Rotary Cutter vibration in bush hog help

[botakix]

hi guys, i am having an issue with my rotary cutter and was wondering if you guys had any ideas. i have a 5 foot bush hog squealer and when i run the rpms up to 540 it vibrates the whole tractor. it is ok, at about 480 or so, but any more than that it really vibrates. i have high lift blades, that are sharp, and run the front of the cutter, about 2 to 3 inchs off the ground, to keep it off the skids. when i lower it, so it is running on the skids, i can run the rpms a little higher without the vibration, but it cuts too low and i really dont like the way it digs in sometimes. i guess what i am asking is, shouldnt a cutter be able to run up off the skids, without shaking the whole hog and tractor, or am i doing something wrong.

 

[MarkLeininger]

I assume you've watched the PTO shaft spin to make sure it isn't bent. One of the blades could be stuck in the folded position, either rust or brush stuck in it. To answer your question, no it shouldn't vibrate at all.

 

[JIGBUILDER]

I run my old 72" Agri-cutter (Fred Cain) on the skids and the blades don't dig in. I have bent the pan and it has some wiggle at 600-700 engine idle speed.

Sounds like the gear box mount frame could be bent which lets the blades run low in the front. Or the blade pan is bent like mine.

 

[geneP]

[Q i guess what i am asking is, shouldnt a cutter be able to run up off the skids, without shaking the whole hog and tractor, or am i doing something wrong.[/QUOTE]

From my experience with brush cutters, different brands cut at different heights when run on the skids. I had a Fred Cain as previously mentioned, and had to run it on the ground to get a cut almost as close as I wanted. It cut too high for my tastes. I'd rather have one that cuts lower and raise the skids off the ground a little. Then you can cut low if you want to.

Yes, you should be able to run the PTO as fast as your engine will take it without that kind of shaking. I agree with the suggestion to check you PTO shaft. It is very easy to let your tail too low and bend the shaft with the deck when you lift the cutter.

 

[shakin]

i have a squealer 148 and it vibrates terribly until the blades swing out but even after that i can feel it through the whole tractor, the gear box also makes quite a bit of noise. i guess you need to determine if the blades swing out and if they do i feel there will always be some vibration.

 

[botakix]

thanks for the input, guys. i have watched the pto shaft spin, but its hard to tell if it wobbling with the guard on there. i have checked the pan and it doesnt seem to be bent. i am going to take the pto shaft off my finish mower and try it on the bush hog, should tell me if the pto shaft from the cutter is a little bent or not. after reading about shakins cutter, i am wondering if this is not the nature of the beast with these squealer cutters. hopefully, i can figure something out, or i am going to get rid of it and try another brand. thanks for all the help guys.

 

[Midsouth]

Mine does not shake at all at 540 rpm. I agree with the others something is bent or out of alignment somewhere. Now that being said i have had one of the blades get stuck on the pan and not swing out and that will definitely get your attention

 

[greg_g]

If the PTO shaft is bent, you'd be able to see it clearly as it revolves. Plus - a bent shaft will bind before collapsing fully. You may have lost a chunk out of one of the blades. I'd take them both off and weigh each individually. Assuming unbalanced blades to be the cause, grind enough off the heavier one so that they end up weighing the same. If one or both are too badly beat up, replace the pair

//greg//

 

[Farmwithjunk]

How severe is the vibration? SOME mowers just aren't perfectly smooth. If the vibration is somewhat "severe", you have a problem, one that SHOULD be easy to spot. Does the vibration ease when you start cutting grass/weeds?

Look at the blades. Are they able to pivot on their mounting bolts as they should be? Are those bolts loose or damaged in any way. Are the blades bent, broken or a chunk knocked out of one? I've NEVER balanced bush hog blades. With the relatively loose standards of balancing the stumpjumpers (from factory) most wouldn't benefit significantly by balancing blades. However, a missing chunk might swing the balance beyond acceptable.

Check the stumpjumper. Is it loose? Is there any debris on the top side of it? Bent?

Look at the PTO shaft. I've got one that has (approx) 1" of bend (bowed) in the middle and has NO vibration. (Just annoying watching it turn....)

 

[botakix]

i put another pto shaft driveline on it this morning, and it still shook. i loaded it up and took it to the dealer, and they worked on it for two hours. the only thing we could find, was the pan was a little loose. everything else was good and we even put new blades on it and hooked it to another tractor and it still shook, not as bad, but they were even baffled. we hooked up a new 6 foot squealer to see if had same issues, and there was some mild vibration, but about what you would expect from a bush hog. guess i am going to sell it and try finding another one, but you can bet new or used, i will hook if up and try it before i buy. i bought this one new about 3 years ago, and just kind of thought the shaking was normal, but after watching my neighbors run theres, i finally realized that much shaking was not normal. oh well, not the end of the world, lesson learned. thanks again guys for all the great input.