Today: My favorite toy.
This model of an SCam brake was designed and printed by ScanningCars he had one on display at WREX2016, and I ordered one on on the spot. I tried to buy the one he had on display, but no dice. He actually made some nice improvements on the design before building this one for me, so I'm glad he didn't let me buy that one.

From outside in, there's a rotating brake drum, two pivoting shoes in yellow that spring back when released, an SCam in white, a slack adjuster in black, a pushrod (grey) and a service brake chamber (applied with blue) and a parking brake or spring brake chamber (applied with RED. The model also has a caging bolt that works, but I didn't demonstrate it here just like a real caging bolt, it screws in the back and grabs the spring brake plate and pulls it back, to compress the spring and allow the wheels to roll when there's no compressed air to do that job for you. What's your favorite demonstrative? Peace. W