PROBLEM Longwall mining operations throughout the world use drag chains with connected flight bars to transfer the coal away from the cut face. The fast moving chains can extend over 2,000 feet with more than 1,000 connected flight bars. Each flight bar, weighing over 200 pounds, requires heavy duty locknuts that can withstand the harsh, abrasive, high-vibration environment. Failure to secure the flight bars causes significant damage and mac

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