Fluid wagon

A fluid wagon is a train cargo vehicle designed exclusively to transport liquids along rail networks. It serves as the rolling-storage component of fluid logistics in train systems and must be loaded and unloaded using pumps at train stops rather than inserters. Fluid wagons connect to the rest of the rail-based logistics by attaching to locomotives and other wagons; each wagon has internal fluid storage slots that can hold large quantities of a single or multiple fluid types depending on gameplay mechanics.

Fluid transfer between a station and a fluid wagon is performed by pumps positioned adjacent to the rails. A train stop with pumps is required to fill or empty a fluid wagon; pumps must be placed so their fluid connection aligns with the wagon while the train is stopped at a station. Up to three pumps may be assigned to a single wagon to increase throughput, and pump tier (quality) directly affects the transfer rate. Transfer times are conventionally expressed as seconds required to completely fill or empty a wagon; using more pumps and higher-tier pumps reduces these times. Because transfer times are rounded up in-game, adding pumps can produce large practical gains.

Correct physical alignment is essential for pumping to work. The wagon must be orthogonally aligned with the rail grid: use a train stop as a schedule destination and arrive with a fueled locomotive to ensure precise placement. The rails directly under the wagon must be straight rails; pumps will not function if the wagon rests on curved rails. Misalignment or curved rails are the most common causes of failed fluid transfers.

Practical notes for efficient use:

• Always provide a train stop with dedicated pump placements for each fluid wagon position you intend to serve. Plan pump counts (1–3) according to desired throughput.
• Prefer higher-tier pumps where faster load/unload cycles are required; pump quality reduces per-wagon transfer time.
• Keep station track straight and use exact stopping (train schedule + locomotive) to guarantee orthogonal alignment and avoid pumping failures.
• When designing multi-wagon trains, ensure pump placement covers the correct wagon positions; pumps only interact with the wagon they are aligned to.
• Remember transfer times are rounded up; small theoretical improvements can be lost unless pump count or pump tier crosses rounding thresholds.