Turning the square peg clockwise drives a wedge between two pistons and forces the shoes apart.
A typical braking system uses disc brakes at the front of the car and drum brakes at the rear.
Usually the handbrake operates on the rear shoes by means of a mechanical linkage — a cable and some levers and pivots.
Wheels are always raised — and in many cases removed — to make brake adjustments. Raise the car at the jacking point nearest to the wheel you are working on, and support it on an axle stand.
The brake pads on disc brakes adjust automatically for wear, whether the car has disc brakes on the front wheels only or on all four.