Employee was bolting on the #3 Section in the #6 Entry 130' inby spad # 12262. The bolt crew had stacked plates and pans on the base of the t-bar where the t-bar meets the frame of the RBM. When the boom of the machine swung, the plates and pans fell off and struck the employee on the side of the rt. knee. Employee was diagnosed with a strain and began missing work on 3/8/13.