Truck stalling

User avatar
JPS
Posts: 714
Joined: 15 Dec 2014 14:56

Re: Truck stalling

#61 Post by JPS » 04 Jul 2016 04:31

Yes, many things have changed over time where people were able to do things with settings they've always had and then suddenly couldn't...

Apparently you'd prefer SCS to not change things instead of changing something (back) yourself. Good luck with that. I give up.

User avatar
Cadde
Global moderator
Posts: 9535
Joined: 24 Apr 2013 18:08
Location: Have no fear, i am from the internets!

Re: Truck stalling

#62 Post by Cadde » 04 Jul 2016 08:16

This reminds me of something. Yes, SCS did change the range of effect on that slider. Hence, 0.29 might be what 1.0 was before and in the "profile upgrade" between those versions, the old 1.0 value is what 0.29 is today.
Either way, play with the clutch range slider. It might mitigate the issue.

But i still feel like the trucks, even the weakest ones, aren't getting the power through the clutch correctly. But i've just decided to live with it for now.
ImageGreen text = Moderator action.
ImageWhite text = Opinions and general banter.
PEBCAK errors... PEBCAK errors everywhere! If my life had a log file, it would be filled with PEBCAK...

Uxot
Posts: 382
Joined: 20 Jun 2013 00:52

Re: Truck stalling

#63 Post by Uxot » 04 Jul 2016 20:23

Well will try to change clutch range then..but im sure it wont change much...ill just keep playing with the W900 600HP for a long while :/

i don't even dare to try a 370HP now (ohgodno)

User avatar
Smarty
Beta tester
Posts: 2120
Joined: 30 Jun 2015 01:56
Location: Ontario, Canada
Contact:

Re: Truck stalling

#64 Post by Smarty » 05 Jul 2016 05:39

Try playing with a 6-71 with real curves (ie 500-600lb-ft @ 800rpm if you're lucky). Getting moving with no trailer before the light changes is... difficult. :lol:

I think the root of the problem is that the engine simulation lacks any kind of underspeed governing at idle. I can't speak for mechanical engines, but electronic controls will increase the fueling in response to an increase in load when idling. That is, the torque output will increase before the speed can drop substantially. Otherwise things like the air compressor, A/C compressor, or power steering pump would stall the engine.

The engine simulation should therefore include an approximation of this behaviour, where the torque output can rise, at a limited rate, up to the maximum for the idle speed to prevent underspeeding.
Image

User avatar
Max
SCS Software
Posts: 5988
Joined: 26 Nov 2012 10:00
Location: SCS, Prague

Re: Truck stalling

#65 Post by Max » 06 Jul 2016 20:28

well, here is list of recent changes i recall about this issue (start moving on manual).
1/ last update there was separated manual clutch viscosity values and set disconnected to 0.5. it was made for better slip during connection. to negate this set 1.0
2/ update before there was change in engine torques. this was made for modders to define torque curve and better fit to real ones (although values are accessible from last update, defaults were there before). its quite possible that we had bit stronger engines on low rpm before. to circumvent this, mod engine and set bit higher torque on 440rpm - like 0.6 or 0.7. part of this update were also changes of rpm limits, that were hardcoded and now are relative to engine rpm ranges. no idea if we forgot something wrong there.
3/ long ago we added connected clutch viscosity to keep clutch not slipping when 100% connected. to revert set value from 10.0 to 1.0.

aside of this some changes were made in powertrain, but its only minor things. one of them is better handling of idle throttle - exactly that fueling when rpm is dropping that smarty mentioned. its linear regulator, on low rpm increases throttle up to twice the idle default, and change was that it react faster than before.

clutch range could be indirectly affected by change 1 or 3 as they modified intervals of clutch interpolation. you can try how the change affect clutch feel by modding viscosity factors.

the fact is, that i can easily start truck on flat plane using clutch only (G27, 100% clutch range). with medium load it is trivial on crawls and easy on low gears 1 and 2. truck on idle could move with medium load to slight hill and regulated throttle is enough. all tested on master build.
Nobody can tell you anything about it. Those who know about it aren't allowed to talk. And those who talk know nothing.

User avatar
Cadde
Global moderator
Posts: 9535
Joined: 24 Apr 2013 18:08
Location: Have no fear, i am from the internets!

Re: Truck stalling

#66 Post by Cadde » 06 Jul 2016 21:34

Max wrote:the fact is, that i can easily start truck on flat plane using clutch only (G27, 100% clutch range). with medium load it is trivial on crawls and easy on low gears 1 and 2. truck on idle could move with medium load to slight hill and regulated throttle is enough. all tested on master build.
Thanks for the run through of the recent changes. I especially appreciate the insight on the engine torque bit.
I haven't experimented more with it, i've just dealt with it because let's face it. The few times i actually play the game I want to play the game, not fiddle with definition files and do lots of development for it.

Now, for the quoted part. Which truck, which engine?
Because i have tried the Scania R and gone through all engines up to 500 HP and they all suffer, even with 8 tonne loads. I no longer have issues with crawling at idle or getting moving without a load at idle, i assume it was something outdated with my clutch mod and i brought that up to date with the latest def from 1.24.
But once you slap a trailer on, i have to feather the clutch a lot and it doesn't matter if i keep the RPM's between 1,000 - 1,500 or 500 - 1,000. It struggles all the same. This is the part that i have just decided to live with but it just doesn't feel natural. I would imagine a truck would spin the back wheels at those torque outputs if the trailer was that tough to get moving.

I did try using a modified gearbox though with a 16.406:1 ratio in first gear and that too suffered from this slow start but the duration of the slow start was mitigated.
Again, i must stress that last time i played with my wheel (1.19 thereabouts?) i did not experience this. So there is a huge gap in changes that have occurred since last i played. Perhaps you have had smaller transitions which have made you more used to each change?

EDIT: In fact, the only way for me to settle this is for me to try it on 1.19 and verifying it.
ImageGreen text = Moderator action.
ImageWhite text = Opinions and general banter.
PEBCAK errors... PEBCAK errors everywhere! If my life had a log file, it would be filled with PEBCAK...

User avatar
Max
SCS Software
Posts: 5988
Joined: 26 Nov 2012 10:00
Location: SCS, Prague

Re: Truck stalling

#67 Post by Max » 07 Jul 2016 07:24

i tested wide set of engines and some trucks (scania & volvo for they have most of engine sizes, iveco for it has weakest engine). definitely not all but many. medium load is near 15t of cargo (or 12t in ATS as we are in ATS bug section ;)).

if your issue is on any rpm, its not engine issue but clutch issue. try to tweak viscosity factors to see how it affects behavior. plain changing from 1-10 to 0.5-10 can change a lot. lower viscosity can make exactly the loosing power effect you describe - engine is working, wheels are not because of higher slip ...

and yes, performing and testing continual smaller improvements is different than one big step. from time to time i check older builds for comparison, but i'm still pretty convinced its more real now than before. but i still collect your opinions and arguments as they are invaluable for us.
Nobody can tell you anything about it. Those who know about it aren't allowed to talk. And those who talk know nothing.

User avatar
Cadde
Global moderator
Posts: 9535
Joined: 24 Apr 2013 18:08
Location: Have no fear, i am from the internets!

Re: Truck stalling

#68 Post by Cadde » 07 Jul 2016 08:10

Yep, please don't get me wrong. I think you are doing a great job!
It's just my own personal observation and that could just as well be confirmation bias. Which is why i have to compare versions first and foremost.

Another observation that i just thought of is that i feel engines used to be more "revvy". What i am talking about is when clutched in and pushing it to the floor, the engine RPMs used to go up much faster.

But either way and as i said, i've just learned to live with it. If it was a real truck then i would be worried about wearing the clutch out prematurely.
ImageGreen text = Moderator action.
ImageWhite text = Opinions and general banter.
PEBCAK errors... PEBCAK errors everywhere! If my life had a log file, it would be filled with PEBCAK...

User avatar
Smarty
Beta tester
Posts: 2120
Joined: 30 Jun 2015 01:56
Location: Ontario, Canada
Contact:

Re: Truck stalling

#69 Post by Smarty » 29 Jul 2016 15:20

With some more practice, I've found that avoiding stalling is quite possible even with very low-powered trucks. I still feel like something important is missing from the driveline model that could lead to more realistic behaviour if remedied: elasticity of the driveshaft and tires! If the clutch is aggressively engaged while the vehicle is stationary, the driveshaft and tires act like torsional springs (some suspensions do as well if they are not well-designed, leading to wheel hop and other drivability issues). From outside, it will look kind of like the vehicle is 'slingshotting' from a standstill. Case in point, depending on the gearing, the engine may turn a considerable amount before the full feedback torque from the road is 'felt' at the flywheel.

Just my CAD$0.02. ;)
Image

User avatar
dg370z
Posts: 23
Joined: 02 May 2013 23:28

Re: Truck stalling

#70 Post by dg370z » 10 Sep 2017 04:15

Smarty wrote:
29 Jul 2016 15:20
With some more practice, I've found that avoiding stalling is quite possible even with very low-powered trucks. I still feel like something important is missing from the driveline model that could lead to more realistic behaviour if remedied: elasticity of the driveshaft and tires! If the clutch is aggressively engaged while the vehicle is stationary, the driveshaft and tires act like torsional springs (some suspensions do as well if they are not well-designed, leading to wheel hop and other drivability issues). From outside, it will look kind of like the vehicle is 'slingshotting' from a standstill. Case in point, depending on the gearing, the engine may turn a considerable amount before the full feedback torque from the road is 'felt' at the flywheel.

Just my CAD$0.02. ;)
I been experienced this slingshot effect with extreme up hill (dlc peru 1.4 Ats 1.28) my rigs spec 800hp@1400rpm (4000nm output torque) ef 18 speeds no matter physics.sii mod or vanilla i cant go up hill without stalling and diff lock is useless i hope scs fix this

Post Reply

Return to “Bugs 1.3”

Who is online

Users browsing this forum: No registered users and 1 guest