Usage: on trains
Chunk loaders can be placed on trains to keep the train and its surroundings loaded while the train is moving. They do not require rotational power, but they only work when the train is assembled. This mode of usage can be disabled in the server config or by using a contraption control in game.
Chunk loading on trains is NOT based on the exact location of the chunk loader block on the assembled train contraption. Instead, having a chunk loader on a train carriage ensures that the whole carriage is loaded as long as it is within a reasonable size. More specifically, when a chunk loader is on board, 2 sets of 3x3 chunk areas, centered around the back wheel of the leading bogey and the front wheel of the trailing bogey, are loaded for that carriage. (Both wheels of the carriage are loaded if it only has one bogey.) As a result, when a chunk loader is on board, it will force-load anywhere between 9 to 18 chunks depending on the size and position of the carriage.
When a train carriage is crossing a portal and its two bogies are in different dimensions, they will each load a 3x3 area in their dimensions. For the split second when a bogey is located directly on the portal, it will load both sides of the portal.
Since Create trains can travel through unloaded areas without issues, there are very few instances where you genuinely need a chunk loader on an assembled train. If you don't need actors (like drills and rollers) to function on trains while they are traveling, you may reduce lag by moving the chunk loader from the trains to their respective stations, so that chunks are only loaded when trains load/unload their goods at stations.
Only add chunk loaders to carriages that have functional actors. Carriages that are decorative or only contain drivers/train controls don't need to be loaded to function properly.
Having more than one chunk loader on the same carriage serves no extra purpose other than aesthetics. They appear functional with an active core but do not contribute to additional lag.
Contraption controls are respected, so you can toggle the assembled loaders on the fly/with redstone.
