Brush Cutter Vibration

[ltrain]

Hello all,

I had noticed a vibration using a King Kutter 5' brush cutter with my Kubota B2910 last year. Today I cut for the first time this year. After hitting a rock poking up in the field the vibration got much worse. I inspected, found nothing obvious and finished mowing anyway.

I'm afraid maybe the vertical "shaft" is bent. How can I diagnose a bent shaft or any other source of the vibration which is pretty bad now?

Thanks

ltrain

 

[ltrain]

Hello all,

I had noticed a vibration using a King Kutter 5' brush cutter with my Kubota B2910 last year. Today I cut for the first time this year. After hitting a rock poking up in the field the vibration got much worse. I inspected, found nothing obvious and finished mowing anyway.

I'm afraid maybe the vertical "shaft" is bent. How can I diagnose a bent shaft or any other source of the vibration which is pretty bad now?

Thanks

ltrain

 

[Stimw]

I just rebuilt my rusty 20 year old 5' Woods brush cutter. It had been vibrating for a while. I found that the stump jumper was rusted and shifted to one side. They wanted $125. for a new one so I made one from some 3/16" that I had.
To check for bent just take a stick or rod and use it for a gage. Check one side of blade mount an rotate 180* and check other side.

 

[Stimw]

I just rebuilt my rusty 20 year old 5' Woods brush cutter. It had been vibrating for a while. I found that the stump jumper was rusted and shifted to one side. They wanted $125. for a new one so I made one from some 3/16" that I had.
To check for bent just take a stick or rod and use it for a gage. Check one side of blade mount an rotate 180* and check other side.

 

[Soundguy]

While it could be a bent stump jumper.. I'd check to see if it was a stuck blade. The stump jumper ont he 5' KK is very beefy.

Sometimes those blades are on trhe SJ tight and don't freely swing. on mine.. I had to hit it with PB oil, and clang on it a few times with a hammer back and forth to free up the blades. that was the end of my vibration problems.

Soundguy

 

[Soundguy]

While it could be a bent stump jumper.. I'd check to see if it was a stuck blade. The stump jumper ont he 5' KK is very beefy.

Sometimes those blades are on trhe SJ tight and don't freely swing. on mine.. I had to hit it with PB oil, and clang on it a few times with a hammer back and forth to free up the blades. that was the end of my vibration problems.

Soundguy

 

[ltrain]

Stim, thanks that makes sense to measure at both sides of the mower - I presume it applies to both vertical and horizontal measurements.

Chris, now that you mention it, I only verified that one of the two blades was mobile. I hope you are right. I'll check tomorrow.

 

[ltrain]

Stim, thanks that makes sense to measure at both sides of the mower - I presume it applies to both vertical and horizontal measurements.

Chris, now that you mention it, I only verified that one of the two blades was mobile. I hope you are right. I'll check tomorrow.

 

[Charolais]

I had the same problem with a 7 ft. model King Kutter. What I found, the tapered splined shaft that holds the stump jumper on had paint on it from assembly. Once the unit was run some the paint came out of the splines and the stump jumper was no longer tight on the shaft. There's a nut in the center of the stump jumper on the 7 ft. model with a cotter pin through the shaft and nut. I removed the pin and tightened the nut and the vibration went away.

Next time you're near your cutter. Turn the blades so one is at the rear of the deck. Grab the end of the blade and lift it up and down. If that nut needs to be tightened you'll see the stump jumper move on the shaft some when lifting the blade and going back down. Your vibration may come from something different but I'd sure start with that first. It's easy to check and there shouldn't be any free play on that shaft.

 

[Charolais]

I had the same problem with a 7 ft. model King Kutter. What I found, the tapered splined shaft that holds the stump jumper on had paint on it from assembly. Once the unit was run some the paint came out of the splines and the stump jumper was no longer tight on the shaft. There's a nut in the center of the stump jumper on the 7 ft. model with a cotter pin through the shaft and nut. I removed the pin and tightened the nut and the vibration went away.

Next time you're near your cutter. Turn the blades so one is at the rear of the deck. Grab the end of the blade and lift it up and down. If that nut needs to be tightened you'll see the stump jumper move on the shaft some when lifting the blade and going back down. Your vibration may come from something different but I'd sure start with that first. It's easy to check and there shouldn't be any free play on that shaft.