A stone trap assembly including an entrance and an exit. The entrance receives objects from a crop flow path for accumulation into the assembly during a harvesting operation, and the exit allows evacuation of the accumulated foreign objects out of the assembly during an evacuation operation. The assembly further includes a door configured to be rotatable around a first rotation axis, substantially transverse to the crop flow path, for movement along a door movement trajectory between a closed position and an evacuation position, and an impeller for forcing the accumulated foreign objects towards the exit. The impeller is configured to be rotatable around a second rotation axis, substantially transverse to the crop flow path, for movement along an impeller movement trajectory between a retracted position and an extended position closer towards the exit. The door and impeller are separately movable during at least a part of the trajectories.