Stress acting on Rack?

I have a valve system. The Blue (racks) experience wear on the red spots there. The Rack slides parallel back and forth in which the Yellow(Guide) keeps the Rack in position. The racks allow the butterfly plate to open and close. I am not sure what kinds of forces are acting to that rack which causes it to wear the surface. Will there be any shear force or what kinds of forces will act up on it?

I am planning to weld to build up material on that wear. And need to calculate positive a margin of safety.

The tensile strength of the weld material is 65,000 psi. I guess we can use Fsu = Ftu * .577 to find out the ultimate shear strength. If 200 lbs (hypothetically) acts on pushing that rack on the bottom to move the Rack. Is there anyway I can find the shear stress for that top face in red? The wear area is 0.050" deep and length of wear is 0.95". Is there any way to come up with an short analysis?


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