6 foot Bush Hog rotary mower

   #1  

yanmars

Platinum Member
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Nov 29, 2009
Messages
702
I have a 3 pt 6 foot wide heavy duty Bush Hog brand rotary mower. It was a Township mower until they got a new one. This has happened 3 times in 6 years after about 50 hours of mowing each time. The nut holding the stump jumper and blade on comes loose and the stump jumper and blade then falls to the ground. After the second time I specifically asked them to torque the bolt to I think 180 foot pounds or factory spec whatever that was or lock tite it or spot weld the nut so it would not fail again. Well today the first time out for Spring mowing and the unit fell off in the first 50 feet of mowing. I recovered the lock washer and blade and stump jumper. The nut was not recovered and really unsure when it may have fallen off.
When I asked the shop again about this (the same one I bought it used from and that did all the work) they said this should not occur as the direction of the thread is such that it would tighten on rotation and not loosen.
The money I put in this on purchase and repairs etc. would have let me buy a light weight new unit but I had one of those once and it got beat to death so that is not an option. I cut mostly tall grasses but occasionally some trees up to nearly 3 inches in diameter. Many at 1.5 to 2.5. The tractor is 45 HP and is capable of the cuts as long as the trees are not too close together to bog it down. Then chain saw some.
Question- Why is this occurring? Hate to buy a new HD mower, quite expensive and a used one I may get another's troubles, maybe that is what I already have. I have used up 4 other mowers in the last 20 plus years just keeping my wood lanes , field edges etc. passable. Thanks
 
   #3  

frogracer

Bronze Member
Joined
Jan 15, 2018
Messages
67
Location
Sealy/Columbus, TX
Tractor
NH T4.120 - ArmstrongAg Grapple, Pallet Fork
Check if the mower is rotating I the correct direction - gears somehow in backwards - PTO spinning wrong direction somehow? If the bolt sticks out beyond the nut a bit maybe drill a hole through it and put a corresponding in.

Cutting threads or tack welding will make it very difficult to ever remove when needed.
 
   #4  

mcfarmall

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Oct 1, 2015
Messages
1,316
Location
Kalamazoo, MI
Tractor
Kubota M5660, Farmall C, JD 260 lawn tractor
The gearbox output shaft is tapered and probably is damaged/misshapen from the nut being loose. Time for a new gearbox and stump jumper.
 
   #5  

CoyPatton

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Aug 10, 2015
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1,415
Location
Poplar Bluff, MO
Tractor
Yanmar YM2002D with Koyker 110 FEL
When the shop tells you it should not be happening (and I tend to agree with their logic), it is my opinion that a decent shop is going to want to check into why it is happening.
It should be simple for them to verify that the gearbox output shaft is turning the correct direction and for you to verify the gearbox input shaft turns the same direct in their testing as your PTO spins. (These should be simple for you to perform as well as a test)
Once these are verified as being good or not, you know where to focus. Then you must decide if the cost of repair is the best investment or the purchase of a different implement.
If you go the route of the one suggestion of drilling a hole in the threads to use a cotter pin, consider using a castle nut type set up. You may have to make this.
 
   #6  

FTG-05

Elite Member
Joined
Jan 7, 2011
Messages
2,523
Location
TN
Tractor
Kubota L4330 GST w/FEL, Kubota RTV-XG850, Kubota ZD326S
The damage from my Bushhog 286 spindle and nut from years ago:

IMG_20190416_125826751 (Large).jpg


IMG_20190416_132931016_HDR (Large).jpg


So I was looking at:

Replacing the bushhog
Replacing the gearbox and stump jumper
Replacing the spindle and stump jumper
Welding the crap out of it.

$10 says you can figure out what I chose to do. :)

IMG_20190424_115159246 (Large).jpg


After welding it and running it a few times, I found myself constantly looking back over my shoulder seeing if it was still running. Compared to before, it was very quiet!

Did that repair April 2019, so it's had two seasons of cutting since then; no problems. If it breaks, I'm no worse off than I was then.

Good luck!
 
  
  • Thread Starter
#7  
OP
Y

yanmars

Platinum Member
Joined
Nov 29, 2009
Messages
702
The shop was able to chase the threads and put the blades and stump jumper back on. They attached it with a jam nut this time. The direction of travel is correct. Hope that helps this time.
 
 
 
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