Palletiser with preparation crates layers

The palletizer comprises a device (24) for preparing and prestacking layers of crates which consists of: - a table (25) movable vertically, - a table (26, 26 ') shaped noria, capable of take the place of said table (25) and to deposit another layer of crates on the layer that is waiting on said table (25), - means for calibrating each layer of boxes according to the palletization layout. The table (25) and the table (26, 26 ') are used to carry the crates layers calibration operation by moving said boxes against a stop (40) which, in inoperative position, is sole office between the table (25) and the table (7) palletizing. The table (26, 26 ') is provided by rollers (30) which are mounted on non-return bearings.