The Yoke of the telescope is assembled

Now that the base of the telescope has been carefully assembled and tested, the next stage is to position two columns on the base box to form the yoke of the instrument.

The columns are extremely strong structures, designed by TTLto support the tube assembly that contains the main (primary) mirror which itself weighs 1.25 tonnes. As the telescope tracks the stars in the night sky it is important that the whole structure does not shake or wobble, and, if the wind on the top of the mountain picks up and begins to buffet the instrument, the strength and stiffness of the columns again becomes very important.

The use of triangular cross-members, as often used in the construction of bridges and other large structures, improves strength and rigidity and you can see how this technique is adopted in the design of the columns.

With the hydrostatic bearing operating it is possible to push the base box causing the yoke structure to move round (azimuth). Considering that the base box and columns weigh some 11 tonnes you can see how effective the hydrostatic bearing are in producing smooth movement.