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elevator trim servo

C

cholladay

Well Known Member
I just put togather my elevator trim and I have to much travel on my trim servo when compared to the diagram. Does anyone know the correct trim servo for the elevator? I have the Ray Allen T3-12A which has 1.2" of shaft movement. I think I may have the wrong servo.
 
Check the triangle shaped piece especially...

and make sure everything matches diagrams. I did not have any problem with travel until I connected cables. Very poor instructions in this area. I ended up figuring it all out and noted all thread amounts on each side of brackets in front and rear of cables as well as rod ends if you need that info. Whatever you do, don't rivet the rear brackets on like I did. Use #6 screws and nut plates. It will make it much easier to make adjustments at elevator end. Also use a 1/2" drum sander on forward brackets where cables touch to provide 1/32" clearance. Good luck.
 
Mouser

OK in your first photo according to the diagrams from Vans you have to much rotation of the bell crank. Vans shows the cable closest to you in the photo to be horizontal to the mounting plate. Your photo ,which is also looks like mine goes below the point that the instruction call out for Max. travel.
 
The photographs look correct to me...

Van's drawing (of the cables) appears to depict the neutral position, with the shadow drawings (of the bell crank) depicting full nose-down and nose-up limits.

The photograph shows the full nose-down position.

Elev_Trim.jpg
 
Last edited:
OK i got it. I guess I was thinking about it to much. Thanks for the pics and the input, I understand now. I originally thought the actual pic was full nose down. It makes sense, I was not looking at the shadow drawings.
 
I had the same problem with my
Rv10 elevator trim. I was staring at the plans for several hours. Though my one cable was too far down because it didn’t match the plans. When I read about the cables being in neutral position with a shadow of the positions on arm …. It all makes sense. Sometimes we overthink things.
 
jerseypilot83 said:
I had the same problem with my
Rv10 elevator trim. I was staring at the plans for several hours. Though my one cable was too far down because it didn’t match the plans. When I read about the cables being in neutral position with a shadow of the positions on arm …. It all makes sense. Sometimes we overthink things.
Click to expand...

The instructions here are very poor and if you follow them, you may end up with the two tabs in an assymetric condition at neutral. Tim has a good set of instructions on his site for setting it up a different way that leaves the two tabs perfectly aligned at neutral. Suggest reviewing it.
 
lr172 said:
The instructions here are very poor and if you follow them, you may end up with the two tabs in an assymetric condition at neutral. Tim has a good set of instructions on his site for setting it up a different way that leaves the two tabs perfectly aligned at neutral. Suggest reviewing it.
Click to expand...

Could you please add a link or name of the build log site?

Thanks!
 
Elevator trim servo wiring

I was wondering what is the best type of wire to run my RA actuator servo elevator trim to the panel…. I heard it’s not too big of deal and was going to run thermostat 5 conductor wire 20 or 22awg stranded?? Thoughts anyone. Does shielding become mandatory here? And can the black wire be grounded to a AN3 bolt near the aft?


Thanks all
 
I used shielded wire because I had some. But ran the black wire back to the panel EMS as it’s the earth for the position sensor. (To avoid any ground loops on the sensor)

Regards Peter
 
jerseypilot83 said:
I was wondering what is the best type of wire to run my RA actuator servo elevator trim to the panel…. I heard it’s not too big of deal and was going to run thermostat 5 conductor wire 20 or 22awg stranded?? Thoughts anyone. Does shielding become mandatory here? And can the black wire be grounded to a AN3 bolt near the aft?


Thanks all
Click to expand...

While I do a fair amount of frame grounding, I do not use it for potentiometers like that found in that servo, as they are typically sensitive. The ground on a servo is not for the motor, but for the potentiometer.
 
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