Stone guard door for harvesters

Abstract From the Canadian patent

A harvester has a threshing head pivotally mounted at the front end for raising and lowering movement between a lower operative position and an upper inoperative position. The threshing head comprises a rotatable threshing cylinder a concave adjacent to and spaced from the threshing cylinder means for feeding crop along a flow path to the space between the threshing cylinder and the concave and a stone guard, door in the flow path. A latch normally retains the door in a closed position, and is operable by a stone above a predetermined size to cause opening of the door and discharge of the stone from the flow path before the stone enters the space between the threshing cylinder and the …