Farm_Kid2
Guest
I talked to Michael about that very thing. He has done a bunch of these pumps and he said that in one case the idle speed was not steady. I cant remember if it was the high speed or the low speed idle, but as soon as you put a load on the engine the RPM became steady. Im not sure if it was bad enough that they readjusted the pump or whether they just lived with it. The governor weights can get worn, which might play a role in the stability, I didnt think to ask him that. He did say if the weights are worn they have to be replaced before the governor is adjusted. There is no doubt that as the gain of a mechanical system is increased the stability is decreased. However, I doubt these pump governors are in danger of going into resonance and oscillating from stop to stop. Probably just a little RPM variation around the set point under no load conditions is the worst-case scenario in a combine. Of course you would never want to set the pump like this in a tractor or a truck.