AC 180 Power Director Questions

I managed to load the tractor when I bought it before fully understanding the PD system. I read the operator manual and the archives, now I think I understand the basics.

I understand the PD to be a hydraulic wet clutch pack. 3 clutches high, 4 clutches high. I understand when they are cold they tend to creep a bit (it does). I tried all gears high and low and it will pull through the brakes. I did notice that at low engine RPM's it tends to slip a little when taking off from a dead stop, especially in 7th and 8th. But if I rev the motor it pulls hard, quick. The PD when going from high to low will "engine brake" and it holds speed going down hill. I did shift from low to high at low engine RPM in 3rd and it slipped going across a creek crossing.

My question is why at low RPM does it seem to slip in the higher gears taking off and at higher RPM's its a rocket. Is this a hydraulic pump/valve pressure issue at low RPM's? Is this normal? Do they not like to be run at low idle? Is the PD going to require "shimming" in the future?

I do have a new filters in the mail. The fluids look good, but will all be changed within a week or so. Could this be some of my issues?

Thanks!
CT

These things are decades older than when I worked with them. I assume that accounts for some of your slippage. When they were newer, the engine would stall before oil pressure was lost on the clutch. In other words, they didn't slip.
The old hand operated power director was much easier to control, but your hydraulically controlled one requires no adjustment as oil pressure activates the clutch. There are no shims in the clutch. The adjustment you may need to look into is hyd. pressure. A service book will show you the valve, and where and how to measure and adjust pressure. And as I tried to say earlier, your plates may be quite worn. From what you describe, I would check pressures, and run it for a while, before tearing it apart.

Thanks Bob. I did read in the service manual about where and how to check the pressures. That is where I will start after fluid and filter changes. I did read that an old filter will cause problems. I guess I got confused reading the archives about the different series of power directors when I saw shimming.

CT