Abstract: The ceramic roller-hearth kiln is divided into three zones, of which the first and last are utilized for the initial heating and the cooling of the material respectively, and the central zone, which is provided with combustion means and utilized for high-temperature firing, comprises a conduit for the forced counter-current suction of the gaseous products of combustion between said second and said first zone, from said conduit there branching two ducts for the feed and recovery of part of the hot gas to and from the first zone; the cooling zone being constituted by three successive sections comprising, respectively, direct cooling by blowing air on to the material, cooling by induction and cooling by forced ventilation, the hot air recovered from said cooling zones being fed to the head of the kiln, to flow into said forced suction conduit.

Abstract: A roller table comprising a plurality of equidistant hollow metal or ceramic rollers, at the drive end of each one there being provided a friction clutch device, from the driven element of which there branch means for rotating the roller, together with retention means for this latter which are arranged to prevent its withdrawal from the respective firing tunnel.