Tracked vehicles, tuning problem

[ViiK]

I've tried building a medium size tracked vehicle and ran into a problem of missing something similar to a final gear (final drive). The core of the problem is that tracks are considered as one big wheel, which is correct. But unfortunately we have only gearboxes to change ratios and each gearbox brings lose of power into the system. The longer is track the more gearboxes is needed. The other way is to raise RPM but that quickly leads to higher fuel consumption and excessive temperature. So you either get a good rpm on engine but tracks move very slowly or you get to a maximum of RPM cut-off which is bad for fuel economy.
To combat this, I could split each track into two parts (4 tracks in total) making "wheel" smaller. The issue with that from what I see, the splitting can be done only by having road wheels and sprocket on different positions, you can't just divide them by inserting blocks in-between.
Would be great to have something similar to a final gear, which is literally a gear that transmits power from the drive shaft to the wheel shaft, in RL it's often used to "optimize" drive train for a specific wheel size and drive train design. We could use it for a fast adjustment of the drive train when you swap wheels for example.

[ViiK]

So cutting track length in half and turning vehicle into a half truck makes it pretty much twice as fast. Taking into account that a wheel of the same size has a better off-roading capability than a track, I'm not sure if tracks have any purpose besides cosmetics.

[Ra-Ra-Rasputin]

Since the way power delivery works on electric motors, you can use electric motors to assist the drive of the engines so that they're directly powering the tracks. Unlike conventional engines, they don't struggle when giving out very high torque and scale to giving out speed as well without gear changes.

You'll likely need one or two small engines to work as generators for this, though preferrably a medium one if you have space. If you link your vehicle, i can see what i can do about it.

There are also ways to make such a gear using parallel gearbox setups.

[ViiK]

Originally posted by Ra-Ra-Rasputin:

Since the way power delivery works on electric motors, you can use electric motors to assist the drive of the engines so that they're directly powering the tracks. Unlike conventional engines, they don't struggle when giving out very high torque and scale to giving out speed as well without gear changes.

You'll likely need one or two small engines to work as generators for this, though preferrably a medium one if you have space. If you link your vehicle, i can see what i can do about it.

There are also ways to make such a gear using parallel gearbox setups.

I've tried diesel-electric drive and even just two small electric engines per track are draining battery faster than two small generators on medium engine can charge it. Not sure if hybrid would do any different.

[Ra-Ra-Rasputin]

That's due to poor generator utilization. A small engine can hold parity with about 1.6~ small engines pushed to full load when running at 9RPS, a medium engine should be able to supply 5-8 depending on how high you want to rev it.

The generators generate more based on RPS pushed into them, but the more RPS they have, the more resistant they are to receiving more. It's a delicate balance.

[ViiK]

Originally posted by Ra-Ra-Rasputin:

That's due to poor generator utilization. A small engine can hold parity with about 1.6~ small engines pushed to full load when running at 9RPS, a medium engine should be able to supply 5-8 depending on how high you want to rev it.

The generators generate more based on RPS pushed into them, but the more RPS they have, the more resistant they are to receiving more. It's a delicate balance.

Two gear boxes with 3-1 and 2-1 ratio, increasing ratio or adding generators get less power. Maximum I could get is about 110-120. What would be a more efficient design?

[Ra-Ra-Rasputin]

Originally posted by ViiK:

Two gear boxes with 3-1 and 2-1 ratio, increasing ratio or adding generators get less power. Maximum I could get is about 110-120. What would be a more efficient design?

Give me about 6 minutes

[ViiK]

Even if I could power 3 small electric engines per track. Two per track where twice as worse as just a direct power from the engine. The medium electric engine did get much better results but it's mass and the fact that it drains battery even faster is just no go.

[Ra-Ra-Rasputin]

Here you go. This should be able to run about 3 per track.
https://steamcommunity.com/sharedfiles/filedetails/?id=2036541914

I'll show you what it can do with tracks in 6 more minutes when coupled with a small engine.

[ViiK]

It generates 170 and 110 was not enough to power 4 in total small engines (in total with the rest of the things like lights and etc). Do you mean to use a one medium engine per track?

[Ra-Ra-Rasputin]

Here you go, 3 motors per track and small engine.

https://steamcommunity.com/sharedfiles/filedetails/?id=2036554888

That was more of 12 minutes to be honest, but i really needed ice cream and i put the other set of treads backwards the first time round. It can't turn, but it's not really what it's for!

[ViiK]

I appreciate the help but it illustrates what I was complaining about in the first post. Diesel-electric might get a better fuel consumption but its not able to push vehicle as fast as it goes if powered directly. I can get similar performance with a direct drive just by using different gear ratios.
Cutting track in half, doubles the performance, replacing it with wheels triples/quadruples that or pushes it even more. This is happens simply because of the RPM ratios difference on the wheels of different size and tracks of difference size. If we would have something like a final gear, you could set it to 15:1 in one place and get much more optimal performance out of the direct drive. Just as it's done on real tanks.

[ViiK]

Here is fully tracked:
https://steamcommunity.com/sharedfiles/filedetails/?id=2036574555

[Ra-Ra-Rasputin]

Keep in mind that with the setup i made the tracks are being ran at ~10 RPS and the engine is managing nearly 1:1 ratio, it in fact could, but i forcibly limited it to 12 RPS because i couldn't be arsed with cooling.
While it's a relatively light vehicle doing this, without the electric assistance you would not get close to 1:1 ratio with just a medium engine trying to pull that, or for equivalent power-to-weight ratio, 2 smalls per track. In a similar weight tracked vehicle pure combustion drive can't compete with the way electric motors provide their force.

If you want a better example, i can take a look at the tank you made and see what i can do with it, smaller analogs usually don't make for the best examples

[ViiK]

and this is half truck version:
https://steamcommunity.com/sharedfiles/filedetails/?id=2036577686
Notice that I could drop gear even more and get it running even better.

[ViiK]

Originally posted by Ra-Ra-Rasputin:

Keep in mind that with the setup i made the tracks are being ran at ~10 RPS and the engine is managing nearly 1:1 ratio, it in fact could, but i forcibly limited it to 12 RPS because i couldn't be arsed with cooling.
While it's a relatively light vehicle doing this, without the electric assistance you would not get close to 1:1 ratio with just a medium engine trying to pull that, or for equivalent power-to-weight ratio, 2 smalls per track. In a similar weight tracked vehicle pure combustion drive can't compete with the way electric motors provide their force.

If you want a better example, i can take a look at the tank you made and see what i can do with it, smaller analogs usually don't make for the best examples

But the middle engine is still at 20 RPS, so it's comparable. Yes I agree that you can match RPS, but you can do that only for specific sets of RPS. So if you do your track longer or shorter it can shift from an ideal RPS that you set on the engine.