In real life cars with automatic transmission it is possible to limit the gearbox from going into the higher gears. Normally the driver puts the gear into D and off he goes. But e.g. when going uphill it might be better to stay in low gear. I think there is a position "2" and sometimes even a "1" for that. Is such a feature modelled in the game automatic transmission? Does IRL automatic
Jake Brake with Automatic Transmission #1 by Polarlicht ยป 01 May 2020 13:02. In ETS2 when you activate the jake-or engine Brake (not the retarder) the automatic transmission shift down a few gears to get better engine braking. But in ATS it doesn't shift down. You can tap the throttle to let it shift down, but then it shift up again
The 1st gear ratio on the 12+2 transmission is higher than on the 12 speed gearbox mentioned earlier so the truck will be able to crawl up steeper terrain due to the slower minimum tire rotation speed. I hope I didn't overcomplicate that or make it too confusing but I'll link an Engineering Explained video below to help explain better.
Jake brake is an engine brake, EU trucks use something called an exhaust brake, which pretty much blocks the exhaust flow, forcing combustion gases back into the engine. Jake brake adjusts the valvetrain to create a vacuum like you explained. Jake brake is slightly more powerful but the effect is more or less the same.