var how_many_ads = 4;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;
if (ad==1) {
url="/_pdfs/sell_sheets/cc750.pdf";
banner="/_images/product/cc750.jpg";

}
if (ad==2) {
url="/_pdfs/sell_sheets/umsr.pdf";
banner="/_images/product/umsr.jpg";

}
if (ad==3) {
url="/_pdfs/sell_sheets/us_motors.pdf";
banner="/_images/product/motors.jpg";

}
if (ad==4) {
url="/_pdfs/sell_sheets/rdf150.pdf";
banner="/_images/product/rdf150.jpg";

}

if (ad==5) {
url="/_pdfs/sell_sheets/unit_bearing_hussman.pdf";
banner="/_images/product/unit_bearing.jpg";

}

if (ad==6) {
url="/_pdfs/sell_sheets/PSC_blowers.pdf";
banner="/_images/product/psc_blowers.jpg";

}

if (ad==7) {
url="/_pdfs/sell_sheets/NUCO_One_Sheet.pd";
banner="/_images/product/nuco_sticks.jpg";

}