A hydraulic transaxle facilitates mounting a parking brake unit which requires no link mechanism and is compact. The parking brake unit includes a brake rotor provided on a rotation shaft and a locking member being displaceable between a first position where the brake rotor is locked and a second position where the brake rotor is unlocked. The locking member includes a locking portion which is engaged in a recess formed in the brake rotor that locks the brake rotor in the first position, and a non-locking portion which is placed at a position corresponding to the recess and which separates from the brake rotor in the second position. The hydraulic transaxle further includes an oil-supply mechanism capable of displacing the locking member to the second position.

A hydraulic transaxle facilitates mounting a parking brake unit which requires no link mechanism and is compact. The parking brake unit includes a brake rotor provided on a rotation shaft and a locking member being displaceable between a first position where the brake rotor is locked and a second position where the brake rotor is unlocked. The locking member includes a locking portion which is engaged in a recess formed in the brake rotor that locks the brake rotor in the first position, and a non-locking portion which is placed at a position corresponding to the recess and which separates from the brake rotor in the second position. The hydraulic transaxle further includes an oil-supply mechanism capable of displacing the locking member to the second position.

A micro-traction drive unit according to the present invention includes an inner ring, an outer ring, a plurality of rolling elements, a retainer, a micro-traction drive case and a power-transmitting shaft coaxial with the inner ring and incapable of relative rotation around an axis to the retainer. An opposite end of the power-transmitting shaft from the inner ring forms an input end operatively connected to a driving source. An input end of the pump shaft is detachably connected to a central hole of the inner ring in a state incapable of relative rotation around the axis via the access opening of the micro-traction drive case by connecting the micro-traction drive case to the HST case so as to surround the input end of the pump shaft of the HST.

A micro-traction drive unit according to the present invention includes an inner ring, an outer ring, a plurality of rolling elements, a retainer, a micro-traction drive case and a power-transmitting shaft coaxial with the inner ring and incapable of relative rotation around an axis to the retainer. An opposite end of the power-transmitting shaft from the inner ring forms an input end operatively connected to a driving source. An input end of the pump shaft is detachably connected to a central hole of the inner ring in a state incapable of relative rotation around the axis via the access opening of the micro-traction drive case by connecting the micro-traction drive case to the HST case so as to surround the input end of the pump shaft of the HST.

An HST of the present invention includes a main plate and a sub-plate supporting a center section, a pump-side swash plate holder and a motor-side swash plate holder by their inner surfaces facing each other. The main plate is provided with an extended region that extends farther outward in a planar direction of the main plate than an installation space of the center section, the pump-side swash plate holder and the motor-side swash plate holder and than the sub-plate as viewed along a direction in which the main plate and the sub-plate face each other.

An HST of the present invention includes a main plate and a sub-plate supporting a center section, a pump-side swash plate holder and a motor-side swash plate holder by their inner surfaces facing each other. The main plate is provided with an extended region that extends farther outward in a planar direction of the main plate than an installation space of the center section, the pump-side swash plate holder and the motor-side swash plate holder and than the sub-plate as viewed along a direction in which the main plate and the sub-plate face each other.

A hydrostatic drive system (1) has a hydrostatic pump (3) driven by a drive motor (2) and connected in a closed circuit with a hydrostatic motor (4). The hydrostatic motor (4) drives a consumer (5) and the closed circuit is formed by a first hydraulic connection (6a) and a second hydraulic connection (6b). A hydrostatic accumulator (30) can be connected with at least one of the two hydraulic connections (6a, 6b). A hydrostatic drive unit is located in an accumulator flow path (21) between one of the two hydraulic connections (6a, 6b) and the hydrostatic accumulator (30) and an additional hydrostatic drive unit is located in a tank flow path (22) between the other of the two hydraulic connections (6a, 6b) and a tank (17). The hydrostatic drive unit and the additional hydrostatic drive unit are a hydrostatic dual-flow double drive unit (20) provided in the accumulator flow path (21) and in the tank flow path (22).

A hydrostatic drive system (1) has a hydrostatic pump (3) driven by a drive motor (2) and connected in a closed circuit with a hydrostatic motor (4). The hydrostatic motor (4) drives a consumer (5) and the closed circuit is formed by a first hydraulic connection (6a) and a second hydraulic connection (6b). A hydrostatic accumulator (30) can be connected with at least one of the two hydraulic connections (6a, 6b). A hydrostatic drive unit is located in an accumulator flow path (21) between one of the two hydraulic connections (6a, 6b) and the hydrostatic accumulator (30) and an additional hydrostatic drive unit is located in a tank flow path (22) between the other of the two hydraulic connections (6a, 6b) and a tank (17). The hydrostatic drive unit and the additional hydrostatic drive unit are a hydrostatic dual-flow double drive unit (20) provided in the accumulator flow path (21) and in the tank flow path (22).

A hydraulic mechanical transmission includes a first hydraulic unit having a first shaft and a second hydraulic unit having a second shaft. The second hydraulic unit is connected in hydraulic fluid communication with the first hydraulic unit by high and low pressure lines. At least one of the first and second hydraulic units has variable displacement. A mechanical torque transfer arrangement transfers torque between the first shaft and the rotatable component of the second hydraulic unit. One of the first and second hydraulic units operates as a hydraulic pump and the other of the first and second hydraulic units operates as a hydraulic motor.

A hydraulic mechanical transmission includes a first hydraulic unit having a first shaft and a second hydraulic unit having a second shaft. The second hydraulic unit is connected in hydraulic fluid communication with the first hydraulic unit by high and low pressure lines. At least one of the first and second hydraulic units has variable displacement. A mechanical torque transfer arrangement transfers torque between the first shaft and the rotatable component of the second hydraulic unit. One of the first and second hydraulic units operates as a hydraulic pump and the other of the first and second hydraulic units operates as a hydraulic motor.