Abstract: A work vehicle includes a frame including generally upwardly extending laterally spaced side members. A boom structure includes a pair of arms pivotably connecting the boom structure to the frame. A pressurized fluid system is operably associated with the boom structure for raising and lowering jointly each of the arms along a path of travel adjacent a corresponding side member. A stop member selectably extends outwardly from at least one of the side members between a locking position and a retracted position, the locking position extending at least a portion of the stop member into the path of travel of a corresponding arm of the boom structure to prevent a lowering movement of the boom structure beyond a predetermined height. A boom lock system prevents the fluid system from applying a fluid force to lower the boom structure when the stop member is in the locking position.