The Liquid Unloader is a block added by Railcraft used to deposit liquids from a Tank Cart into an adjacent container. When the cart is empty, or meets the requirements set in the GUI the block will emit a Redstone signal.
The Liquid Unloader has to be placed below the track where the minecart to unload will be. Locking Tracks are very useful when combined with Item Loaders, when set to Holding or Boarding mode, because they will stop the cart when there is no Redstone signal, and will force the cart to continue when there is a Redstone signal.
In the GUI there is a Filters section, a Buffer section, and a few buttons. The Filters section determines which liquids and how many Buckets are taken from the container. The Buffer section is where the excess liquids go if they cannot fit into the tank, the Buffer has room for 16 buckets.
The buttons determined how the Unloader will function:
- All: Move all liquids.
- Transfer: Move the exact liquids in the Filter.
- Stock: Move liquids until the destination matches the Filter.
- Excess: Keep the liquids in the Filter, and move the rest.
- Immediate: Emit Redstone if no liquids were moved.
- Complete: Emit Redstone when the move is complete.
- Manual: Never emit Redstone.
- Partial: Emit Redstone if no liquids were moved and the cart is not empty.