Trouble with a different Raymarine Autopilot

[oldjags]

My linear drive on my Raymarine autopilot is acting up, and I just read on the other current thread that these mechanical drive units have transmission fluid inside them?

My autopilot engages for about 10 seconds, then I get a message that the drive has disengaged. Reset it, and 10 seconds later it disengages again. I notice that when I try and turn the wheel with the autopilot engaged, I can slowly force the piston back and forth with the wheel, and that is something new.

Before, I was never able to put enough force on the wheel to overcome the piston.

Add fluid or is the drive dead? And if it needs fluid, where do you add it?

[DeepFrz]

The mechanical linear drive units do not have transmission fluid inside. They can be rebuilt. If you use the google custom search on CF you should be able to find quite a bit of information on them. Often the problem is related to brushes or stripped planetary gears.

After you get it apart (careful you don't lose any balls) if you need further help there are lots of people on CF to help you out.

Forcing the wheel to turn while the AP is engaged is not doing it any favors.

[oldjags]

Thanks for the help. I now see that Raymarine has both mechanical and hydraulic linear drives, so that's why I was confused.

This linear drive is the last original component of an old Autohelm autopilot that who knows when it was originally installed. Probably mid-90's??

In turning the wheel while the autopilot was engaged, I was not applying a lot of force - only enough to determine that the drive was no longer capable of holding the rudder straight. The boat likes to turn left under power, and just the prop torque was enough that the boat would not hold a course.

I guess when the autopilot computer figured out something was wrong, it disengaged the drive? It was certainly trying to steer up until the time it disengaged. Based just on that, I'm guessing it's a gear problem more than an electrical one.