When the wind turbine nacelle is positioned on the tower and the yaw bearing assembly is completed it is necessary to adjust the pressure on the individual gliding pads of the bearing. This is necessary in order to avoid un-even wear of the gliding pads and excessive loading on some sectors of the yaw bearing. In order to achieve that, an adjustment mechanism is necessary, which enables the technicians to adjust the contact pressure of each individual gliding element in a controllable and secure way. The most common solution is the utilization of bottom bearing plates equipped with large opening, which accommodate the adjustable gliding bearing systems. These adjustable gliding bearings comprise a gliding unit (i.e. gliding pad) and an adjustable pressure distribution plate. In between the gliding pad and the pressure plate several spring (pre-tension) elements are located. The vertical position of the pressure plates is usually controlled by an adjustment screw. This adjustment screw presses against the pressure plate while being retained by a counter-pressure support plate, fixed on the bearing assembly with strong bolts. In this way it is possible to apply various levels of contact pressure among the different gliding pads and therefore to ensure that each gliding component of the yaw bearing arrangement is performing as anticipated.
