Train parts are used to upgrade your trains.
They are available in 4 rarities:
To be able to upgrade Rare, Epic or Legendary trains you need Common parts + the parts of the same rarity as the train and coins.
Where to get them ?
Train parts can be acquired from the shop -
They can be purchased for keys or gems. Upon purchasing a crate, you will receive 1 type of parts chosen randomly according to the patterns published in the game.
You can also get parts when dismantling your existing trains.