Governer on L3710

[hayden]

I borrowed a friends L3710 and woods 9000 backhoe today to dig a trench for a french drain.

On my 2910, the governer holds the engine speed within 100 or 200 RPM across a wide range of loads and only drops lower when completely overloaded. The 3710, on the other hand, seems to wonder all over the place. I first noticed when driving it over to my house in high gear (it's an HST model). It was behaving almost like there was no governer on the engine. The driving terrain was typical New England over the river and through the woods, but nothing extraordinary. I also remember renting a B20 many years ago and experiencing the same thing. I concluded it's governer was broken.

Anybody know what's happening? I presumed all Kubotas have governers on their engines, but maybe it's not so? It's hard for me to believe that the extra weight of a 3710 would overload a 37HP engine like I was experienceing.

Peter

 

[radman]

Hayden:
I have a 3710 and it doesn't have the varibility in rpm's as you described. I agree it sounds like a governor problem.

 

[hayden]

Any other 3x10 owners want to describe what conditions it takes to drop the RPMs from their set speed?

 

[hayden]

I tried out an L4610 at the local dealer and it behaved exactly like the L3710 I used last summer. The engine speed would drop by 200-300 rpm just moving the tractor around in M range. My B2910 on the other hand holds the engine RPM to within 50 or so RPM across a wide range of loads.

I now believe there is a findamental design difference in the governers in these two lines of tractors/engines.

Does anyone have the workshop manual and/or parts manual for the Grand Ls who would be willing to scan and post the drawings of the guts of the governer? I've got the workshop manual and parts manual for the B series and could compare to see if there is a different design. At least one of the Kubota glossies talks about the integrated governer/fuel injector mechanism and its precise speed regulation, but you can never tell if that means the tractor has anything different than any other tractor, or if they just decided to talk about it in the glossy.

Thanks,

Peter

 

[kubmech]

Hayden, same governor design as practically every kubota engine ever built. I say practically because it's used in the majority. A set of steel balls sandwiched between the fuel camshaft drive gear and a plate. As the engine speed increases the balls move outward moving the plate aft. The plate bumps against a fork attached to linkage that attaches to two springs hooked to the fuel rack of the injection pump.
That's pretty much it in a nut shell, nothing too fancy and a very simple design that I personnaly have never seen fail. The differences you are noticing may just be the difference in the weights/H.P./gear ratio/HST etc. I don't know the exact differences myself, but I see what you're thinking. Bigger tractor more H.P. should compensate for the same rpm drop-off. Never looked close enough to notice the difference myself. I geuss it could also be different torque/H.P. curve at different RPM between the different models.

 

[hayden]

When you're driving B's and L's around your lot etc., see if you notice what I'm talking about. Do you see the same thing? B's regulate to within 50-100 RPM, where the Grand L's seem to easily dip by 100-200 RPM under even a modest load. Or am I nuts?

 

[Taz]

Hi neighbor!

You're right. I noticed it right away. I recently sold a B2910 and moved up to the L4610 and they do seem different. What initially concerned me is that you are not supposed to load the engine down during the break in period. Every time I did something (even just step on the HST pedal), the RPM's would drop significantly. I thought I was working it too hard so I'd crank up the RPM's. As you say, the B held steady.

 

[rbargeron]

Kubmech - have you ever seen a case where one of the internal springs is disconnected from its lever? When I was chasing a fuel-starvation problem the Columbus guys said to check for that. Apparently it is possible. Mine was ok - but it sure would put the governor out of business if either spring was unhooked.

Another diesel pump issue I've noticed is that they are not all perfectly adjusted at the factory. I've reset the max-fuel stops on two of my earlier Kubotas and increased power on both, without over-fueling at full chat. The governors seemed to be more responsive too. Take care - Dick B

 

[kubmech]

I've seen them disconnected, usually by "an external source" and that will cause a few problems, no fuel being one of them.

As far as adjusting the factory pump settings? I have no idea what you're talking about/w3tcompact/icons/wink.gif

Hayden, I'll try to pay attention to that now.

 

[hayden]

Now at least I don't feel crazy.