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Differential and wheels spinn


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Hi,

I see some improvements in 1.6.2 but there are still some issues which keeps game far away from real simulation.

First one 

https://youtu.be/lcjE6G16KWU

Here you can see how fast are wheels spinning on the 5 and 4 gear. It looks like motor have 2000 horsepower instead of 300. It looks like simulation from year 2000. 

https://youtu.be/zOPmFGXn2tU

This video demonstrates absence of gearbox. I don't know how torque is transferred to the wheels but I have strong feeling that you just set some power to the wheel and don't care about wheel RPM, differential or engine characteristics (at least there should be constraint for maximum RPM on wheel for each gear). For example in this case there is no way to spin one wheels so fast on first gear in real conditions. I checked old version 1.3.6 and it was much much better than that. We can say it is huge regression.

Another thing is engine power. As we know every engine has some power and torque characteristics .... for example 

Схема нумерации цилиндров ЯМЗ-238Л, ЯМЗ-238Б

But feeling in game is that engine has only full power or no power, nothing between that. This is visible mostly on 3,4,5 gear. On 1 and 2 gear it is not very visible. 
I am not sure how you implemented physics stuff internally, but in current version feeling in game is that there is no engine, no differential, no transmission ... there is only some magical power spinning every wheel separately fast as hell.  Keep in your mind - truck on 3,4,5 gear will never spin in the mud or whenever else. For such spin is needed much more power than trucks in game have (it is called drift).

In version 1.3.6 all mentioned stuff works like few levels above current implementation, power transfer is smooth, wheels are not spinning to fast considering active gear. But current implementation .... like on video ... is active 3 gear , automatic gearbox set 4 gear and wheels start immediately spin like engine have 2000 horsepower - no smooth transition, truck is going such speed but on 4 and 5 gear wheels are spinning on the place, wheels spin do not correspond with truck move (even wheels are not stuck) - that is the basic of simulation - when wheels is not stuck in the mud then it should spin by the speed of truck.

 

The last thing I want to mention is absolutely ridiculous dust cloud coming from wheels when they are stuck in mud ... really? Do you think there is some dust in mud? :D 

 

Thanks 

 

Edited by rarum
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26 minutes ago, rarum said:

The last thing I want to mention is absolutely ridiculous dust cloud coming from wheels when they are stuck in mud ... really? Do you think there is some dust in mud? :D

This is steam or smoke.  Conventional high RPM + friction = high temperature.  This function has been in the game for a long time...

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1 hour ago, rarum said:

For example in this case there is no way to spin one wheels so fast on first gear in real conditions. I checked old version 1.3.6 and it was much much better than that

The differential when not locked is more open now.  That's why you can see one wheel spinning fast when it doesn't have good traction.  In older version the differentials were like limited-slip or partly locked at all times.

 

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19 hours ago, Unster said:

The differential when not locked is more open now.  That's why you can see one wheel spinning fast when it doesn't have good traction.  In older version the differentials were like limited-slip or partly locked at all times.

 

That is fine, I have no problem with differential lock. I am complaining about stuck wheel Revolutions per minute on first gear. It is spinning so fast, like 4 gear was set. 
When 1 gear is set then truck is going speed 3m\s - it is about 1 wheel spin per second. So on the 1 gear both wheels attached to the same axle are rotating maximum at speed 1 wheel revolution per second. So when one wheel is stuck and differential is open, then one wheel stucked in mud should spin by 2 revolutions per second and the other one with zero revolutions per second (this wheel is on tarmac). But when you take a look at "simulator" you can see that first wheel is spinning at least 5 revolutions per second and the second has zero revolutions per second. This is what I am complaining about - about RPM of stucked wheel.

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I don't think you can really judge what is too fast for an unloaded wheel.  When the wheels are planted on the ground they are not necessarily spinning at their top speed.  They have to push the truck forward and that slows them down.  I think it's more realistic now, where an unloaded wheel spins fast because it's free to spin that fast.

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Disregarding ground resistance slowing the truck down, the speed of a wheel is given by the engine RPM  + the gear ratio of the gear we're in. Yes, there's also the differential gearing and potential gearing in the wheel hubs but we'll disregard them as they're constant and not relevant for our example here.

If in a given gear the truck has reached maximum engine RPM while traveling on the ground and suddenly one wheel looses traction - that wheel cannot spin faster than the rest. Because the gear ratio between the engine and the wheel didn't change and the engine was already at max RPM.

I did a quick test in Proving grounds. I took a truck, put it in 1 and let it drive forward. The engine reached the top RPM for that speed and the wheels spun at a certain speed. The truck got wedged, one wheel broke free and spun significantly faster while the rest stopped. However, the engine RPM, as far as could be determined by the sound, did not increase. So that wheel has no reason to spin faster than it did before.

The potential fix would be to add an additional limiter to wheel spin. For each gear, based on the truck's engine RPM and gear ratio, the wheel speed should be capped. Any further capping should be simply due to torque transmitted vs ground resistance.

Edit.

After more investigation it is possible for a wheel to spin faster when free if the other is stuck, due to the diff. However at most that would be 2x its normal speed. In the game, visually at least it looks more like 4x.

2x is how fast both wheels on the diff spin if they're free. Engaging AWD, for some reason, increases that speed further.

Edited by XenoRad
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If we take the KrAZ-255 as an example, then it has a separate propeller shaft for each axle (there are only 5 of them), but if all 5 wheels are locked and 1 wheel is in a free state, then why does it have such a speed if the torque passes through the transfer case a box where the revolutions in one gear cannot be increased in any way, or is this not taken into account in the game? (as if all 5 wheels are combined into 1)

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