How do Gearboxes Work?

[Thundereye]

Hello ,

I am struggling with Gearboxes.

Can someone please explain me how they work?

Ive built a basic small boat with one small prop, an engine and two gearboxes, arrows pointing towards the engine.
First Ratio on both gearboxes is unchanged. Second Ratio on first gearbox is set to 5:2 and on second gearbox to -1:1.

I did now some testing with these Setups:

One Small Engine, One Small Prop,
Two Small Engines, One Small Prop,
Two Small Engines , Two Small Props.

In Every Testcase the boat behaved the same..

Topspeed was about 50 kph with first gearbox not enabled and 20 RPS.
With Enabled Gearbox RPS dropped to about 6-8 and Topspeed decreased to about 30 kph.

Also changed gear Ratios seem to have zero effect on fuel consumption.
Its the same at the same RPS ( for example if i have no gearbox enabled the consumption at 8 RPS is the same like with enabled gearbox at 8 RPS)

I also tried to turn the Gearboxes so that the arrows are pointing towards the prop, but when i enable the gearbox with this setup it immediately kills the engines..

What am i doing wrong?

[agrimes]

Wierd. I have had a number of successes with gearboxes and a number of failures. I've successfully used gearboxes on a number of land vehicles as 2, 4 and 6 speed transmissions with great success. ( Reverser gearbox + 1 gear select for 2 speed; 1 reverser + 2 gearboxes for 4 speed, 1 reverser + 3 gearboxes in the correct ratio pattern for 6 speed, 8-speed also feasible with 3 gearboxes...)

I've also used gearboxes successfully to drive generators with motors., known excellent combinations:

1 small motor -> 2 gearboxes -> small generator (on my workshop)
1 medium motor -> 2 gearboxes -> medium generator
1 large motor -> 1 gearbox -> 2 medium generators.
2 large motors -> 1 clutch each -> 1 georbox -> 1 large generator. ( the orange train on my workshop uses this), I'ts possible to add a 3rd motor and clutch to above but results aren't as spectacular.

The failure I had was just now when I was trying to overhaul a shunter railroad engine, I was using one small motor and a 3:1 reduction on each of the two wheel trucks. Shifting between 1:1 and 3:1 had no effect on speed or hauling capacity, apparently. I was using the small motor setup outlined above and was drawing only about 50% of the available power. I was thinking about going to two small motors per wheel assembly but that would be placing 4 motors behind 1 generator which just seemed very weird.

[Marflemerfmarf]

The standard before they updated gearboxes was, as I understand it, that you can stack engine facing gearboxes in 1:3 and it would maximize rps at the expense of torque, and leave the engine running at very low rps while your rps at propeller was high.
I am assuming that mechanic has changed as 1:3 is no longer an option. I have been experimenting with it all day today with waterjets and using any stacking in ratios other than 1:1 just kills my engine when I let off the clutch.
I have come to the conclusion that 3:1 does not become 1:3 when the gearbox is faced toward the engine, because I'm unable to reproduce the effects I have seen from before the update.
Edit: Looking at some more stuff on the Discord I am seeing a lot of people talking about it like it still does become 1:3 in engine facing position but I am getting no returns as of now so I'm off to do more experimenting.

[Thundereye]

Hm i dont get it...

[Ra-Ra-Rasputin]

Gearboxes are very simple beasts, but many people seem to struggle with them, i'll try and explain it very cohesively.

There are 2 factors at play here, i will refer to them as SPEED and POWER respectively. They are generally called power and torque, but this distinction is harder to mentally understand.

I will also in this example only use the 1:3 / 3:1 ratio.

When the arrow is pointing at the engine, for every rotation the engine makes, 3 rotations are made at the end of the gearbox, increasing speed, and costing power. When you have 2 gearboxes, their effects are multiplied, meaning the shaft turns 9 rotations at the end of the gearboxes for every one the engine makes.

In these examples your gear ratios are 1:3 and 1:9 respectively. One thing you must keep in mind: Gearboxes are not fully efficient, they cost 5% of output power because the gears cause friction. This doesn't mean that the speed is affected, however.

Now, let's explain what this means in practice (this is a scenario that's not true to game mechanics, just an example):
Your engine can pull 1000kg with no gearboxes in between the engine, and say, wheels. It'll happily pull a 100kg load at 20km/h.

Now, let's put a 1:3 ratio gearbox in it.

Your engine can now only pull about 310kg (keep in mind the loss from gearbox!) but it can do this much faster. It'll pull the 100kg load at 60km/h! However, due to reduced power in exchange of speed, it takes much longer to reach even 20km/h than it took without the gearbox because of the power loss. 100kg is now third of your maximum capacity instead of a tenth!

And now instead, let's put a 3:1 ratio gearbox in it (arrow pointing away from engine)

Your engine can now pull about 2900kg. Pulling a 100kg load takes about as much effort for the engine as it takes for you to take a drink, but we've now significantly reduced the top speed, to around 6-7km/h (from 20), however, due to the engine's brute power, we reach that speed almost instantly.


Do you want to move a 1000kg load at 60km/h with this? It's possible. Start your motion with 3:1 gear ratio, move up to 1:1, then 1:3. When you're already moving, increasing speed of an object in motion takes significantly less force than making it move in the first place, so when we're already moving at 7km/h with a 1000kg load we can easily accelerate to 20km/h using a fraction of the engine's total capacity than starting from 0km/h. This is a very very simplified take on how a car's gears work.



Now, on those fuel ratios...
Generally speaking your engine uses less fuel the less RPS it has. I am hoping they will change this one day for a more realistic, and sensible model, but it's what we have now.

A good spot for the first simple diesel engine to sit on in something speedy is around 9-12 RPS, with a possible boost making it capable of doing more. This doesn't mean it's the most fuel efficient, but it is not woeful in its efficiency.

A gearbox affects the way engine uses fuel massively, because currently the engine doesn't care how much load it's experiencing(as in, how much work its doing), it only cares about the rotations.
Your goal with gearboxes to attain speed is to force your engine to do so much work at full throttle it's within the mentioned margin of RPS (or lower, if you're looking for efficiency). You will want to do this with the least amount of gearboxes possible, given each one costs you 5% of your total power.

[Kanthier]

It is also worth noting that, at least for helis and ships, upping the gear ratio generally has a net drop in propeller/rotor speed (because of increased resistance on the engine outweighing the up in gear ratio). This means you're looking more at achieving a fuel efficient RPS than increasing speed.

[Ra-Ra-Rasputin]

Well, helicopters are more dependant on the speed of the prop than the actual force made to turn the blade so you're generally looking at least a 1:1.75 gear ratio in most cases, but if you're rotating large blades, you're likely looking at 1:2 or even 1:3 depending on application.