A retaining device (10) for a conveyor belt assembly (12) which includes a clamping means (14) for clamping a conveyor belt (36) of the conveyor belt assembly, and a biasing means (38,40) for displacing the clamping means between an inoperative condition and an operative retaining condition wherein the clamping means clamps a part of the belt to tension a material carrying portion of the belt in the event of a loss of tension in the belt.