Analysis of information sources in references of the Wikipedia article "Servo tab" in English language version.
The rudder trim tab incorporates anti-servo action, i.e., as the rudder is displaced from the neutral position the trim tabs moves in the same direction as the control surface. This action increases control pressure as the rudder is deflected from the neutral position.
Elevator and aileron trim tabs incorporate anti-servo action, i.e., as the elevators or ailerons are displaced from the neutral position, the trim tab moves in the same direction as the applied control surface, thus increasing the effective control surface area and the manual force required to apply it. This action increases control pressure.
