When air fills the chamber, it presses against a flexible rubber diaphragm. This action forces a pushrod outward, which rotates the slack adjuster and engages the brake shoes against the drum.

Types of Brake Chambers

• Service Chambers: Standard chambers that only apply the regular running brakes.
• Spring Brakes (Double Chambers): Commonly used on rear axles, these combine service brakes with a heavy-duty mechanical spring that acts as the emergency and parking brake.

Common Sizes

Brake Chambers are standardized by their effective diaphragm area, which dictates the force they can exert.

• Service chambers: Typically range from Type 6 to Type 36.
• Spring brakes: Use dual designations (e.g., Type 30/30).

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