31 Linkages
Moving a big structure all at once is a real headache. Since pistons can only push 12 blocks, we have to chain multiple pistons to pass "motion" along. The catch is that you need to carefully tune the delays, and the longer the chain, the trickier the timing gets.
Therefore, we have the concept of "zero-delay linkages". In this section, we will introduce several types of linkages based on different principles.
1 Unidirectional Linkages Based on Piston Retraction
Sticky piston chain retraction has zero delay.
In fact, sticky pistons respond instantly whether extending or retracting. The moment they act, the pushed or pulled blocks convert to b36, then 2gt later when the motion finishes, they convert back to their actual block type.
Supplement: Detailed Description of Piston Transmission Time
If initially all pistons are in the retracted state, and the first piston can be activated by a lever, pulling the lever at tick 0, the timing is as follows:
However, with piston chains during extension, the next piston only activates after the block has moved and settled into place, so each piston in the chain adds some extra time.
But retraction works completely differently. The instant the Redstone Block becomes b36, the signal disappears, and the previous piston responds immediately. That's why piston chain retraction has zero delay.
Let's modify this to make the pistons actively extend.
As shown, we make the pistons automatically extend after retracting, which keeps the entire piston chain in sync.
Based on this principle, we can apply it to flying machines, specifically the "semi-automatic machine" mentioned earlier:
In the diagram, each structural unit uses an upward-facing sticky piston for zero-delay signal transmission, along with a downward-facing regular piston to reset the sticky piston.
This is the most common linkage structure. Similarly, we can create many linkages with the same structure.
The image shows the docking frame on one side of ilmango's world eater bomber, which is essentially a linkage with several Observers and Pistons attached
The image shows a linkage from 星空花夜、's burst tunnel bore, which moves horizontally but operates on the same principle
2 Extensions of Piston Retraction-Based Linkages
2.1 a) ???
The first time I saw this structure was in Eular's narrow trench world eater, where he used this linkage:
In this linkage, the sticky piston is activated by the Redstone Block at the BUD position—meaning it "loses power" the instant it retracts and the Redstone Block becomes b36. However, once the Redstone Block settles into place, it activates the piston again, preventing it from going down.
Therefore, this structure must push the whole thing down during the brief window after the piston retracts but before it extends again.
Note the Observer position in this structure—it's at the bottom, and it doesn't move during the sticky piston retraction phase. This means that once the regular piston above and the glass (used to update the Observer) are in place, it can fire off a signal immediately without any waiting.
This way, the regular piston immediately pushes the structure down, perfectly catching the timing window.
The Observer above can also be replaced with a Redstone Block, as long as the regular piston can push down immediately without waiting.
2.2 b) Bidirectional Linkages
The special linkage above was preparation for this one, from comet107's expandable tunnel bore main linkage.
The linkage above can only be activated from one end, but this linkage can be activated from any position to make the entire structure advance.
For convenience, let's remove one unit to study it.
This unit advances using the same principle as 3.1.2 a). It connects symmetrically to the Redstone Blocks above on both sides, either of which can activate this structure. At the same time, the structure connects symmetrically above to transmit motion downward.
I've used different colors to distinguish the two parts. The green part moves first, taking the Redstone Block with it, and the blue part moves later, passing the signal downward (although they're simultaneous, there's a slight difference in micro-timing). The reverse works the same way.
3 BUD-Based Linkages
There's another common structure, as shown below.
A BUD-state piston moves when it receives an update, and going from stationary to moving is itself an update, so the signal transmits instantly and all modules move at the same time.
Combining this with the semi-automatic machine from 2.2.1, we can build structures like these:
The second type of linkage is widely used in burst tunnel bores because if you block it at the front, the linkage can only oscillate in place and can't advance, making it useful for transmitting burst signals.
4 Other Linkages
The linkages above are all zero-delay linkages (after all, that's what "linkage" originally means). But functionally speaking, any structure that gets multiple modules moving together can be called a linkage—it doesn't have to be zero-delay.
