bromstrumma

Bromstrumma is the Swedish term for a brake drum, a cylindrical component that forms the friction surface within a drum brake system. The drum rotates with the wheel and encloses the brake shoes, which press outward against its interior when braking.

Construction and materials: Bromstrummor are typically made from cast iron or steel. The inner surface serves as the friction surface, while the outer body is shaped to fit inside the wheel drum assembly. Drums can be solid or, in larger or performance applications, vented to aid heat dissipation. The exact dimensions depend on the vehicle’s brake system and wheel size.

Function: When the brake is applied, hydraulic or mechanical force moves the brake shoes toward the interior of the drum. The shoes rub against the drum’s inner surface, converting kinetic energy into heat and slowing the wheel. In many designs, the rear brake assembly also houses the parking or emergency brake, which mechanically actuates the shoes against the drum.

Maintenance and wear: Bromstrummor are inspected for wear, scoring, out-of-roundness, and heat cracks. If wear or damage exceeds tolerances, the drum is machined or replaced, and the associated brake shoes are serviced or replaced. Proper adjustment ensures the correct clearance between shoes and drum for effective braking.

Usage and context: Drum brakes, including bromstrummor, are common on older vehicles and in some modern cars for rear axles or parking brake systems. They are valued for simple construction and integrated parking brakes but can suffer from heat fade in heavy use, which has led many manufacturers to favor disc brakes for primary stopping power. See also drum brake, brake shoe, wheel cylinder.