Whats the question?
Hand brake operates very small brake pads in a drum found in the rear discs. You pull the brake while moving you wear out those little brake pads designed to keep the car from moving when parked hence "Parking Brake"
We're talking very light braking forces here - not full-on wheel lockup. There is only one loud thump or knock at the moment of applying them but the brakes engage and continue to operate. It sounds as if the structure or the part holding the pads is shifting and banging the frame. If I release the force and then reapply it, another single thump occurs.
Where should I start looking?
When the car is parked, and the parking brake lever is lifted, how many clicks are there until the lever is snug and the parking brake linings hold the car in place?
It should be around 5 or 6 clicks.
When the lever is pulled up, the parking brake linings move out from their rest position to come against the inner surface of the drum (rotor). This movement should be minimal, and is determined by the proper adjustment of the linings. Each wheel set has a star-wheel adjuster.
If the brake shoes aren't set properly, as the lever is pulled, they will move out farther from the rest position in order to contact the drum. In doing so, the tops of the brake shoes (see attached) will initially move away from the retaining pin. Then when their brake friction surfaces contact the moving drum, the two shoes will rotate slightly until one of them comes up against the pin. It's this sudden contact that can cause the "thump".