Hanna furnaces of the Great Lakes Steel Corporation. Detroit, Michigan. Coke oven pusher. A long square pusher is inserted through the entire section of the coke oven, thus pushing the coke out to the other side into the freight car. This coke oven is a modern by-product oven. All the gases and vapors liberated from the coal in the cooking processes are recovered. The coal is heated from fifteen to twenty hours in a temperature of about 1700 degrees F. The gases and vapors released by the coal are condensed for the recovery of such by-products as tar, benzol, and gas. At the end of the coking period, the incandescent coke mass is pushed into the quenching car