Aaron posted that "[t]he problem is that [the 8N] is having problems maintaining steady RPMs while I use it. If the load is steady (such as a steady grade uphill or downhill) everything seems ok. It is when there is a transition or even on level ground, the engine will rev a bit and then back way off, rev a bit then back way off... etc." Aaron sees a problem on the "transition or even level ground" where the "engine will rev a bit and then back off...." Is there a problem when the engine revs a bit or backs off on a transition or even level ground?First, on a transition from a grade to level ground the engine will rev a bit or back off. That is normal, things are working correctly, and Aaron doesn't have a problem there at all. Now is it a problem that the engines will rev a bit and back of even level ground? I say it's not a problem, to a point. Ground is hardly ever truly 'level' and even if it is 'level' it might change from hard to soft or dry to wet or cleared to grassy or some other change that will be some small change in the load on the engine. A hard wind might change the load on the engine. In any case the load can change and the engine might well rev a bit and then back off. Of course a the engine might surge if there is some problem. Like Aaron wonders the governor might be the problem. So how does a guy know if the engine surges are a problem? I replied to Aaron that "the governor is suppose to vary the engine rpm. The governor is trying to keep the ground speed constant and it does that by changing the engine rpm." Jeb2N pointed that out by saying "[a]ctually, the governor maintains constant engine RPMs based on the throttle setting by varying the throttle butterfly in the carb. If a load bogs the engine down, the governor adjusts the carb to give it more "juice" and get the engine back up to the previous RPM setting. Essentially the gov tries to keep the engine at a constant speed through varying loads." SouNdguy points out that "[o]n a direct coupled gear tranny.. ground speed will be in direct proportion to engine rpm. if the engine rpm chaanges.. ground speed changes.." So I say "the governor is trying to keep the ground speed constant", Jeb2N says "governor maintains constant engine RPMs", and SouNdguy reminds us that "if the engine rpm chaanges.. ground speed changes". Now Aaron is not getting an answer here. He wants to know if it's a problem the the engine surges some on level ground. Neither Jeb2N nor SouNdguy said it was a problem or not even though SouNduy did give Aaron some troubleshooting pointers. I think this is an interesting discussion because it's not carved in stone how much and when ground speed or rpm can vary before it's a problem. I mean if you turn up a steep incline the tractor is going to bog down, the engine rpm will drop, the rpm will increase, the tractor will pull up the hill, top the hill, rpm increase, tractor speed up, rpm drop, tractor slow, and fairly quickly find it's new 'legs' at a "constant ground speed" and more or less "constant rpm." So the dang thing is all over the place but that is normal! The operator wants two things to be constant where he sets the throttle; the pto rpm so if he's mowing the mower is good and he wants his ground speed to be where he set it so his impliment is working the way he wants. Back to Aaron's question; if and when is it a problem that the rpm changes? The answer is 'it depends.' Jeb2N came the closest but no one did a good job explaining the governor. The governor neither controls the ground speed nor the rpm. Like Jeb2N mentioned the governor controls the carb fuel flow. That's it! At least that's one way of looking at it. The governor reacts to changes in the engine rpm normally caused by changes in ground speed unusally caused by some change in the load. Then again, the governor 'controls' the engine rpm...and the governor controls the ground speed. Depends how you look at it. I know and recognize normal changes in rpm and also notice if the rpm or ground speed is not experiencing normal and expected changes because I have some seat time and I'm sure Jeb2N and SouNdguy would know. I don't believe that either Jeb2N or SouNdguy are saying that on 'level' ground the rpm's should never vary and if the rpm or ground speed do vary then there is a problem with the governor. But there could be too much change and too often. How does a tractor novice know? Is everything ok if the ground speed is 'comfortably' constant? Well enought of that. Hope I didn't bore you with this and I hope Aaron can figure whether his engines revs are a problem.
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