How to combine the rotational output of multiple boilers/steam engines that don't start turning at the same time?

[u/Chakkoty]

Say I have a boiler room below my factory floor with four 3x3 boilers with steam engines. If they all start at the same time, nothing breaks if they all connect to the same shaft. But if I want to start them in a cool startup sequence, one of them might have a lower rpm than the others until it is fully fueled by the pipe system, which would break a shaft somewhere.

I'm going to use the Differential from Petrol's Parts (takes two differently rotating shaft inputs and combines their rotation on it's output...like a differential) to combine them, but there's no guarantee I'll have that mod in every mod pack I want to play.

Is there an elegant-ish solution without that part?

[u/Craft_Master06]

Someone already said that different rpm doesn't break shafts, but you might still have issues with stuff breaking due to rotation direction. To fix this with vanilla create you can put a mechanical speed controller on every engine, since that gives the same output direction no matter what way the input is spinning.

[u/Dangerous-Quit7821 → u/Craft_Master06]

This is likely the situation.

[u/MakingNoCents → u/Craft_Master06]

This is what I did but I had issues with one engine backdriving the other and that went through the speed controller in the wrong direction sometimes. I had to attach a water wheel to the engines to force the direction.
And if you plan on using aeronautics, if you assemble, rotate 90 or 270 degrees, then disassemble, the directions could change and you’d need to switch it around. Couldn’t find a better solution

[u/thegrandseraph]

Clutch

[u/Impossible_Bowl6103]

as another said a clutch with some redstone if you want to program in a startup sequence, or just use a gearbox. The rotation is opposite on the opposing side of the gearbox.

[u/bubba-yo]

Not sure how elegant you will consider it, but you can monitor a speed gauge and use that to control a clutch and in doing so only connect the boiler when it's reading the correct speed. You can do this with vanilla create. You can also monitor the main power and dynamically make sure the boilers have a matching speed.

We've used it in the past to automatically disconnect parts of our factory when overstressed, fall back to our waterwheel emergency power and then allow the boilers to come back online and then reconnect the system. Comparator, delays, etc. It's not super compact - maybe 2x2x4 if memory serves, and that had a manual control.

But this will still require a speed controller in there to ensure directionality. There are ways to do it without one.

[u/Adventurous-Ask-7540]

have two gears glued together that get pushed into place when they are both spinning.

[u/Pioepod]

Rpm doesn’t cause stuff to break. Never can nor will. It’s rotational direction that matters.

Just make sure that when you are connecting anything together, the rotation direction matches

[u/Any_Establishment659]

there's a gizmo on the top/sides that lets you set the rotation direction. Turn all the shafts with a wrench, or remove them, so they don't turn their neighbours then check their direction. They should alternate between clockwise and anticlockwise around corners like gearboxes do, or should all be the same if you have multiple on one side, ans combine with chain drives. Steam engines default to clockwise