Abstract: A combined kiln and lid prop in which the kiln has an upwardly opening lid pivotally mounted thereon, said prop being pivotally mounted on the kiln and having an upwardly extended propping position in which it is releasably retained by resting the lid thereon, an outward reclining position, and a center of gravity in the propping position outward of the pivotal mounting thereof so that the prop automatically pivots to the reclining position when the weight of the lid is removed therefrom allowing the lid fully to close.

Abstract: A furnace for treating glass sheet material and the like in a glass tempering system. The furnace includes an upper glass treating zone and a lower gas treating and distributing zone for homogenizing gases of different temperatures to minimize exposure of the sheet being treated in the treating zone to uneven temperatures. Diametrically opposed inlets and outlets are provided in the side walls controlled by doors, and a slot in the top wall extends between the inlets and outlets to permit movement of a material carrier through the furnace. A pressure chamber communicates with the slot to cool conveyor elements at the top of the furnace, and also to provide a pressure barrier resisting the escape of gases from the furnace through the slots. Air curtains impinge on the tops of the doors in their closed positions to reduce leakage at the top of the doors.

Abstract: A furnace for heat treating glass sheet material including a circular enclosure having top, bottom and side walls of refractory material. Inlet and outlet openings are formed in the side walls. The side walls have an outer insulating layer and an inner layer of material having a low coefficient of thermal expansion, the inner layer having spaced end portions projecting beyond the outer layers and the periphery of the side walls to define said inlet and outlet openings. Each opening is controlled by doors, and each door includes an elongated support bar with a plurality of blocks of refractory material supported on the bar in end-to-end relationship. The blocks are adjustably secured to the bar to accommodate irregularities in the openings.