Is there any known mechanism to take two or more moving ‘stacked’/‘merged’ minecarts (occupying the same space) and separate them automatically? I have seen splits happen at T-junctions, but haven't been able to reproduce them.

(For some reason merges happen spontaneously in my cart stack when I save and reload.)

I have thought of a mechanism to extract merged carts (send a slow cart up a slope; if it hits the top it was a double cart, but if it goes back down it was a single) but not one to separate them and put them back in service.

One phenomenon that might be useful that I have found is that bumping into carts while they are in a cart stack tends to cause one of the merged carts to ooze out of the stack (if it has room to move, i.e. the stack is boxed in on one side but not the other).

  • When you say "two 'stacked' minecarts", do you mean like in a double booster? Commented Jan 12, 2011 at 21:08
  • Michael Madsen: Yes. In my minecart system it seems to happen spontaneously in the cart dispenser/circulating loop, when I save and reload — this results in misbehaviors and an effective reduction in the number of available carts, so I'd like to automatically clear it out.
    – Kevin Reid
    Commented Jan 12, 2011 at 23:09
  • @Kevin: I haven't played Minecraft very much yet, and I'm not even close to gathering materials for a minecart track, let alone a Pez dispenser, but from what I've gathered, you shouldn't have any issues of this sort if you place a half-step at the bottom of your stack. Maybe that's standard for all Pez dispensers in general; I haven't looked enough into all of this to know for sure... Commented Jan 12, 2011 at 23:43
  • Two different senses of "stack" here... I do use the half-step, and it does its job. I don't know exactly how the 'merged' carts are occurring.
    – Kevin Reid
    Commented Jan 14, 2011 at 3:42
  • Do you want to separate them while they remain on the track? If not you could shoot them off the track and attempt to separate them then.
    – Sadly Not
    Commented Jan 14, 2011 at 23:57

2 Answers 2


Here you go: How to Split Up Merged Carts

  • 2
    +1. Since you made that video extra for here, you could add the shortlink to the question there and maybe earn the announcer, booster or even the publicist badge ;)
    – Zommuter
    Commented Mar 10, 2011 at 6:37
  • OK, I've played with this a bit, but haven't quite gotten it to work reliably. Do I correctly understand that the water-and-one-double-booster component should suffice to split the carts into two carts on one track, and the later jammed-carts-and-door is just to send back the unwanted cart? (I will be busy today, but I'll get back to this within the bounty period.)
    – Kevin Reid
    Commented Mar 11, 2011 at 12:19
  • Yes. Sending the doubled carts across a stretch of water splits them up. You can make it go across a few blocks of water and not worry about dropping it down onto the double booster if you don't mind waiting for it to slowly move across multiple blocks of water.
    – Polt
    Commented Mar 12, 2011 at 4:42
  • Okay I made some adjustments. Try this out if you are still having trouble: link
    – Polt
    Commented Mar 13, 2011 at 2:25
  • Success! I got yours working, but it was too slow to feed my cart stack into it, and my idea about detecting merged carts didn't work very well, so I invented a different solution — but your water splitting idea is the core of it. See my answer.
    – Kevin Reid
    Commented Mar 13, 2011 at 16:50

Note: This mechanism no longer works, due to water not pushing minecarts. I have filed a bug for that change in behavior: MC-665.

This design is based off of Polt's water-based splitter idea, but splits carts as fast as they can be fed and sends them on separate tracks automatically.

The water flows leftward in the first picture. Carts come in on the upper track at the bottom of the picture, drop through the water (getting pushed slightly to the left), and hit the center lower track. If there are two carts, then they rapidly push apart and land on the center and left tracks (and all boost away together).

It still needs tuning; in particular, I think more vertical distance is needed as sometimes merged carts hit the middle track together (on the other hand, I've also seen them hit the left track together). But this seems like the core of an effective solution. A refinement might be using multiple water layers to steer the trajectories further.

  • Haha, wish I had thought of that!
    – Polt
    Commented Mar 13, 2011 at 17:02
  • Polt: Your designs were helpful beyond just knowing that water could split carts, though, as I spent a while playing with them and considering how to speed them up; and the 2-deep-starting track beyond the water was a definite inspiration too.
    – Kevin Reid
    Commented Mar 13, 2011 at 22:29
  • making the water be 2 deep makes the carts split perfectly
    – user9205
    Commented May 2, 2011 at 7:16

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