BRAKE CHAMBERS & COMPONENTS

Brake Chambers & Components For Peterbilt Trucks

Brake chambers convert air pressure into the mechanical force that actuates your Peterbilt's foundation brakes. On a fully loaded Class 8, that means brake chambers are working hard at every stop — and failure is not an option. We carry service brake chambers, spring brake chambers (piggyback units), and related hardware for Peterbilt trucks in a range of sizes including the common Type 30/30 combination units used on drive axles.

Frequently asked questions about brake chambers & components

What's the difference between a service brake chamber and a spring brake chamber?

A service brake chamber actuates the brakes using air pressure when the driver applies the foot valve. A spring brake chamber (often called a piggyback or maxi-brake) adds a heavy-duty spring that applies the brakes when air pressure is released — this is your parking brake and emergency brake system. The spring chamber portion engages automatically if the truck loses system air pressure below approximately 20–45 PSI.

How do I know what size brake chamber I need?

Brake chambers are sized by the effective area of the diaphragm, measured in square inches — common sizes for Class 8 trucks include Type 20, 24, and 30. The required size is determined by your brake system spec and FMCSA stopping distance requirements for your axle weight rating. Never replace a brake chamber with a smaller size than what was originally fitted, as this reduces braking force and may create an out-of-compliance condition.

Can I replace just the diaphragm in a brake chamber, or do I have to replace the whole unit?

Diaphragm-only replacements are possible on some service chambers and are a common shop repair when the housing is still in good condition. However, on piggyback spring chambers, the spring section contains a powerful compressed spring that requires specialized tools to safely disassemble — most shops and manufacturers recommend replacing the entire spring chamber as a unit rather than attempting field repair of the spring section.

Other parts you might need

Shop all air brake components for Peterbilt trucks