regulator (3A) adjusts the tilt angle of the first hydraulic pump (21) such that the discharge flow rate of the first hydraulic pump (21) reduces the higher the discharge pressure of the first hydraulic pump (21) and the higher a first power shift pressure. A second regulator (3B) adjusts the tilt angle of the second hydraulic pump (22) such that the discharge flow rate of the second hydraulic pump (22) reduces the higher the discharge pressure of the second hydraulic pump (22) and the higher a second power shift pressure. The first power shift pressure is set by a first proportional valve (72a) and the second power shift pressure is set by a second proportional valve (72b).