A transmission system includes a power take-off for driving an implement and a hydrostatic unit for transmitting power from the engine to the power take-off. The hydrostatic unit includes a first hydraulic power unit having a first connection line and a second connection line, and a second hydraulic power unit having a first connection line and a second connection line. The hydrostatic unit also includes a valve for connecting the first hydraulic power unit and the second hydraulic power unit, the valve being positionable at least in a first position a first position and in a second position.

In an anti-reverse valve, a first communication passage that allows the first supply and discharge passage to communicate with the first pressure chamber and a second communication passage that allows the second supply and discharge passage to communicate with the second pressure chamber are provided inside the spool, a first restrictor is provided in the first communication passage, a second restrictor is provided in the second communication passage, and a first annular groove that allows the first supply and discharge passage to communicate with the drain passage when the spool is placed at the first communication position and a second annular groove that allows the second supply and discharge passage to communicate with the drain passage when the spool is placed at the second communication position are provided in an outer periphery of the spool.

A hydrostatic valve arrangement for flushing pressure medium from a working line of a hydraulic circuit includes a flushing valve with a first flushing connection for connecting to a first working line and an output connection for connecting to a pressure medium sink. The arrangement also includes a pressure valve arranged in a pressure medium flow path of the arrangement from the output connection in the direction of the pressure medium sink. The pressure valve has a valve body on which a force equilibrium is formed. The force equilibrium includes a pressure equivalent that acts on the valve body in a direction that blocks the pressure medium flow path and an opening pressure that acts in a direction that opens the pressure medium flow path and is dependent on the pressure at the output connection. The arrangement further includes an adjusting device for shifting the force equilibrium.

A hydrostatic valve arrangement for flushing pressure medium from a working line of a hydraulic circuit includes a flushing valve with a first flushing connection for connecting to a first working line and an output connection for connecting to a pressure medium sink. The arrangement also includes a pressure valve arranged in a pressure medium flow path of the arrangement from the output connection in the direction of the pressure medium sink. The pressure valve has a valve body on which a force equilibrium is formed. The force equilibrium includes a pressure equivalent that acts on the valve body in a direction that blocks the pressure medium flow path and an opening pressure that acts in a direction that opens the pressure medium flow path and is dependent on the pressure at the output connection. The arrangement further includes an adjusting device for shifting the force equilibrium.

An axial piston machine of oblique axis design has a pivot angle that is adjustable via a set piston and a control valve and includes a first valve slide that is linearly movable relative to a first valve axis and is connected at two opposite ends to a first or a second fluid port. The first valve slide has a central region that defines a control point at which the lower of pressures at the first and second fluid ports act. The control point is connected via a fixed first throttle and a second throttle to a housing interior. A second valve slide that is linearly movable relative to a second valve axis is configured to adjust the second throttle. The first valve axis is arranged between the set piston and the control valve or a region of the control valve and is oriented transverse to the adjusting axis.

A hydraulic flushing valve arrangement includes a flushing valve having a housing, flushing piston, and at least one spring. The housing includes a valve bore, two circular housing control edges, two inlet channels fluidically connected to the bore, and an outlet channel opening into the bore between the inlet channels. The piston includes two control collars, a piston neck, and piston control edges that delimit the collars from the neck, and that have circular shapes with a recess. The recess has a portion that, in a cross-sectional plane perpendicular to an axis of the piston, is constant and sized such that a flushing quantity is reduced when the portion of the recess is situated in a region of a corresponding housing control edge relative to a quantity when the piston is in an end position. The collars guide the piston so as to be longitudinally displaceable in the bore, and are spaced apart by the neck. The piston and control edges are configured to control the fluidic connections between the bore, the inlet channels, and the outlet channel. The spring preloads the piston in a middle position whereat the outlet channel is blocked from the inlet channels. The piston is configured to move out of the middle position in response to a specific difference between pressures of the two inlet channels. The control collars are respectively configured to open the fluidic connection between a corresponding inlet channel in which a lower pressure prevails and the outlet channel. Such a flushing valve arrangement is usable in hydrostatic travel drives in which two hydromachines are operated in a closed hydraulic circuit.

A hydraulic flushing valve arrangement includes a flushing valve having a housing, flushing piston, and at least one spring. The housing includes a valve bore, two circular housing control edges, two inlet channels fluidically connected to the bore, and an outlet channel opening into the bore between the inlet channels. The piston includes two control collars, a piston neck, and piston control edges that delimit the collars from the neck, and that have circular shapes with a recess. The recess has a portion that, in a cross-sectional plane perpendicular to an axis of the piston, is constant and sized such that a flushing quantity is reduced when the portion of the recess is situated in a region of a corresponding housing control edge relative to a quantity when the piston is in an end position. The collars guide the piston so as to be longitudinally displaceable in the bore, and are spaced apart by the neck. The piston and control edges are configured to control the fluidic connections between the bore, the inlet channels, and the outlet channel. The spring preloads the piston in a middle position whereat the outlet channel is blocked from the inlet channels. The piston is configured to move out of the middle position in response to a specific difference between pressures of the two inlet channels. The control collars are respectively configured to open the fluidic connection between a corresponding inlet channel in which a lower pressure prevails and the outlet channel. Such a flushing valve arrangement is usable in hydrostatic travel drives in which two hydromachines are operated in a closed hydraulic circuit.

A work machine includes a closed circuit system in which there is provided a flushing valve. The flushing valve is equipped with: a valve main body; a spool which can select, in accordance with a position where the spool is arranged in the valve main body, connection between a first flow line and a third flow line, connection between a second flow line and the third flow line, or interruption of the connection between the first flow line, the second flow line, and the third flow line; a first liquid chamber that is provided inside the valve main body and into which a hydraulic working fluid from the first flow line flows; a first piston pressurizing the hydraulic working fluid having flowed into the first liquid chamber and moving the spool to a position where the second flow line and the third flow line are connected together, by the hydraulic pressure of the first liquid chamber; a second liquid chamber that is provided inside the valve main body and into which the hydraulic working fluid from the second flow line flows; and a second piston pressurizing the hydraulic working fluid having flowed into the second liquid chamber and moving the spool to a position where the first flow line and the third flow line are connected together, by the hydraulic pressure of the second liquid chamber.

A work machine includes a closed circuit system in which there is provided a flushing valve. The flushing valve is equipped with: a valve main body; a spool which can select, in accordance with a position where the spool is arranged in the valve main body, connection between a first flow line and a third flow line, connection between a second flow line and the third flow line, or interruption of the connection between the first flow line, the second flow line, and the third flow line; a first liquid chamber that is provided inside the valve main body and into which a hydraulic working fluid from the first flow line flows; a first piston pressurizing the hydraulic working fluid having flowed into the first liquid chamber and moving the spool to a position where the second flow line and the third flow line are connected together, by the hydraulic pressure of the first liquid chamber; a second liquid chamber that is provided inside the valve main body and into which the hydraulic working fluid from the second flow line flows; and a second piston pressurizing the hydraulic working fluid having flowed into the second liquid chamber and moving the spool to a position where the first flow line and the third flow line are connected together, by the hydraulic pressure of the second liquid chamber.

A hydraulic system that has a hydraulic pump connected to and in communication with a hydraulic motor, at least one hydraulic cylinder, or both by a first conduit and a second conduit (i.e., a high side and a low side). The hydraulic system has a bypass valve connected to and in communication with the first conduit and the second conduit. The bypass valve has a preset pressure that is above a minimum low side pressure. When a shock load occurs in the hydraulic system and a related drop in pressure on the low side occurs, the bypass valve opens when the preset pressure is passed thereby preventing the pressure from dropping to the minimum low side pressure. The hydraulic system thereby avoids a low loop event that could cause damage to the hydraulic system without the presence of larger charge pumps or accumulators.