Cross-Belt Sorter

Overview

A cross-belt sorter carries each item on a short powered belt mounted crosswise on a moving carrier, and to sort an item it simply runs that belt sideways to fire the item off the loop into a chute. Because the discharge is an active belt rather than a tip or a push, it places items gently and precisely, handles flat and flimsy goods that other sorters struggle with, and sorts to both sides of the loop. That combination makes it the preferred machine for e-commerce and returns operations, where the item mix runs from stiff cartons to limp polybags and the destination count is high.

The sorter is built from a Track Loop the carriers run on, a Cross-Belt Carriers of carts, a Belt Cells cell on each cart, a Linear Induction Drive that propels the loop, the Induction Stations stations that load items, the Discharge Chutes that catch them, and a Sortation Control that runs the sort.

The loop and carriers

The Track Loop is a closed circuit of Rail Section rail and banked Curve Section curves on Support Leg legs. Around it runs the Cross-Belt Carriers, a chain of Carrier Cart carts joined by Cart Coupling couplings. Each cart rolls on polyurethane-treaded Running Wheel wheels on Ball Bearing bearings, stays centred on Guide Wheel guide wheels, and its cast Cart Frame carries one belt cell. The carts run nose to tail so the loop is a continuous string of addressable cells.

The cross belt cell

The defining part is the Belt Cells on each cart. A short Cell Belt runs across the cart, at right angles to the direction of travel, wrapped around Cell Roller rollers and driven by a compact Cell Belt Motor. While the cart circulates the cell belt holds the item still. When the cart reaches the assigned chute, an on-cart Cell Control Board spins the cell belt hard for a fraction of a second, and the belt accelerates the item sideways and flings it cleanly into the chute. Because the belt can run either way, the cart can discharge to a chute on the left or the right, which is how the machine sorts to both sides of the loop. The active belt is also what lets the sorter handle delicate and irregular items: it carries them along on grip rather than balance, and sets them off rather than tipping or shoving them.

Propelling the loop

The carrier train is moved by the same contactless method as other loop sorters. Wayside Linear Motor Stator linear motor stators set up a travelling field that drags the Reaction Plate under each cart, so the train is pushed without contact. The stators wind a Laminated Core laminated core and are fed by a Linear Motor Drive that holds the train at speed, while a Speed Encoder reads cart position so the loop speed and the cell discharges stay in time. Keeping the train at a steady, known speed is what lets a cell fire its item over the chute at exactly the right instant.

Loading items on

Items join the loop at the Induction Stations stations. A Induction Belt accelerates the item to loop speed while a Barcode Scanner reads its label and a Dimensioning Unit confirms it fits one cell. A Photoeye checks the next cell is empty, and the induction belt and the cell belt run together to slide the item onto the cell in step with the moving loop. The sort decision is set here, and from this point the control tracks which cell holds which item.

Chutes and discharge

The Discharge Chutes run along both sides of the loop. When a cell fires, the item flies through a Divert Plate into a sloped Chute that carries it to a bin or packing station, and a Chute-Full Sensor tells the control when that destination is full so it pauses sorting there. Putting chutes on both sides doubles the destinations the machine serves in a given length of loop, which is a large part of why cross-belt sorters reach high destination counts.

Control and use

The Sortation Control runs the sort. A Sort Controller holds the label-to-chute map, tracks every cell around the loop, and decides which cell fires at which chute and in which direction. It commands the carts through wayside Cart Comms Board boards as each cart enters a chute zone, over a network joined by a Network Switch, and shows status on an LCD Panel screen. Cross-belt sorters scale from compact single-loop units in mid-size fulfilment centres to long high-throughput loops in parcel hubs, and they are often paired with an upstream Induction Stations bank of several stations to keep the high loop speed fully fed. Their strength is the active cell belt, which sorts a mixed, hard-to-handle item stream gently and accurately to a large number of destinations.