Brake chamber part number

[Tom Y]

Big $$$$ yes, but not that hard to work on. And after market parts are out there, as there are a lot of these on the road yet. I picked one up from a GMC and you can see the effects of no air dryer, or one that did not work.  Tom Y

[bevans6]

There are three types of brake chamber that bus people usually have to worry about.  The DD3 are used on about all the older MCI's and many other brands of buses for the drive axle position only, and about always in the 30 size.  The DD3 has a unique emergency/parking brake system suitable for buses.  The "30" is the size of the main chamber diaphragm in square inches, and that governs the power the chamber will deliver for a given amount of air pressure.

The other, far more common and less expensive, drive axle brake chamber is a spring brake type.  That's a type 30/30, or a type 24/30, or similar designation.   the "/30" indicates that it has a spring chamber and the size of the spring.  These come in standard stroke and long stroke models, the long stroke type is the preferred type since it allows more stroke on the pushrod before adjustment is mandatory.  Spring brake chambers are larger physically than the DD3 and on MCI's they interfere with the suspension and cannot be substituted without major surgery.

A steer or tag axle brake chamber is a Type 20 or a Type 24, with no "/XX" in the name, and that indicates a plain brake chamber with no added spring brake section.  As always, the number designates the size of the diaphragm and the power the chamber develops for a given air pressure.  Brake balance depends on the correct size of chamber and the correct slack adjuster per the design of the bus, axle weights, etc.  The front chambers on my MC-5C are Type 20's, and on some larger buses they may be Type 24's.  These also come in standard stroke and long stroke types, and a useful upgrade is to change to long stroke when you buy new (and these are regular maintenance items) but the advice is that you always have the same type on both sides of an axle, and on the whole vehicle so that no one gets confused when checking brake stroke and slack adjustment.

Brian

[luvrbus]

Most of the larger buses like a H-45 Prevost with disc brakes use the SC 16 , on the Eagle most  of those were type 24 or 30 with 30/30 spring brakes, you never know what you will find on these old buses


good luck