Algodoo

Nicely done, but not totally accurate. Drum brakes employ what's called a "self-applying" characteristic that assists the brake shoes in gripping the drum as the drum rotates ( see: SELF-APPLYING CHARACTERISTIC )

Also, the brake pedal action can be improved. You have a spring return on the pedal, but you enabled the brake on the hinge that allows the pedal to rotate. I found that the pedal moves more naturally if I disable the brake on that hinge, and increase both the spring tension, and the hinge motor force. Play with those values until it looks and feels right.

Other than that, you did a nice job on the scene!

The self-energizing effect is present. The left shoe rotates about the anchor bolt at the 12:00 position which helps force the shoe into the drum.

Not really. There appears to be a bit of play between the left shoe and the anchor pin, but I believe it was put there only due to accident, not by design. In a real drum brake assembly, the self energizing action is visibly noticeable, and the amount of "play" has been designed into the system to maximize the action. Also, the brake assembly in this scene is quite different from an actual hydraulic brake system, because the actuator (a hydraulic cylinder in a real system) is located in the same position as the upper spring, not at the bottom as in this scene. The cylinder expands when the brake is applied, pushing the shoes AWAY from the anchor pin. Depending on the direction of rotation, the self energizing action forces one of the shoes further away from the anchor pin, and the other shoe gets pressed hard against it. Check out this video for a basic brake system tutorial: Drum Brakes . You can skip over to the discussion about the self-energizing action which begins at 5:18.

I'm not saying that this scene will not work as an effective brake system. It probably would work for a simple wagon or similar low-power vehicle. But it is quite different from how a hydraulic brake system in a high power vehicle (such as a car, bus, or truck) operates.

I disagree. According to Wikipedia:

"Note: In most designs, the "self-applying" effect only occurs on one shoe. While this shoe is further forced into the drum surface by a moment due to friction, the opposite effect is happening on the other shoe. The friction force is trying to rotate it away from the drum. The forces are different on each brake shoe resulting in one shoe wearing faster. It is possible to design a two-shoe drum brake where both shoes are self-applying (having separate actuators and pivoted at opposite ends), but these are very uncommon in practice"

The drum brake in this scene has more self-energizing effect than the one in the video. This was judged by measuring the distance between the anchor pin and the nearest point on the drum, and dividing that by the drum diameter. I don't believe free play in the pivot has anything to do with self-energizing. The anchor pin and the corresponding notch in the brake shoe is just an inexpensive, forgiving, and rugged way to make a pivot.

There is one thing I did notice, and that is that there is not enough clearance between the two shoes (when the brakes are applied) in the area between the anchor post and the drum. I don't think this was intended nor part of our discussion. If this shortcoming was the point of your previous discussion, then I apologize.

You, s_noonan, are obviously a knowledgeable engineer, and you probably had a more structured education than I did. Therefore, your points are well taken, and you are probably correct on most or all of them. For me, mechanical engineering is not my strong point, and so I'd better back out of this discussion before I say something that makes me look exceedingly naïve (and it wouldn't be the first time).

The system we have relied to do, was my motorcycle that is "Suzuki Intruder 250" (released in 1997 more or less). Really, this system only applies to bikes.
(Sorry if the text went something inconsistent, not very demesne inglês.Eu speak Portuguese-BR). Tankspor have commented!

(If possible, translate the review before the google translator to Portuguese because I can not copy here)