Bush Hog S072 shaking

[marvinminor]

I'm new here and am probably posting in the wrong place. I have a Bush Hog S072 attached to my Ford 4000. I bought it used and I guess I got taken. It vibrates all day, enough to shake the tractor and me. Do you think this is a blade problem or maybe a bent shaft. It shakes so much the frame has split in several places. Any suggestions appreciated.

 

[Happy Gilmore]

If the driveshaft connected to the PTO is bent (it happens) you'll notice it while the shaft is turning with the PTO engaged. Another thing to check is the pivot points on the blades. They sometimes get stuck in position and will shake the heck out of everything. When this happens I will free them up and smear grease between the blade and carrier, usually fixes the problem. Check for a severely bent blade. All of these things will cause the mower to be out of balance.

 

[Happy Gilmore]

Is the splitting you refer to cracked welds? Pics?

 

[Dozernut]

I think Happy Gilmore nailed it. Sounds like a blade has folded in on itself and stuck. The blades are hinged, they swivel on a bolt or pin. If you hit something the blades will fold back to prevent damage. Lift the mower up and look and see if both blades are free, if not you might need a hammer or bar to free the blade so they both swing free.

 

[Tx Jim]

marvinminor
Have you ever looked under the deck at the blades????

 

[sawtooth]

Yes bent or damage blades would be first area to check

 

[Happy Gilmore]

How'd you make out:confused3:

 

[marvinminor]

Thanks for replying guys! Sorry, but the notice that I had replies had gone to my spam box and I just now found it. I need to do some cutting on Thursday and I will check the blades and driveshaft for bends or sticking blades let you know. The cracks are in the welds. I had it re-welded last year by what I thought was a pretty good welder but the shaking broke them all again. I've been under there before and didn't see anything real obvious, but I'll look a lot closer look this time. This old bushog is a pain to use.

 

[marvinminor]

How'd you make out:confused3:

No bent blades, no bent crankshaft, no stuck blades. Shakes and shimmies just the same. Does have a stumpjumper that the blades are attached to.

 

[whistlepig]

Make sure the stump jumper isn't bent. Measure from the tip of the blade to a concrete floor on both blades. I've bent a stump jumper or two in my time.

 

[hslogger]

One other thought comes to mind for you and your vibrations. I rebuilt an old unit last year, and found that the four bolts that hold the gearbox to the deck had worked themselves loose enough that they needed to be tightened. Trouble was, the threads were pretty buggered up, so instead of running a bunch of washers to shim it,I cut he old bolts off or heated and removed them, replaced them with new bolts and lock washers. That fixed the problem.

Another aspect, like previous posters said, the arms are on bolts and if one gets stuck it won't swing out and that is a major contributor of this kind of problem. Now that I have my thirty year old unit sandblasted, primed and painted with epoxy underneath and above, with all new main bolts and swing bolts, I hose it down once in a while and figure with water and grease it will last another thirty years

 

[JRobyn]

There's not really a lot on a simple rotary cutter that will cause SEVERE vibration EXCEPT for something with the blades. Anything else (bent PTO shaft, loose gearbox, chunks missing out of the stump-jumper) would likely be very easily noticeable. As others have mentioned, anything to prevent the blades from swinging freely on their mounts is a common reason for vibration. Other than that, I'd remove the blades and weigh them or hang them on a teeter-totter balance to ensure that they are identical (or at least very close) to the same weight. It may be that a previous owner replaced ONE blade in the past and that the blades are now badly mis-matched in weight. Good luck fixing it!

- Jay

 

[dieselcrawler]

I have noticed that even a slight bend in one blade will make my brush hog vibrate. Bought new last summer, ran smooth as you please... hit a dirt crown, which sucked in the blade, bending it to where it hung about 3/4" lower than the other blade. I heated it at the bend, put it back to match the other blade, ran smooth again. Noticed yesterday that it's starting to vibrate again, I need to check the blades, as I have not done so this season.

If in doubt, replace both blades with a new matched set.

 

[marvinminor]

Thanks for all the help. I turned it over and the whole stump jumper and blades was wobbling up and down. I removed the nut with cotter pin and removed the stumpjumper. The inside teeth, where it attaches to the splined shaft from the gearbox, were worn and would not fit tightly. I ordered a blade weldment and new blades and put it back together and it now runs so smooth and quiet that I keep looking back to see if it is running.