var num = 1;
image1 = new Image();
image1.src = "images/drawings/bolt.gif";
image2 = new Image();
image2.src = "images/drawings/machine.gif";
image3 = new Image();
image3.src = "images/drawings/pipe.gif";
image4 = new Image();
image4.src = "images/drawings/safetyvalve.gif";
image5 = new Image();
image5.src = "images/drawings/tool.gif";


function show_images()
{
	
	if(!document.images)
	{
		return;
	}
	else
	{
		document.images["drawings"].src=eval("image"+num+".src");
		if(num<5) 
		{
			num++;
		}
		else
		{
			num=1
		}
		setTimeout("show_images()",3500);
	}
}
show_images();