A work vehicle includes a valve for switching between a merging position for causing a first oil passage for driving a bucket and a second oil passage for driving an arm to communicate with each other, and a diverging position for separating the first oil passage and the second oil passage. The work vehicle is adapted to switch the valve from the merging position to the diverging position, when one of a pump pressure in the first pump and a pump pressure in the second pump comes to be equal to a predetermined value during an excavation operation. The work vehicle is adapted to control both pumps, such that the amount of the oil discharged from the first pump is larger than the amount of the oil discharged from the second pump, when the pump pressure in the first pump is equal to or more than the predetermined value.

A hydraulic system for a machine includes a first pump, an implement pump, a control valve, and an auxiliary circuit. The first pump is configured to supply a first fluid flow to a first circuit, such as a steering circuit. The implement pump is configured to supply a second fluid flow to an implement circuit to actuate a primary implement function. The auxiliary circuit is configured to deliver fluid flow to actuate an auxiliary implement function. The auxiliary circuit is fluidly coupled to the implement circuit. The auxiliary circuit is also coupled to the first circuit by the control valve. The control valve is located downstream, in the direction of fluid flow, of the implement pump and the first pump. The control valve is configured to allow at least a portion of the first fluid flow to enter the auxiliary circuit and be delivered to the auxiliary implement function.

A hydraulic system for a work machine includes a tank to store an operation fluid, a hydraulic device to be operated by the operation fluid, a control valve to control the hydraulic device, a first fluid tube connecting the hydraulic device and the control valve, the first fluid tube being to supply the operation fluid from the control valve to the hydraulic device, a second fluid tube branching from the first fluid tube and connected to the tank, a switch valve provided to the second fluid tube, the switch valve being to control a flow rate of the operation fluid, and an oil cooler provided to the second fluid tube between the switch valve and the tank.

A hydraulic system for a work machine includes a tank to store an operation fluid, a hydraulic device to be operated by the operation fluid, a control valve to control the hydraulic device, a first fluid tube connecting the hydraulic device and the control valve, the first fluid tube being to supply the operation fluid from the control valve to the hydraulic device, a second fluid tube branching from the first fluid tube and connected to the tank, a switch valve provided to the second fluid tube, the switch valve being to control a flow rate of the operation fluid, and an oil cooler provided to the second fluid tube between the switch valve and the tank.

A shovel may has a first pump that discharges a first hydraulic oil, a second pump that discharges a second hydraulic oil, a pump/motor that discharges a third hydraulic oil, an arm cylinder that at least the first hydraulic oil can flow into, and a boom cylinder that at least the second hydraulic oil can flow into. When the arm cylinder and the boom cylinder operate simultaneously, the arm cylinder is actuated by the first hydraulic oil or the third hydraulic oil, and the boom cylinder is actuated by the second hydraulic oil.

A control system includes: first and second hydraulic pumps; an opening/closing device provided in a passage connecting the first and second hydraulic pumps and configured to open and close the passage; a control device controlling the opening/closing device to switch between connected and unconnected states of the first and second hydraulic pumps; a first hydraulic cylinder to which hydraulic fluid from the first hydraulic pump is supplied in the unconnected state; and a second hydraulic cylinder to which hydraulic fluid from the second hydraulic pump is supplied in the unconnected state. The control device controls the opening/closing device to be in the connected state when distributed flow rates of the hydraulic cylinders are a predetermined supply flow rate or lower and a difference between a pressure in a rod-side space and a pressure in a cap-side space of the hydraulic cylinder is a defined value or smaller.

The present invention provides a controller for hydraulic apparatus (100). The controller is configured to determine (310) that an energy return criteria has been met by movement of a first movement component of a first hydraulic actuator. In response thereto, the controller is further configured to select (320) at least one among a plurality of energy control strategies based on at least one operational characteristic of the hydraulic apparatus, and to control (330) the hydraulic apparatus to implement the energy control strategy during movement of the first movable component in such a way as to meet the energy return criteria. The plurality of energy control strategies comprises a first energy control strategy and a second energy control strategy. The at least one operational characteristic of the hydraulic apparatus comprises an indication of an expected energy recovery of one or more of the energy control strategies. The first energy control strategy comprises transferring energy from the first hydraulic actuator, via a hydraulic machine, to an energy consumer in torque connection with the hydraulic machine. The second energy control strategy comprises transferring energy from the first hydraulic actuator to a low-pressure reservoir of hydraulic fluid in the hydraulic circuit.

A hydraulic apparatus has a plurality of pump modules each of which is formed by a plurality of working chambers having a common high pressure manifold. A connecting circuit switchably connects pump modules to first and second hydraulic circuit portions to allocate capacity as first and second demands for hydraulic fluid vary. In an apparatus which may have two or more connecting circuit outputs, valves may be controlled or working chamber pumping cycles made inactive to facilitate the reallocation of a pump module from one output to another, and a control strategy addresses pump module allocation when the demands for hydraulic fluid exceed available capacity.

A hydraulic system for a machine includes a first pump, an implement pump, a control valve, and an auxiliary circuit. The first pump is configured to supply a first fluid flow to a first circuit, such as a steering circuit. The implement pump is configured to supply a second fluid flow to an implement circuit to actuate a primary implement function. The auxiliary circuit is configured to deliver fluid flow to actuate an auxiliary implement function. The auxiliary circuit is fluidly coupled to the implement circuit. The auxiliary circuit is also coupled to the first circuit by the control valve. The control valve is located downstream, in the direction of fluid flow, of the implement pump and the first pump. The control valve is configured to allow at least a portion of the first fluid flow to enter the auxiliary circuit and be delivered to the auxiliary implement function.

A control system includes: calculating a distribution flow rate of hydraulic fluid to be supplied to first and second hydraulic actuators based on a pressure of hydraulic fluid in the first and second hydraulic actuators and an operation amount operated to drive the first and second hydraulic actuators; calculating merged-state pump output indicating outputs of first and second hydraulic pumps required in a merged state based on the distribution flow rate; calculating separated-state pump output indicating outputs of the first and second hydraulic pumps required in the separated state based on the distribution flow rate; calculating excessive output of an engine based on the merged-state pump output and the separated-state pump output; calculating reduced output of the engine more reduced than target output by correcting the target output of the engine based on the excessive output; and controlling the engine based on the reduced output in the separated state.