Generators and Motors
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Electric Motors General Discussion > Onan Generators
Forgot Password? Join Us!

Notices

Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

Onan Mechanical Governors, Torque and Springs


this thread has 23 replies and has been viewed 7685 times

Reply
 
Thread Tools Display Modes
  #11  
Old 02-29-2012, 03:19:23 PM
Magnetite Magnetite is offline
Registered-II
 
Join Date: Nov 2011
Location: New Haven, Connecticut
Posts: 447
Thanks: 50
Thanked 190 Times in 122 Posts
Default 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.
Reply With Quote
Sponsored Links
  #12  
Old 03-02-2012, 09:52:31 AM
Magnetite Magnetite is offline
Registered-II
 
Join Date: Nov 2011
Location: New Haven, Connecticut
Posts: 447
Thanks: 50
Thanked 190 Times in 122 Posts
Default Re: Onan Mechanical governors, torque and springs

Quote:
Originally Posted by Magnetite View Post
For now, I'm going to try changing the length of the governor rod and see if that helps.
I shortened the rod as much as I could. With the engine off, the throttle arm was not against the fully open stop. I started it, warmed it up and adjusted no load to 62-63 Hz. The spring was as close as possible to the governor shaft. The first thing I noticed was that it was now hunting. Previously, there was no hunting. I could get closer to the specified 4 Hz droop at full load, but couldn't get rid of the hunting. If I turned sensitivity clockwise (increased R=distance from governor shaft) I could prevent it from hunting, but that put it pretty close to where it had been before - excessive droop at full load.

I wonder if the idle mixture screw on the carb should be removed and the passage cleaned? I cleaned all of the carb except for that passage/screw (it's under a sealed cap). Other than that, I can try changing the spring constant with a torsion or opposite spring.
Reply With Quote
  #13  
Old 03-02-2012, 11:50:33 AM
RSCurtis RSCurtis is offline
Registered-III
 
Join Date: Jul 2009
Location: St. Thomas, Pennsylvania
Posts: 801
Thanks: 0
Thanked 257 Times in 222 Posts
Default Re: Onan Mechanical governors, torque and springs

Manually close the throttle and see how the engine idles. It it wants to stall from a lean mixture, that could be your problem. If it idles OK, lengthen the rod just enough to get rid of the hunting.
Reply With Quote
  #14  
Old 03-02-2012, 12:18:30 PM
Magnetite Magnetite is offline
Registered-II
 
Join Date: Nov 2011
Location: New Haven, Connecticut
Posts: 447
Thanks: 50
Thanked 190 Times in 122 Posts
Default Re: Onan Mechanical governors, torque and springs

Quote:
Originally Posted by RSCurtis View Post
Manually close the throttle and see how the engine idles. It it wants to stall from a lean mixture, that could be your problem. If it idles OK, lengthen the rod just enough to get rid of the hunting.
One of the first steps in setup is to set the idle stop screw at 56Hz (or close to that - I've forgotten the actual number). I found that it becomes very sensitive near that stop position. Under no load, it drops quickly to below 56 Hz, at which point the VR shuts off the output. I'm going to remove the cap and clean the idle mixture port and needle just for peace of mind.
Reply With Quote
  #15  
Old 03-05-2012, 11:10:41 AM
Magnetite Magnetite is offline
Registered-II
 
Join Date: Nov 2011
Location: New Haven, Connecticut
Posts: 447
Thanks: 50
Thanked 190 Times in 122 Posts
Default Re: Onan Mechanical governors, torque and springs

I've got it within specs, just barely. I lengthened the governor arm about 3/4", shortened the rod between the arm and the throttle, removed the idle mixture cap, cleaned and adjusted the idle mixture screw and reversed the orientation of the spring, while squeezing it slightly, so that I could adjust sensitivity to get it closer to the governor shaft.

Working on the idle mixture helped set the idle stop. It's now much less sensitive and I can get smooth idle at 56 Hz per the manual with the throttle held against the idle stop.

I still think something is wrong, as I don't think I should have to be set to the maximum sensitivity with the spring so close to the governor shaft, but since it's within specs, I'm going to leave it alone (for now).
Reply With Quote
  #16  
Old 05-14-2014, 05:41:51 PM
Johnray13 Johnray13 is offline
Registered-III
 
Join Date: Jun 2009
Location: Chantilly, Virginia
Posts: 39
Thanks: 4
Thanked 2 Times in 2 Posts
Default Re: Onan Mechanical governors, torque and springs

I know this is an old thread but since I have the same generator and same governor issue, I wanted to update the thread with my two cents since I found this one very helpful.

I had to replace my carb because the float filled with gas and would float no more. Since I got a NOS carb, I knew I the only issue was the throttle/droop setting (which I monkeyed with while my old carb was drowning and was now really whacked.)

Basically Magnetite was right on but I think he overlooked the importance of the idle stop screw. Following the manual, (governor adjustments) after the rod length adjustment, you are to set the idle stop screw, no load, to 54-55 hz, then dial up the idle speed using gov. speed adjusting screw.

I could not get this to work to save my life. I had too much droop, but after turning the droop screw CC, my no load frequency would be too high. I finally starting using the stop screw to dial in the no load frequency to 63 hz. instead of the speed screw.

I think you follow the manual procedures up to the point magnetite and I were at and then fine tune it using the stop screw to finesse your no load frequency to 63 hertz.

I finished up today at no load- 63 hertz @ 126v and loaded (50 amps resistive)- 58 hz @120v .
Reply With Quote
  #17  
Old 05-14-2014, 05:58:09 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 16,915
Thanks: 485
Thanked 6,177 Times in 4,488 Posts
Default Re: Onan Mechanical governors, torque and springs

Springs can get weak with age/rust. Been years since I used it but among other things, I think spring constant is proportional to 4 th power of wire dia. So a little metal removed by rust can have a large impact.

I haven't had to deal with this as my 7NHM has electronic gov.

Opps .....old thread.
Reply With Quote
  #18  
Old 05-14-2014, 08:41:35 PM
Kpack
Guest
 
Posts: n/a
Default Re: Onan Mechanical governors, torque and springs

I sure wish magnetite was still on the forum I liked his input.
Reply With Quote
  #19  
Old 05-14-2014, 11:46:27 PM
armandh armandh is offline
Sponsor
 
Join Date: Aug 2006
Location: Suburban St. Louis, Missouri
Posts: 2,961
Thanks: 234
Thanked 774 Times in 605 Posts
Default Re: Onan Mechanical governors, torque and springs ANGLE

picture the governor arm vertical and the spring horizontal to the right
at light load and at 60 hz operating
the spring is tangent to the arc of the arm travel

as the load increases the arm and spring tension stabilize
with the arm at, let us say, the 1 O-clock position, the throttle farther open.

the spring exerts less less force for two reasons
it is not streached as far as it was and
the angle is no longer tangent to the arc

it is this change in angle that provides a changing rate of inverse feed back
a spring long enough that
it provides a near constant pull through the arm travel

will hunt about the target speed
raising the fixed end of the spring adds inverse feed back [or lowering the moving end]
and allows the system to quickly stabilize
best shown in this Kohler 582 drawing page 5.2 B
http://www.kohlerengines.com/onlinec...pdf/en_607.pdf

if the spring runs out of tension B4 the throttle is fully open
a longer spring or the moving end in a hole closer to the arm pivot [less travel]
the arm must also travel far enough to open the throttle.

it is all a bit tricky to sort out
follow available instructions if possible

Last edited by armandh; 05-14-2014 at 11:58:01 PM.
Reply With Quote
The Following User Says Thank You to armandh For This Post:
  #20  
Old 11-20-2017, 08:14:08 PM
Jerry B Jerry B is offline
Registered-II
 
Join Date: Nov 2006
Location: Pleasant Hope MO.USA
Posts: 350
Thanks: 308
Thanked 5 Times in 5 Posts
Default Re: Onan Mechanical governors, 4,0cck

My gen. has ben setting for 4 years, I got it out to day & the shaft that comes out the fan housing it is stuck, what can I do to fix it
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
Onan 3.0DJA Mechanical Fuel Pump PN 803mastiff Onan Generators 5 04-06-2013 10:11:24 AM
Onan 5.0CCK-3CR/12018P fuel pump Mechanical or Electric? mattgrooms Onan Generators 2 10-04-2011 01:27:08 AM
Adjustment for hoof, pierce, foley mechanical governors used on older motors/gensets kg5388 Onan Generators 0 04-17-2011 10:30:37 PM
Mechanical Belt Driver Governors Joe Batts Kohler Generators 3 11-20-2010 08:30:38 PM
Mechanical external oil pump for JC Onan flagmaster Onan Generators 14 11-13-2008 11:51:24 PM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 11:16:15 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2016 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277