Abstract: An upper line comprises three furnaces 1, 2, 3 and a washing machine 4, in straight side-by-side arrangement. A lower line comprises movable treatment elements 7, 8, 9 movable on conveyor track 5, and fixed vat 17. Car 6 permits feeding all the elements of the upper line, as well as materials handling equipment 11, from entry station 20. Elements 7, 8, 9 and 17 can be fed either directly from the furnaces 1, 2, 3 via the materials handling equipment 11.

Abstract: A bell furnace (2) and hardening vat (3) arrangement comprises charge (4) supporting means (14, resp. 29, 32, 33) connected to the bell and extending toward the center of the bell. It comprises means (18, 18', resp. 28) for imparting solely to the bell either a vertical and rotary movement or only solely a vertical movement, while the vat (3) is under the furnace (1), in such a way that the bell can be brought against the top plane of the vat, the bell/vat unit forming a tight enclosure at the time of hardening. A lift can introduce into the bell, and the means (18, 18;, resp. 31, 34, 37) co-operate at the same time in the release of the charge and in the placing of the latter on the supporting means (14).