Lister Petter Hi temperature switch 570-34790 commonly used on the Read Screen-all products570 34790 Hi Temperature safety switch, commonly used on the Read Screen All products, Model RD 20, RD 40, Rd 90 and the RD 150 screeners This will be item number 2 and it will include items 3 and 4 on the Lister Petter drawings. You will notice on page 12 this switch works above 1850 rpm and its a normally closed contact switch. its listed as a code JB item. this item can be tested by starting the engine and disconnecting one of the wires, the engine