A header is supported by a pair of hydraulic float cylinders, where a float pressure to the cylinders is directly controlled by an electronic control supplying a variable control signal to a PPRR valve arrangement to maintain the float pressure at a predetermined value. At the set pressure a predetermined lifting force is provided to the header. A position sensor is used to generate an indication of movement and/or acceleration and/or velocity. The electronic control is arranged, in response to changes in the sensor signal, to temporarily change the control signal to vary the lifting force and thus change the dynamic response of the hydraulic float cylinder. A lift force greater than that required to lift the header can be provided by a lift cylinder and can be opposed in a controlled manner to apply a controlled downforce by the back of the same cylinder or by a separate component.

There is provided a hydraulic driving device for working machine having operability handling a change in burden weight in a front working device due to a loaded burden and the like when the working machine that accumulates energy in an accumulator and recovers and regenerates the energy performs an operation of lowering the front working device. A hydraulic driving device 5 includes a main pump 101, a boom cylinder 3, a tank 20, a flow rate control valve 6, an accumulator 300, a first differential pressure control valve 201, and a second differential pressure control valve 202. The first differential pressure control valve 201 is located between the boom cylinder 3 and the accumulator 300. The first differential pressure control valve 201 performs control on discharge oil from the boom cylinder 3 such that a differential pressure between before and after the flow rate control valve 6 becomes a target differential pressure. The second differential pressure control valve 202 is located between the accumulator 300 and the tank 20. The second differential pressure control valve 202 performs control on the discharge oil such that a differential pressure between an upstream pressure and a downstream pressure of the flow rate control valve 6 and the first differential pressure control valve 201 becomes the target differential pressure. The first and the second differential pressure control valves 201 and 202 are configured such that the target differential pressure increases according to an increase in pressure of the discharge oil.

A valve block arrangement configured as a closed center system includes at least one main spool for controlling a hydraulic consumer. The main spool is configured to open and close at least one pressure medium connection between a hydraulic pump and the consumer in controlled, continuous fashion and, in at least one embodiment, is electrically activated. A bypass flow path with a cut valve branches off between the adjustable, hydraulic pump and the main spool. The cut valve is configured to open and close a pressure medium connection between the hydraulic pump and a tank in controlled, continuous fashion. The cut valve is electrically activatable.

An actuator control device performs a reception process in which designations of a minimum operation amount and maximum operation amount of an operation unit for driving an actuator, and a maximum driving speed which is the actuator driving speed corresponding to the maximum operation amount are received. It also performs a determination process in which a function representing a characteristic line that links a first point, which corresponds to the minimum operation amount and the driving speed of 0, and a second point, which corresponds to the maximum operation amount and the maximum driving speed, is stored in a storage unit as a drive control characteristic and a drive control process in which, in response to operation of the operation unit, the actuator is driven at a driving speed corresponding to the operation amount specified by the drive control characteristic stored in the storage unit.

A monitoring device includes a first pressure sensor that detects a first pressure value of a pressurized fluid in a first pipe, a second pressure sensor that detects a second pressure value of a pressurized fluid in a second pipe, and a detector that determines, on the basis of the first pressure value and the second pressure value, whether or not a piston has reached one end or the other inside a cylinder body.

A header is supported by a pair of hydraulic float cylinders, where a float pressure to the cylinders is directly controlled by an electronic control supplying a variable control signal to a PPRR valve arrangement to maintain the float pressure at a predetermined value. At the set pressure a predetermined lifting force is provided to the header. A position sensor is used to generate an indication of movement and/or acceleration and/or velocity. The electronic control is arranged, in response to changes in the sensor signal, to temporarily change the control signal to vary the lifting force and thus change the dynamic response of the hydraulic float cylinder. A lift force greater than that required to lift the header can be provided by a lift cylinder and can be opposed in a controlled manner to apply a controlled downforce by the back of the same cylinder or by a separate component.

A fluid pressure control device includes a switching valve, a main pilot passage and a sub pilot passage, the switching valve is configured to be switched to the open position when the working fluid is supplied to the pilot chamber, and to be switched to the throttled position with opening on the downstream side of the switching valve in the neutral passage, and the sub pilot passage is provided with a throttle portion and a check valve in parallel in the throttle portion.

A header is supported by a pair of hydraulic float cylinders, where a float pressure to the cylinders is directly controlled by an electronic control supplying a variable control signal to a PPRR valve arrangement to maintain the float pressure at a predetermined value. At the set pressure a predetermined lifting force is provided to the header. A position sensor is used to generate an indication of movement and/or acceleration and/or velocity. The electronic control is arranged, in response to changes in the sensor signal, to temporarily change the control signal to vary the lifting force and thus change the dynamic response of the hydraulic float cylinder. A lift force greater than that required to lift the header can be provided by a lift cylinder and can be opposed in a controlled manner to apply a controlled downforce by the back of the same cylinder or by a separate component.

A hydraulic drive for executing a linear movement includes a motor, a pump, a lifting cylinder having the one linearly movable piston and a cylinder housing with at least one first connection and at least one second connection, a spring arranged such that the piston can be extended or retracted when the spring is in the relaxed state, and at least one first valve with which the first connection and the second connection of the cylinder housing can be fluidly connected. At least one second valve connected in parallel with the first valve is further provided, wherein the first valve has a maximum volumetric throughflow which is greater than the maximum volumetric through-flow of the second valve.

A fluid control device provided with a plurality of switching valves and a plurality of relief valves. A sub-relief passage communicating with a tank when the switching valves are in any state other than neutral is branched from a parallel passage for guiding a high-pressure hydraulic fluid to the switching valves. A sub-relief valve is provided within the sub-relief passage, and a check valve that minimizes the flow of hydraulic fluid toward a hydraulic pressure supply source is provided between switching valves and the point of branching of the sub-relief passage in the parallel passage.