Repairs... My garage door has counterweights, and the weight of the door is connected to the counterweights with a steel cable which runs over two pulleys. The original (cast iron) pulleys had needle roller bearings, but lacked any lubrication, and probably incorrect termination/hardening of the outer ring caused excessive wear, and I had to replace them.
I found size-compatible replacements, but they have 'normal' ball bearings, which should be able to bear the load. I've been trying to find a way to tell if the axis will stand hold the narrower load though. The simplified configuration is now:
White is the axle, blue is the fixed hardware, and green is the bearing of the new pulley. All measures are in mm. The extra space is because the original roller bearing was wider.
This is the path the cable follows:
I've looked over many pages, and I'm not sure how to tackle this. The problem is not completely shearing stress. I've found precious little info on 'bending' limits of round bars (axle). The weight of the door is about 60 kg (same as weights, of course) and the load is distributed at each side of the door.
Intuitively I suspect this will hold, but then my mechanical intuition isn't as developed (I'm an electronics engineer). In short, will the (mild steel) 10 mm axis bear the weight? Or do I need some more hardened material?