A dual-mode active rear-wheel steering device, including: a steering motor, a main shaft, an intermediate gear, a transmission gear, a planetary gear coupling mechanism and a mode switching assembly. An output end of the steering motor is provided with a first input gear. An end of the main shaft drives a first rear wheel to rotate by a two-stage gear transmission system and a first rear-wheel motion conversion mechanism, and the other end of the main shaft drives a second rear wheel to rotate by the planetary gear coupling mechanism and a second rear-wheel motion conversion mechanism. The intermediate gear, the transmission gear and a sun gear of the planetary gear coupling mechanism are provided on the main shaft. The intermediate gear meshes with the first input gear.

In a transmission structure according to this invention, speed change ratios of input side first and second transmission mechanisms are set so that the rotational speed of a planetary second element is the same when an HST output is set to a second HST speed in either a first transmission state or a second transmission state, and the rotational speed of a planetary first element is the same when the HST output is set to the second HST speed in either the second transmission state or the first transmission state. The speed change ratios of an output side first and second transmission mechanisms are set so that the rotational speed developed in a speed change output shaft when the HST output is set to the second HST speed is the same in either the first or second transmission states.

In a transmission structure according to this invention, speed change ratios of input side first and second transmission mechanisms are set so that the rotational speed of a planetary second element is the same when an HST output is set to a second HST speed in either a first transmission state or a second transmission state, and the rotational speed of a planetary first element is the same when the HST output is set to the second HST speed in either the second transmission state or the first transmission state. The speed change ratios of an output side first and second transmission mechanisms are set so that the rotational speed developed in a speed change output shaft when the HST output is set to the second HST speed is the same in either the first or second transmission states.

A planetary gear assembly includes a wheel hub surrounding an axis, and having an end face and a plurality of engaging recesses formed in the end face, and a planetary gear reduce mechanism including a sun gear disposed on and rotatable about the axis, a plurality of planet gears, and first and second ring gears. The planet gears angularly surround the sun gear and mesh with the sun gear and the first and second ring gears. The first ring gear is stationary relative to the planet gears. The second ring gear is arranged between the wheel hub and the first ring gear along the axis. The second ring gear includes a wheel-hub-facing face surrounding the axis and facing the end face, and a plurality of joining protrusions disposed on the wheel-hub-facing face and respectively complementary in shape with and respectively engage the engaging recesses.

A planetary gear assembly includes a wheel hub surrounding an axis, and having an end face and a plurality of engaging recesses formed in the end face, and a planetary gear reduce mechanism including a sun gear disposed on and rotatable about the axis, a plurality of planet gears, and first and second ring gears. The planet gears angularly surround the sun gear and mesh with the sun gear and the first and second ring gears. The first ring gear is stationary relative to the planet gears. The second ring gear is arranged between the wheel hub and the first ring gear along the axis. The second ring gear includes a wheel-hub-facing face surrounding the axis and facing the end face, and a plurality of joining protrusions disposed on the wheel-hub-facing face and respectively complementary in shape with and respectively engage the engaging recesses.

A transmission apparatus and associated methods for a transportation system. The transmission apparatus includes a clutch assembly and a planetary gear assembly. The clutch assembly includes a clutch hub, a first clutch sleeve, and a second clutch sleeve. The first clutch sleeve is axially movable relative to the clutch hub to selectively engage a first component of a planetary gear assembly. The second clutch sleeve is axially movable relative to the clutch hub to selectively engage a second component of the planetary gear assembly. The planetary gear assembly includes a plurality of planet gears and a planet carrier. Each of the plurality of planet gears is supported in a rotatable manner by the planet carrier. In some embodiments, the first component of the planetary gear assembly is a first sun gear that engages each of the plurality of planet gears.

A transfer includes: an input shaft; a motor; first and second output shafts; first and second planetary gear devices; an input switching unit; a transmission switching unit; and a distribution switching unit. Further, connection states of the input shaft, the first and the second planetary gear devices, the first and the second output shafts can be switched to a plurality of modes including first, second, and third modes by the input switching unit, the transmission switching unit, and the distribution switching unit.

A transfer includes: an input shaft; a motor; first and second output shafts; first and second planetary gear devices; an input switching unit; a transmission switching unit; and a distribution switching unit. Further, connection states of the input shaft, the first and the second planetary gear devices, the first and the second output shafts can be switched to a plurality of modes including first, second, and third modes by the input switching unit, the transmission switching unit, and the distribution switching unit.

A transmission assembly for a hybrid vehicle includes an internal combustion engine and an electric machine, wherein a first drive torque of the internal combustion engine and a second drive torque of the electric machine are transferable to a drive shaft of the hybrid vehicle via the transmission assembly, wherein the transmission assembly comprises: a first transmission input shaft, via which the first drive torque 1 of the internal combustion engine is introduced into the transmission assembly; a second transmission input shaft, via which the second drive torque of the electric machine is introduced into the transmission assembly; the drive shaft; and at least a first planetary transmission including a first ring gear, a first planetary carrier and a first sun gear;
wherein the first transmission input shaft is connected via the first planetary transmission to the second transmission input shaft and to the drive shaft.

A transmission assembly for a hybrid vehicle includes an internal combustion engine and an electric machine, wherein a first drive torque of the internal combustion engine and a second drive torque of the electric machine are transferable to a drive shaft of the hybrid vehicle via the transmission assembly, wherein the transmission assembly comprises: a first transmission input shaft, via which the first drive torque 1 of the internal combustion engine is introduced into the transmission assembly; a second transmission input shaft, via which the second drive torque of the electric machine is introduced into the transmission assembly; the drive shaft; and at least a first planetary transmission including a first ring gear, a first planetary carrier and a first sun gear;
wherein the first transmission input shaft is connected via the first planetary transmission to the second transmission input shaft and to the drive shaft.