Carts are the vehicles that travel the rails in Railcraft, moving people and resources from one place to another. They can be self-powered, or powered by the rails they're traveling on. Additionally, they can be autonomously guided from one place to another by careful positioning of Block Signals and motorized Switch Tracks.
Trains and Cart-Linking
Using a crowbar, the player can now link two or more carts together to form a train; that is, a procession of carts that travel together as a unit.
More or less functions the same as it did in Vanilla Minecraft, but with the added feature of being able to be linked to other carts to form a train. (see above)
A Storage Cart is a Chest on rails, which can be used to move quantities of inventory items from one place to another. If cart-linked to a Tunnel Bore, the Bore will deposit the blocks it mines out in the Storage Carts, and fetch fuel, rails, and Gravel from them.
Made from a Workbench and a Minecart, the Workcart serves as one might assume: a mobile workbench.
Essentially a World Anchor on wheels. This entity keeps a three-by-three chunk buffer (nine chunks total) loaded around it, even while in motion and while the player is not nearby. In essence, it allows a train to travel outside the active chunk by continually loading and unloading the area around it.
WARNING: Keeping large numbers of chunks active at the same time can put significant strain on one's PC; use World Anchors sparingly!
Energy Carts are a co-operation between Railcraft and Industrial Craft. Energy Carts come in three varieties: BatCarts, MFECarts, and MFSUCarts. Each is made from a Battery Box, a Multi-Function Electrical Unit, or a Multi-Functional Storage Unit, respectively. Energy Carts transport EUs (Energy Units) from one point to another and and are filled or emptied using an Energy Loader or Energy Unloader.
TankCarts are a co-operation between Railcraft and Buildcraft. Tank Carts are, as their name would suggest, liquid storage tank on wheels, and can be used to send large quantities of liquid resources between two points without the use of Buckets or running large amounts of Waterproof Piping.
A TNT Cart is very simple, if somewhat costly, means of propelling mining explosives towards an intended target to keep players and property safely clear of the blast. The cart will detonate if jarred sharply (i.e. crashes) or is lit on fire. Additionally, TNT Carts can be lit by passing over Priming Rails. The length of the TNT Cart's fuse can be adjusted by adding String; a TNT Cart's fuse is measured in units of 1/20th of a second, or one Minecraft 'tick'.
The Tunnel Bore is a very special machine, halfway between an IndustrialCraft Miner and a Powered Minecart. When filled with stacks of fuel, rails, gravel, and a cutting head, it will start building a railway forward, cutting a 3x3 tunnel through any terrain it comes into contact with in the process.