I recently pulled an m105a3 off base. While jacking up the trailer one side of the rolled while the brake lever was down. I blocked that tire and jacked up the trailer and pulled off base. I didn't feel like the brakes were dragging when I first started driving. I drove across the train tracks and that Is when the trailer brakes started dragging. I read over the tm for a3 version of the trailer and haven't isolated the problem. If I release the brake lines of pressure should that stop the trailer from dragging?
Two items cause the brakes on the A3 trailers to drag.
Check the adjustment of the brake shoes. When adjusted too tight they drag. Also my A3 has had the drums rust up a bit for lack of use and then dragged until I hit the brakes hard a couple of times.
The second issue is the rollers that the surge coupler rolls on. See if you can push the coupler in an inch or so, if not there is a good chance that the wheels are rusted to the small spindle that they roll on..
Viewing the coupler from the top, there is a hole in front of the emergency break-away cable. If you don't see an un-blocked hole the rollers need to be removed and lubricated.
You have four bolts on each side of the coupler, only remove one at a time and make reference of the "clocking" of the shaft, as this is how the adjustment is made to keep everything rolling free. The two large pins that are cotter pinned have to be removed as well as the emergency break-away parts.
