The present invention, which, preferably, to the planetary gear set of the gear unit for a wind turbine having at least one planetary gear set, at least one stationary sealing surface 404 and at least one cavity (106) is a rotatable planetary carrier and a rotatable ring gear, joint 106 has a relatively arranged in a rotational fixed one or more openings (108, 302) for a rotatable planetary carrier or a rotatable ring gear, the gear device is holding the oil reservoir configuration and is rotatable planetary carrier or a rotatable ring gear is able to take at least a first position, at least one second position and at least one third position, by a rotatable planetary carrier or a rotatable ring gear is rotated to the to a second position from the first position and the second it may be converted to the third position from the second position, a rotatable planetary Cary Or rotatable ring if the gear is located in the first position, the oil can reach the cavity 106 through an opening (108, 302) from the oil storage, and a rotatable planet carrier or a rotatable ring gear is a third position if it is located in, and the oil can be discharged from the cavity 106 through an opening (108, 302). If the rotatable planetary carrier or a rotatable ring gear is positioned at the second position, an opening (108, 302) it is closed by the sealing surface 404. The