A receiver device for engaging a landing gear adapter unit with a tug. In exemplary embodiments, the adapter may include a tow bar with a neck portion between a pair of spaced arm portions. The receiver device forms a travel path boundary for the neck portion and is configured to be complementary with and to engage the neck portion. A mounting portion is provided for mounting the receiver device on the tug in an operative configuration relative to a landing gear-receiving base thereon. At least one releasable locking member is positioned along the travel path to interrupt travel of the neck portion. The locking member is movable between a first unlocked position and a second locked position. Further, in the second locked position, the locking member is configured to lock the mounting portion in the operative configuration.