01How the loop works
Carriers on a loop frame never stop and never return empty along a separate path — they circulate. An inducted parcel rides its carrier around the loop until the carrier reaches the chute assigned in the parcel's record; the cross belt then drives sideways and sets the parcel into the chute. A parcel whose chute is busy or whose record arrives late simply rides another circuit — the loop forgives timing problems that a one-pass linear track cannot.
Induction can be arranged at several points around the loop, which lets a loop sorter gather parcels from multiple upstream flows — different DWS lines, different building zones — into one sort. Discharge chutes pack densely around both the straights and the ends of the oval, which is where the destination-per-footprint advantage comes from.
02Where the loop is the right frame
Express hubs and e-commerce sortation centres with dozens of destinations are the loop's home ground: route splits, carrier splits and service splits multiply destinations quickly, and hub buildings are usually squarer than they are long. The loop also suits phased destination growth within a fixed building — chutes can be re-mapped in configuration as the network changes, and the frame's capacity for additional induction points gives the operation somewhere to grow.
The trade-offs are the mirror of the linear frame: a loop wants a clear oval of floor, and extending it means re-framing rather than adding a section. Where the building offers a long run and the sort plan reads as a sequence, linear is the more natural frame. The discharge — and therefore the parcel care — is identical on both, as the parent cross-belt sorter page explains.
03The loop inside a measured line
Loop sorters are almost always fed by measured induction: singulators spacing parcels, DWS sections capturing dimensions, weight and identity, and the record assigning carrier and chute. That pairing is what turns a sorter into a sortation system — the sortation system page covers the full stage sequence, and the logistics sorting application page walks a hub scenario from inbound to loaded vehicle.