Hand or Foot Throttle Operation - PTO rpm's

[volunteer]

Thought I would ask the experts a question concerning my Ford -New Holland 3930 tractor. When bush hogging my 17 acres I have noticed that my 3930 does not stay at the 540 rpm indicator but slows down. In order to maintain the 540 rpm I have to manually increase the throttle. Is this normal or should the throttle stay at or very near the 540? Does this on flat land as well as hilly slopes. I probably understand why it would occur going up a slope but thought that flat land would be fairly consistent in terms of rpm.

Thanks for any info.

 

[Grrrr]

You will probably find that the rpm's will vary slightly as the stuff you are mowing changes. To a certain extent, the governor should adjust things to keep the rpm's the same. I tend to set the pto to 540 with the hand throttle at the beginning and then continue like that. If the rpm's drop a bit it doesn't really matter. If the engine starts to bog down then I step on the foot throttle till it gets easier again. I think what you are experiencing is normal.

 

[volunteer]

That's good to hear. Appreciate it.

 

[charlesw]

Huh. You know... I've got a 3930 and I've never noticed that. But then... I set the hand throttle and then just go. Depending on the terrain just going is anywhere from 2 low to 2 high (I've got the synchro shuttle and I'm using a 6' cutter). And I rarely look at the guage once I've set the throttle.

I see you've got a 6' cutter. So... How fast are you going? I'm actually not looking for an answer so that I can point out what you're doing wrong - I'm just curious to know what other people do with this tractor! From a recent thread on chugging I've decided I'm not doing that and I could maybe even mow downhill in 3 high. If the terrain wasn't so darned bumpy!

 

[volunteer]

On one large steep hill I am either in 1 or 2 low, usually 1. On another hill 2 or 3 low. Flat land 2 or 3 high. I'm still new at this so generally I'm going slow, learning exactly where all the rocks are. Just bought a new set of blades fo cutter, the kind that are curved for lifting up what is being cut. They sure bring a nice look to the cut but they sure can throw a mean rock.

 

[charlesw]

Huh. Not 4 low? 'Cause you don't have one or other? I find it to be an awfully whiney gear!

 

[Ford850]

It sounds like your thottle pressure plate needs to be tightened, or your spring is weak. That's what holds it in position when you adjust your throttle. You are overriding that when you hold pressure on your foot throttle.

 

[volunteer]

Thanks for the tip. I'll check the manuals and check it out. Appreciate it!

 

[Soundguy]

I agree with ford 850. I believe your 3930 has a hand throttle assembly similar to my 7610s.. And I had to tighten the nuts holding the friction disc.. or mine would slowly loose RPM as well.

Soundguy

 

[volunteer]

Thanks for the info. I'm hoping this is minor mechanics as I'm new to this. I hate to admit it but this little Ford 3930 so far has been a great tractor. I now understand (in reading various posts) what a great time it is in getting seat time on the tractor.