Caged Brake Chamber?

You insert a T head bolt into the end of the chamber and engauge the spring that operates the emergency brake application when air pressure is lost. Tightening the nut draws the spring back to it's shortest length so it will not force a brake application. Applying the parking brake usually releases this spring so the bolt holds it in the caged or energised position allowing the chamber to be opened without an explosive release of the spring.

The most common use is when a mechanic has to remove the brake chamber to replace the air diaphram that operates the service side +/or the one that compresses the spring to release the emergency/parking brake.

New units used to come w/ the cage bolts mounted on the outside of the chamber. The prep mechanics used to remove them on the big fleets I worked for so they would not be available to the drivers.

Wrecker drivers often cage the spring brakes on a damaged unit for towing. That is probably the 2nd most comon reason to cage brakes.

 

When you have an air leak inside a brake chamber, the spring brake comes on and that dual will slide down the road, until you apply the t-bolt and tighten down the bolt with a 3/4" wrench or a crescent wrench. You should carry a cage bolt or two and a wrench to tighten the bolt, otherwise you can get stranded on a roadside. Also, carry a Vise Grip to clamp over the air hose going into the brake chamber, otherwise you risk not having enough air go to the other dual to keep that spring brake from stopping you. I got caught without a cage bolt at night and had to unhook and drive to a truckstop and get a bolt from a mechanic and then I installed it and got back on the road.

This procedure should be taught in detail in driving school, but it was not.....but we had the theory and could figure it out from there. Every new driver should be told to carry these tools/part. I keep a flashlight, a t-bolt and a 3/4" wrench in my travel bag, as I slip seat and you never know what tools will be in the truck.....likely not the ones you need.

 

Here you go.

393.41 Interpretations Question 2:
Question 2: Does 393.41 prohibit air brake systems from being equipped with a means to release the spring brakes for purposes of towing disabled vehicles in emergency situations?
Guidance: No, provided the brakes are designed and maintained so they cannot be released unless adequate energy is available to make immediate reapplication of the brakes when the brake system is operable.

It would be a brake defect, yes, and a violation under 383.41. But it would not equal "one defective brake", since the service brake would still be operable. It would not contribute to OOS under the 20% which applies only to service brakes.

 

I caged some brakes a month ago and the new bolts required a 13/16 wrench not 3/4.

 

A little off topic here--but think it needs to be said--IF you haven't ever caged a brake chamber(s)--please do not try to read about how to and then attempt it--you just might find yourself in a world of hurt--it is NOT as simple or as safe to do as it may seem...
Just sayin.......

 

That was safety 101 when I first worked in a truck shop. the took me over by the one bench and showed the close to 8" hole in the block wall saying how lucky the mechanic was 'cause it missed him! Same reason they removed the t bolts from the new tractors, they wanted the driver to call for help.

 

Wondering what brand of brake chambers are the best quality. The made in China thing doesn't do much for me. Thanks