Re: Onan Mechanical governors, torque and springs
I just don't see that buying a new spring will help. I'm willing to listen to anyone who can explain why they think it would help, but, at this point I just don't see how it can help.
I know that moving the spring farther from the governor shaft won't help. It gets hopelessly out of whack. The droop at full throttle is so great that the voltage regulator shuts down the output due to low frequency (my VR monitors frequency and voltage).
During testing, I tried a weaker spring (smaller spring constant). That worked well, but the spring was so long that I could no longer use the speed adjustment. I also tried adding a parallel spring. Adding a second spring is equivalent to increasing the spring constant. (Two springs in parallel add their respective spring constants k1+k2.) It made the governor response work like increasing R. I could adjust to the correct speed for any load, but then the speed was way too low at increased loads and much too high at lesser loads. That was one thing that convinced me that buying a new spring isn't the correct fix for this. Adding a second spring is equivalent to using a stronger (new) spring.
I also tried putting a spring on the opposite side of the governor to pull in the "wrong" direction and decrease the spring constant. That worked. Having a spring pull the opposite way produces the effect of decreasing the spring constant (the effective spring constant is k1-k2). However, there was no good place to mount the second spring. I also considered using a torsion spring on the governor shaft to resist the main spring. That should work, too, and I may eventually try that, but before going that route, I wanted to hear some suggestions from here.
For now, I'm going to try changing the length of the governor rod and see if that helps. If that fails, I'm going to try putting a torsion spring on the governor shaft to work against the pull of the main spring. That should reduce its effective spring constant and perhaps get me into a range where I can adjust droop with R using the sensitivity control.