EMPLOYEE STATES HE WAS DEADHEADING 950 ENDLOADER/FORKLIFT TO DRILL SITE IN THE PIT TO USE ON DRILL REPAIR. HE TESTED BRAKES AT TOP OF RAMP AND THEY WERE WORKING, HOWEVER AS HE TRAVELED DOWN RAMP THE BRAKES FAILED. HE TURNED THE ENDLOADER INTO SPIL ON LEFT SIDE OF RAMP, CAUSING THE ENDLOADER TO TURN ON THE RIGHT SIDE.