certain parameters in a high speed order change in a corrugator , including a small gap between orders and the relative lengths of the old and new order sheets , require altered order change and discharge routines on the downstacker conveyor system in order to prevent edge butt between the last sheet of the old order and the first sheet of the new order . alternate order change and order discharge routines , which are automatically implemented by the downstacker system controller , include accelerated movement of the old order shingle out of the downstacker vacuum conveyor to outrun the incoming first sheet of the new order or , alternately , allowing the first sheet of the new order to overrun the tail end of the old order and utilizing , if necessary , a device to divert the lead edge of the first new order sheet upwardly to allow the shingle to be reestablished .