Auto-Sweeper

The Auto-Sweeper is a duplicant-free logistics building that can move solid items within a 9×9 area centered on itself, reaching four tiles in every direction. It can supply nearby buildings and containers, including loading ingredients into an Electric Grill and transferring finished food into storage such as a Refrigerator. Its range can be viewed at any time by clicking the building.

Auto-Sweepers follow the game’s priority system. They move items from lower-priority containers to higher-priority ones, which matters when multiple eligible destinations are in range. For example, if a Conveyor Loader has lower priority than a Storage Bin, the sweeper will not load items from the bin into the loader. Likewise, if a Conveyor Receptacle has higher priority than a bin, items may remain in the receptacle and cause the connected Conveyor Rail to back up.

Some practical properties make Auto-Sweepers especially useful in base automation:

• They consume power only while moving.
• They can transport up to 1 tonne per swing.
• They need to remain enabled for about 2 seconds per item they try to pick up in a single sweep, then another 2 seconds to store what they are holding.
• If disabled after picking up items but before storing them, they drop their contents from their center tile.
• They do not exchange heat with the items they move.
• They work while submerged in water.
• They can plant seeds into Planter Boxes and Farm Tiles if those tiles are in range.
• They can see through diagonal openings and closed Pneumatic Doors, so they can move items between sealed rooms.

Because of their line-of-sight behavior, Auto-Sweepers can often service separated rooms without breaking airlocks, as long as the path includes diagonal visibility or a closed Pneumatic Door. They can also be daisy-chained with Automatic Dispensers placed between multiple sweepers, creating a larger sweeping network whose throughput is limited mainly by the sweepers themselves rather than by a single Conveyor Rail line.

When using them with storage, it is best to manage priorities carefully. A sweeper in range of both a storage destination and a transport system may prefer one over the other based on assigned priority, which can be used to stage materials before loading them into conveyors. This also means poorly configured storage can interfere with conveyor loading.

Auto-Sweepers briefly hold transported materials inside themselves before placing them, which has an important consequence for volatile items: they may release immediately from the sweeper’s center tile if the item would normally off-gas while being carried.

One known issue is that a Storage Bin with certain selected item filters can sometimes cause an Auto-Sweeper to load random items into it. Another interaction worth noting is that Light’s work bonus also applies to Auto-Sweepers.