Provided is a hydraulic circuit, for a construction machine, which drives an actuator by merging pressure oil from a fixed-volume pump into a center bypass oil path from a variable-volume pump to an oil tank, wherein the flow rate of flow from the fixed-volume pump to the center bypass oil path can be controlled in accordance with a requested flow rate of the actuator. A distribution direction-switching valve, which has a first oil path from a fixed-volume pump to an oil tank and a second oil path from the fixed-volume pump to a first center bypass oil path, has a first signal reception unit which causes a spool to slide in a direction in which the first oil path is formed, and a second signal reception unit which causes a spool to slide in a direction in which the second oil path is formed, and determines a distribution ratio of pressure oil flowing to the first oil path and the second oil path in accordance with the difference in size of the signals received by the first signal reception unit and the second signal reception unit, the first signal reception unit receiving a signal based on a negative control signal.

A direction control valve group for a construction machine that controls an amount of pressure oil supplied to a hydraulic actuator from a hydraulic pump that discharges the pressure oil is provided. The direction control valve includes a cylinder port that supplies the pressure oil to the hydraulic actuator, a bridge passage that is switchably connected and disconnected to the cylinder port according to a change in position of a first spool, and an internal passage that supplies the pressure oil discharged from the hydraulic pump to the bridge passage. The first spool is provided in the internal passage.

A drive control method of a hydraulic actuator of a construction machine includes: determining whether a rotation operation lever and a working device operation lever are operated; calculating the required pressure of a hydraulic cylinder fix a working device according to the operation amount of the rotation operation lever; calculating the required flow rates of a swing motor and the hydraulic cylinder for the working device, the required flow rates corresponding to the operation amounts of the working device operation lever and the rotation operation lever; calculating the opening areas of the first and second proportional solenoid valves of an inlet side and an outlet side by using the calculated required pressure and required flow rates of the hydraulic cylinder for the working device and the swing motor; and calculating current values to be inputted into the first and second proportional solenoid valves of the inlet side and the outlet side according to preset data values or a table in comparison with the calculated opening areas of the first and second proportional solenoid valves of the inlet side and the outlet side.

Agricultural implements and hydraulic circuits for agricultural implements are disclosed herein. An agricultural implement includes a fluid source, a plurality of fluid demand devices, a delivery control valve, and a priority valve. The fluid source is configured to supply hydraulic fluid. The plurality of fluid demand devices are each configured to receive hydraulic fluid supplied by the fluid source during operation of the agricultural implement. The delivery control valve is fluidly coupled between the fluid source and a first fluid demand device. The delivery control valve is configured to selectively deliver hydraulic fluid supplied by the fluid source to the first fluid demand device during operation of the agricultural implement. The priority valve is fluidly coupled between the delivery control valve and the first fluid demand device.

A hydraulic apparatus comprises first and second manifolds each of which is connected to a plurality of actuators via corresponding actuator valves connected in parallel and operated responsive to inputs to regulate the flow of fluid to the actuators. A plurality of working chambers are connectable to either the first or second manifold and have a net flow which is controlled responsive to a negative feedback signal. The negative feedback signal is determined in response to a calculated pressure or flow rate in virtual fluid flow paths extending from the first and second manifolds.

The present invention relates to a stand-alone or inbuilt logical element associated with a hydraulic system for effective regeneration to improve the efficiency of any hydraulic system of a machine or equipment, including but not limited to farm machinery, industrial machinery, construction and mining machinery which uses hydraulic system. The logical element senses the cavitation or low pressure in the hydraulic system and automatically regulates and diverts the portion of hydraulic oil flow to caveated and required areas by regenerating through the anti-cavitation feature of the valve by automatically sensing and applying selective restriction to the set or adjustable pressure limit for the passage of oil.

A working machine includes: a plurality of hydraulic actuators including a high-load hydraulic actuator and a low-load hydraulic actuator whose hydraulic pressure for actuation thereof is lower than that of the high-load hydraulic actuator; a plurality of direction switching valves each of which switches a direction of a hydraulic fluid for a corresponding one of the hydraulic actuators, the plurality of direction switching valves including a low-load direction switching valve that switches a direction of hydraulic fluid for the low-load hydraulic actuator; and a dummy-load forming unit that forms a dummy load in the low-load direction switching valve to suppress a variation in an actuation speed of the low-load hydraulic actuator between a time when the high-load hydraulic actuator and the low-load hydraulic actuator are operated in combination and a time when the low-load hydraulic actuator is operated singly.

A confluence control part of a slewing-type construction machine controls a confluence switch valve such that the confluence switch valve is switched to a suspension state when a slewing and boom raising manipulation action is performed. A pump capacity control part of the slewing-type construction machine executes a capacity control when the slewing and boom raising manipulation action is performed, the capacity control including regulating a first pump capacity and a second pump capacity respectively in such a manner that the first pump capacity increases and the second pump capacity decreases as an operating pressure difference resulting from the subtraction of a slewing operating pressure from a boom operating pressure increases, and the first pump capacity decreases and the second pump capacity increases as the operating pressure difference decreases.

This disclosure relates to a hydraulic system for a hydro-mechanical machine comprising a rotary mechanism and a boom cylinder The hydraulic system includes a primary accumulator configured to receive and store high-pressure fluid in response to starting and stopping of the rotary mechanism. A control system configured to enable passage of the high-pressure fluid stored in the primary accumulator to a rotary control valve configured to control the rotary mechanism, and a boom control valve configured to control the boom cylinder through the hydraulic supply circuit, based on a predefined pressure threshold associated with the primary accumulator. A secondary accumulator coupled to the primary accumulator and the control system via the hydraulic supply circuit is configured to store surplus high-pressure fluid provided by the primary accumulator through the hydraulic supply circuit.

A mining or construction vehicle comprising a boom extending in a first direction, which boom, via a first and a second rotation device, is connected to a hydraulic device arranged on a mounting device arranged at a free end of said boom, the first rotation device being arranged to provide a rotation around a first axis that is substantially parallel to the first direction, and a second rotation device being arranged to provide a rotation around a second axis that is arranged at an angle with respect to the first axis. Hydraulic conduits for supply of hydraulic fluid to said hydraulic device on said mounting device are arranged through at least one of the first and second rotation devices.