In the most relevant of all known food processing installations, dough deposits are loaded onto flat or compartmented product support trays and are conveyed serially through an oven chamber. The trays would normally also be conveyed through at least one further chamber, for example a cooling chamber, a refrigerating chamber or a tray washing chamber. In moving through the oven chamber (and, similarly, through other chambers) the trays are conveyed in a manner such that they make a succession of forward-and-return horizontal passes along the length of the chamber. The trays are supported by individual carriers, from which they may be removed, and each carrier is connected to and extends between two spaced-apart parallel conveyor chains which are driven by a common drive system to move through the chamber. The respective conveyor chains are guided by sprockets to make the changes in direction between the forward-and-return horizontal passes and, also, at opposite ends of the chamber to direct the conveyor chains in vertical directions between the upper and lower levels of the chamber.
The tray carriers extend across substantially the full width of the chamber and they are pivotably connected at their ends (adjacent side walls of the chamber) to the conveyor chains. The pivotable connection permits each tray carrier to maintain a horizontal disposition when being conveyed around the sprockets and when being conveyed (upwardly or downwardly) in a vertical direction.
Horizontal rails are provided at each side of the chamber and they are used to maintain the tray carriers in a stable, horizontal disposition when the carriers are moved along the horizontal passes within the chamber. However, the known food processing installation does not make any provision for maintaining the trays in a horizontal disposition other than when the tray carriers are supported by the horizontal rails.
A significant problem that has been found to exist in the known food processing installations is that, with any eccentric loading or disturbance of any of the trays, the affected trays and tray carriers are caused to rock when being transported around sprockets or in a vertical direction. This problem is exacerbated with large sized trays and/or when relatively large dough deposits are carried by the trays.
When rocking of a tray becomes sufficiently pronounced, the associated tray carriers that are about to move into a horizontal pass may momentarily be tilted to such an extent that they will be misdirected below the intended horizontal support rails. When this happens, crashing may (and has been known to) occur between moving trays and fixed structures within the chamber.
An attempt has been made to alleviate the above stated problem by connecting each pair of tray carriers with a relatively heavy transversely extending metal bar. The use of these bars has to a limited extend been helpful in minimizing rocking of the trays, but the use of the bars has created further problems. Given the fact that, in a typical installation, something in the order of 200 trays may be conveyed through and from the oven chamber (and other associated chambers) in the installation, the bars add significantly to the thermal mass of the system, to the drive power requirements and to cooling requirements if the trays are to be conveyed through a cooling chamber following movement through the oven chamber.