RAF Tai Mo Shan - Project Cabbage Leaf 1958.

Ground Radar Fitter Bert Faraday (on the left) and Aerial Erector Ernie Einstein carrying out the final "tightening up" of the steelwork ready for the installation of  the turning gear.  The towers are erected "loose", that is the steelwork is bolted together and the bolts only partly tighted. This is to allow the steelwork to settle into place as the weight of the structure increases and also gives flexibility within the structure during the build. Once all the steelwork is in place the  "tightened up" process starts, working from the bottom centre of the tower and working outwards and upwards.  Once a bolt and nut is fully tightened a "pal" nut is added to lock them in place so that no further movement takes place.