Motorized trim Wheels.

I have been trying to motorize trim wheels for quite some time now. That is one of the last things I’ve been missing on pedestal. There are many examples of motorizing the trim on the internet using stepper motors, servo motors, geared DC motors, you name it. With or without slip clutches and with so many different controller boards and position feedback options you can get confused.

I really liked a setup I saw with a club member and his KingAir B200 cockpit. He is using geared DC motor, multi turn pot for feedback, two end position switches and OC motor board controller. Nice and simple, something I want.

I decided to do it same way as I already had a geared DC motor (Takanawa 555) that looked suitable for the task. When OC USB DCmotor Plus card arrived I started with SIOC coding. After some trial and error motor finally stared rotating in trim direction like it should, depending on the value from the FSX trim and feedback position of the potentiometer, rotated by hand. Next challenge was mounting all that to pedestal.

If you are lucky to have a genuine pedestal, trim wheels and scales will already have complete drive system with gears and chain linkages. At the lower left side of pedestal you can find trim drive axle. This axle will turn approximately six times for full trim range from 13,5 nose up to 4 nose down. This is ideal for 10 turn feedback pot on 1,5 or 1,6 gear ratio on axis.  I attached my engine using plastic motor bracket and custom made piece to connect motor axis with moving joint (sort of U-joint).

This is useful because it is difficult to 100% accurately align motor axis with this chain axis and joint will smooth that error. On the same axis I used 45 teeth gear for feedback on 30 teeth gear pot.

That’s it, simple as that. Connect motor and feedback pot to DCmotor board, run SIOC code (using JeeHell trim offsets), some fine tuning and trim wheels started spinning. Ok, SIOC code part might not be that simple I agree… Also as geared DC motors tend to be loud I added some sound insulating foam inside the carrier box to prevent resonating and dampen sound.

It looks really nice it’s just, when flying I’m usually busy so I barely notice it spinning but it is nice to know that it’s spinning.

Motorized trim Wheels.
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