Yes that's exactly I thought. Now I can see that better. These pedal actuators/swivels or screws as I called them above, were joined to the rudder bar. What is more these were the square pipes in the cross section. What could mean that the foot rests had the metal bars/sticks put into them. Thanks to that it was possible to adjust the pedals to the pilot's height by sliding in or sliding out. The bolts that joined the two separate arms with the actuators were also locking pins for the foot rest bars inside. In the way the pedals could be still of the same length even if a pilot pressed them strongly.