Gas Turbine turning gear

Hello everyone,
I trying to learn about gas turbune turning gear and i looked for study material on the subject. I can not find so much material on the Internet
Can anyone help and give me an explanation of the system?

Dear idannb, I did a simple Google search for Steam Turbine Turning Gear and Gas Turbine Turning Gear and was able to find a large number of articles describing the system.
You can also use the search feature of this forum to find many articles talking about issues with turning gear. There has been much written about this subject that should be a great place to start. Then if there is something specific that has not been answered please come back and ask that specific question.
Just to add to MIKEVI's excellent response, just below this reply box is a list of threads the site's algorithm deemed similar (aptly called 'Similar threads'...). On my current page, there are five (5) threads--all with the words turning gear and gas turbine in them; there's even another thread titled "Gas Turbine Turning Gear."