Mechanical over speed trips often need adjustment. I assume you reached trip speed and it did not trip? And you then tripped it manually?

If so you need to adjust is out ( for a lower rpm set) and try it again. At the same time make sure that it is working properly and not jammed.

yah you are right
it reaches trip speed but it didnt trip
what you have said seems to me OK
but I have problem that I can't call operators team for solo run without being sure for what I did

by the way that's turbine work smoothly and not jammed

any other ideas please help

and thanks for your response

I have seen jigs that allow you to put the trip bolt in a lathe and test the trip speed in the lathe before putting it in the machine. If you have a spare, and can rig up such a setup in your workshop it might allow you to test the adjustment before putting it in the turbine.

any ideas

Another option is to retrofit an electronic overspeed trip system, then you won't ever have this problem again....

this is Elliott turbine, trip speed at 4500 it went up to 4590(2% * trip speed+ trip speed). i order new parts (pin, spring ,u locks...) and every thing was OK.

i asked someone to help and what I recognised is that he decreased the gap between the pin and plunger to 0.045'' then thats turbine trip at correct speed.

now the question is: how its trip when the gap is adjusted by different value than the standard?

by the way thanks alot Steve S. for lath idea