Longwall mining is used to more efficiently remove underground coal deposists in large rectangular blocks. After a “pass” of coal has been mined, the equipment assembly including the armored face conveyor and shields must be moved forward to repeat the process. The shield, which stabilizes the immediate roof strata where the coal has been removed, is slid forward on a relay bar by a hydraulic cylinder. Before the shield is removed, it is lowered and the base-lift cylinder is engaged, which picks the front of the shield off the mine floor to more easily slide it forward. Due to the weight of the shield, force exerted by the base lift cylinder, and the height of the front of the relay bar above the ground, the relay bar deflects, causing significant stresses. OCE was asked to perform the structural integrity and fatigue life of an original and modified relay bar.