Remove rusted hardened pin from cast housing

[FOMOGO]

I think a 3" cutoff wheel on a die grinder would be quicker and easier than burrs, if you want the head off the pin. Mike

 

[dansawyer]

The failure is: The clevis is supposed to rotate on the arm to allow the rod to remain centered on the brake chamber hole. The pin is frozen so when the brake is applied the rod gets jammed against the side of the chamber, causing it to hang up. This in turn causes the brake to drag. I believe it was caught early and no damage to the shoes, drum, or bearings was done. I will change and inspect the bearing oil to ensure it does not show damage.
My thought is the only way to assure it is working is to remove it, clean it, and re-assemble. The thought is if the pin is free to rotate in the arm it will not hang up.
If I can get it free enough 'in situ' there is a possibility it may be operable with monitoring without actually removing it. It is currently fully operable, the arm retracts normally and the wheel is free. My fear is it could re-seize without warning.
Thank you. Dan

 

[Jake M]

I see. So I'm gathering from this (but open to correction), that this WAS binding, but you've got it to a point when it binds less? When that happens full on binding happens, if all else is well, "normally", the pushrod binds on the way out under the full force of the chamber, but still releases until the rod rubs on the opposite side of the hole in the chamber, and stops short of a full retraction. The shoes run too close, which isn't good, but they release. The pushrod rubs and grinds, but it releases. In my shop, that would have a new clevis, pin, and bushing obviously, but if it stuck in the "out" position, the light releasing force makes me think that the anchor pins, rollers, main spring, and cam bushings are suspect. The wheel would be coming off, and all of those items individually inspected. These brakes are dirt simple, almost archaic in their operating mechanisms, which is what makes them as good, and as reliable, and durable as they are, but they do work as a balanced system, and rely heavily on everything being dead nutz right. What's good enough on a static test is way different than what works under normal service conditions. Bottom line, whatever you find when you get in there, make sure that you're sure, and never forget that rust seldom gets to only one place.

FWIW, if it's got hot enough that the bearing oil smells "cooked", (or if there's barely visible "glitter" in the bearing oil, but that's somewhat it's own issue), cups and cones are done, and will continue to disintegrate no matter what oil you put back. Replacing those is a given as well regardless of their appearance), but if the oil is burnt, the friction material has been past it's point of no return (that's where the heat came from after all), so no matter what you do, it'll never be as effective as it was.

 

[finsruskw]

I see. So I'm gathering from this (but open to correction), that this WAS binding, but you've got it to a point when it binds less? When that happens full on binding happens, if all else is well, "normally", the pushrod binds on the way out under the full force of the chamber, but still releases until the rod rubs on the opposite side of the hole in the chamber, and stops short of a full retraction. The shoes run too close, which isn't good, but they release. The pushrod rubs and grinds, but it releases. In my shop, that would have a new clevis, pin, and bushing obviously, but if it stuck in the "out" position, the light releasing force makes me think that the anchor pins, rollers, main spring, and cam bushings are suspect. The wheel would be coming off, and all of those items individually inspected. These brakes are dirt simple, almost archaic in their operating mechanisms, which is what makes them as good, and as reliable, and durable as they are, but they do work as a balanced system, and rely heavily on everything being dead nutz right. What's good enough on a static test is way different than what works under normal service conditions. Bottom line, whatever you find when you get in there, make sure that you're sure, and never forget that rust seldom gets to only one place.

FWIW, if it's got hot enough that the bearing oil smells "cooked", (or if there's barely visible "glitter" in the bearing oil, but that's somewhat it's own issue), cups and cones are done, and will continue to disintegrate no matter what oil you put back. Replacing those is a given as well regardless of their appearance), but if the oil is burnt, the friction material has been past it's point of no return (that's where the heat came from after all), so no matter what you do, it'll never be as effective as it was.

Older piece of unknow equipment??

Replace the assembly and be done with it.
Be DOT safe is much more important than saving a few dimes.