in an installation for bending glass panes , the glass panes are heated to bending temperature in a horizontal once - through furnace . at the end of the once - through furnace , they are taken over by an endless conveyor belt and are conveyed by this conveyor belt into the bending station , where they are bent together with the conveyor belt . the bent glass pane is conveyed of the conveyor belt into the succeeding cooling or tempering station . in order to support the bent glass pane over the largest possible area , an upper deflector roll for the conveyor belt , disposed at the exit end from the bending station , has a form corresponding to the transverse bend of the glass pane . a lower deflector roll , following the upper deflector roll , has a form complementary to the form of the upper deflector roll . in this way the relative changes in length of the conveyor belt caused by the upper deflector roll are compensated .