18-07-14, 11:14 PM
With rear disc brakes the handbrake operates the Caliper piston with a screw type system, which is why you have to wind the piston back on the screw system when replacing the pads, unlike the front where the pistons can be pushed back 
As the pads wear the piston is pushed out and operating the handbrake sets the automatic adjuster to take up the slack
As the pads wear the piston is pushed out and operating the handbrake sets the automatic adjuster to take up the slack