Just watch a 330 or 777 (non-er so no bogie lock) on take-off. The bogie stays level with the ground as the ac rotates around the center of the bogie - so relative to the ac it is nose down. Then as the aircraft unsticks the back wheels falls and the bogie hangs nose up due to the weight distrubition (*pitch trimmer positioning), then the gear pitch trimmer (or its equivalent in the 777) moves the bogie nose down for the retraction.
Last edited by mrfox; 10th November 2017 at 02:30.