Drum Parking Brakes
An integral parking brake system is part of the rear drum brake system. Parking brake systems like the one in the illustration use a cable, a lever, and a strut to bypass the hydraulic system and apply the parking brakes.
Parking brake cables attach the brake handle/pedal/lever inside the passenger compartment to the parking brake lever inside the brake drum. The lever pushes the rear secondary shoe outward, and the brake strut forces the primary forward shoe into the drum.
The secondary shoe faces the rear of the vehicle. In the illustration, you see that the parking brake strut is the member that acts upon the primary shoe. These two parts (cable | strut) work together to equally apply the secondary and primary shoes.
Drum in Hat Rotors
A self-contained drum in rotor parking brake system has a small parking brake that operates inside the hub of the rear brake rotors (Drum in Hat). They have similar characteristics to integral drum parking brakes; instead of hydraulic pressure, the driver uses a brake lever or pedal to apply mechanical pressure.