Some questions remains:
- when a card is discarded, does it return to the deck ?
- when a caravan is disbanded, does it return to the deck and should we play another card the next turn (to have 3 caravans at any time) ?
- when a caravan is overburdened, is it still possible to play faces card ?
- is the first one to have 2 sold caravans the winner ?
1) No, the cards are out of play.
2) No, all cards in the caravan are out of play when the caravan is disbanded. On the next turn you may re-establish a caravan, though it is possible to win with only two caravans on your side of the table (though the third "track" would have to be between 21 and 26 for your opponent).
3) Yes, and it's very important because often you can bring a caravan back into range by playing a jack on one of your own cards.
4) All three "tracks" must have a winning caravan in them. This means that the caravan is a) between 21 and 26 (inclusive) b.) higher than the opposing caravan. If two caravans on the same track are tied, the game continues.
N.B.: It is entirely possible for you to lose a game of caravan by bringing one of your caravans into range on a track while your opponent has claim to the two other tracks. E.g.:
A/B/C
22 21 12 <-- your caravans
22 22 26 <-- your opponent's caravans
Let's say you play an 3 on your A caravan (current total 22), taking it to 25. A track has 25 (yours), B track has 22 (opponent) and C track has 26 (opponent). Congrats, you lose.