There was a recumbent trike kit sold by a guy who built them out of aluminium box tubing, not a good trike at all except at the time is was the cheapest option by far; but actually dangerous - at the front braking was two side-pulls each mounted on a arm that extended from its hub. The braking torque was taken by

a: the friction between the (unkeyed) axle axle nuts and the frame; and
b: a small machine screw bolted through a hole connecting the two parts that should NOT rotate relative to each other (the brake mounting arm and the frame), said hole about an inch or so from the axle.

Of course the torque was enough to break the bolt, it was only about 4mm dia, and when that happens the arm rotates forward; the rider is then pulled forward out of the seat; if lucky their nether regions missing the chainring as they are launched out of the trike and into the path of whatever they were trying to avoid.

After this happened I contacted the inventor/seller, got a reply saying essentially nothing other than he wasn't in business anymore. I see a relative is making a similar trike, with the same torque-arm system - the screw looks a bigger diameter but if that's all there is I wouldn't trust it.

I did tell the inventor how I modified the trike I had so it was safe; a strip of aluminium triangulating the end of the brake mounting arm, a hole in each end, two matching holes on the trike, two screws and it looks the same as the rest of the machine. He didn't seem interested, probably thought he was litigation-proof.