Shaking brush cutter

[PondCreekFarm]

I have a 5' King Kutter rotary cutter paired to a Kubota L3130. I took it to the field today and it shook me almost to death. This cannot be ok, and it has never done it before. There is nothing in the blades, but to bolts that hold the gear box down are loose. I looked underneath the deck and cannot seem to find a place to tighten the bolts. Has anyone had this problem, and if so do you have any tips on fixing it?

 

[deepNdirt]

Loose gearboxes can certainly cause some shake
Sometimes one of the blades will sling and hang inward of the shaft and will throw it out of balance enough to shake badly, although usually a stop and restart of the cutter will sling it back out, if this is not the case then you might want to check out the U-joints being sure their not loose,

 

[whistlepig]

The stump jumper may be loose on the shaft. See if it rocks on the shaft if you wiggle it. Be careful. Prop the brush cutter up before you get under it.

 

[Soundguy]

if the blades can't swing freely, you may have to lube them and manuall move them into position.

if you can't find the bolts / nuts / studs.. time to break out the manual. the loose gearbox is a bad thing waiting to happen.. both for safety and property damage.

soundguy

 

[browny]

Sometimes one of the blades will sling and hang inward of the shaft and will throw it out of balance enough to shake badly, although usually a stop and restart of the cutter will sling it back out

This is what happens to mine when it shakes bad. I just stop it and re-engage it after the blades have completely stopped.

 

[kebo]

Those bolts that came loose might have to be replaced now. If you let that vibration go too long, it will gall up the threads on the bolts. Hopefully yours will be ok, but you won't know till you starting trying to tighten them back down. Just pay attention to how the threads feel as you tighten them back.

We had the very same issue with the 5ft KK bush hog we keep at my hunt club and had to replace some (maybe all can't remember now) of the bolts.

 

[RalphVa]

I've had the blades get tangled together on my LX4 twice, both early in the season. I've learned now when I take the blades off and sharpen them to lube the swing points well with silicone lube. Of course, one time I put a blade on upside down. Not good for balance.

Found one of the 4 bolts on the LX4 gearbox missing a bolt. I'm waiting to see if they loosen up again because it isn't easy to get them tightened to the required 200+ ft-lb underneath. I've an air torque wrench, but can't figure out how to set the torque on it to know it's anywhere close to the ft-lbage. Good for taking nuts off, but no good for torquing them back up. I can easily torque the blade bolts to their 450 ft-lb because I can use a 6 foot pipe on my wrench to put around 80 # of force (or until the nut won't move any more, probably close). No way I can get 200 ft-lb on the gearbox nuts underneath the machine. If they loosen again, I may have to figure something out, maybe some way to hold the nuts underneath and use a pipe on the bolts from above?

Ralph

 

[boggen]

manual for what it looks like all there rottory cutters.

http://www.kingkutter.com/downloads/manRKRK.pdf

there might be a nut or bolt head holder on bottom side of deck. so as you tighten on top. it will not spin on the bottom. and won't require another wrench or like on bottom side.

you may also have a bunch of crusted on grass and weeds on bottom side. and a flat head screw driver, metal paint scrapper, wire brush may be needed to clean bottom side off to see bolt heads.

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my one dislike, is on rotatory cutters. the shear pin will break near the gear box. and you end up dropping the rotatory cutter down far enough, that the pto/drive shaft slides off the end near gear box. and you end up loosing the lower portion of the drive shaft some place in pasture. ((remember this happening a few times over the years))

but general bolts / nuts coming loose. i am use to. and when greasing everything, i also tend to have a few size wrenches handy, to double check everything is tight. vibrations of finishing mowers to rotatory cutters. just seem like they will cause bolts to go by by in a heart beat at times. and if they loosen just a little bit. the sheet metal / sharp corners of the holes will cut the bolts in half.

 

[MarkV]

I had the gear box bolts loosen on a KK rotary mower. I hope you have better luck removing the stump jumper than I did. I tried everything I could think of and all that was suggested here on the forum. The darn thing just would not come loose. What I finally had to do was torch a hole in the stump jumper to access the gear box bolts. Once tightened I spot welded them so it would not happen again. That did solve the problem without any ill effects that I have noticed in the last year.

MarkV