I found a 'print'/ picture of an archbar truck that showed the actuating lever sticking upward, midway-above the axle. The linkage would attach to this and apparently pull the lever(s), toward the middle of the car thus setting the brake. In the pic, it appears the brake shoes are pulled outward to the 'off' position by springs attached to the bolster. Of course there would be another lever arrangement connecting the second axle in the truck. I'm building some 'skeleton' log cars and wanted to duplicate whatever braking they had-turn of the Century and before. In pictures one can see the wheel and locking pawl system that wound /pulled the chain-in this case mounted on the center 'beam'. I can not, however, see brake shoes as described above. Therefore, I'm still not sure how the bracks actually worked, or if they were somehow hidden inside.