A zero turning radius mower is provided with twin operating levers that are manipulated by the driver to control steering, speed and forward or reverse direction of the mower. When the two drive levers are in the neutral mode, they may be swung outwardly to widespread positions to facilitate operator dismount. If both drive levers are spread apart, a park lever may be operated by the driver to position blocking bars into the path of the levers to prevent their return from the widespread positions. Once the engine is shut off, it can only be restarted when the mower is in its park mode with the park lever engaged.