Cockpitbuilders.com

Gents,

I have a query for those of you that have converted real TQs.

Im looking for what brand/model of slip clutch you are using, and how much backlash you have with it.

My setup uses Polyclutch Slip-ease EAS16, which seem to be a popular choice, however they have a backlash of 2-3 degrees when changing direction.
This results in around 1/2" of free movement at the throttle handle that I am trying to eliminate (I also have some backlash in the gear motor drive, but i am moving to planetary gear motors with 0 backlash.

I also have tried the Huco clutches with similar results, but they are a pain to adjust and secure.

I have measured the movement in an actual NG, and it is almost nothing. (the Spec in the AFMM is 0.10"/2.5mm)

So what movement and backlash are you guys seeing?

By backlash I assume you mean that there is a 2-3 degree back movement of the levers after they reach target position.

I am using the Sterling Instruments (SPD/SI) slip clutches....#S98CA6MMOC320838.  I experience none of that.

Perhaps what you are seeing is due to your drive motors?  You do need to be careful about your selection for gear motors....make sure that there is minimal (no) play in the gearing. Otherwise you will get a loose/cheap feel in the manual lever operation.  Mine feel tight in that regard.

Also...I have found that slower is better with the speed of the levers.  If the motor speed is too fast momentum will overrun the target position causing "hunting".  Perhaps that is what you are seeing? Your movement needs to stay behind the curve.

My understanding is that at cruise altitude a full sweep of the 737 throttle travel is calibrated to 14 seconds....which is very slow.   I recently replaced my 15 rpm motors with 6 rpm motors running at half speed to achieve that (such is relative to your particular gearing of course).  That did serve to minimize the "hunting".  TOGA sweep speed is calibrated faster.....about half that.

Fred K

Thanks Fred,

I am referring to the movement at the handle when changing throttle direction of throttle travel before the clutch is loaded up and providing the correct feel.

The actual movement and operation of the auto-throttle is fine, I have no hunting or speed issues, its more in manual operation that you notice it.

My motors do have a small amount of play as well, that's is why I am changing to planetary ones as stated above, but the clutches currently have the most play.

I'm running 5 rpm motors

I will try the Sterling clutches and see how they go for me.

Cheers

I use poly slipclutches and have also some backlash. I dont think it is possible to get rid of it if you are using a dc motor and slipclutch. I use 6RPM motors.

I would investigate motortypes with buildin clutches, but it gets expensive fast.

I will try to tighten my cables some more and make each linkage as short as possible, but for me i am kind of satisfied with my results allready, cant have it all. :)