Is there a way to switch L2/R2 between Straight and Drivers Brakes? On the first mission I did, using L2/R2 was for drivers brakes, the next mission it seemed to use the Straight Brakes, which aren't as effective. Why the two types of brakes anyway?
The "Square" button is the one that toggles between the braking systems. The drivers (train) brake works on the whole train, loco and consist, and is the main braking system. The straight (loco) brake only works on the loco's wheels. It can be used when running light engine (no consist). It also useful when descending an incline to maintain speed by giving a constant braking force - where using the train brake would cause the train to slow too much giving a yoyo effect as you apply and release the brakes.
2 types of brake. Straight brake is the locos own stopping system. Train brake/Drivers brake- The system passing air throughout the train to apply braking to each railcar including the loco.
Like the comments above me. Loco brake or straight brake is for the loco when you are running light. Train brake is for when you have carriages or goods wagons(br heavy pack) coupled up. Though i just use the train brake. If you dont have the br heavy pack i recommend it