The retarder uses your transmission to slow the truck down, hence the whirling sound you hear with the retarder engaged. Typically it is used to maintain your speed going down hills to prevent the truck from accelerating to an uncontrollable speed. In real life, you would use your retarder to limit the amount of speed your truck picks up.If you take the "`joy.ry`" bit, which is Right Stick Y-axis(up/down), and place that in a spot that would be for example `joy.a`, or A button on Xbox controllers, it will now work with an axis. I used to use this for engaging the engine brake non-toggle version when I was experimenting with using a flight stick for extra controls. Bad idea.
Toggle Engine brake: turns the engine brake on or off, at whichever power you have selected (High/Med/Low for example) Engine brake: does what it says on the tin, full power or off. If you have engine brake up/down set, and DONT have toggle engine brake set, those buttons will cycle through Off > low > med > high, then engine brake down: High
In my real personal experience, basically, engine brake commonly used for accommodating light/slow speed deceleration, meanwhile retarder is suitable for heavy/fast speed deceleration. All those posters from 2018 are grateful for your input. 5-year necro, SMH. I use retarder as my main brake method. When there's a traffic light, or tight curve BYPHl.