Trutrak Servo problem

[decrocker]

I have a Trutrak auto pilot with a roll servo (DSB B) that is not working properly. I may have overridden the servo by testing the break away feature. Now it will not work unless I apply pressure in the direction of the roll. On the ground it chatters like it has a clutch. I read sometime ago that some servos have a shear pin. l opened it up and the two gears seam to be ok, but didn't want to go any farther without more information. Anybody have ideas?
Thanks.

[Jesse]

The shear screw is on the arm, not inside. It also has a clutch that can be overridden with a certain amount of force. I have a few used servos on the shelf. I can send you one to see if it works better.

[civengpe]

I just had a very similar failure of my TruTrak roll servo. Coming out of sun n fun, I engaged the AP, but noticed the plane was not flying the selected course. The roll servo would engage, but would not execute the commanded turns. It would basically lock in what ever position it was in when engaged.

On the ground, I tested it and when I would input a roll command, by the heading bug, it would chatter like it was trying to turn, but nothing changed with the ailerons.

I then put in place of the pitch servo with the same results, until it just all of a sudden started acting normal again. I sent it into TruTrak along with the control head and everything looked normal on their end. I reinstalled it in the wing after getting it back and had been working well since.

[decrocker]

The arm is firmly attach to the gear shaft so it must be the clutch assemble. Where oh where is the clutch located? It doesn't seam to be in the gear box.

[civengpe]

Try hooking it up to the pitch servo harness and see if it works normally.

[decrocker]

I'll give it a go tomorrow. Thanks for you help.

[Tbone]

Jesse, do you have a set for a digiflight II? Capstan? For sale?

[BillL]

I just called TruTrak a couple of days ago for a false alarm on my roll servo. They will completely rebuild and upgrade all to the latest components for $300. The replacement list for me was extensive. Turned out to be several near frozen heim joints.

[civengpe]

Originally Posted by BillL

I just called TruTrak a couple of days ago for a false alarm on my roll servo. They will completely rebuild and upgrade all to the latest components for $300. The replacement list for me was extensive. Turned out to be several near frozen heim joints.

Bill, what was the false alarm?

[skylor]

Originally Posted by decrocker

The arm is firmly attach to the gear shaft so it must be the clutch assemble. Where oh where is the clutch located? It doesn't seam to be in the gear box.

There is a bit of misinformation here because TruTrak servos do not have an internal clutch. When users "override" engaged servos by forcing the controls, they are simply overriding the torque of the stepper motor itself. When the servo is not engaged or powered, the stepper motor simply free-wheels.

Skylor
RV-8