A system including a gearbox and a hydraulic machine connected by a working fluid circuit. The gearbox including a gearbox housing having first and second gearbox fluid passages integrated into the gearbox housing. The hydraulic machine including a case having first and second hydraulic machine fluid passages, the first and second hydraulic machine fluid passages being integrated into the case. A set of rotating elements enclosed within the case. The first gearbox fluid passage and the first hydraulic machine fluid passage align to form a feed passage to conduct fluid at a first pressure from a first source to the set of rotating elements. The second gearbox fluid passage and the second hydraulic machine fluid passage align to form a charge passage to conduct fluid at a second pressure from a second source to the set of rotating elements. The first pressure being less than the second pressure.

A system including a gearbox and a hydraulic machine connected by a working fluid circuit. The gearbox including a gearbox housing having first and second gearbox fluid passages integrated into the gearbox housing. The hydraulic machine including a case having first and second hydraulic machine fluid passages, the first and second hydraulic machine fluid passages being integrated into the case. A set of rotating elements enclosed within the case. The first gearbox fluid passage and the first hydraulic machine fluid passage align to form a feed passage to conduct fluid at a first pressure from a first source to the set of rotating elements. The second gearbox fluid passage and the second hydraulic machine fluid passage align to form a charge passage to conduct fluid at a second pressure from a second source to the set of rotating elements. The first pressure being less than the second pressure.

A fluid pressure drive device includes a flushing circuit configured to discharge a working fluid from one of the pair of main passages to a tank. The flushing circuit has a low pressure selection valve provided between the pair of main passages and configured to be switched by a pressure difference between the pair of main passages, the low pressure selection valve being configured to select the main passage on the low pressure side; and a flushing passage configured to lead the working fluid passing through the low pressure selection valve to the tank. The flushing passage has a first orifice and a bent portion formed on the downstream side of the first orifice.

A fluid pressure drive device includes a flushing circuit configured to discharge a working fluid from one of the pair of main passages to a tank. The flushing circuit has a low pressure selection valve provided between the pair of main passages and configured to be switched by a pressure difference between the pair of main passages, the low pressure selection valve being configured to select the main passage on the low pressure side; and a flushing passage configured to lead the working fluid passing through the low pressure selection valve to the tank. The flushing passage has a first orifice and a bent portion formed on the downstream side of the first orifice.

A fluid pressure drive device includes a flushing circuit configured to discharge a working fluid from one of the pair of main passages to a tank. The flushing circuit has a low pressure selection valve provided between the pair of main passages and configured to be switched by a pressure difference between the pair of main passages, the low pressure selection valve being configured to select the main passage on the low pressure side; and a flushing passage configured to lead the working fluid passing through the low pressure selection valve to the tank. The flushing passage has a first orifice and a bent portion formed on the downstream side of the first orifice.

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.

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 liquid-pressure driving system includes: a pump connected to an actuator through two pressure liquid passages; pressurizing mechanisms interposed on the passages and applying pressure to the operating oil returning from the actuator; a low pressure selector valve connected to parts of the passages and introducing to a cooling passage the operating liquid having lower pressure between the operating liquids flowing through the two pressure liquid passages; a restrictor mechanism interposed on the cooling passage; a cooler apparatus interposed on the cooling passage downstream of the restrictor mechanism, the cooler apparatus cooling the operating liquid flowing through the cooling passage; and a pressure liquid returning mechanism connected to parts of the two pressure liquid passages, each of the parts being at one side of the corresponding pressurizing mechanism close to the pump, the pressure liquid returning mechanism returning the cooled operating liquid to the two pressure liquid passages.

A liquid-pressure driving system includes: a pump connected to an actuator through two pressure liquid passages; pressurizing mechanisms interposed on the passages and applying pressure to the operating oil returning from the actuator; a low pressure selector valve connected to parts of the passages and introducing to a cooling passage the operating liquid having lower pressure between the operating liquids flowing through the two pressure liquid passages; a restrictor mechanism interposed on the cooling passage; a cooler apparatus interposed on the cooling passage downstream of the restrictor mechanism, the cooler apparatus cooling the operating liquid flowing through the cooling passage; and a pressure liquid returning mechanism connected to parts of the two pressure liquid passages, each of the parts being at one side of the corresponding pressurizing mechanism close to the pump, the pressure liquid returning mechanism returning the cooled operating liquid to the two pressure liquid passages.

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.