Questions about Fluids, Hopper stacksizes and Custom Gearboxes

Good day, Greg, I hope you’re feeling at least a little better after all those events… I have a few questions.

First, is there a way to prioritize between two fluid inputs without using Aluminium covers? For example, I’d like my boilers to prioritize using Distilled Water returned from turbines and engines, and only then take it from the external tank. I’ve tried using the setup with two barrels on top of each other, but unfortunately it didn’t work. If possible, I’d like to avoid making a separate pipe from turbines/engines all the way to the main tank.

Second, what exactly Fluid-o-Meter shows when the value is too large to fit on its display (when it is connected to a 3x3x3 tank)?

Third, I’m not sure if this is a bug or not, but Hoppers don’t seem to respect their output stacksize limit when outputing to another hopper - a single pulse of 0 signal will make it output its whole contents. If I’ll make it output to the chest instead, it outputs the correct amount. And yes, the hopper was set to the exact stacksize.

And my fourth question is about Custom Gearboxes. Are they 100% effficient, or do they have some loss due to friction?
Because I’m trying a simple setup where I’m trying to power two Mixers with one turbine (for the Sulfuric Acid production). From my understanding it should work, but doesn’t.
Here’s my setup:
Invar Dense Burning Box (64 HU/t) + Invar Burning Box (16 HU/t)
Strong Invar Boiler (64 HU/t -> 128 S/t) + Invar Boiler (16 HU/t -> 32 S/t)
​Invar Steam Turbine (160 S/t -> 53 RU/t * 66%eff ~ 35 RU/t) (I’m not even sure I should multiply by efficiency, but still…)

So, if divided by half, it should be enough to power two 16 GU/t recipes.

The Steam Turbine is facing upwards and is connected to a Custom Bronze Gearbox with vertical internal axle, and with gears on the bottom and right.
To the right of that Gearbox is another one with gears on its left and top.
Finally, on top of both Gearboxes are two mixers.

Here’s the screenshot:​

When I try to power this setup, I start to hear constant “I BROKE” sounds from both mixers, as if they are not getting enough power. Both of them are using 16 GU/t recipes.

Speaking of which, it would be great to have a way to measure the current output of RU/KU from the turbine/engine :).


There was a Setup using Fluid Extenders that did that. Heck Bear found that Setup for some reason somehow. it involved 1 Fluid Extender and one extra Fluid Pipe as far as I remember. Maybe try experimenting that out. :wink:

You mean the Bucket-O-Meter?

It will emit bundles of that exact stacksize, and it will do it once if you only give it a short Redstone pulse. If the Redstone is too long you will end up with the Hopper dumping itself.

Also if you do Hopper->Hopper do NOT vertically stack the hoppers! Otherwise the lower Hopper will just empty the top hopper instantly.

All Gearboxes are Lossless during normal operation. Unsure about your Setup though, are you sure it gets enough Steam?

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Thank you for replying!

[quote=“Gregorius, post:2, topic:711”]
There was a Setup using Fluid Extenders that did that. Heck Bear found that Setup for some reason somehow. it involved 1 Fluid Extender and one extra Fluid Pipe as far as I remember. Maybe try experimenting that out. [/quote]
Hm, thanks, I even forgot that extenders existed! After reading about Universal Extenders Welp, time to rebuild all of my autosmelteries…
Although, I’ve just tried to do it with two stacked barrels, and this time it worked flawlessly. Huh…

Nope, I meant Fluid-O-Meter specifically. I placed both of them on the same tank and they show two completely different values…

Ah, I see, so that’s what happened! I didn’t even think about bottom hopper snatching items from the top one… Thanks!

From my understanding, it should - the pressure on boilers is not increasing, so all the Steam should go into Turbine. Bronze Pipe has a bandwidth of 450 L/t, which should be enough.
Even if I replace the basic Invar BB + Boiler with the Steel versions, which pushes Steam production to the Turbine’s hard upper limit, the problem still persists.


Yeah there is this thing called integer overflow, guess what happened to the fluidometer once you reached 65535 :wink:

As for the Turbine, it outputs the right amount, according to its Tooltip, right? remember it scales with the input ofcourse.


… wow, for some reason I’ve completely missed the possibility of it using UInt16… Thanks, that clears that up!

Yes, I’ve mentioned it in my calculations. The turbine tooltip states that it converts 96 S/t to 32 RU/t, so the conversion ratio is 3:1. Which means that if I input 160 S/t, it should output 53 RU/t (or 35.2 RU/t, if we apply 66% efficiency).
I’d also like to mention that they make the IBROKE sound once each ~5 ticks. If I increase the amount of RU/t I give to Gearboxes, the sound starts going off each tick.
It is as if the Gearbox alternates between sending energy packets to each of its output, which leads to the machine periodically not getting energy, which in turn leads to it resetting the progress


Does the Gearbox itself go to two different output targets? because it would do that in that case.

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Well, yes. The turbine is connected to a Gearbox, one side of which is connected to one machine, the other connected with another Gearbox, which in turn is connected to a second machine.


Yeah you cant power two Machines at the same time with one Turbine unless you split it into 4 RU Packets using a Planetary Gearbox, in which case you need a bigger Turbine.

For your Setup you always have to disconnect the Gearboxes entirely or else it will alternate between one direction and the other.

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Aw, I see. Thanks for answering my questions!


I’m looking for details, how to prioritize a fluid source just like this.


I can’t remember which video that was, but I did find it at some point… no idea how. Although it was for prioritizing outputs rather than inputs.

So, an extender has one main side, one secondary side, and other sides are neutral. And there are three rules:

  1. If it’s pushed into main side - it gets pushed out of the secondary side.
  2. If it’s pushed into secondary side - it gets pushed out of the main side.
  3. If it’s pushed into neutral side - it gets pushed out of the main side.

And Bear found a very interesting trick - if an extender directs liquid into a pipe, but that pipe can’t pass that liquid further, the liquid “splooshes” back into the extender.
So, if the liquid goes into extender’s neutral side, it gets out of the main side, and then “sploshes” back into that main side, and gets out of the secondary side!

And there might be a way to use this trick for prioritizing inputs rather than outputs. Suppose we have source A and source B, and A should be prioritized.
What if we connect A to neutral side, B to the main side, and output to the secondary side? That way, source A will be pushed into source B, and always try to fill its pipe from the extender’s side.


xarses priority input pipe


Ok, so the key concept here is that in GT a smaller pipe can NEVER fill a larger pipe. It can only add as much as the small pipe can carry, leaving the larger pipe with open capacity.

In the video they said the drum isn’t needed, just different size pipes. However the drum makes it more obvious and has a higher throughput capacity. It should fill the mainline pipe first.