By now you have read me referring to the acronym, OSS. The Optical Support Structure is composed of all the mechanical components large and small combined to handle and manipulate the mirror optics and support equipment. L&F Industries had a long and rich history designing and building large and small aerospace tooling and machinery. Boeing Aircraft being one of their largest customers, L&F built many very large stretch forming presses that produce aircraft wing and fuselage skins. They produced a myriad of machine tool equipment for many heavy industries, and large equipment and machines for the US Government.
Having said all that, I learned early on this project, "Don't call the telescope a machine!" I learned this from Mr. Marlow Marrs, the company's previous owner who maintained an office on the property and would make his rounds around the plant just to have a stroll or say hello to employees and such. He told me sharply, "That's an Instrument Mr. Johnson, and don't let any of your subordinates climb on it like a machine especially the welders. Make sure people wear boot socks before they climb around on The Instrument."
I have never forgot that reminder by Marlow. It really put an importance on understanding just how delicate the OSS was yet so big...
The OSS Drives move the instrument on a frictionless surface as described in other posts. Remember, the instrument is a 300,000 pound behemoth that when stationary, drives must gently overcome the mass weight to get running but not overshoot the electronic command given. Encoders are installed on the drive shaft to show exact axis position and velocity rate. They also need to slow the mass as well very smoothly down to a slow crawl you can barley see. Ultimately they track the stars at velocity rates that are so slow and perfect, the drives are absolutely crucial they perform flawlessly.
Drives are strategically mounted on the azimuth and altitude axis of the telescope and forced onto the ground and hardened drive arch surface with about 2,000 pounds of force. This to eliminate any slippage and maintain a positive drive motion. Any imperfections on the drive surfaces will show up on the camera image and that would not make the astronomers happy.
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