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Kohler Generators Restoring, maintaining and operating vintage Kohler generators.

Kohler Generators

Governor Adjustment


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  #1  
Old 12-04-2018, 09:26:06 PM
Tbirddillon Tbirddillon is offline
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Default Governor Adjustment

What is the proper way to adjust this governor? At full load the hertz and volts are to low. The governor does work just needs some tweaking.
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  #2  
Old 12-04-2018, 10:20:36 PM
Vanman Vanman is offline
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Default Re: Governor adjustment

That linkage is non-original, but still retains the necessary adjustments.

The nut on the left, at the end of the spring, controls the speed at all loads.

The two nuts on the right, one on each side of the part that the other end of the spring attaches to, are how the governor droop is adjusted. Changing that adjustment will also change the speed, requiring that to be readjusted.

With the engine fully warmed up, the choke off, and the carburetor mixture properly adjusted, you want to start with the governor droop adjustment. Moving that spring bracket UP on the threaded rod will decrease the droop, ie making the governor more sensitive. You want to get it as sensitive as possible, without hunting.

With that set, go back and raise the speed with the nut on the left. I like to set them for 60 cycles at 1/2 load, but voltage is more important (for incandescent bulbs).

You should be able to go from no load to full load and vice versa in one step with no hunting and minimal overshoot. The more sensitive you can get away with setting the governor, the better the regulation.

I'd set the mixture as lean as it can be while still being able to take full load in one step without stumbling.

Each of these adjustments effects all of the others to at least some extent, so get close first, then go back and fine tune them all.

Lastly, (should have been first) are you still running the square finned Selenium rectifier in the control box? If so I would advise against running the set with load until it is replaced with a Silicon recrifier. If the rectifier fails, the compounding transformer will be ruined. It would have to be rewound as they are not an off the shelf component.
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  #3  
Old 12-04-2018, 10:35:54 PM
Birken Vogt Birken Vogt is offline
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Default Re: Governor adjustment

It is also possible that the governor is getting sluggish and old and no amount of adjustment will be able to take it away.
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Old 12-04-2018, 10:42:51 PM
Vanman Vanman is offline
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Default Re: Governor adjustment

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Originally Posted by Birken Vogt View Post
It is also possible that the governor is getting sluggish and old and no amount of adjustment will be able to take it away.

True, though in that case I'd imagine that changing the length of the rod between the carburetor and the governor could find a "new" and unworn section within the governor?

For that matter, since the linkage is all custom, we cannot assume that the governor arm is properly positioned on the shaft. If it can't be adjusted sensitive enough to hunt, we'll have to look at other adjustments.

To start with, is the throttle held wide open with the engine stopped?
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Old 12-04-2018, 10:50:08 PM
Tbirddillon Tbirddillon is offline
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Default Re: Governor adjustment

Thanks for the info on how to adjust it. I am still using the finned rectifier mine is actually cylindrical. I've read about how to do it but I'm still not sure how to figure out which wire goes where on the new rectifier once I buy it.

[QUOTE=Birken Vogt;1534877]It is also possible that the governor is getting sluggish and old and no amount of adjustment will be able to take it away.

The governor doesn't seem to be worn it responds rather quickly when load is applied.
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Old 12-05-2018, 12:39:33 PM
dkamp dkamp is offline
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Default Re: Governor Adjustment

Keith's instructions above will get you in the right direction.

He mentioned a term you're probably unfamiliar with- DROOP.

When the generator is running in an unloaded state... it's running slightly ABOVE your target frequency... and the governor is HOLDING BACK the throttle. Once you apply a load, the frequency DROOPS... and the governor goes from holding back throttle, to opening up throttle, to meet the load.

DROOP is a necessary evil... the governor, being a mechanical device, is using leverage, spring force, and angles to provide feedback, gain, and phase shift... to respond to changing load, thus, provide governance.

Feedback, gain, and phase shift are the two necessary components for OSCILLATION. If you have too much of any combination of F+B+P, you'll get Oscillation... aka 'hunting'.

A heavier flywheel, and more static load (like a cooling fan) provide inertial and static DAMPING, which helps stabilize hunting... at the cost of fuel use and load response.

The governor goes from holding-back, to pushing forward... that transition is 'droop'.. where your 61hz generator drops to 58.8, and in that span, goes from closed throttle, to full throttle... and back... without going into oscillation.

SO... don't be inclined to fight the governor adjustment to make it 60hz at no load, and 60hz at full load. You'll be more like 61hz no load, and 59hz at full.

The Selenium Rectifier has four wires connected. I believe the OEM units were square, but they MAY have had alternative sourcing that resulted in round cooling fins... they all work (and fail) same way.

Two of the wires going in are AC... the other two (out to the field) are DC.

The two AC wires... if you switch 'em around, no difference. The DC wires to field... one positive, the other negative. You MIGHT notice on your selenium stack... that one terminal has a red paint-dab or a + stamped in it somewhere... perhaps the other DC wire has a dab of black. The AC wires, or the rectifier may have a ~ symbol to indicate AC.

Since your machine is running, you can use a voltmeter to identify the AC and DC wires... set your meter to AC, and measure across two... then the other two... and then switch to DC... most meters will show you a substantial difference in voltage when reading DC with AC meter setting, or vise versa.

Replacement- I used a silicon bridge rectifier of 1000v peak reverse voltage, and I think it's about a 30A module. it takes up less than 1/10th of the space of the Selenium breadslicer... if someone hasn't done it by time I get back home, I'll post a part number and link to one of the major parts houses... I usually get mine through DigiKey or Mouser.
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  #7  
Old 12-05-2018, 01:38:25 PM
Kevin K Kevin K is offline
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Default Re: Governor Adjustment

I used a 1,000 volt 50 amp bridge rectifier from Mouser. $3.14 each for 1 or $2.52 each if you buy 10. Plus shipping.

https://www.mouser.com/ProductDetail...bzTd48Tw%3d%3d

If you don't mind waiting a few weeks you can buy one for $1.21 and free shipping via Ali Express.

https://www.aliexpress.com/item/1PC-...b-975d2a16d462

If you have Amazon Prime you can get 5 pieces for $12.99 with free shipping.

https://www.amazon.com/BestTong-KBPC...ctifier+50+amp

The shipping charge from Digi-Key and Mouser is why I don't use them much any more unless I have a large order or need a specialty item quickly.
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  #8  
Old 12-05-2018, 05:27:21 PM
Tbirddillon Tbirddillon is offline
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Default Re: Governor Adjustment

Thank you guys so much. I'm very grateful for all the help and knowledge you guys are providing.
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  #9  
Old 12-06-2018, 07:46:50 AM
dkamp dkamp is offline
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Default Re: Governor Adjustment

Tbird-

When you order that bridge... look around and see if you have any dysfunctional automotive battery chargers. If you do, order a half-dozen bridge rectifiers, rather than just one. Most of the time, when a battery charger goes kaput, it's because of a broken battery lead, or a zapped diode. The bridge rectifier module is perfect for solving zapped diode problems!!!

(don't ask me how I know)
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  #10  
Old 12-08-2018, 03:29:55 PM
Tbirddillon Tbirddillon is offline
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Default Re: Governor Adjustment

So I ordered the diode rectifier as recommended by you guys and this may be a stupid question but the legs aren't marked. How do I know what leg does what?
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