Provided is a construction machine that can prevent a machine body from being lowered without placing a blade in a floating state when the machine body is jacked up, even if the operator performs an erroneous operation, and that can perform favorable leveling work by placing the blade in the floating state when the machine body is not jacked up. A hydraulic excavator includes a pressure sensor that detects the pressure in a bottom-side oil chamber of a blade cylinder, and a controller that switches between validation and invalidation of a floating command and a lowering command for a blade operation device. In the case where the pressure detected by the pressure sensor is less than a predetermined value, the controller switches a solenoid selector valve to an interruption position to invalidate the floating command when a forward stroke of the operation lever is equal to or more than a reference value. In the case where the pressure detected by the pressure sensor is equal to or more than the predetermined value, the controller holds the solenoid selector valve in a communication position to validate the floating command when the forward stroke of the operation lever is equal to or more than the reference value.

A hydraulic excavator drive system includes: a boom cylinder; a boom first control valve connected to the boom cylinder by a boom raising supply line and a boom lowering supply line, and connected to a first pump by a first boom distribution line; a boom second control valve connected to the boom raising supply line by a boom replenishment line, and connected to a second pump by a second boom distribution line; an arm cylinder; an arm control valve connected to the arm cylinder by an arm crowding supply line and an arm pushing supply line, and connected to the second pump by an arm distribution line; a regenerative line connecting between the boom replenishment line and the arm distribution line; and an openable and closeable regenerative valve provided on the regenerative line.

A hydraulic system embodying a method for combining two or more hydraulic functions from operatively associated distributor valves to selectively increase fluid flow using only hydraulic switches and valves is provided. Each two or more preselected hydraulic functions may each have a piloted diverter valve operatively associated with the other(s) so that when a control valve of the first hydraulic function is selectively positioned to a maximum pressure the first diverter valve actuates the second (and other) diverter valve(s) to couple to the first hydraulic function. Solving the problem where a user has two hydraulic flows that are limited by the diameter/distance of the hoses or pipes to a maximum flow rate almost regardless of pressure but needs to increase that flow to efficiently perform a task.

A hydraulic system embodying a method for combining two or more hydraulic functions from operatively associated distributor valves to selectively increase fluid flow using only hydraulic switches and valves is provided. Each two or more preselected hydraulic functions may each have a piloted diverter valve operatively associated with the other(s) so that when a control valve of the first hydraulic function is selectively positioned to a maximum pressure the first diverter valve actuates the second (and other) diverter valve(s) to couple to the first hydraulic function. Solving the problem where a user has two hydraulic flows that are limited by the diameter/distance of the hoses or pipes to a maximum flow rate almost regardless of pressure but needs to increase that flow to efficiently perform a task.

A control system may be used to control actuators that actuate movement of flight control surfaces of an aircraft. Each actuator is couplable to a flight control surface and includes a motion control assembly having a hydraulic motor and a drive path from the hydraulic motor to the flight control surface. Each hydraulic motor includes an extend port and a retract port. The system includes a hydraulic control module fluidly connected to the extend port and the retract port of each hydraulic motor and a controller operable to output hydraulic power from the hydraulic control module to the motion control assembly to actuate movement of the flight control surfaces. The controller is configured to identify an actuator that positionally leads the other actuators and reduce hydraulic power to the motion control assembly assigned to such actuator.

The present invention relates to an electric driven hydraulic power system for heavy equipment, and more particularly, to a hydraulic power system, which includes a hydraulic pump operated by a battery and a motor, a supply line for supplying a hydraulic oil that is supplied by the hydraulic pump, a plurality of actuators, and a controller for controlling the motor and the actuators, in which electrical efficiency is significantly improved. In particular, the present invention relates to an electric driven hydraulic power system in which a plurality of motors and a plurality of hydraulic pumps corresponding to the motors, respectively, are provided, and a main control valve (MCV) for receiving a hydraulic oil from the hydraulic pumps to supply the hydraulic oil to a plurality of actuators is provided, so that efficient control is performed according to an operating load, an operating temperature, a supply flow rate, and the like to minimize power consumption of the motor, and thus electrical efficiency is improved to dramatically increase an operating time.

A failsafe vale provides Hole-In-The-Wall failsafe functionality for thin-wing aircraft control surface actuation systems having a geared rotary actuator powered by a hydraulic rotary motor. The failsafe valve is associated with the hydraulic rotary motor and mechanically connected to the control surface, and enables the flight control surface to return to an aerodynamically neutral failsafe position if electrical control and/or hydraulic pressure is lost. When the failsafe valve receives a normal command pressure from the hydraulic system, the valve is inactive and the actuation system operates normally. However, if there is a loss of electrical command capacity to control hydraulic valves and/or a loss of hydraulic pressure, the failsafe valve is activated and connects one of the motor hydraulic control lines to the case return line for the motor if the control surface is away from its failsafe position. Consequently, the control surface will be hydraulically powered or aerodynamically ratcheted to its failsafe position in the failure event.

A construction machine incorporates a hydraulic closed circuit system capable of suppressing, even where a selector valve is stuck in an open state by a failure of the selector valve or a control system therefor, unintended operation of a hydraulic actuator and continuing operation of a machine body. The construction machine includes first sensors that detect open-closed states of a plurality of switching valves, first compulsory valve closing devices that change over the plurality of switching valves to a closed position irrespective of open-close control by a machine body controller, and a valve device controller that controls, when it is detected based on the open-closed states of the plurality of selector values detected by the first sensors that one of the plurality of selector values is stuck in an open state, the first compulsory valve closing device such that other selector valve connected to one of the plurality of closed circuit pumps to which the one selector valve is connected is closed.

Apparatus and methods for metering fluid to a fluid actuator. An example apparatus may include a hydraulic actuator, a fluid chamber, and a hydraulic directional control valve. The fluid chamber may include a piston slidably movable between first and second ends of the fluid chamber and dividing the chamber into first and second chamber portions. The hydraulic directional control valve may direct a fluid from a fluid source into the first chamber portion to cause a volume of fluid to be discharged out of the second chamber portion into the hydraulic actuator to actuate the hydraulic actuator by a distance corresponding to the volume of fluid received by the hydraulic actuator.

A hydraulic excavator drive system includes: a boom cylinder; a boom first control valve connected to the boom cylinder by a boom raising supply line and a boom lowering supply line, and connected to a first pump by a first boom distribution line; a boom second control valve connected to the boom raising supply line by a boom replenishment line, and connected to a second pump by a second boom distribution line; an arm cylinder; an arm control valve connected to the arm cylinder by an arm crowding supply line and an arm pushing supply line, and connected to the second pump by an arm distribution line; a regenerative line connecting between the boom replenishment line and the arm distribution line; and an openable and closeable regenerative valve provided on the regenerative line.