Originally Posted by
MechEngr
I believe Airbus uses an electrohydraulic system to connect what look like fake trim wheels. I cannot tell if they are complete wheels or just an arc exposed above the console, but they provide no force feedback to the actual loads on the horizontal stabilizer and no way to put a full grip on them. It looked to me like their function could be handled with a paddle switch.
Wrong again
On the A320-330-340 they are full wheels that are mechanically connected to the trim actuator and turn when the stab moves.
They are in fact a final backup for longitudinal control should all electrics fail. Still need hydraulics though, like the 747 and all later Boeings - the 737-o-saurus must be the only airliner of any size still flying with a direct mechanical connection to the THS. On the A350-380 they're gone completely and replaced by switches.