A device is provided for detecting and adjusting the tension of the scraper chain. The device identifies broken chain as it leaves the return sprocket and enters the top race of the conveyor. When detected, the chain can be stopped automatically by the armored face conveyor control system, to avoid the potential for further damage, and warn the operators that repair of the chain is required.The device also provides a conveyor with sliding frames at both ends to allow the conveyor ends to be independently adjusted to each end of the coal block, whilst maintaining good chain tension and control.