A harvester head having at least one hydraulic actuator with a cylinder and a piston. The hydraulic actuator having at least a cylinder chamber and a piston rod chamber, both chambers being connected to a hydraulic circuit. The piston separating the cylinder chamber and the piston rod chamber, a cavity provided in the piston, hydraulically connecting the cylinder chamber with the piston rod chamber and a check valve in connection with the cavity that allows hydraulic medium flow in an opening direction of the check valve.

A cylinder driving device includes: an electric motor; a pump; a main passage and a main passage; a hydraulic cylinder; an operation check valve and an operation check valve; and a restriction valve and a restriction valve configured to restrict a flow of the working oil directed to the operation check valve and an operation check valve, wherein an opening area of the restriction valve and the restriction valve is reduced in response to an increase in a flow rate of the working oil discharged from the hydraulic cylinder to the main passage and a main passage.

A safe hydraulic drive system and process, comprising at least one first cylinder chamber and a second, separate cylinder chamber which are connected to one another via a connecting line to form a fluid-filled hydraulic circuit, and a hydraulic drive for conveying the fluid from one cylinder chamber, via the connecting line, into the other cylinder chamber in which the connecting line is arranged. The connecting line has at least one parallel system, between the hydraulic drive and one of the two cylinder chambers, including at least one first sub-connection with at least one first stop valve and a second sub-connection with a baffle arranged therein. The connecting line, excluding the second sub-connection, has a first flow resistance and the second sub-connection has a second flow resistance due to the baffle arranged therein, which is greater than the first flow resistance for the fluid, wherein the drive system is provided with at least one open first stop valve in normal mode and with a closed first stop valve in safe mode for conveying the fluid, and a suitably high second flow resistance has been selected so that a maximum permissible speed for a piston rod is not exceeded in safe mode, even when an external force acts on the drive system in the direction of movement of the piston rod.

A cylinder driving device includes: an electric motor; a pump; a main passage and a main passage; a hydraulic cylinder; an operation check valve and an operation check valve; and a restriction valve and a restriction valve configured to restrict a flow of the working oil directed to the operation check valve and an operation check valve, wherein an opening area of the restriction valve and the restriction valve is reduced in response to an increase in a flow rate of the working oil discharged from the hydraulic cylinder to the main passage and a main passage.

A harvester head having at least one hydraulic actuator with a cylinder and a piston. The hydraulic actuator having at least a cylinder chamber and a piston rod chamber, both chambers being connected to a hydraulic circuit. The piston separating the cylinder chamber and the piston rod chamber, a cavity provided in the piston, hydraulically connecting the cylinder chamber with the piston rod chamber and a check valve in connection with the cavity that allows hydraulic medium flow in an opening direction of the check valve.

In a hydraulic driving device for a cargo handling vehicle, a power running torque limit value setting unit sets a power running torque limit value to a minimum rotation speed set in advance, in a case where a determination unit determines that operations of second hydraulic cylinders including a lowering operation of a first operating portion are simultaneously performed, a rotation speed command value setting unit sets a rotation speed command value to a maximum value from between a lowering required rotation speed based on an operation amount of the first operating portion and a second hydraulic cylinder required rotation speed based on operation amounts of the second operating portions, and the power running torque limit value setting unit sets the power running torque limit value to the second hydraulic cylinder required rotation speed based on the operation amounts of the second operating portions, and a control unit controls an electric motor to rotate at a rotation speed based on the rotation speed command value and controls the electric motor to rotate at a rotation speed based on the power running torque limit value in a case where an output torque of the electric motor shifts toward a power running side.

A safe hydraulic drive system and process, comprising at least one first cylinder chamber and a second, separate cylinder chamber which are connected to one another via a connecting line to form a fluid-filled hydraulic circuit, and a hydraulic drive for conveying the fluid from one cylinder chamber, via the connecting line, into the other cylinder chamber in which the connecting line is arranged. The connecting line has at least one parallel system, between the hydraulic drive and one of the two cylinder chambers, including at least one first sub-connection with at least one first stop valve and a second sub-connection with a baffle arranged therein. The connecting line, excluding the second sub-connection, has a first flow resistance and the second sub-connection has a second flow resistance due to the baffle arranged therein, which is greater than the first flow resistance for the fluid, wherein the drive system is provided with at least one open first stop valve in normal mode and with a closed first stop valve in safe mode for conveying the fluid, and a suitably high second flow resistance has been selected so that a maximum permissible speed for a piston rod is not exceeded in safe mode, even when an external force acts on the drive system in the direction of movement of the piston rod.