EE WAS TOWING IMPACT CRUSHER DOWN RAMP WHEN TRACKS BEGAN TO LOOSE GRIP ON FROZEN GRADE. DOZER SLID TO SIDE AND JACK-KNIFED THE DOLLEY BECAUSE OF MOMENTUM OF CRUSHER. AFTER GETTING DOZER STOP PED OPERATOR GOT NERVOUS & BAILED OFF MACHINE INA HURRY AND LOST HIS BALANCE, FALLING TO THE GROUND, LANDING ON BOTH HANDS TO CATCH HIS FALL. LT. WRIST BROKEN, RIGHT WRIST SPRAINED.