Abstract: An improved locking device for a trim chain take-up for mining machines in which the trim chain extends around the auger and the auger support arms and is driven by the auger to cut clearance for the support arm. The take-up is slidably mounted behind the auger support arm in guide means affixed to the machine frame. When the take-up is moved away from the support arm to increase the tension on the chain, the locking device moves into the space developed between the take-up and support arm to prevent the take-up from backing off and reducing the chain tension. The locking device comprises a plurality of thin spacers pivotably retained in a side-by-side stacked relationship on a rod mounted to the support arm. The spacers are further disposed such that they are held in an inoperative position resting on the take-up until the take-up has moved past their respective positions whereupon they pivot about the rod into the operative position between the take-up and support arm.