The pump hangs on the pto output shaft of the tractor. The pin on the top of the pump fits in the slot you see on the back of the tractor that you see just above the pto. The purpose of the pin in the hole is to keep the pump from turning with the pto. The shaft you see in the pictures is part of the snow blower that is on the tractor now. It is not used when the backhoe in in use.