Lifting Platform and Carriage for VLT Primary Mirrors
Every two years, the large 8-meters mirrors of VLT Telescopes have to be moved out of the telescopes in order to be recoated.
In order to allow this complex and very critical operation, AMOS designed and manufactured the system to extract the mirror from the telescope in a safe way, to lower it on a transport carrier, and after re-coating, to raise the mirror to the telescope height and re-insert it in the telescope, all while preventing any risk of damage on the mirror and telescope, in this sensitive seismic region.
The lifting platform is 11m x 11m and 7m high in order to lift a handling carriage from the ground up to the telescope. The assembly is able to lift a load of 70 Tons by means of four motorised and synchronised actuators.
The procedure for removing mirrors is as follows. The carriage (also designed and manufactured by AMOS) is moved inside the telescope building on air cushions and is positioned very accurately under the telescope. The mirror cell (50 Tons) is moved down by the carriage by using synchronised hydraulic cylinders.
The carriage then moves out the building and lifts down on a truck using the platform. The truck drives the whole assembly ‘carriage-cell-mirror’ to the coating building.
The carriage is equipped with four legs that allows moving the carriage out of the truck automatically.
The systems were calculated by finite elements to resist to earthquakes. Tests were also conducted in Europe and on site in Chile in order to check the performances.