On Friday, July 19, 2019 at 7:10:41 PM UTC-4, wrote:
I've trailered my 1992 Cobra back and forth myriad times from NJ to Hobbs, Uvalde, Nephi, Cordele, TSA, etc. Most of the time everything is fine. The hubs are barely warm and everything works right.

But once in a while, from when the trailer was a few years old, a hard stop (not a locking-the-wheels, screeching-tires panic stop but just when someone cuts in front and you have to brake suddenly), the surge brake locks up and won't release. And with no backup cam, I can't see it. I just know to pull over and check right away. And now I watch the TPMS: the temperature rise seems to give me a heads up that it's happening.

I'm a mechanical engineer originally. I've been doing brake work for almost 50 years on my vehicles. I worked for 10 years for a company that made OEM and aftermarket brake parts. IMO, there's some vulnerability in the Al-Ko system that--when triggered--causes bad things to happen. As I detailed before, I've tried nearly everything this time. It locked up on the way back from TSA/Dallas last summer so I did a lot of maintenance/adjustment/replacement then and thought I had it fixed. And apparently I did--for a while. But on the way back from Columbus, OH last month (after the Stds. were postponed), I had to brake hard. I pulled over a few miles later and, sure enough, same problem. I just disconnected the brake system then to get home (I've had a lot of practice). More work after that. Last week on the way to and from Blairstown, the same problem. I'm running out of things to do.

There's a problem. I'm sure something is out of adjustment or alignment or something somewhere. And when that happens, disaster. As much as I love [most] German engineering, I shouldn't have to ship the trailer back to Germany to get it to work right!

Chip Bearden

Chip,

don't get me wrong - that has nothing to do with waving the German engineering flag! I am a ME too and deal a lot with complex mechanical systems.
Your brake system is purely made up from levers, cams, pull-rods, bell-cranks and maybe a set of Bowden-Cables. Somewhere in that system is one element, which - when you brake hard - goes into a lock-up condition and won't release. It could be a cam that rotates too far or a pull rod, which gets hung up somehow. I found a few YouTube videos showing how to adjust an ALKO Auflaufbremse but they are all in German.
Have you contacted Spindelberger (or W&W) to get a schematic for your axle and brake set-up? I am sure they can provide you with a trouble shooting guide and an adjustment instruction. With some additional info, you can return the system to function properly - it's not rocket surgery!

Uli
'AS'