[GUIDE] [1.19.2.1] Vehicle physics explained.

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Cadde
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Re: [GUIDE] [1.19.2.1] Vehicle physics explained.

#31 Post by Cadde » 30 Aug 2015 05:55

reventes, i don't understand your question.
That being said, the lateral factor reportedly doesn't do anything currently.

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natvander
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Re: [GUIDE] [1.19.2.1] Vehicle physics explained.

#32 Post by natvander » 04 Sep 2015 11:50

Any idea what controls the starting gear and subsequent gear shifts for auto transmissions? I would like to at least understand why a 16 speed auto box will start in 6 or 7 when unloaded.
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Re: [GUIDE] [1.19.2.1] Vehicle physics explained.

#33 Post by Cadde » 04 Sep 2015 13:17

That's hardcoded methinks. Everything about the auto transmission is probably hardcoded.
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Re: [GUIDE] [1.19.2.1] Vehicle physics explained.

#34 Post by natvander » 04 Sep 2015 13:50

That's a bit of a pain. It seems to me that the starting gear (esp when empty) is derived from a percentage of the total gears, not a fixed number.
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Re: [GUIDE] [1.19.2.1] Vehicle physics explained.

#35 Post by room217au » 04 Sep 2015 14:02

That derivation of a percentage of total gears will always be the same gear though, when bobtail.
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Re: [GUIDE] [1.19.2.1] Vehicle physics explained.

#36 Post by natvander » 04 Sep 2015 22:18

No it won't necessarily be the same gear, or ratio. Compare a 12 and 16 speed Mercedes Benz box. In a 16 speed I'm started in 6th or 7th (depending on the AI's mood) which is a ratio of 4.4 or 3.636. In a 12 speed I'm started in 4th which is a lower ratio of 5.452. Both these boxes are overdrive boxes as well so a direct drive box would give lower ratios again.

It would be handy if the starting gear (empty and loaded) was configured in the transmission file.
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Re: [GUIDE] [1.19.2.1] Vehicle physics explained.

#37 Post by CristianoH125 » 05 Sep 2015 00:21

Is there a way to mess around with lift axle animations/animations ?
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Re: [GUIDE] [1.19.2.1] Vehicle physics explained.

#38 Post by Cadde » 05 Sep 2015 03:07

Not via these definitions no, if you want to edit animations you would have to do so in Blender. (does Blender even support that as far as this game goes? perhaps even zmod)
I have yet to see an animation being customizable in any definition file. Any .sii file to you mortals.
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Re: [GUIDE] [1.19.2.1] Vehicle physics explained.

#39 Post by nudelife0 » 16 Sep 2015 03:12

This thread is helpful.

How about the differential_ratio om transmission folder per truck means ?
I like to play with the private car mod but the car physic always feels like a truck. ;)

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Re: [GUIDE] [1.19.2.1] Vehicle physics explained.

#40 Post by Cadde » 16 Sep 2015 07:01

For every <gear ratio> turns of the flywheel, the transmission makes one turn which drives the driveshaft.
For every <diff ratio> turns of the driveshaft, the drive axle(s) makes one turn.

So at gear 11, your driveshaft turns once per engine rotation on the Scania 12 speed transmission.
And at 3.08 at 1500 engine rpm on gear 11 you have 487 rpm on the drive axle.
If your wheels are 0.98 meters in diameter which by the way is why the diff ratio is at 3.08 because the circumference of a ~0.98 diameter wheel is diameter * pi = 3.08.

Well, if your wheels are 0.98 meters in diameter you get 90 kph using those figures.

Speed in m/s = engine rpm / gear ratio / diff ratio / 60 * (wheel diameter * pi)
25 m/s = 1500 / 1 / 3.08 / 60 * (0.98 * pi)

25 m/s is 90 km/h by the way and the 60 in there is to turn RPM to revolutions per second.

To calculate what engine RPM you need to maintain 90 km/h at gear 12 you do...

engine rpm = target speed m/s * gear ratio * diff ratio * 60 / (wheel diameter * pi)
1200 = 25 * 0.8 * 3.08 * 60 / (0.98 * pi)

Simple really.

EDIT: Forgot...

Since the wheel circumference is 3.08 one can cancel out the wheel and diff altogether when the diff ratio is 3.08

25 = 1500 / 1 / 60 (for 11th gear)
25 = 1200 / 0.8 / 60 (for 12th gear)
1500 = 25 * 1 * 60 (for 11th gear)
1200 = 25 * 0.8 * 60 (for 12th gear)
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