A hydraulic circuit is disclosed. The hydraulic circuit may include a hydrostatic pump to provide, at a flow rate, a fluid to a hydraulic motor, wherein the hydrostatic pump has a displacement, and wherein the hydraulic motor drives a swinging element; a swing circuit pressure sensor to sense a circuit pressure of the hydraulic circuit; a pilot pressure actuator to control, based on a supply pressure, the displacement of the hydrostatic pump; a pilot pressure override valve to control the supply pressure; and a controller configured to adjust, based on sensed signals and with the pilot pressure override valve, the supply pressure, wherein the sensed signals include: a circuit pressure signal based on the circuit pressure sensed by the swing circuit pressure sensor; and a sensed swing speed signal based on a swing speed of the swinging element sensed by one or more machine sensors.

A hydraulic pressurizing medium supply assembly having a hydro machine for supplying pressurizing medium of at least one hydraulic consumer, includes a hydraulic control block for controlling the at least one consumer, a first control module, and a second control module. The control block, by way of the first control module, is able to be controlled by at least one actuating signal. A data interface is included between the control modules. The first control module, by way of the data interface, as a further actuating signal transfers to the second control module as input variable/variables a nominal outlet pressure for the hydro machine and/or a nominal delivery volume for the hydro machine. The second control module by way of the nominal outlet pressure and/or by way of the nominal delivery volume controls an adjusting mechanism of the hydro machine by way of a valve actuating signal.

The present disclosure relates to a load dependent flow control system for directing hydraulic fluid to a hydraulic actuator. The load dependent flow control system includes a closed-center valve device for controlling hydraulic fluid flow to the actuator. The closed-center valve device includes a valve spool and an electro-actuator that adjusts a position of the valve spool to adjust a rate of the hydraulic fluid flow supplied to the hydraulic actuator. A pressure sensor is provided for sensing a pressure of the hydraulic fluid provided to the hydraulic actuator. The system also includes an electronic controller configured to receive an operator flow command from an operator interface. The operator flow command corresponds to a base flow through the closed-center valve device. The electronic controller interfaces with the electro-actuator of the closed-center valve device and with the pressure sensor. At least when the sensed pressure is above a threshold pressure, the electronic controller uses the operator flow command and the sensed pressure to generate a pressure-modified flow command that is sent to the closed-center valve device to control flow through the closed-center valve device. The pressure-modified flow command corresponds to a pressure-modified flow through the closed-center valve device. The pressure-modified flow is less than the base flow through the closed-center valve device.

A hydraulic drive apparatus includes a boom flow rate control valve, a target boom cylinder speed calculation part calculating a target boom cylinder speed for making a construction surface by a bucket closer to a target construction surface based on the cylinder speed of a boom cylinder and the like, and a boom flow rate operation part. The boom flow rate operation part operates the boom flow rate control valve to make a boom cylinder supply flow rate be a target supply flow rate corresponding to the target boom cylinder speed when the target boom cylinder speed direction coincides with a cylinder thrust direction, and operates the boom flow rate control valve to make the boom cylinder discharge flow rate be a target discharge flow rate corresponding to the target boom cylinder speed when the target boom cylinder speed direction is opposite to the cylinder thrust direction.

A hydraulic system for an agricultural baler includes: a hydraulic motor; a hydraulically driven component fluidly coupled to the hydraulic motor such that fluid flow between the hydraulic motor and the hydraulically driven component causes the hydraulically driven component to move between a first position and a second position; a flow sensor associated with the hydraulically driven component; and a controller operatively coupled to the flow sensor and the hydraulic motor. The controller is configured to: enter a learning mode to learn a driven movement of the hydraulically driven component from the first position to the second position; determine fluid flow between the hydraulic motor and the hydraulically driven component during the driven movement while in the learning mode; associate the determined fluid flow with the driven movement; and output control signals to the hydraulic motor to reproduce the associated fluid flow and reproduce the driven movement.

A hydraulic drive apparatus capable of automatic control with high accuracy regardless of regeneration operation includes a boom flow rate control valve, an arm flow rate control valve, a regeneration control valve, a pump control device for performing horsepower control, a posture detection device, a boom flow rate control device switchable between a normal control mode and an automatic control mode, and a regeneration control device. The boom flow rate control device adjusts the boom flow rate in the automatic control mode so that a work attachment moves along a target locus. The regeneration control device sets the regeneration control valve to a regeneration position in a low load situation and to a regeneration cut position in a high load situation, and lowers the regeneration rate in the low load situation when the boom flow rate control device is switched to the automatic control mode.

A control system for construction machinery, includes a hydraulic pump, first and second actuators connected to the hydraulic pump through first and second parallel lines respectively, first and second control valves installed in the first and second parallel lines respectively and configured to control operations of the first and second actuators, first and second spool displacement adjusting valves configured to control displacement amounts of the spools of the first and second control valves, and a controller configured to output a control signal to the first and second spool displacement adjusting valves corresponding to a manipulation signal of an operator, and configured to limit a spool displacement amount of the second control valve according to the manipulation signal for the first actuator when the manipulation signal for a multiple operation of the first and second actuators is received.

A boom lift system includes a primary conduit, a pump-motor arrangement having a motor operable to drive a pump to move a fluid through the primary conduit, first and second actuators in fluid communication with the primary conduit and actuatable in response to first and second user input to perform hydraulic function via the fluid, a valve arrangement configured to control flow of the fluid from the primary conduit to the first and second actuators, and a controller programmed to selectively actuate the valve arrangement in response to the first and second user inputs. When the controller receives both of the inputs, the valve arrangement is actuated by the controller to vary the flow rate of fluid to each of the first and second actuators. When the controller receives only one of the first input or the second input, the controller varies a flow rate output of the pump.

A ride control valve includes a valve body defining a work passage, a pump passage, a tank passage, and an accumulator passage configure to couple to an accumulator. A ride control spool is movably disposed within the valve body and configured to move between a a first ride control position to discharge the accumulator, a second ride control position configured to charge the accumulator at a variable charge rate, a third ride control configured to balance the accumulator pressure with the work passage pressure, and a fourth ride control position configured to couple the accumulator to the work passage. A pressure balancing spool is movably disposed within the ride control spool to selectively couple the accumulator passage with each of the pump passage and the tank passage to balance the accumulator pressure. The ride control valve is configured couple to a directional control valve without external conduit.

A hydraulic pressure supply device includes: a hydraulic pump capable of changing a discharge capacity; an electric motor capable of changing a rotational frequency; a discharge capacity adjustment mechanism capable of adjusting the discharge capacity of the pump between a maximum and minimum discharge capacity; a pressure detector configured to detect pressure of an operating liquid discharged from the pump; a rotational frequency detector configured to detect the rotational frequency of the motor; and a controller configured to control operations of the motor and adjustment mechanism based on the rotational frequency, detected by the detector, to keep pressure of an actuator at arbitrary pressure, wherein, the controller controls the operation of the adjustment mechanism so the discharge capacity of the pump becomes a set lower limit discharge capacity. The set lower limit discharge capacity is set to be larger than the minimum discharge capacity and be adjustable by the controller.