A transmission assembly comprising a common ring gear assembly, a first sun gear, a first planet carrier carrying a set of planet gears, a second sun gear and a second planet carrier carrying a set of planet gears, said set of planet gears (52, 58) of each one of said first and second planet carriers (50, 56) meshing with said common ring gear assembly, said set of planet gears of said first planet carrier meshing with said first sun gear and said set of planet gears of said second planet carrier meshing with said second sun gear, said transmission assembly further comprising a transmission housing, said transmission assembly being configured such that: - said second sun gear is adapted to be connected to a transmission input shaft; - said common ring gear assembly is adapted to be connected to a transmission output shaft; - said second planet carrier and said first sun gear are operatively connected to each other, wherein said transmission assembly further comprises said transmission input shaft and said transmission output shaft, said transmission input shaft being connected to said second sun gear and said transmission output shaft being connected to said common ring gear assembly, characterized in that said transmission assembly comprises a gear selection arrangement comprising: - a first locking mechanism being adapted to be controlled by a first fluid pressure conducted to said first locking mechanism such that: ∘ for at least a first fluid pressure equal to zero overpressure, said first locking mechanism is adapted to assume a locked condition in which said first planet carrier is locked to said transmission housing, and - a second locking mechanism being adapted to be controlled by a second fluid pressure conducted to said second locking mechanism such that: ∘ for at least a second fluid pressure equal to zero overpressure, said second locking mechanism is adapted to assume a locked condition in which said second planet carrier and said first sun gear are locked to said transmission housing, wherein said transmission housing comprises a transmission housing wall assembly defining a transmission housing cavity enclosing at least said common ring gear assembly, said first sun gear, said first planet carrier, said second sun gear and said second planet carrier, wherein at least an external portion of each one of said first and second locking mechanisms (64, 66) is located on one side of said transmission housing wall assembly and said transmission housing cavity is located on an opposite side of said transmission housing wall assembly. - said second sun gear is adapted to be connected to a transmission input shaft; - said common ring gear assembly is adapted to be connected to a transmission output shaft; - said second planet carrier and said first sun gear are operatively connected to each other, wherein said transmission assembly further comprises said transmission input shaft and said transmission output shaft, said transmission input shaft being connected to said second sun gear and said transmission output shaft being connected to said common ring gear assembly, characterized in that said transmission assembly comprises a gear selection arrangement comprising: - a first locking mechanism being adapted to be controlled by a first fluid pressure conducted to said first locking mechanism such that: ∘ for at least a first fluid pressure equal to zero overpressure, said first locking mechanism is adapted to assume a locked condition in which said first planet carrier is locked to said transmission housing, and - a second locking mechanism being adapted to be controlled by a second fluid pressure conducted to said second locking mechanism such that: ∘ for at least a second fluid pressure equal to zero overpressure, said second locking mechanism is adapted to assume a locked condition in which said second planet carrier and said first sun gear are locked to said transmission housing, - a first locking mechanism being adapted to be controlled by a first fluid pressure conducted to said first locking mechanism such that: ∘ for at least a first fluid pressure equal to zero overpressure, said first locking mechanism is adapted to assume a locked condition in which said first planet carrier is locked to said transmission housing, and ∘ for at least a first fluid pressure equal to zero overpressure, said first locking mechanism is adapted to assume a locked condition in which said first planet carrier is locked to said transmission housing, and - a second locking mechanism being adapted to be controlled by a second fluid pressure conducted to said second locking mechanism such that: ∘ for at least a second fluid pressure equal to zero overpressure, said second locking mechanism is adapted to assume a locked condition in which said second planet carrier and said first sun gear are locked to said transmission housing, ∘ for at least a second fluid pressure equal to zero overpressure, said second locking mechanism is adapted to assume a locked condition in which said second planet carrier and said first sun gear are locked to said transmission housing, wherein said transmission housing comprises a transmission housing wall assembly defining a transmission housing cavity enclosing at least said common ring gear assembly, said first sun gear, said first planet carrier, said second sun gear and said second planet carrier, wherein at least an external portion of each one of said first and second locking mechanisms (64, 66) is located on one side of said transmission housing wall assembly and said transmission housing cavity is located on an opposite side of said transmission housing wall assembly.