The figure shows a conveyor so fitted with lifting appliances ´a´. The conveyor, b. Wheels running on the hearth without rails, c. Recess in hearth. d. Rails running the length of the hearth, e. Flanged wheels which determine the path of the machine, f. Toothed rack running the length of the hearth, by means of which and a wheel coupled to the motor the machine can traverse the length of the hearth, g. Motor, coupled at one end to the travelling gear, and to the conveyor and the coke-lifting apparatus, h.