The Empire Turbine Ventilator is a dependable rotary that works automatically, continuously and silently without operating or maintenance costs. It is outside braced for strength, safety and perfect alignment. Ventilators up to and including 14" are aluminum braced. Larger sizes are steel braced for additional strength. Operation is simple and sure. When the slightest breeze touches the scientific blade construction it causes the turbine to rotate. The centrifugal force caused by the revolving turbine creates a partial vacuum within the turbine. This vacuum is then replaced by a strong upward draft of air. A powerful exhaust is thus achieved. The lower thrust bearing is a hardened steel ball riding in a hardened steel concave seat (in sizes up to 8") for extreme sensitivity and wearability. In larger sizes, thrust type ball bearings are used. Upper bearings on all ventilators are bronze oilless. The rigid construction of these stormproof ventilators assures years of efficient service. No adjusting or servicing is required.