Owing to the comnaratively small amount of letters, it is found possible to have a travelling post office on all principal trains (while almost every train has a travelling sorter, for whom a compartment is reserved) without a late fee being exacted in either case.
Add a paper sorter to hold papers and sticker sheets and you'll have nearly everything under control.
The grapes arrive to the winery and are put on a sorter conveyor belt to be sorted through again.
Figure 2. The Sortex Niagara color sorter processing Chardonnay grapes at an Australian winery.
The top was clean except for accessories and a few letters standing upright in a sorter.