Wheeled working machine

A wheeled working machine comprising:

• a lower traveling body having front wheels and rear wheels;
• an upper rotating body rotatably mounted on the lower traveling body;
• a cab arranged on one of the left and right sides of the upper rotating body for serving as an operating room during working as well as a driving room during traveling;
• and
• a steering apparatus, the steering apparatus comprising:
• mechanical steering means for steering the front wheels in accordance with the operation of operating means arranged within the cab by connecting the operating means to a link member for changing the direction of the front wheels so as to transmit a steering force;
• full-hydraulic steering means, having steering cylinders for respectively changing the directions of the front wheels and the rear wheels, for steering at least one of the front wheels and the rear wheels by introducing hydraulic oil to predetermined steering cylinders in accordance with the operation of the operating means and a selected mode relating to the steering of the front wheels and the rear wheels;
• and
• switching means for switching one of the mechanical steering means and the full-hydraulic steering means so as to be selectively actuated.