Rotary Cutter loose stump jumper

[bdmcgrane]

I have a bushhog sq 60. This weekend i when i engaged the PTO my tractor (kubota 3130) would shake really bad. I searched the forums for a possible reason and i checked the blades which seemed to be in good condition and moving well. But i did notice that the stump jumper was loose and it could be easily moved by just holding one of the blades and moving it back and forth. I haven't ever done much of my own maintenance but i really need to cut grass this weekend and if i take it to the dealer it will be a couple of weeks before i get it back.

I took a look under it and noticed it has a castle nut and cotter. Would i just need to pull the cotter pin and turn the nut? I have owned the cutter for 5 years now, so typically are they hard to turn?

I have attached a couple of pics. I am assuming the gap in the picture i attached shouldn't be there. I guess it is between the bottom of the gearbox housing and the top of the blade bar.

Any suggestions would be great!!!

 

[RoyJackson]

After you first engaged the PTO and got the vibration...did it smooth out after 5 seconds or so?
After checking to see if the blades pivoted, did you try to run the cutter again?
I'm going to suggest you try your cutter again, before making any adjustments. You may have just had one blade locked up or jammed.

Normally, a castellated nut is tightened snug, then a bit more until the cross hole in the bolt and the nut are aligned to get a cotter pin in. But I suggest you check the manual (if you don't have it, here's a link: Manuals)
Unlike most nuts, a castellated nut cannot loosen unless the cotter pin breaks.

As far as the gap between the the gearbox and rotating components...doesn't look excessive.

 

[mattridessleds]

Mine was the same way on my sq600. Ends up that the spline that comes out of the gear box that that jumper slides over was starting to get "wallowed" out, at least I think that's the term for it. The bottom half of the splines were starting to get worn off. I tightened that nut up with a breaker bar and a cheater to get the jumper to catch the splines farther up the spline and it has been ok so far. I'm sure I will have to order a spline at some point but for now it's working. I beat the balls off mine so I'm surprised it's held up this well so far.
-matt

 

[ENG18LT]

I bought a used bush hog 286 from a dealer, ran smoothly in his parking lot. Got to my property, 3 hours from dealer and it would not cut. After tipping it up with FEL I found the hub on the stump jumper spun freely. I castle nut was tight and pinned. I took off the jumper and found the hub was completely stripped of splines. The output shaft looked good though. Dealer wouldn't return my messages. I wound up buying a new stump jumper, about $600 after shipping. Bush hog works great now. Won't ever buy from that dealer again. Good luck.

 

[gwdixon]

When you say the "stump jumper was loose and it could be easily moved by just holding one of the blades and moving it back and forth" do you mean that it could move rotationally back and forth (same directions as the blades)?

Does it move and the castle nut not move? Does the castle nut move with the stump jumper while the shaft of the gear box does not move?

Or was it loose in the vertical direction (up and down)? Maybe both?

If it is solid up and down and the castle nut moves in conjunction with the stump jumper then the diagnosis by others that the gear box shaft splines might be shot is a good one.

My suggestion would be to take off the castle nut and inspect the inside of the stump jumper and the investigate the condition of the splines. It might be discovered that a weld or two could have broken on the stump jumper.

This does you no good when you are in a hurry to mow but the mower sounds unusable as it is anyway.

 

[Gary Fowler]

On a 4 foot JD mower, started to get some movement in the stump jumper. Removed the castle nut and took off the stump jumper to examine the underside. What I found was the flat bar that welds to the center hub (where the castle nut holds everything on) had broken completle off on one side and the only thing holding one blade on was the stump jumper pan.

I would take the nut off and remove the whole pan assembly and check everything for cracks, loose bolts etc.
This is easily done if the bush hog is picked up using the FEL to stand on its side. It is sometimes a little hard to get that splined fit to come apart without some persuasion. Work it from both sides a bit after putting in some penetrating oil and it usually comes loose. I was beating and beating on that one and finally I just pulled straight out on it and it slide right off.

 

[bdmcgrane]

I went ahead and removed the stump jumper to see if anything stood out. Seems like the bolt washer had gotten mangled. The castle nut must not have been snug up against it. I will get replacements and see if it tightens it up.

Do you think i will need to get a file out and work on the splines?

 

[ENG18LT]

Those splines could definitely use some work since you have it off. Be glad you have splines to file. Mine were gone altogether.

 

[SPYDERLK]

I went ahead and removed the stump jumper to see if anything stood out. Seems like the bolt washer had gotten mangled. The castle nut must not have been snug up against it. I will get replacements and see if it tightens it up.

Do you think i will need to get a file out and work on the splines?

Those dings on the end of the splines make me think someone has been fooling with it already. Does the male spline have a taper? The one on a Howse BH does. If so, and the splines are there enuf to engage, probably replacing that washer and tightening the nut tight with a good impact wrench will assure that the joint stops moving and destroying the splines. Use a high strength washer. Regular low strength steel will crush and render looseness.
larry

 

[RickB]

Those dings on the end of the splines make me think someone has been fooling with it already. Does the male spline have a taper? The one on a Howse BH does. If so, and the splines are there enuf to engage, probably replacing that washer and tightening the nut tight with a good impact wrench will assure that the joint stops moving and destroying the splines. Use a high strength washer. Regular low strength steel will crush and render looseness.
larry

Almost looks like somebody has been in there with a welder. It is hard to tell from the photo, but a SQ60 is likely to NOT have a tapered spline. My SQ 72 has straight splines. With a little wear in the shaft/blade bar splines it is hard to get all the vibration out regardless of nut torque if there is no taper to work with.