governor mystery?

hey guy's i was wondering if some can explain governor operation/theory. i have a IH 300u and i see the throttle linkage goes right past the carb????to the thing they call the governor, how in the world does this thing adjust throttle position??

i see a pipe going from the gov to the carb what does that do??

hey guy's thanks in advance for trying to educate me i know it's not an easy job, many a teacher has failed the task....

The rod/linkage/mechanism from the governor to the carburetor is enclosed inside the tube and associated parts.

Governors, like the one on your tractor, control the engines speed. The common speed control on a gasoline engine is the throttle plate. A shaft linkage is connected to the throttle shaft where that tube connects (a tricky connection to get correct as well, if taken apart) coming from the governor. The governor is similar to a rock on a string. When whirled around over head, the faster the whirling, the stronger the pull on the string.
This is speed sensing, and (metaphorically) the string is connected to the throttle plate, and a spring. To make the engine run faster, the spring holds the throttle open more. increasing the RPM of the "rock". When the rock pulls hard enough to close the throttle some, it levels out the RPM.
Your speed control on the steering column of the tractor, pulls on the spring when it is moved downward, and releases pressure when idled down.
When it is used in the field, working the tractor, the throttle plate is adjusted to keep the engine speed constant (within a narrow range) as loads increase. As the load gets tougher, the engine speed slows down a little. THis allows the "Rock" to come closer in as the spring pulls it. This opens the throttle and gives more power. When the throttle is fully open, and the speed continues to fall, the engine will be putting out max HP. At some point the engine will have less power than needed to continue running at a reasonable RPM, and shifting down will be needed. The governor then takes over again.
Max RPM is determined by spring design, and loading of the spring. Idle is set by a stop in the carb that keeps the throttle plate open at a tiny crack. I hope this worked. Jim

This is necessarily basic.. There are other ways to do it (like on small engines) but the Farmall model is what it commonly called a flyball or centrifugal governor.

Did you ever see an engine that had three or four balls spinning in a circle on top with arms above and below them, kind of a whirligig affair? That would be its governor. Given their head, the tendency of the balls, unrestricted, as they spin is to spin as fast as they can, (think of an ice skater with his/her arms tucked in) as close as they can to the center, allowing the motor to turn as fast as it can. To slow them down, the governor control pushes down on the assembly, which forces the ball weights outward making the whole deal spin more slowly, and restricting the speed.

The Farmall governor operates on the same principle. Only because the whole thing is encased and out of sight, it's not as pretty. It uses two rough cast but balanced weights. The shape they are cast in allows them do act on a linkage to the carb to adjust the fuel flow. That linkage is housed inside the pipe you see surrounding it. How far out the weights are allowed to spin is controlled by the throttle/governor control/speed control lever that you operate from the seat. So, if the motor slows down under a load, the gear turning those weights will slow down, too. But the momentum on those weights will make them want to stay inward, spinning at the whole speed they were making. And they will do just that, and compress a carefully engineered spring built into the shaft they spin around, with the spring tension such that the momentum of the weights can overcome it, with the compression of the spring allowing the weights to move to add more fuel to keep the engine up to speed.

Clear as mud, right? But that's kinda the basics.

The tractor carbueration system is a gravity feed and governor operated system. Just like on a Briggs and Stratton gas engine. The throttle goes to the governor.

A car and truck engine is driven by a fuel pump and the carbuerator has an injector/fuel accellerator inside the carb. The throttle goes directly to the carb.

They operate under different principles. Once you understand the separate operating theories, it makes it easier to troubleshoot problems. Too many people apply car engine troubleshooting techniques and symptons to tractor carbueration techniques and symptoms and it doesn't work the same.

Go to a steam power farm show. Watch the fly ball governor spread and draw in as the load changes. They are out in the open on those old steam engines. It is interesting. I had worked on them on tractors and been told how they worked. But to see it in action.

hey Scotty and Janicholson, if only i had guy's like you for teachers back in high school!! yes your descriptions have helped clear up this whole thing for me, i do understand the theory behind this now....and wow i thought todays idle air control motors and throttle position sensors connected to a pcm were complicated??
it's amazing that way back then that someone thought up this governor thing to control fuel delivery!!!

In the late 1700s !! Steam engines were the deadliest! Operators were controlling boiler pressure, boiler water, air to the fire, fuel to the fire (with shovel or by hand throwing in wood). On top of those he (few shes in this mix) controlled the valve admitting steam to the pistons.
In the earliest he even controlled which end of the piston got steam. (or steam and condensing water)
There were no pressure limiting popoff valves, or safety devices at all! EXCEPT the engineer.
In the 1930s my grandfather was a Sawyer for WPA making timbers in Southern Illinois. The engineer was lazy and (even after repeated warnings) failed to repair the governor belt. It broke and allowed the governor to slow, thus opening the throttle all the way, thus spinning the 48" insert toothed saw way beyond spec.
The teeth went first and sprayed shrapnel to the wind, then the blade went into two pieces. One was buried in the ground out of sight, and the other half sailed 1/2 mile into the air over a hill. Everyone knew to run sideways. The FW blew into 3 pieces big enough to use for scrap, and the rest was history. Jim

yes very much like a briggs, i'm a diesel mechanic by trade and my knowledge works against me at times when i see anything other than a international 466e truck engine!
but now that you guy's cleared this up for me i just gotta take this thing apart to see this thing.....thanks again guy's.

If you are curious as to why you need a governor, trying running a farmall M with the throttle directly hooked to the carb, kinda wild.

lol! Primitive but effective -- purely Newtonian physics whithout a trace of 19th century developments in electricity. I'm not all THAT old, but my neighbors are young enough that ignition points are outside their experience, making me the neigborhood guru (a totally undeserved distinction) when it comes to the way motors used to be.

Glad we could help.

We always need a diesel mechanic around here. Stick around and help.

The way I was told, was that most every governor has a spring and a set of flyweights. The spring is compressed to give fuel to or speed up the engine, as that happens the flyweights spread open causing the linkage to the carb to shut the fuel down or slow down the engine. If you watch those old governors on the steam engines they are never at a steady state, they are always adjusting to keep the engine at a given RPM. This would be where the thottle is positioned and in turn gives a preload on the governor spring. In other words the weights and spring are constantly working against each other to maintain a steady RPM.

(quoted from post at 21:10:23 02/07/10) We always need a diesel mechanic around here. Stick around and help.

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yes just hammer away, would be glad to help, i'm trained in chevy duramax and currently work on bigger stuff, international, mercedes, cummins, also can help with air brake and air suspension systems if needed.......do also know a bit about todays gas engines, sensors, and drivability etc...

Hey mike, if you are so familiar with a dt 466, put that in your 300 and then nothing short of a concrete bridge will stop ya. Just my crazy 2 cents.

Jim, Sounds like your a steam guy.

I made a career working on old steam ships - Started out on the old steam recip engines. The principle is so simple they have to work! After they became obsolete I saw all steam turbines (they need speed governors also). Now turbines are dying out on ships in favor of diesels due to the difference in fuel consumption.

Unrelated to the Farmall, I know.

I do like steam. (I like mechanical things of all descriptions) High efficiency steam systems with enough technology are efficient. Good condensers, compounding and thermal control. (insulation) They are heavy though. Stationary makes it work. There is a massive Coreless in St. Stephens, MN and also one at the Albany, MN Pioneer site. Jim

There is Corliss at Mt. Pleasant Iowa Old Threshers that operates labor day weekend every year. Impressive! Lots of others too.