The locking pin (red cylinder in the image) for the Spitfire family undercarriage rotated 180 degrees depending on whether it was acting as an uplock or a downlock. The sloped face allowed the gear strut to push the pin out of the way once it was rotated. The rotation was achieved via a chain and cog controlled via cables connected to the undercarriage controls. Originally I hadn’t planned on modelling these that accurately, because it’s in the gear bay and it seemed a lot of detail for something that’s mostly obscured. But as the alternative was trying to give the impression of a chain with textures I ended up doing it anyway. The picture below shows where it goes, the cables having been disconnected for removal.
I’ve done a short video that shows a) how impressive the animation is and b) how hard it is to actually see in P3D because of the undercarriage and wing being in the way!