The pump rod is the item which connects the windmill pump to the windmill engine. In examining windmill pumping system failures it is found that pump rod failures are the major cause. Windmill engine or tower failures are rare if a proven windmill design is chosen and the windmill is correctly installed. One will often hear that a windmill is broken. In the great majority of cases in fact the pump rods have become disconnected from the windmill pump due to breakage or twisting loose. Breakages are caused by a number of reasons dealt with elsewhere in this document. It is also obviously essential that adequately sized pump rods be selected. One of the major failure modes further is the propensity of the individual pump rod lengths to twist loose from each other. This is due to incorrect installation, poor windmill design which leads the pump rods to be twisted by the windmill engine as it turns to follow the wind direction or by poor machining of the threads on the individual pump rods. Photo of pump rods.