different rear brake caliper

Don't laugh turbogt, Husky44 was actually right. The screw-in mechanism allows the piston to be pushed out when the parking brake cable is pulled. There's no hydraulic pressure when pulling the parking brake, so how else are the rear brakes applied?

Basically, as the pads wear down the design internally adjusts the screw mechanism so the parking brake will work properly. I don't know exactly how that part works, I just know it does. To reset that screw mechanism for the parking brake, you have to screw in the piston when replacing the pads. Kinda like threading in a big screw. Why the system can't auto-reset by compressing the piston like you do the front calipers, I don't know.