Re: 1937 Farmall F-20 Throttle Problems

Posted by LenRahilly on May 07, 2007 at 07:00:19 from (75.69.133.121):

In Reply to: 1937 Farmall F-20 Throttle Problems posted by Mpuller44 on May 06, 2007 at 16:57:44:

To clarify the "works at full-throttle" problem:
The F-20 governor with the notched pull-rod (like on an F-12 or F-14) is a "variable governor." This governs from just above idle to full-speed. As a practical matter, it means that you can pull a light load (hay rake, for example) in a high gear, throttled back to give a fairly-low speed, and the governor will keep the rpms where you set them.
The early IH governors used on 15-30, 22-36, 10-20, Farmall, F-20, F-30, W-30 were then called "throttling governors" (I hope my memory of the term is right). The only governing action occurs when the throttle is open. What the throttle control does on those tractors is force the governor rod going to the carb (over on the left side of the engine) to a slower position. It really overrides the governor. The springs on the governor weights try to pull the throttle open. When the throttle is moved to a slower position, it is really working against those springs.
The later, "variable governor" operates differently. The throttle control pulls on a spring. There are no springs on the governor weights, so the tension on the throttle control is what determines the engine speed. The governor weights then keep the engine speed very close to where the operator sets it.
If you have a late F-20 operator's manual, you will see an engineering drawing of the later governor. The throttling governor can be seen in older operator's manuals. I have both and would be happy to photocopy and send to anybody interested.
I spent a lot of time on a Farmall and an
F-20 with the older governor, and I can tell you that it is a pain in the unmentionable in hilly territory if you are trying to operate in a high gear but throttled back. The governor just doesn't do anything, and the operator has to keep jiggling the throttle. That isn't much fun, as there is a lot of friction in the throttle lever (if you oil it, then it won't stay where you put it!).
Can't help much with the repairs, but I expect the advice other fellows have given is good. That rod going back to the carb has a couple of bushings, I think, and they could be sticking. Everything in a governor has to be free, AND free of play. All work and no play. Looseness in the weights or the various rods and joints results in "hunting." The governor gets out of synch with the demand for more or less power.

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