Abstract: A lock for railway switch adjusting devices, including a locking member having a guide contour extending in the direction in which the switch is actuated and forms a locking seat projecting transversely from the guide contour; a locking lever hinged to an engaging tongue and carries, at the end remote from the tongue, an arresting bolt to be blocked at the locking seat; a guide bolt slidable in the guide contour; a hinge bolt connected to a remote tongue; a bearing block rotatable about the guide bolt axis and in which the arresting bolt, the guide bolt and the hinge bolt are journalled in a triangular configuration such that the arresting bolt and the hinge bolt are positioned on opposite sides of the guide contour and are closer to the engaging tongue than the guide bolt, and a spring that biases the remote tongue towards its remote position.