EMPLOYEE STATED THAT HE WAS OPERATING NO.6 COALHAULER AND AFTER THE COALHAULER WAS LOADED IN NO.1 ENTRY HE TRAMMED TO NO.2 ENTRY WHERE HE RAN OVER A TIMBER (12'X10"") THAT WAS LYING IN THE ROAD WAY APPROXIMATELY 60 FT. OUTBY SPAD NO.7899. HE STATED THAT THIS CAUSED HIM TO BOUNCE IN THE SEAT OF THE COALHAULER AND JARRED HIS BACK.