POWER CONTROLLER FOR AT LEAST TWO VARIABLE DISCHARGE HYDRAULIC PUMP

摘要

PURPOSE: To provide a power control device with a simple structure and being deliverable from a plant in the form of having a built-in power throttle. CONSTITUTION: A power control device 18 for controlling in a direction of reducing a displacement of variable displacement pumps along a hyperbolic control curve is actuated by control pressures against a pressure difference in a direction of a control position. The pressure difference is generated between a back pressure of a spring device against a first control pressure and a second pressure corresponding to an actuation pressure in an actuation line of another variable displacement hydraulic pump. This pressure difference decreases from a predetermined maximum value till a predetermined minimum value with increase of the second control pressure. The spring device is divided into a first pressure spring 22 and a second pressure spring 30. The first spring device is set to a force corresponding to the minimum value of the pressure difference, and the second spring device is set to a force corresponding to a difference between the maximum value and the minimum value of the pressure difference. The first pressure spring acts on the power control valve with the set force, and the second pressure spring acts on the power control valve at a force decreases with the increase of the second control pressure.