A tilt-tray sorter is a mechanical assembly similar to a conveyor belt but instead of a continuous belt, it consists of individual trays traveling in the same direction.
A tilt-tray sorter can be configured in an inline (AKA over/under) formation, or in a continuous-loop.
Items are loaded onto the passing trays at the front end of the sorter and travel towards a series of destinations on either side of the sorter.
Items are loaded on to trays individually and their sort destination is determined in advance.
[1] A tilt-tray sorter is a continuous-loop sortation conveyor that uses a technique of tilting a tray at a chute to slide the object into the chute.