A method for controlling a hydrodynamic machine, including the steps of: providing a hydrodynamic machine which includes a bladed primary wheel and a bladed secondary wheel, which together form a working chamber, which can be filled with a working medium from a working medium supply contained in a working medium reservoir, to transfer drive power hydrodynamically from the bladed primary wheel to the bladed secondary wheel by forming a working medium circuit in the working chamber; applying a control pressure to the working medium supply in order to force the working medium from the working medium supply into the working chamber; detecting, at least indirectly, a pressure increase in the working medium reservoir, when the control pressure is applied to the working medium supply; and determining, as a function of the pressure increase that has been detected, a fill level of the working medium supply in the working medium reservoir.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly. The valve assembly includes a housing defining an interior. The housing defines a first orifice operably coupled to the pump and a second orifice operably coupled to the clutch. The valve assembly also includes a piston operably coupled to the motor and disposed within the interior of said housing. The piston is movable between a first position for allowing the fluid flow between the first orifice and the second orifice, a second position for obstructing the fluid flow between the first orifice and the second orifice, and a third position for limiting the fluid flow between the first orifice and the second orifice. The valve assembly additionally includes a biasing member coupled to the piston. The biasing member biases the piston toward the first position.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly. The valve assembly includes a housing defining an interior. The housing defines a first orifice operably coupled to the pump and a second orifice operably coupled to the clutch. The valve assembly also includes a piston operably coupled to the motor and disposed within the interior of said housing. The piston is movable between a first position for allowing the fluid flow between the first orifice and the second orifice, a second position for obstructing the fluid flow between the first orifice and the second orifice, and a third position for limiting the fluid flow between the first orifice and the second orifice. The valve assembly additionally includes a biasing member coupled to the piston. The biasing member biases the piston toward the first position.

An automatic transmission where the control portion controls the adjustment solenoid valve so that the circulation hydraulic pressure equals to a second circulation hydraulic pressure higher than the first circulation hydraulic pressure when the rotational speed difference between the output rotational speed of the fluid transmission device and the rotational speed of the driving source is more than the predetermined rotational speed.

A drag torque reduction device for an automatic transmission includes a hydraulic controller with a parallel connection of a pressure relief valve, a constant aperture and a temperature-dependent, switchable aperture that is positioned upstream of a radiator relative to a flow of fluid to the radiator. The parallel connection is disposed between a first control edge of a converter switching valve and a first line. The first line leads to both to the radiator and through a check valve to the converter ring. The first control edge of the converter switching valve is open and lubricating oil flows through the parallel connection when the converter switching valve is in a first switching position. The first control edge of the converter switching valve is closed and lubricating oil does not flow through the parallel connection when the converter switching valve is in a second switching position.

A method for controlling a hydrodynamic machine, including the steps of: providing a hydrodynamic machine which includes a bladed primary wheel and a bladed secondary wheel, which together form a working chamber, which can be filled with a working medium from a working medium supply contained in a working medium reservoir, to transfer drive power hydrodynamically from the bladed primary wheel to the bladed secondary wheel by forming a working medium circuit in the working chamber; applying a control pressure to the working medium supply in order to force the working medium from the working medium supply into the working chamber; detecting, at least indirectly, a pressure increase in the working medium reservoir, when the control pressure is applied to the working medium supply; and determining, as a function of the pressure increase that has been detected, a fill level of the working medium supply in the working medium reservoir.

A work vehicle that includes a hydraulic system. The hydraulic system includes a hydraulic motor that generates rotational power for one or more wheels on the work vehicle. A hydraulic pump couples to the hydraulic motor. The hydraulic pump pumps hydraulic fluid to the hydraulic motor. A hydraulic shift control system controls shifting of the hydraulic system. The hydraulic shift control system includes a controller that controls a hydraulic motor volume of the hydraulic motor and a fluid volume pumped by the hydraulic pump to gradually change a speed of the work vehicle during a shift.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly, which includes a housing defining an interior and a first orifice operably coupled to the pump, a second orifice operably coupled to the clutch, and a third orifice fluidly coupled to one of said first and second orifices. A piston is operably coupled to the motor, is disposed within the interior, is movable between a first position for allowing a fluid flow between the first and second orifices, a second position for obstructing the fluid flow between the first and second orifices, and a third position for limiting the fluid flow between the first and second orifices. A biasing member is coupled to the piston, and biases the piston toward the first position when the motor is off. When the pump is activated and a pressure proximate the first orifice is equal to a pressure proximate the second orifice, the motor is energized and moves the piston to the second position. When pressure proximate the second orifice exceeds a predetermined threshold pressure, the energized motor is turned off and the biasing member moves the piston to the first position, or power in the energized motor is reduced and the piston moves to the third position.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly, which includes a housing defining an interior and a first orifice operably coupled to the pump, a second orifice operably coupled to the clutch, and a third orifice fluidly coupled to one of said first and second orifices. A piston is operably coupled to the motor, is disposed within the interior, is movable between a first position for allowing a fluid flow between the first and second orifices, a second position for obstructing the fluid flow between the first and second orifices, and a third position for limiting the fluid flow between the first and second orifices. A biasing member is coupled to the piston, and biases the piston toward the first position when the motor is off. When the pump is activated and a pressure proximate the first orifice is equal to a pressure proximate the second orifice, the motor is energized and moves the piston to the second position. When pressure proximate the second orifice exceeds a predetermined threshold pressure, the energized motor is turned off and the biasing member moves the piston to the first position, or power in the energized motor is reduced and the piston moves to the third position.

A method operates a drive train for driving a working machine with variable rotation speed. The method includes running up the electric drive machine from a standstill with evacuated hydrodynamic rotation speed/torque converter to a predefined value which indirectly characterizes the operating mode of the drive machine. Simultaneously with reaching the predefined value which indirectly characterizes the operating mode of the drive machine or with a temporal offset after reaching this, filling the hydrodynamic rotation speed/torque converter and driving the turbine vane wheel. Thereafter, the third element of the planetary gear mechanism is driven with a rotation speed which results from a superposition, defined by the planetary gear mechanism, of the rotation speed of the first element of the planetary gear mechanism connected to the electric drive machine and the rotation speed of the second element of the planetary gear mechanism which is indirectly connected to the turbine wheel.