You can accelerate while using exhaust brake

Post Reply
User avatar
michbret
Posts: 200
Joined: 27 Sep 2013 13:06
Location: France

You can accelerate while using exhaust brake

#1 Post by michbret » 20 Jan 2014 20:28

If a stupid driver like me :oops: has the strange idea to accelerate when he activates the exhaust brake it works.

The effect is to nullify the exhaust brake but that's not the problem except the stupidity.

The problem is that I think that there is a mechanical impossibility to do this with real truck engines ...
User avatar
Cadde
Posts: 6806
Joined: 24 Apr 2013 18:08
Location: Have no fear, i am from the internets!

Re: You can accelerate while using exhaust brake

#2 Post by Cadde » 20 Jan 2014 23:47

Actually, from what i heard it's possible to accelerate with a jake brake on. Not sure how different an exhaust brake is when it comes to this.
Either way, relevant video:
He does accelerate with it on at around the 1 minute 30 second mark and more so at 2 minutes beyond.
On extended hiatus.
User avatar
thebigbadonion
Posts: 2556
Joined: 21 Jul 2013 18:23
Location: Greater Manchester, England

Re: You can accelerate while using exhaust brake

#3 Post by thebigbadonion » 20 Jan 2014 23:55

is it just me that thinks it sounds like its farting? :lol:

EDIT: Reading the comments on you tube....NO! :lol:
User avatar
michbret
Posts: 200
Joined: 27 Sep 2013 13:06
Location: France

Re: You can accelerate while using exhaust brake

#4 Post by michbret » 21 Jan 2014 07:46

Hi Cadde,

I am not really certain about my analysis on this topic but here is my understanding.

However, the mechanics are different between jake brake and exhaust brake:

On an exhaust brake, the exhaust path is closed, somewhere after the exit of the core of the engine. This create a back pressure towards the engine. This back pressure would compromise fresh air intake and turbocharger operation as well. My opinion is that, if diesel injection still happens with exhaust path closed, the explosion would stop after a few stoke since oxygen will start to lack (the few store would have transformed the oxygen into mostly CO2). So formally, you can still accelerate but without propulsive effect after a few stroke.

A jake brake has an additional camshaft that force the exhaust valve (at the cylinder top) to open at the top of the air compression phase. But nothing blocks the exhaust path which explains the loud noise generated. In theory, diesel injection could still take place at the same point of the cylinder rotation but I am not sure it would properly explode if the air pressure is too low (exhaust valve opened by the jake). If it explode this would increase the noise a lot and have a poor propulsive effect.

No idea about the potential damage or wear implied by the fact of accelerating (injecting diesel) while using any of these feature.

To be discussed, of course.

Best regards
cleber_oro
Posts: 198
Joined: 20 Dec 2012 21:21
Location: Brazil
Contact:

Re: You can accelerate while using exhaust brake

#5 Post by cleber_oro » 21 Jan 2014 11:27

All new trucks are equipped with a protection system to exhaust brake. When the driver touch the throttle or clutch immediately exhaust brake is turned off. Eg. the driver can keep always turned on the button but exhaust brake only be triggered when he aren't touching the throttle or clutch.

To solve this problem, I have wrote some lines in "control.sii". Now my exhaust brake works correctly and I can leave the button activated.

sorry bad english
User avatar
michbret
Posts: 200
Joined: 27 Sep 2013 13:06
Location: France

Re: You can accelerate while using exhaust brake

#6 Post by michbret » 21 Jan 2014 14:26

Hello cleber_oro

I totally agree with you about the multiple protection systems available in modern trucks.
Your idea of modifying control.sii to mock-up these protection is smart :D . I will probably try something like this to protect myself from being so silly.

On my previous message, I was focusing on the intrinsic behaviour of a basic / manual truck.

Thanks for the hint.
Last edited by michbret on 21 Jan 2014 18:07, edited 1 time in total.
cleber_oro
Posts: 198
Joined: 20 Dec 2012 21:21
Location: Brazil
Contact:

Re: You can accelerate while using exhaust brake

#7 Post by cleber_oro » 21 Jan 2014 16:05

@michbret I understand you. When I get home I'll post my setup here.
cleber_oro
Posts: 198
Joined: 20 Dec 2012 21:21
Location: Brazil
Contact:

Re: You can accelerate while using exhaust brake

#8 Post by cleber_oro » 21 Jan 2014 19:18

Code: Select all

config_lines[160]: "mix motorbrake `(j_clutch?0 - 0.5) &  (j_throttle?0 - 0.5) & (! dforward?0) & (joy2.b7?0 | keyboard.b?0)`"
actuation:
keyboard: b
Joystick 2: button 7
User avatar
michbret
Posts: 200
Joined: 27 Sep 2013 13:06
Location: France

Re: You can accelerate while using exhaust brake

#9 Post by michbret » 21 Jan 2014 19:59

Very good cleber_oro !

I like the trick (j_clutch?0 - 0.5) ... :D I was turning around this one and the throttle.

Would have to change this if SCS makes a proper clutch one day ...

Thanks for sharing.

Enjoy trucking
cleber_oro
Posts: 198
Joined: 20 Dec 2012 21:21
Location: Brazil
Contact:

Re: You can accelerate while using exhaust brake

#10 Post by cleber_oro » 22 Jan 2014 16:15

You're welcome! Worked fine?

I believe the SCS will not make big changes. Maybe have a new clutch system in ATS. So if is necessary I'll try to do it again.
Post Reply

Return to “Bugs 1.8”

Who is online

Users browsing this forum: No registered users and 5 guests