Drum Brakes
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 1990 Pontiac Bonneville, 1990 Oldsmobile Ninety-Eight, 1990 Oldsmobile Eighty-Eight, 1990 Cadillac Fleetwood, and 1990 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
Rear brakes are hydraulic leading/trailing type drum brake. The return springs hold both shoes against the wheel cylinder at the top and against the fixed anchor at the bottom. When the brakes are applied, the wheel cylinder moves both side out to contact the drum. The forward shoe wraps itself into the drum and self-energizes during forward application. With application in reverse, the rear shoe wraps itself into the drum providing self energization.