| 摘要 |
PURPOSE:To greatly reduce the loss of horsepower by controlling the discharge of a variable discharge pump automatically to a mimimum value when all of operating valves are restored to neutral position. CONSTITUTION:When all spools of operating valve groups are restored to neutral position due to the temporary stoppage of the operation of a construction equipment, etc., between the pilot port and the tank port of each operation valve is broken, whereby the pressure of the pressure chamber 15c of a PC pilot switch valve 15 becomes equal to that of the spring chamber 15g and the spool 15b is pushed toward left side by a compression spring 16. Since the charge pressure of the pump port 153 is supplied through a PC port 154 to the pressure chamber of a pump neutral controller, piston inside the pressure chamber moves toward discharge-reducing direction, so that the discharge of each discharge pump is maintained at minimum value. Thus, the loss of horsepower can be greatly reduce and the cost of fuel can be also improved. |
