A drum-in-hat parking brake system uses a small drum brake incorporated into the ________?

A drum-in-hat parking brake system integrates a small drum brake within the rear rotor. This design utilizes the inner surface of the rotor as a drum for the parking brake mechanism. When the parking brake is engaged, friction is applied within this drum to prevent the vehicle from moving. This system's advantage lies in its compact design, as it eliminates the need for an external drum assembly while effectively utilizing existing components in the braking system.

Other options do not correctly represent where the drum-in-hat system is located. The pressure differential valve and proportioning valve are components involved in fluid distribution and balancing braking force across the wheels, but they do not relate to the drum-in-hat mechanism. The screw and nut reference may pertain to different mechanical systems but does not accurately describe the location or design of the drum-in-hat parking brake within the vehicle's braking setup.