var timesierra

function FirstImageSierra() {
  if (document.images) {
        clearTimeout(timesierra)
        document.sierraimage.src="http://www.hemig-erle.com/images/sierra_01.jpg";
        timesierra=setTimeout("SecondImageSierra()",5000);
      }
}


function SecondImageSierra() {
  if (document.images) {
        clearTimeout(timesierra)
        document.sierraimage.src="http://www.hemig-erle.com/images/sierra_02.jpg";
        timesierra=setTimeout("ThirdImageSierra()",5000);
      }
}

function ThirdImageSierra() {
  if (document.images) {
        clearTimeout(timesierra)
        document.sierraimage.src="http://www.hemig-erle.com/images/sierra_03.jpg";
        timesierra=setTimeout("FirstImageSierra()",5000);
      }
}