REFLECTOR: Roll trim mod suggestions

[Reiff Lorenz]

Don,

Instead of micro-switches to turn off the motor, how about something really simple . . .

A wire that limits how far the chain can travel. Attach a wire to the end of the chain. The other end of the wire is fixed to the whale tail. Make the length of the wire such that it limits how far the trim-chain can travel. In the event of a run-away trim, the wire pulls tight and the motor grinds to a halt. (Just make sure the wire is strong enough to avoid breaking.)  It's about as simple a solution as you can get.

Hope this helps!

Reiff


From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Don Johnston
Sent: Tuesday, December 10, 2013 9:52 PM
To: reflector at tvbf.org
Subject: REFLECTOR: Roll trim mod suggestions

Requesting suggestions from the hive mind...
After hearing all the comments about the stock roll trim slipping, I decided that I would go another way. When I saw Geoff's solution, I felt it was perfect.
Except he has a motor with a .25" shaft where mine is 5/16". The pulleys for the 5/16" shafts are only available in a larger diameter and that caused interference issues with the aileron torque-tube bellcrank and cables.
So I decided to go with a system similar to what is in my Cessna. Chains!  Absolutely no slipping with chains. And it works great. Positive motion and no slipping. In fact, it will pull the spring around the pulley. Which causes it to derail and get caught in the bellcrank. :-(
I'm wondering if anyone has any suggestions on how to put in a (simple) motion limiting mechanism. It would have to be on the motor or chain. My first thought was microswitches that reverse the motor direction. But I cant' figure out how to trigger the switches.
Don

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