While you are mostly accurate, you would need to know how to cage the brake cans, there is usually a "bolt" (more of a piece of allthread with a t at the top) that you would install in the brake can and then tighten the nut and washer down until the bolt pulls the plate inside against the springs to release them, this needs to be done on the cans on both sides of each drive Axle. The drives are usually the only spring brakes on a rig. Trailers follow suit.