Originally Posted by
MemberBerry
From what I understand the system is indeed designed so that holding the trim wheels while the electric motor is adjusting the trim will disengage the electric motor, via a clutch mechanism. But, if you don't touch the trim wheels, that clutch should remain engaged and electric trim should work fine, in both directions, no matter how out of trim the stab is.
Also, no matter how low friction that ball nut is, it seems what's preventing the use of the trim wheels when severely out of trim is somehow friction related. For example in Mentour's video it was getting harder and harder to trim AND the more they trimmed AND. At some point, at around 2.5 units from full AND, it became impossible to trim more AND. Assuming that was not a quirk of the simulator, this indicates that manual trimming in both directions is affected when the stabilizer is out of trim, both AND and ANU changes become harder.
I note your reply on the clutch thanks. My logic for my description of the clutch /trim wheel / stab motor went like this:-
If holding the trim wheel against rotation from the stab motor stops HS movement then that is the torque at which the clutch disengages - this will be the maximum torque the stab motor can exert.
I think there is agreement that in a severe out of trim condition the trim wheels can't be used to move the HS even when a very large force is applied to the handles. Given that this force must be greater than that above (to just hold the trim wheel) doesn't that mean that the torque being applied (which is not enough to turn the jackscrew) is then greater than that at which the clutch disengages. If this is the case then the stab motor will cause its clutch to disengage if it tries to drive the jackscrew. What do you think?
As I conceded previously all these arguments depend on actual values of the forces involved which we do not know - to some extent they may also depend on the design and operation of the clutch ( breakout torque, slipping torque, reset torque etc).
Cheers