Bad Day / Good Day

Shop I work at we just replace the piggy back....unless the service spring is broken. I wish we had brake chambers that lasted 5 years. Our front load garbage trucks have to set the brakes at every dumpster. Sometimes 200 cans per day!

 

Funny thing is, the whole can is only a buck or two more than the partial. Most of the time, I'll get the whole thing even if I only planned on changing out what broke. Sometimes all it needs is the rubber diaphragm, though...keep a few of those on hand.

 

I always change the whole can, unless it this situation. Side of the road, need to boogie, then piggy back. I like the new spring to retract the rod.

 

New can only. You are there, why screw around doing half a job. For those in the northern rust belt: while you are jacking around doing half a can, if it has enough corrosion you could find yourself hurt badly when the can explodes while working on it. Or it could explode if you screw up while working on it. How do I know this? I have a friend who woke up in the hospital with unintended facial reconstruction that the doctors had to fix as best they could.

 

Yup. Tested that theory the other day while changing out an improperly installed diaphragm on a trailer I'd hooked to. Since I had the brake chamber caged anyway to do the work, and always test to see if it's going to leak, it was a good time to satisfy a curiosity I've had ever since I read your post. (I'd always been under the impression that caging the brake chamber rendered it inoperative). Anyway, brake caged w/air supplied to trailer, brake drum rang like a bell when I thumped on it with a hammer. Applied the service brakes, and just the solid sounding "thud" you get when the brake shoes are pressed against the drum.

So, apparently service brakes do, in fact, continue to function even if the spring brakes have been manually released. Good to know!